Basement Floor Slab - Horizontal Crack Repairs using Sika Crack Fix

The past three weeks we've been upgrading the basement foundation wall insulation - so I've had to move all the shelving and storage units away from the basement walls to get at the walls. Since all the heavy lifting was done to move everything away from the walls, I decided it was an excellent opportunity to give the concrete floors a coat of paint. Prior to painting, it was the perfect time to repair the horizontal cracks in the concrete slab - so I've been at this in parallel with the insulation job.

Final Crack Repair - Sika Crack Fix

Following some reasearch - I've settled on using Sika Crack Fix - a structural epoxy that is very fluid and can penetrate very narrow cracks, and is also commonly available at my local home improvement stores. It's not inexpensive, at about $20 a tube, but if I can get a permanent repair to these slab cracks I'll be satisfied.

Sika Crack Fix - Comes in a Cartridge designed for a standard small caulking gun, with two mixing tips. 

Cartridge installed in the caulking gun

The first step to a smooth repair is to open up the top of the cracks with an angle grinder and a concrete wheel. Create a groove at the top of the crack - 2 to 4 mm wide - and relatively straight - this will create a channel that will make the application of the epoxy much easier, and create a small well for the epoxy to pool before it penetrates the crack. This is the key to a neat, easy crack repair. When creating the groove with the grinder, use your shop vac with the hose end held right next to the grinder wheel, this will pick up 95% of the dust, and help keep your work area clean.

Groove the top of your cracks with an angle grinder prior to application of the epoxy

Once the cracks have been grooved, you can start applying the epoxy. Since I have no way of plugging the crack at the bottom of the slab - the epoxy is so thin it will run right down through the crack, and out the bottom of the slab. To minimize waste, I would apply one or two tubes of Sika Crack Fix to about 25 feet of prepared cracks - and allow the epoxy to penetrate the cracks. I would then wait 24 hours and repeat the process - to allow the crack to shrink in width over subsequent applications and minimize the leakage out the bottom of the crack.

Once the crack is filling up - you'll find that the epoxy will run horizontally as well - moving down any slope in the floor slab. This isn't a problem, it helps to distribute the epoxy fully through the crack, but you may find that some epoxy will pool out of the crack on the surface of the floor. The hardened epoxy is so hard that it is difficult to remove by scraping or sanding. After about 4 to 6 hours following the application of the epoxy - the epoxy will set up and start to harden - yet it will still be soft enough to scrape off any unwanted excess. This is an excellent time to level out any sections where the epoxy is convex - and extending above the surface of the surrounding floor. 

Completed crack repair - where the epoxy has been scraped flat before completely hardening. 

The Sika Crack Fix can also be used to fix broken surfaces - I have some small areas around a floor sump where the concrete surface has chipped away slighly exposing some aggregate. I've been using the Sika Crack Fix to smooth these areas prior to painting.

Wider surface repairs using Sika Crack Fix - This section is still slightly concave, and will require a subsequent application of Crack Fix to get it flat. 

I've used about 10 tubes of the Sika Crack Fix in about 40 feet of narrow cracks averaging about 1mm wide. That's a bit expensive at $20 a tube - but if it does a "permanent" long term repair - I'll be happy with that. It looks like the epoxy will have to be roughened prior to painting with sandpaper - if left to settle on its own it hardens very smooth - almost glass like, and I'll be looking for good adhesion with the floor paint. I'll post on the floor paint process later, as I get that task done.

Now - for a few other points now that I've almost finished all the crack repairs in the basement.

Sometimes, the part A and part B doesn't mix correctly, and won't harden in the crack. This may happen at the start of the tube, at the end of the tube, or if you interrupt application and restart with a new mixing tip. The instructions for the product suggest pouring out product in a waste container until all the air bubbles are gone - this ensures the product being applied has a proper mix of both components - and is very important. When you get to the end of the tube, and the mixing tube starts spouting bubbles - stop there and discard the tube. I've had a few instances where the product hasn't mixed correctly, and the epoxy stays sticky and doesn't harden. You can use a putty knife or rag to scrape off as much of this material as possible, and then finish cleanup with a solvent. The product guide recommends "Sika Equipment Cleaner" to clean up unmixed or uncured epoxy.  This product contains Xylene according to the MSDS, and so does the brake cleaner that I had in my garage, so I've cleaned some of this unmixed epoxy with a small amount of brake cleaner. (Try getting some "Sika Equipment Cleaner" on a Sunday morning....)

Unmixed epoxy cleaned up with Brake Cleaner, ready for re-application of mixed Crack Fix

Another issue that I ran into is that the Crack Fix is so watery when applied, it flows with any slight slope in the concrete slab. I have a few cracks that extend to a floor sump, with a slight grade. The crack fix kept on flowing along the crack, and leaving a trough in the crack, and puddling out of the crack at the bottom of the slope. The solution to this is to shoot some Crack Fix into a small plastic container, and let it set for 2 to 3 hours. Once the product starts setting up, and not flowing, apply it to the crack with a putty knife. It should stay in the crack without flowing down. Check and retrowel with the putty knife after 30 minutes.

Crack Fix setting up in a plastic cap, almost ready to apply.

Finally, in preparation for painting, I've found that a belt sander is really the best way to level out cracks. I had always managed to get by without a belt sander until now. I went out, purchased an inexpensive Skil 3 x 18 sander, and a few belts of 80 grit. This machine works great for levelling out the cracks and getting a nice flat surface equal with the concrete prior to painting. 

Skil 7510-01 3 x 18" belt sander, with vacuum attached. Perfect for levelling epoxy Crack Fix.

The sander accepts a 1 1/2" shop vac hose for dust collection, which also helps remove heat from the motor during operation. I highly recommend operating this tool with a vacuum attached. It's really efficient at levelling out cracks.

Epoxy filled cracks levelled with the belt sander, ready for painting. 

This has been a good job to get done - so far, I've used about a dozen tubes of Crack Fix. It's not inexpensive, but compared to bringing in a conctractor to replace your basement floor slab, this is an excellent way to prolong the life of your basement floor.

Getting near the end of the job. Perimeter of the floor - painting completed. Now filling all the cracks in the center of the floor, almost ready to complete the painting. 

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Upgrading Basement Insulation - Finishing the Job and Insulating the Garage Stairwell

If you've been following the past several posts - I've been upgrading the basement insulation in my 25 year old home, working on improving energy efficiency and indoor air quality. Following the installation of polyurethane spray foam in most of my basement walls with a spray foam contractor, I had half of a Touch-n-Foam 600 spray foam kit left to use up. We were in the process of re-closing all the basement walls - installing the drywall and getting the drywall joints taped and finished. I realised that I had not done anything with a stairwell in the back corner of my home - which runs from the heated utility space underneath my garage elevated slab floor and the garage. So I decided to attack that final section of the foundation wall - pull off all the drywall and use up the rest of the Touch-N-Foam kit.

Garage Stairwell - Drywall and 1.5" partial coverage of styrofoam removed

First step was to remove the drywall. The drywall had been installed before the stairs were installed - so the drywall was cut just above the framing of the stairwell. The drywall was removed to just below the level of the rim joist on top of the concrete foundation wall. There was a layer of foam sheet installed on the top of the foundation wall below the rim joist - no other sealing.

Rim joist. The styrofoam you can see here has been cast into the foundation wall - intended as a slot for pouring the elevated slab. Since the slab doesn't extend to this corner because of the opening for the stairwell, the builders left it in place. I decided to leave it in place as well, since it was cast in the foundation wall - and apply spray foam directly overtop. 

With the drywall removed, it was time to get started with the Touch-N-Foam kit. One of my lessons learned from the previous application was to get my hands on a 3M full face organic vapour cartridge respirator - which I did. I purchased the medium size - I have a pretty large head - and was able to get an effective face seal and performance.

3M Full Face respirator. 

On to the foam application. I started with foaming the corners, rim joist space, and the bottom wall cavities. 

Start applying foam on all corners, rim joist, bottom wall gaps. 

Once the perimeters were foamed - then I got onto the wall spaces. This time - I didn't have time to try to heat the concrete wall before the application of the Touch-N-Foam - I guess that my wall temperature was about 8 degrees Celcius (46 F) - below the recommended 16 C (70 F) minimum surface temperature recommended by Touch-N-Foam. What I found was that as the foam cured, it contracted slightly and pulled away from the wall studs. You can see the 1" wide gap in the photo below:

Note the gap next to the two studs - the foam contracted due to the low surface temperature of the concrete wall.

In my case this wasn't catastrophic - I justed gave the foam 30 minutes to cure, and then came back and foamed the gaps where they appeared, but it was interesting to see the effect of applying this product on a substrate that was below the manufacturers recommended application temperature.

Underneath the stairs - there was no insulation at all in this portion of the wall:

No insulation in this portion of the wall underneath the drywall.

So - this space was foamed as well.

In my other post about using the Touch-N-Foam kit - I wrote about what happens when you reach the end of the cylinder - and the resulting uncured foam and the requirement to physically remove it to prevent odours within the house. This time - I was much more vigilent when I was getting to the bottom of the cylinders - as soon as I noticed a change in the consistency of the applied foam - I immediately stopped applying the foam and checked the cylinders. A test shot into a garbage can confirmed that I had run out of the Part A chemical - and that it was time to stop applying foam. The photo below shows about 6 cubic inches of foam at the end of the application that did not have sufficient Part A in the mix. 

The end of the application of the Touch-N-Foam - some runny foam which only has Part B, and no Part A. 

This small amount of uncured foam was easy to remove with a putty knife, and I finished up the application with some single part foam from a spray can.

Re-applying the drywall over the foam installation. 

And, again, as desribed in the previous post - it is extremely important to cover all the spray foam with drywall to give you the fire resistance.

All in all - I am satisfied with the performance of the Touch-N-Foam kits - they are better suited for small to medium sized insulation jobs - such as a portion of a wall or a specific sealing job. Larger jobs - consider going with a spray foam contractor - which will be more cost effective and quicker. 

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Foundation Wall Vertical Crack Repair

I've been writing about my basement insulation upgrade project, which was driven by some air quality issues in my home - such as musty odours during humid periods in the summer. We made the decision to take down all the drywall from the perimeter walls in the basement, remove all the old insulation and vapour barrier, and replace the insulation and vapour barrier with 4" minimum sprayed polyurethane closed cell foam, from the top to the bottom of the walls, including the rim joist area at the top of the foundation wall.

Injecting crack with Sika Crack Fix structural epoxy

Once we got the drywall removed from the perimeter of the basement, we quickly noted three issues - two vertical cracks in our poured concrete foundation walls, and some water entering around a bundle of cables coming through the foundation wall about 2' below grade. We couldn't proceed with the foam installation until the vertical cracks were dealt with - water leaking in behind the foam may be able to force it's way through the foam and find its way into the structure of the wall, causing decay, damage and possibly mould.

Vertical foundation wall crack, running from bottom corner of basement window, to just above the footing

The cracks were quite narrow - about 1mm wide on average, and extended from the corners of two windows in the basement, vertically down towards the foundation footing at the base of the wall. The cracks narrowed in the last foot above the footing. It didn't appear that these cracks were actively leaking, however efflorescence around the cracks seemed to indicate that they had leaked in the past, and that the enormous air movement in the underinsulated walls permitted any water entry to mostly evaporate. There was no evidence of mould or structural damage. I would suggest here that if the cracks are significant, the water ingress is significant, and if there is any damage to the interior walls, etc - it might be a good idea to get the assistance of a professional foundation repair contractor. A foundation crack is significant, and needs to be repaired correctly. Consider professional help with this.

I've been using Sika Crack Fix - a two part structural epoxy - to repair some floor slab cracks in the basement, so I have some experience with its properties. This product ships in the format of a small caulking tube - and is applied using a standard caulking gun. About half of the tube contains usable product, and it uses special mixing tube tips which mix the two parts of epoxy as the product is expelled from the gun. The product is very fluid (non-viscous) - it flows very freely and can infiltrate narrow cracks. It is a structural epoxy, which means that it bonds to both sides of the crack in the concrete - repairing the original strength of the concrete. It is not flexible however, and once the concrete is bonded together with the epoxy, it should resist further movement.

Sika Crack Fix structural epoxy, note the mixing tips on the left that mix the 2 components on application

Sika Crack Fix installed in a standard caulking gun, ready for application

Larger cracks, or cracks that move - may require a different repair product. There are polyurethane foam products like SikaFix PU which are expanding - and that I have no experience with - another good reason to consider the assistance of a crack repair contractor - they should be able to guide you into the selection of the best product / solution for your problem. Finally - I believe that cracks in concrete block walls are a whole other problem entirely due to the voids in the blocks. Again - no experience here - and consider getting in a pro for this type of problem.

So - since the cracks were thin, didn't appear to be active, and should benefit from a structural repair - I decided to do a structural epoxy repair. I've used Sika products in the past, so I decided to use Sika products for this repair - but there are other manufacturers offering similar products that could be considered for this job. I don't have any experience with other products, so I can't make any comparisons.

The datasheet for Sika Crack Fix provides detailed instructions for performing both horizontal and vertical repairs. I followed the datasheet guidelines for the vertical crack repair, which required some other products to make the repair. In short - here are the steps:

• Clean out the crack with a vacuum or compressed air;
• Bond injection ports along the crack - spaced out every 6 inches or so
• Cover the crack using a waterstop repair cement
• Inject the crack fix epoxy into the injection ports - completely filling the crack from bottom to top
• Plug the injection ports to avoid losing the epoxy through the lower ports

My first attempt with the first crack was less than perfect - I was in a rush and tried to get the repair done in one evening, the injection ports had not bonded against the concrete, and the waterstop cement had not cured / hardened, and when I injected the epoxy - I ended up with a fair amount leaking out and running down the wall. My second repair went much better - so here's what I learned and how I did it. 

To help with getting the best bond with the injection ports to the wall - I started by using my small 5" orbital sander to clean the concrete wall surface, and take out the small surface irregularities / loose material. I then cleaned the crack and wall surface really well with the Shop-Vac.

Wall surface cleaned and ready for installation of injection ports

I used 5 minute epoxy to bond the injection ports to the wall - a quick set time for this epoxy greatly simplifies installation, and ensures a good bond to the wall. Note that the epoxy will not bond well to the injection port plastic material - so use a bit of extra epoxy at the end to overlap the edges of the injection port to assure a good bond to the wall. This epoxy cures in 8 hours - and I allowed the full cure time to ensure the ports were well installed on the wall - this will make the application of the waterstop repair cement much easier and reliable. Other adhesives can also be used, such as hot melt glue and silicone adhesive - hot melt glue may speed the job by setting up more quickly, and allowing you to move to the next step without delay.

Injection port installed with 5 minute epoxy. 

With the injection ports well bonded to the wall, it's time to apply the waterstop repair cement. Sika recommends Sikaset Plug. It's sold in many different formats at your local home improvement store, 1kg, 5kg and 25kg sizes. For the repair of 2 vertical cracks - about 6 feet long each, the 5kg bag was perfect. This product sets in 2 to 3 minutes - its working time is very very quick. This required some organization to get the best results out of the product, and make an effective repair. I went to the dollar store, picked up 2 sets of plastic measuring cups - so that I could make the mix consistently every time without fiddling with adding a bit more water or a bit more cement. The mix ratio is three parts cement to one part water - and you don't want to make too stiff a mix otherwise it will set even quicker - and give you only about a minute of working time. I was mixing about 1/2 a cup of cement at a time.

Sikaset Plug hydraulic repair mortar - note the dollar store measuring cup to make successive small mixes quickly and consistent.

In addition, I was working behind a 2x4 wall stud - it's important to give yourself enough space to trowel this material onto the wall - taking the time to move the stud out of the way will improve the quality of the finished job. Finally - I took a pointing trowel and bent the tip at 90 degrees - so I could work between the surrounding 2x4 studs, and work the material around the injection ports within the limited space. This was my most important trick for successful application.

Pointing trowel bent to 90 degrees - for working in the wall space between surrounding wall studs

It's important to follow the directions for the Sikaset Plug, begin by cleaning and wetting the wall surface, and keep the wall surface wet - it will improve the adhesion of the Sikaset Plug to the wall. I applied the cement about 1/2" thick, 4" on each side of the crack, with a bit of extra cement around the injection ports, just to ensure the injection ports are well supported by the cement for later when the epoxy will be injected.

Concrete wall surface wet, working the Sikaset plug up from bottom to top

Working Sikaset Plug around the injection ports

With the Sikaset Plug applied from top to bottom of the crack, I allowed the morter to fully cure for 8 hours prior to injection of the epoxy. If you don't give the mortar enough time to cure, the epoxy under pressure will force up the injection ports breaking the mortar, and the mortar will lift off the wall. When it's time to inject the epoxy, set up the cartridge by removing the cap and plug, inserting the adapter and mixing tube, screwing on the retaining ring, and putting the cartridge into the caulking gun. Slow, steady, even pressure and patience to give time for the epoxy to work it's way through the crack is required. I applied pressure for about 2 minutes for each injection port, and waited until epoxy started flowing out the next injection ports above and below before moving up to the next port. Once I injected all the ports, I started back at the bottom and gave each port a second application to ensure the crack was completely filled, and then capped all the injection ports.

Capped injection port

My wall is about 8 inches thick, and the cracks were about 6 feet long. Each crack, about 1mm wide, took about 3/4 of a tube of epoxy each. If your cracks are wider - consider using the expanding polyurethane foam product instead of the epoxy.

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Upgrading Basement Insulation - Completing the Job with a Spray Foam Contractor

I've written a few posts about my project to upgrade the insulation in my basement perimeter walls. The bottom two feet of the foundation walls had no insulation, just the top 6 feet of the 2x4 stud walls had 6" batts of fibreglass insulation and a foil backed paper vapour barrier.

I started the job thinking I could achieve enough coverage with the Touch-N-Foam System 600 kits - but found with experience that although the kits provide good quality foam, they are slow to apply in quantity, and multiple passes are required to get the three inches required for the foam to act as a vapour barrier.

Contractor Installed Demilec Heatlok Soya Medium Density Spray Polyurethane Closed Cell Foam Insulation

So - I called and made an appointment with an insulation contractor, one that had previously sprayed foam in my attic around a skylight. This contractor sprays Demilec Heatlok Soya - a medium density spray polyurethane closed cell foam that is manufactured in Canada, and the United States. 3" of this foam replaces the requirement for a vapour barrier. Some features of this product:

• Zero Ozone Depletion Substances (ZODS) as defined by the Montreal Protocol
• RSI 1.05 per 25mm (R6 per inch)
• ASTM E96 Water Vapour Permeance, 50 mm 37 ng/Pa.s.m2 (0.65 Perm)
• CCMC 07273 Air Barrier Material, 25-30 mm 0.00004 L/s/m2 @ 75 Pa
• Contains post consumer recycled plastic, and Soya oil. I'm not sure the content of recycled plastic in the foam, but according to the company they've diverted 300 million plastic bottles since 2004 - which is an interesting statistic. 

For full information on this product, look up it's technical datasheet on the internet.

The contractor visited, took measurements of the surface areas and thicknesses to be installed, and also checked out the Touch-N-Foam installation that I had installed a few days earlier. I happy that the contractor thought that the final result was good quality foam, good adhesion to the concrete foundation walls, and good consistency. He didn't see any issues with applying his foam overtop of the Touch-N-Foam to increase the foam thickness from an average of one inch, to four inches.

Prior to the arrival of the foam conractor, make sure that you are ready for the foam installation, by ensuring that all electrical, automation and home entertainment cabling was completed. In my case, I had some home theatre surround wiring to run before the foam was installed, and I also made sure all the electrical wiring was supported properly with ties, ensuring there would be nothing hanging in the gap between my floor slab and the foundation walls. 

Home theatre surround speaker cabling pulled prior to foam installation, coiled and protected in a plastic bag prior to the foam installation

Electrical wiring zip tied and suspended from inner wall studs, to clear the gap between the slab and wall for best possible foam application

When I was removing the drywall from the foundation walls, and removing the old fibreglas batt insulation from the walls, I found two thin vertical cracks in the foundation walls - both were located at corners of basement wall cutouts in the foundation wall. It's important to resolve and cracks or leaks prior to applying spray foam. Particularly cracks in concrete - it is important to have a structural repair done which maintains the strength, integrity and waterproofness of the wall. I'll describe how I dealt with these vertical cracks in a new post.

Thin vertical crack behind one of the wall studs. Note the efflorescence (white powdery substance) on the wall next to the crack.

In a few days, the contractor arrived to install the foam, and started by masking off all the electrical outlets, and cover all exposed carpet, furniture, painted wall surfaces, etc. from overspray using painters plastic sheet. This is very important - this material is extremely sticky and difficult to cleanly remove from finished surfaces. 

The contractor uses special equipment installed in a cube van or truck - the raw materials are pumped at high pressure via a 300 foot long heated hose into the home, mixed in the heated application gun, and expand and cure in seconds once the mixed foam hits the application surface. Since this foam is essentially manufactured in the home - it is very important to use an experienced, licensed contractor that will take responsibility for the installation, and responsibility for any application issues. 

There are things that can go wrong with a foam installation, this could include things like overheating following installation, potentially causing undesired chemical byproducts and odours, and even possibly fire. It's important that the installation contractor follow the foam manufacturer's guidelines for single and multipass application thicknesses - foam applied too thick can cause potentially serious consequences. Discuss this with your contractor and ensure that you are satisfied with the responses you receive. Since you shouldn't be in the vicinity of the applicator while it is being installed, without wearing an organic carbon respirator, you won't be able to monitor the installation yourself. You'll have to rely on the experience and reputation of your contractor. Protect yourself by asking questions, checking references, and working from a written quotation and contract. Verify your contractor's license number, and if possible, do a search on the license number to ensure the license is valid, and there isn't a history of complaints or issues with the contractor. In the worst case, the consequence of a bad spray foam insulation job is the complete removal of all the foam - which can be difficult and time consuming. Some verification and research here could save massive headaches later. We selected a contractor called Isolam from Varennes, QC, and were perfectly satisfied with their experience, application and performance. 

Contractor installing spray foam - note the full coverage suit, and the respirator supplied with fresh air from the truck

The spray foam expands and cures rapidly, but it will off-gas for several days creating a faint chemical odour in your home. You may wish to let it aerate for a few days if you can afford staying elsewhere. It's now been a week since the application of foam, and the chemical odour is now barely noticeable, We're currently in the process of topping up the insulation in the wall spaces with our leftover fibreglas batt insulation, and installing new drywall. The installation of drywall should help to reduce the residual odours in the home, and continuous ventilation until all traces of the chemical odour may be a good idea. It's also important to note that the spray foam needs to be covered with at least 3/8" thick drywall as a fire barrier in order for the insulation to meet the Canada national building code - your contractor should mention this fact when the job is quoted, and you'll likely have that specific point noted on your invoice.

Spray foam is excellent for sealing air leaks in and around the rim joists around the circumference of the home at the edges of the floors. It's worth opening the drywall or ceiling to access these spaces. 

So - in summary - I believe that a proper, well applied, closed cell spray foam insulation is one of the best ways of insulating a basement located in the snow belt, and here are the most important points that I've found with this project:

• Get all your wiring, central vac, ventilation, and all other in wall services completed before the spray foam contractor arrives;
• Use a licensed contractor, with an experienced applicator, that warrants their work and will follow the foam manufacturer's application guidelines, particularly with respect to application thickness; 
• Correct all wall cracks or water leaks prior to the installation of the foam;
• Vacate the house during the application, ventilate the house very well following the installation of the foam, and you may wish to leave the house for a few days while the foam cures and off-gasses.
• Ensure the fire break is installed over the foam following the foam installation, per the manufacturer's recommendation and any building code requirements - such as a cover of drywall. 

I'm thinking about having my blower door test redone, to check to see if this foam installation has greatly reduced my air leakage rate. I'll get all the drywall and crack repairs completed first, then report the results when I get the blower door test completed. Stay tuned for further posts on the crack repairs, and the continuation of the indoor air quality project. 

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Upgrading Basement Insulation - Touch-N-Foam System 600 Polyurethane Spray Foam Kits

Our original plan for sealing the gap between the slab and the wall was to apply spray foam to the bottom 2 feet of the walls - only where there wasn't any existing fibreglass batt insulation, in the finished part of the basement, and the complete walls in the utility room. Based on the perimeter of the basement, and the yield of the Touch-N-Foam System 600 kit - up to 600 board feet (600 feet long, one foot wide, one inch thick) I figured with two the of the System 600 kits I would be able to get a 2 inch thick minimum coverage.

One inch thick application of Touch-N-Foam System 600

The instructions for the kit, the videos that demonstrate the kit, and the packaging all reinforce the importance of three temperatures for optimum yield - the temperature of the cylinders (minimum 21C, 70F), the temperature of the air (minimum 16C, 60F), and the temperature of the suface the foam is to be applied on (minimum 16C, 60F). When spraying basement concrete walls in late winter - achieving the minimum temperature of the concrete was a challenge. I installed a 2000W convectair in the utility room to supplement the central forced air furnace. My furnace has a zoning system, so I closed the zones for the main floor and upper floor of the house, and forced recirculation only in the basement. I disabled the heat pump to force the electric backup heat in the furnace to run, and I had this run for 2 days straight to try to heat up the concrete walls. I just managed to get the concrete to 16C in most places, some places a bit higher, some places a bit lower.

A note of caution before getting into the details - these kits are recommended for professionals - and improperly mixed or applied foam can cause poor results - in the worst case - you may be removing and cleaning up improperly applied foam. I'm not recommending that you follow this example - I'm just trying to demonstrate my experience. Unless your completely confident in your abilities - take a second thought and strongly consider hiring a professional, licensed contractor.

I made sure to take care of all the preliminary preparations ahead of the day that I was going to apply the foam. All the void spaces were vacuumed out with a shop vac - removing all the cobwebs and loose construction debris to optimize the bonding of the foam to the concrete. Electrical cables that were unsupported in the void behind the stud wall were fixed to the studs so they would not fall into the gap at the bottom of the wall between the slab. I also bundled the wires as much as possible, to have fewer interferences to deal with when spraying foam. All the electrical outlets were protected with plastic bags and tape.

Protect your outlets.

Protect anything in front of your walls - these are electrical cables and irrigation lines that run into the back yard

Buy a couple of rolls of painters plastic - it will come in very handy to protect from overspray

The foam is shipped in two cylinders, a part A and part B, and the chemicals mix in the replaceable nozzle of the gun. If you pause for more than 30 seconds, the chemicals start to set in the nozzle, and you have to replace the nozzle. Since I had to work around the perimeter of my basement, I decided to make a simple dolly on four casters to support the cylinders, so I could move the cylinders quickly and easily.

Four Casters Installed on top of an Ikea Ivar Shelf Make an ideal foam kit dolly

These castors are inexpensive, can be picked up at any home improvement store

Once the drywall was off all the walls in the utility room, I got an early start on a weekday once everyone was out of the house. The application guide recommends adequate ventilation, so I opened a door passage to the garage, and opened the garage door to allow some air circulation when spraying.

I went with the recommended personal protective equipment (PPE) - a painters tyvek suit, the safety glasses supplied in the kit, and a half mask organic cartridge painting respirator by 3M.

3M Half Mask Organic Cartridge Respirator

I watched the instruction videos a few times to familiarize myself with the operation of the kits and the application of the foam, and followed the instructions carefully. I won't repeat the instructions here - the videos are excellent and easy to follow.

Everything laid out and ready to start - Foam Kit with hoses and gun attached, scrap cardboard for testing, garbage can with bag for priming gun and testing foam.

Everything went pretty well as shown in the video - once the gun was primed and shooting well mixed foam - I started by foaming the gap in the slab, and the contours of the wall openings. I was careful to apply the foam no thicker than recommended - 1" at a pass - to try to optimize the yield of the foam. This meant that I would have to go back and do a second pass.

Foam Application - Perimeter Pass

The kit did not come with any fan nozzles, only the spot nozzles which spray about a 4" wide bead of foam. It took me about an hour and 30 minutes to completely empty a kit - it takes a fair bit of time to do wall coverage with only a 4" wide pass in thin layers.

Completed wall after the second pass.

When the first kit was running low on foam - I noticed air bubbles coming up the line a bit more frequently, and the pressure dropped in the spray. I didn't notice right away that I had completely exhausted the A cylinder. I ended up with about 6 square feed of foam that hadn't mixed properly and wasn't setting, so I had to scrape it out with a paint scraper and then start the second kit to re-apply fresh foam.

Once all was completed, and had cured for a day - I went back and measured my application. I had averaged about 3/4" thick application over about 600 square feet of wall surface, plus about 75 feet long of sealing the gap between the slab and the wall. I figure I got fairly close to the advertised yield of the kit - but in order to achieve 3 inches of cured foam in order for the foam to act as a vapour barrier - I figured I was going to have to purchase another 4 or 5 kits. I was now in the cost territory of having a foam contractor come in, and, I had spend a total of about 6 hours in preparation, application and cleanup in order to do about half of my surface area to about 1/3 the required foam thickness. So - the decision was easy - I was going to get a contractor in to complete the job. I had already hired an insulation contractor during the original renovation to apply spray foam to a window well in my attic, and to blow cellulose into my attic. I called him and set up an appointment for the end of the following week. 

Another issue was that at the end of applying one and a half kits - my eyes were getting irritated. I was limited with how much ventilation I could allow without dropping the air temperature due to the cold weather. I ended up purchasing a full face organic cartridge respirator in order to finish off the second half kit remaining - just to avoid further eye irritation. If you're going to apply one of these large kits indoors - I would highly recommend the full face respirator. 

3M Full Face Organic Vapour Respirator

In the end - I got a good quality foam that adhered well to the concrete - but I underestimated how labour intensive it was going to be for a large job. I think these kits are ideally suited for smaller jobs - where you need to apply a single kit - such as doing all your rim joists in your basement, for example. Larger jobs - where you're applying to entire wall surfaces - you're probably better off with hiring a professional contractor.

If you are going to apply one of these kits yourself, my biggest recommendation would be to follow the manufacturers application instructions to the letter - application temperatures, work procedures, and so on - to maximize the chance you get a quality result. 

And - don't try to get every last bit of chemical out of the tanks - as soon as you notice a change in the foam output quality - stop, change the foam nozzle so you have a clean applicator, and check the foam by doing another test on scrap material. Any foam that isn't properly mixed will not cure and you'll be scraping it out - not an easy job considering how viscous and sticky the product is. 

An example of improperly mixed foam - the A cylinder had run out, and I had continued applying foam. This foam didn't expand and cure, and stayed wet and sticky, and had to be scraped out, cleaned, and foam reapplied overtop. 

In my next post, I discuss completing the basement job with a contractor, and what we found behind some of the finished basement walls that caused some difficulty - some vertical foundation wall cracks. 

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Indoor Air Quality Project Part 2 - Upgrading Basement Insulation

One of the indoor air quality complaints that we have is now that we've improved the envelope of the house, installed mechanical ventilation (ERV - energy recovery ventilator), and have improved the insulation around all the doors, windows, and attic, we have conditions in the summertime where there is a musty odour when entering the house. I knew we had excessive humidity in the house in the summertime with the air conditioning running - from tracking humidity using a simple digital hygrometer - getting levels up to 60% relative humidity.

Completed Polyurethane Foam Installation in the Basement

Research into this problem led to some findings, some of which have already been corrected:

• A blocked air conditioner condensate drain - which prevents water removed from the air from the air conditioning from escaping, and eventually gets re-evaporated and redistributed into the household air. The fix was resloping the condensate drain line and adding unions to be able to remove and clean the trap;
• The furnace fan running continuously following an air conditioning cycle - not allowing enough time for condensate collected on the air conditioning evaporator to drip off and drain out the condensate drain. The furnace fan would not shut off because of the interlock with the Venmar ERV. The solution was removing the independant Venmar control panel and furnace interlock, and installing a thermostat that can intelligently control ventilation, humidification and dehumidification - my selection was the Honeywell Prestige 2.0 IAQ thermostat. 

The third and final issue was in the way our basement walls were constructed 25 years ago - typical for the time - all the perimeter walls of the house were framed with standard 2x4 stud walls, with an air gap between the poured concrete foundation wall and the stud wall. The stud walls were then insulated with fibreglass batts from the top down to 2 feet from the slab, with no insulation at all in the bottom 2 feet of the wall. Instead of a poly vapour barrier, a foil backed paper was installed, but only where there was fibreglass batt insulation. So - there was nothing to prevent humid air from inside the house permeating the drywall or finding its way to the cold concrete foundations through air leakage through the tops of the stud walls which were not sealed, the bottom, or the many apertures for plumbing access, outlets, etc. When I opened up a 2' x 2' section of the basement wall - I found the lack of insulation, and evidence of seasonal moisture accumulation - cobwebs and spiders, efflorescence on the concrete, water stains on the electrical wiring, and a humid, musty odour. 

Inspection Hole in Basement Wall - White dust is from cutting the hole in the drywall. Note the cobwebs, Efflorescence on the Concrete Wall, Construction Debris, and Gap between the Wall and the Slab

Another issue revealed with the inspection hole was that our basement concrete slab was poured with a formed gap of 1 1/2" between the concrete wall. I believe this is referred to as a "floating slab" installation - which is done in cases where there is a concern that the slab may either raise or settle. If the slab is poured directly against the wall - the perimeter of the slab can't rise or fall, and if the slab moves, it may cause cracks. The issue, however, is that this gap was never filled prior to the construction of the perimeter insulated inner wall. Once the gap was cleaned under the inspection port, wet sand was evident in the gap. The construction debris left in this gap seemed to trap the humidity in this area, and this seemed to be the source of our musty odour getting into the rest of the basement, and distributed in the whole house by the central HVAC system.

Top of photo - poured concrete wall. Bottom of photo - base plate for inner wall - pressure treated 2x4. Just above the 2x4 is the poured concrete slab, and the 1 1/2" gap with gravel and damp sand at the bottom. 

Photos of construction debris taken from the space behind the perimeter wall, sitting in the gap between the slab and wall. Note the water stains on the scrap of drywall at the top. Definitely an accumulation of moisture here.

So - we've found our source of moisture, the cause for the moisture, and the probably source of our musty odour. Before getting into the repairs from the inside of the house - it was almost wintertime at this point, and we wanted to rule out poor foundation drainage as a cause of the moisture at the interface between the slab and the footing. So - we called in a drain company to excavate and inspect the foundation footing perimeter french drain. I'll write about that inspection in another post, but the result was that our french drains were clean, dry, and working well. So it was on to the planning for the repair of the basement wall insulation problem, and the gap in the slab.

I researched the best ways to seal the gap in the slab and the wall. Some believe that this gap can serve as a drain - a way for condensation that forms on the cold walls of the basement to trickle down and escape without collecting on the slab and damaging the walls or finishing of the basement. Well - in our case - we don't want the condensation in the first place - we want a clean, dry basement that is properly air conditioned with good air quality. Multiple sources, including the Canada National Research Council (NRC) publications on building construction, advise to repair all sources of water entry into the basement prior to interior finishing or insulation. In my case - I didn't think that I had any cracks or leaks, and I had my foundation drains inspected and found them to be working. So - on to how to seal this crack between the wall and the slab. There are different products available to seal a gap in concrete - there are caulks designed for expansion / construction joints, there are epoxies designed for structural repairs, and there is expanding polyurethane foams designed for waterproofing and non-structural repairs. I sought out the advice of contractors and a civil engineer, and in the end decided that since this gap is not structural, and that the slab may continue to move slightly, a product that had some flexibility and was highly adhesive and would bond to the concrete would be the best fit. Closed cell polyurethane expanding foam was my choice. By the way - if you ever get into this type of situation - I advise you to not only do your own research, but to also consult professionals with appropriate experience. Your building envelope is critically important for the integrity of your dwelling - improper decisions can lead to further problems - moisture, rot, mould, etc. Seek professional assistance. 

Now - as a minimum, I was going to have to open up the bottom of all my basement walls and seal the gap between the slab and the wall with closed cell polyurethane spray foam. I also needed to insulate the bottom 2 feet of the walls where there was no insulation - so an obvious choice was to continue with the closed cell polyurethan spray foam. At this point, it was obvious the best solution was to open up all the basement perimeter walls - and insulate with the same foam. The basement is about 50% finished living space, and 50% storage / mechanical space - extending under the structural slab which is the garage floor. Total basement permimeter wall surface area - approximately 1400 square feet. At this point it's worth mentioning that when you consult the building construction literature - such as NRC "Keeping the Heat In" basement insulation chapter, or Bulding Science Corporation basement insulation - there are many different ways of constructing a basement wall insulation system - which includes insulating the exterior of the foundation wall, and various ways of insulating the inside of the foundation wall - 2x4 walls with mineral wool / fibreglass batt insulation, rigid polystyrene foam insulation, spray polyurethane foam insulation, etc. Again - I recommend highly that if your considering a repair or retrofit, that you consult reputable sources of information, and that you pick an appropriate system with professional advise as required, and implement the complete system carefully. If you or your contractor cut corners here - you may be exposing yourself to potentially significant problems in the future - water problems, condensation, wood rot, mould, etc. Take your time, think it through, get professional assistance. I really don't think this is a place to be cutting corners. 

I pulled together three different contractor / self perform scenarios, consisting of two contractor quotations and a self-perform option where I would hire some demolition and construction labour to help out with me assisting. I finally decided on the third option - and got started on the project about 2 weeks ago. 

We started by removing all the drywall and starting in the storage room, mechanical room under the garage slab. About half the drywall was fairly easy to remove - it wasn't even taped yet. The remainder was taped, and some of it could be saved, some of it couldn't. In a full day - we had exposed the concrete basement walls of about half the perimeter of the house. 

Perimeter wall with gyproc and fibreglass batts removed. 2' of rigid polyurethane foam at the top of the wall, gap between the interior wall and the foundation wall.

At this point - I decided I would try using the Touch-n-Foam closed cell kits to do the 3" minimum foam - so that I could proceed with the project sequentially and move into the living space later. I went out to my local home improvement store, and purchased two of the 600 board feet kits - each kit consists of 2 cylinders (A and B which mix together in the gun) of 45 pounds for each cylinder. So - 2 kits - 180 pounds of foam in the 4 cylinders.

• Part 1 - Touch-N-Foam System 600 Polyurethane Spray Foam Kits
• Part 2 - Completing the Job with a Spray Foam Contractor
• Part 3 - Foundation Wall Vertical Crack Repair
• Part 4 - Finishing the Job and Insulating the Garage Stairwell
• Part 5 - Basement Floor Slab - Horizontal Crack Repairs using Sika Crack Fix

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