Mold in your Basement?

360renos was called in to review a finished basement which had a sub-floor that was sagging and warped due to a basement concrete slab that had heaved in some places and sunk on other places over time.


Well, the heaving was so bad that the 3 teleposts which support the main center beam of the home had either sunk into the earth or heaved up on their pads. It was a very dangerous situation as if this had not been rectified it would have eventually brought down the house.


The concrete slab needed to be demolished, so the sub-floor and interior walls were removed by 360renos. When this was completed we found a huge mold problem in one corner of the basement. This is an older home in Ottawa with cinder block foundation walls. The foundation and environmental experts have been called in!

So first to get this cleaned up with the experts before the next stage of pouring a new basement slab and re-building of the finished basement.


All of this reminded me of a great new article and tips by Bryan Baeumler and his series 'Room for Improvement'

Q: We have a major disaster in our basement due to a mold issue and now we are in a race to fix it. What is the best way to insulate the concrete block walls in the basement? Also, what are the best material to use for a basement subfloor? The current floor has foam insulation and plywood which seems to have worked extremely well but was 20 years old. Of course you could always drop by to take a look …. Cheryl and Mike

A: Hi Cheryl and Mike!

Sorry to hear about the mold in the basement – you’re definitely not alone! A lot of people have similar issues with finished basements that haven’t been waterproofed properly, have had a flood, or have high humidity levels in their homes. The silver lining in the cloud is that you now have the chance to finish the basement properly to avoid experiencing the same problem in the future.

It sounds like you’ve done the demo, which means you have a blank slate to work with. The first thing you ‘ll want to do is make sure you’ve taken care of the moisture problem. If it was a foundation leak, that means waterproofing the foundation wall properly, making sure your weeping tile system is operating effectively, ensuring proper grading of soil around your home, and directing water away from the house with downspouts. If you had a plumbing leak, obviously you’ll want to make sure the problem has been identified and corrected. And finally, if the mold was due to high humidity in the house, you’ll want to make sure you consult with an HVAC specialist to balance the system and install a dehumidifier to assist in lowering the humidity.

When it comes to insulating the foundation walls, you have a number of options. The best method by far is a closed cell spray foam – we use Walltite Eco, which you can ask about and have installed at your local Lowes. The reason spray foam works so well is that it has a high R value / inch, and eliminates any airflow – the biggest cause of heat loss. It can be sprayed right onto the foundation wall (block or concrete), and creates a monolithic insulation layer that won’t feed mold or lose R value due to moisture. You can also use the batt over spray method, which means spraying an inch of foam on the foundation wall, and adding either fiberglass or Roxul batts between the studs to increase R value, while still having the benefits of the air barrier from the foam. Roxul mineral wool insulation is another great product to use in a basement, as it’s fire proof and is a natural repellant to insects and rodents. If you plan on using batts, you’ll also need to vapour barrier the entire wall, tape the seams, and seal the top and bottom with an acoustic sealant. You’ll also want to be sure that you fully insulate and seal the joist bays (the area where your floor joists rest on the foundation) as the rim joist is one of the biggest culprits of heat loss. Not insulating and sealing the joist bays is a big reason people end up with cold floors above the basement, as cold air gets trapped in between the drywall ceiling and the floor above. If you go the spray foam route, joist bays and walls are all sprayed at once. We foamed our entire home, and we currently spend less than $50 / month heating it. We also filled all of the interior walls with Roxul to absorb sound and eliminate any wall cavities where fire could potentially spread.

When it comes to laying a subfloor, head for the Dricore – it has tongue and groove on all 4 sides to keep everything in place, it creates a thermal break from the floor that warms up the room, and also leaves an air space under the subfloor which allows for airflow so any moisture coming through the basement slab can evaporate. It also saves your finished flooring should you have a small amount of water under the floor, where it can flow to the drain. It’s also so easy and fast to install that it ends up being cheaper than other methods when you consider the cost of labour, or sanity. Foam laid directly on the subfloor will also keep your feet warm, but like a sheet of plastic it will eventually trap moisture – the idea is to give any water coming out of your slab somewhere to go and evaporate, something an impermeable layer laid directly on the concrete won’t do.

Of course there are lots of different products and methods to install a subfloor and insulate a basement (of which all done properly will perform well), so you have to make a decision based on your budget and skill level when it comes time to do the job. Most people would agree that the best method is never the cheapest, and the cheapest method is never the best. But when you look at the big picture, the best method is indeed often the cheapest in the long run.

Good luck, and have fun! (I’ll be over as soon as I can!)

Cheers,

Bryan

Fantastic info that can help a lot of home owners

360renos 
Dave Bennett
Owner
phone 613.429.5000 
mobile 613.282.2124
email dbennett@360renos.ca
www.360renos.ca

"Everything you can imagine is real" - Pablo Picasso