What Causes Mold in Crawlspaces? VIDEO

Mark: Hi, it’s Mark from Top Local Lead Generation. We’re here with Mr. David Fairbairn of Fairbairn Inspections in Vancouver. We’re talking about mold. What an exciting Christmas topic David.

David: Just what you’re hoping for Mark, eh?

Mark: So mold in crawlspaces, let’s talk about it, where does it come from?

David: Absolutely, Mark. We’re going to see a lot of similar themes here that line up with a lot of the other mold talks we’ve done because the causes are still the same so I’d like to screen share here a little bit so you can look at what we’re talking about, so let me know if you can see the image that comes up here.

So here we’ve got a diagram courtesy of Price and Dunlop. Let me know when you see it.

Mark: Yes, it’s there.

David: O.K. great, so one of the things that you’ll see with every single mold related problem is that they’re all caused by generally the same thing. If you have moisture problems you’re going to have a mold problem and mold is a symptom of a moisture problem that is somewhere in your home. Crawlspaces are very, very sceptical to mold due to the fact that they’re extremely wet environments, they’re generally neglected a little bit; people don’t often go down into the crawlspace all the time the same way they do with checking their windows or even their attic. I would say the attic probably gets looked at a little bit more than the crawlspace depending upon how much storage is down there but here in this drawing we can actually see depending on the style of crawlspace you have it’s going to be extremely damp and you know, these are the areas where mold can really thrive. So we’re looking at two different floors. We’ve got one on the left, it’s a dirt floor and this is a very old style crawlspace. You probably are never going to see this in new construction or anything later than a certain date but if you go back far enough you do have these dirt floors and if they’re not ventilated properly you’ve got what’s called rising damp so that moisture is actually rising up from the dirt and it’s equivalent to here it’s says several gallons a day which I feel that that’s not wrong, so you can get this damage to the floor framing and the other thing about crawlspaces is there’s lots of wet wood down there for them to latch onto. Mold really likes organic surfaces and especially porous services so if you have something like wood or drywall it really latches on when you’ve got a lot of moisture and it set up shop pretty quickly.

So, on the right hand side you can see that they’re recommending you should have a vapour barrier down in the crawlspace. Now a vapour barrier is basically a poly sheet and you’ve probably seen them in a lot of crawlspaces and one of the biggest problems with these vapour barriers is that they’re usually not tight and here we can see it says seal at edges, that’s an important concept. We’re going to want to seal the vapour barrier down, this plastic sheet and weigh it down with gravel and that’s going to prevent what’s called rising damp. So, the main thing is just to show you how much moisture you can get in these spaces.

So, that’s number one, it’s called rising damp and it’s pretty easy to solve, you basically seal up the base of your crawlspace and that’ll hopefully mitigate that.

So, problem number two, we’ve got a photo here, this is a crawlspace in Langley and what has happened here is we’ve got a drain tile issue. Now drain tile is your perimeter drain, it runs around the outside of the house. It’s a big pipe and it carries water, ground water and rain water away from the house. It keeps it from ingressing into the basement, the foundation or crawlspace and what we have here is, it’s become blocked so this house was built in the 80’s and we’ve got this old type of pipe called Big O Tile which is a black corrugated plastic and it plugged up and actually this particular house, there was a root punching through the side of it from a tree, it had actually broken through the drain tile and it’s actually a leak, you can see a puddle inside the crawlspace. So here’s the source of moisture right here and again this is going to cause mold growth in the crawlspace. So that’s number two.

Number three, so this is that really nasty photo I was going to show you. This is one of the worst mold problems that I’ve come across not in terms of how broad it is and all over the place it is but it was very localized it was just in one spot but what we actually have here was a plumbing leak so we can see there’s kind of a grey pipe running across the top of the picture horizontally and that was going to an exterior hose bit and what happened, he didn’t winterize his hose bit. As the temperature drops you can have freezing at that hose bit and it will crack and burst and you’ve got a pinhole leak and this had been leaking for years and years and we can see that you’ve got a lot of mold, that white fluffy stuff is actually fungal growth, that’s sort of a really extreme version of some mold. O.K., that’s the third reason here, plumbing leaks.
Fourth reason is, we’ve got a photo of a crawlspace vent. This is something I see a lot of where someone has actually blocked off these crawlspace vents and when you block off crawlspace vents you are starving your crawlspace ventilation. You don’t have any fresh air coming in, so you’ve got this moist stagnant air in the crawlspace and the mold will quickly grow in that case so a lot of the time it’s very simple, just remove the cover off of these crawlspace vents and sometimes the home owner will put bat insulation behind it and if you can remove that and go back to the original design condition of the crawlspace, you can solve a lot of your mold problems.
Now the next question is what do I do about, what do I do if I have a mold problem. The thing with that is you want to call a mold remediation company to come in and remove the mold because some of this stuff is really nasty and you don’t want to be breathing it in and if it gets all over your wood, it’s all over your crawlspace, it can get quite expensive in the same way that we were talking about attic mold, you can be looking at thousands of dollars to remediate your crawlspace and in really extreme cases you can have structural damage. Going back to this photo you can see that the bottom plate of the wall frame is actually rotten away and this house now is sitting on a rotten piece of wood so what we’re going to need to do is actually jack it up and replace that plate underneath to get at that support so you don’t what to leave this too long because you can have structural damage.

I think the last thing I do want to point is if you think you have, you think you have crawlspace mold but you’re not sure is to get your crawlspace inspected and we can assist with that. We do crawlspace inspections on large scale, small scale, we can do one house or we can do an entire strata complex. If you have a crawlspace you’re not sure, kind of smells musty down there, an air quality test would be a great idea. If you can get some air sample of that crawlspace, send it to a lab and we can actually tell you what kind of mold is down there and how much there is.

Mark: Great, so we’ve been talking with Mr. David Fairbairn. He’s not only a home inspector in Vancouver; he’s also is a certified mold remediation specialist, so he’s the guy to call. Check out his website, fairbairninspections.com or give him a call at 604-395-2795. Thanks David.

David: Thanks Mark, take care.

About the Author DavidFairbairn

Author David Fairbairn is a certified, licensed home inspector serving Vancouver and the Lower Mainland. He has been featured in the media and has contributed to "24" Newspaper, and Global TV. He has spent years working with residential and commercial building projects, and holds a Power Engineering License in BC. Why not give him a call for your next Home Inspection? Call 604 395-2795 or email david@fairbairninspections.com today!

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