Attic Mold

Why It’s Critical to Know What It Looks Like, How to Test for It and How to Get Rid of It!

Mark: Hi, it’s Mark from Top Local Lead Generation. We’re here with Mr. David Fairbairn talking about attic mold, attic mold, mold in your attic, I’ve got lots of that, you can see here. The details about what’s critical about it, why you need to know whether you’ve got it or not, how to test for it, how to get rid of it. How are you doing today David?

David: I’m doing good Mark; hope you’re ready to see some pictures of moldy attics.

Mark: Love it.

David: Yeah, so attic mold, this is a huge, huge question I get as a home inspector about, first of all is there mold in my attic, you know, that’s probably the number one question when we do a home inspection and we go up to the attic and the two questions I get are is there mice in the attic and is there mold in the attic. Those are the two scary sort of unknowns when you go up to an attic and if you think about an attic and you look at the sort of design of it they’re very, very prone to moisture and humidity problems because they are basically a sealed wood box sitting on top of your house so if you don’t have proper ventilation and a waterproof roof membrane above you that’s keeping the water out and you aren’t adding unnecessary moisture into the attic, then you’ll have a dry attic. If you’re ventilating it properly, you’re not adding moisture and your roof doesn’t leak you will generally have a dry attic. But if you miss any of those points generally you’ll get mold growth or some sort of growth up there that has to be dealt with so, what I like to do is show you some visuals. I’m just going to do a screen share so let me know when that pops up for you, if you don’t see it let me know, you should see it come up pretty quick.

Mark: You got it.

David: Alright, so what I wanted to do was give you a case study of the house that we inspected; this property in Vancouver and they had a considerable problem with moisture and condensation in the attic. Now this is a concrete tile roof which is very popular in East Vancouver and they generally breathe pretty well but you have to be careful with them because in this case you’ll see why. So we’re looking at the soffits here, this is the underside of the eave’s and it doesn’t come out really that clearly in the picture here but what we have is there is a lot of staining around the actual soffit vents and these soffits are perforated so the air will rise up and travel through the attic and carry all the moisture out but in this case there was a lot of staining and rust around the soffits so that’s, when we are doing a home inspection and we come up to this property for a mold inspection, that’s the first thing we look at, what’s the condition of our soffits and generally you can tell if you have an issue right off the bat before you even go into the attic; if you see this, this is a big red flag.

So, I labelled it heavy growth; this is the inside of the attic, it was quite bad, it was a cold day and there was literally water dripping off the ceiling and we’ve got what looks like some black mold growth growing in the attic here. And this is your sheathing, a sort of metal sheathing paper that they use on concrete tile roofs and just as an aside, I just wanted to point out, here a lot of people say you have mildew growth in your house, I don’t know if you’ve ever heard that Mark, somebody said you know, there’s mildew in the bathroom shower, that’s actually the wrong term for it because mildew in nature will only grow on plants, they will not grow on any other surfaces, so mildew is pretty much a plant specific mold and it will not grow in homes unless you have plants. So it’s not mildew, what we’re actually looking at is mold growth, we’ve got some different colours, we’ve got some white, we’ve got some black. We took a sample and sent it to the lab and it came back as a combination of a few different types of mold, all of which were needing to be remediated.

So there was a lot of damage to this attic and here is another photo of the insulation below and we can see the condensation in this attic was so bad that is was dripping on the insulation and those little pock marks on the insulation are from the water dripping off the top of the attic onto the insulation so the insulation in this case was damaged. So if you do see that, even if it’s dry when you go up in the middle of summer and you see insulation that looks like this, this is another big red flag that you may have a serious moisture problem in your attic. Not necessarily a leak, it can look like a leak when you first go up but if you’ve got water dripping in a uniform pattern like that as opposed to one area it’s generally going to be a condensation problem.

Alright, so I want to go into the causes of attic mold because there are only a handful of them and ninety
percent of the time they’ll fall into one of the few categories. So here we are, we’re looking at some bathroom vents . . .

Mark: That’s brilliant, oh my God.

David: My favourite part about this is how he decided to use an exterior hood, like I don’t know what the benefit of that is, it’s generally to keep the rain out, but he decided to terminate and on the left you’ve got another one coming up and it goes right there and stops right there and it’s got a little hood on it too, you can’t see it in the picture. So we’ve got two bathroom fans, now we’ve got a family that’s taking showers every morning, sometimes twice a day if they’re doing sports and you can have one fifteen minute shower can generate an incredible amount of steam, I think it’s somewhere around .83 of a kilogram of vapour for a fifteen minute shower which is actually quite a lot, right, if you think about that, how many pounds is that, it’s just under, it’s about 1 ¾ pounds right, of vapour and you’re adding that straight into the attic and that’s a terrible, terrible design. So the big thing here is that probably most, the majority of attic mold is caused by improper bathroom fan termination so that’s the first thing we’ve got to look for, are you adding extra unnecessary moisture into the attic and this is a huge one. We always report this if we see it and it’s usually caused some damage by the time we find it.

So our next issue is this is something we come across especially in older homes where the owner has added additional insulation into the attic. What happens is they put insulation in and make it thicker and what they do is, they actually block off the soffits, o.k., so the soffits like I showed you in the first picture, you’ve got a vent at the bottom of that eave and the air is going to rise up through the soffit pass through the attic and out through the roof vents and in this case you can see that the soffits are actually blocked on the left two rafter base and on the right hand one you can see they’ve added what’s called the soffit baffle so if you’re adding insulation to your attic you need to put a soffit baffle in. It’s a Styrofoam tray that slides in between the rafters and it allow air to pass above because otherwise you’re going to choke your attic and you’re going to create a huge amount of moisture in your attic so this is probably number two on our list of what causes mold in attics is people getting a little bit too excited with the insulation. The other thing you’re going to want to do is if you’re changing your roof out to a different type, have a guy check out how much ventilation you actually have. If you’ve got one roof vent and you’ve got a huge roof area you might want to add two or three more and there are calculations on this based on the square footage of the attic, so you have to check that.

So the answer to what can we do about mold; this is an example of a treated attic, so when you see white like this you know one of two things have happened; they’ve either had a fire and they have painted the smoke damaged wood and I’ve come across that many times where there has been a fire and the homeowner is usually pretty up front with it or you’ve got a mold problem in the attic that’s been remediated. In this case it’s been remediated and it also sprayed a layer of product onto it that prevents regrowth of the mold.

Mark: That’s like a silver based paint?

David: Yeah, there’s a couple different products, I’m not entirely sure which one this one is but I can get you a list of the different products they offer, it’s basically a layer you can spray onto the attic that prevents mold from ever happening again, taking root again and it’s particularly important in attics where you have OSB sheathing so the OSB is, you’re probably familiar with the different types of sheathing you can have in the attic, that’s those boards between the rafters. In this case I believe it was actually plywood, in a lot of attics you’ll have OSB or even Strand Board which is very, very susceptible to mold growth and that’s why I don’t recommend it for roof replacement. If you’re ever doing a roof replacement don’t put in OSB sheathing, put in good quality plywood that’s going to resist mold growth and your attic will last longer. So this has been fully remediated by a mold abatement company and per attic, if you have an attic that you have mold in you’re probably wondering about cost. It generally, I mean the minimum you’re ever going to get this done for is probably, if it’s just a small area, you’re looking at a thousand dollars, if you go in a large area, I’ve seen it go as high as four thousand for a complete remediation and there’s a number of different ways that they can remediate it, they can do a chemical scrub on the wood, the one that I like that’s sort of getting a lot of traction now is called dry ice blasting, it’s almost like a sand blaster and you blast dry ice along the material, it actually removes a layer of the wood but it’s very, very effective if you want to go scorched earth on your attic and there’s no chance of anything, that’s actually really a good method by which you can do it.

I think we’re actually back around to the start. Switch off the slide show there. Just to recap, ventilation is everything when it comes to attics especially in a wet climate like ours as well as making sure that you’re not adding any moisture to the attic so, bathroom fans, check your bathroom fans, check your dryer exhaust and check your kitchen range hood. All three of those I’ve seen in a lot of attics where they actually dump into the attic and you can create some really nasty problems in your attic. If you have a healthy attic it will make your roof last longer, be healthier for your family and it increases your resale value because when you go to sell there’s no surprises. So if you think you have mold call somebody out to have a look at it.

Mark: So does it get worse in the winter in terms of condensation?

David: Absolutely, yes, especially in buildings that has poor insulation to begin with. One thing I don’t think I touched upon is even your attic hatch where you enter and leave the attic, a lot of time those doors aren’t sealed with weather stripping and they aren’t insulated with some insulation on top of it and you can get a lot of heat up there and the heat will just settle, right on the sheathing, right on the nails and that can cause huge condensation, yeah, so that’s true, it’s worse in the winter, during hot humid summer days as well you can get a lot of problems there. I’ve seen attics that have just been completely blocked off and left that way for a couple seasons and the roof is actually starting to collapse in some cases because the plywood is so inferior that, if plywood sits at more than twenty percent moisture content it can actually lose its, it’s called delamination and delamination is where the plys of the plywood actually separates and you can lose the structure. That’s not a roof you’re going to want to walk on and that’s why in some cases

I’ll show up at a property and go I don’t want to walk on that roof, let’s take a look at the attic first. You go in the attic and I would have probably fallen through if I walked on it so, yeah so definitely with the temperature swings you can have a lot of damage up there. So again, ventilation is everything.

Mark: Awesome, so there’s everything you ever wanted to know about attic mold and why it’s very important, the stuff will make you sick or wreck your house pretty quick so it needs to be taken care of! If you have any doubts, if you want to know, if you’re going to buy or sell a home, here’s the guy to call Mr. David Fairbairn of 604-395-2795 Thanks David.

David: Thanks Mark, take care.
Mark: You too.

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 today!

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