Home Inspection

Home Inspection: The Crawl Space

OK, so we just got this call from a homeowner, and they want us to come take a look at their crawl space. She’s got high humidity, she fears mold, she’s got some odors coming out of the crawl space, so come along with me, and we’ll show you how home inspectors do a crawl space inspection. Oh, by the way, stick around to the end of the article, and I’m going to give you a special tip on some Crawl Space home inspector gear that every crawl space home inspector should have in their toolbox. OK, so we just got to the house that we’re going to take a look at, so I’m going to put my gear on, and we’ll jump in the crawl space. Just so you know, normally I have on coveralls, but it’s a standup crawl space, so not really too worried about the coveralls today. OK, so this is a unique crawl space because it has this pad here for the HVAC, and their water heater to sit on, but home inspectors have already been here and taken out the insulation. They had insulation and foil up in the crawl space, up in the subfloor. You can see this foil right here. This was left. They used to put this in crawl spaces back in the 60s, 70s, and even into the 80s. They thought this was some kind of vapor barrier that they would put up there, but the problem with it is it would actually trap moisture up against the subfloor and can cause mold to grow, so if you have this foil that’s installed up in the subfloor, make sure you take this out.

OK, I want to show you something that I just found. Basically, it was kind of hard to see the subfloor because of all the fiberglass insulation, but now you can see that we’ve got some mold growing up in the subfloor, and maybe that’s a better way for you to see. You see all that white raised mold on the subfloor and the joist, so we’re going to soda blast all of that off, that way it’ll be almost like a new piece of wood. A lot of times, what you’ll find is that around a heating and air duct, you’ll see more mold because the heating and air system is condensating more in this area around the duct and especially around the trunk line. As you can see as you go a little bit further away from this, you have less, and then here’s some more. This just popped up here, but most of the time, if you look, if you pay attention, you’ll see more mold and more wetness around the duct system. One other thing I want to show you is this right here. That’s not mold. That’s cricket poop. It’s amazing that that cannot come off with a soda blaster. If you see this in your crawl space, don’t be concerned. I don’t know if the save crickets drill a hole, poop in it, and then cover it up, but that stuff won’t come off. It’s amazing. It’s sticky. NASA needs to figure out what to use that for, because it’s amazing. Then, you got more mold over here.

More cricket poop. If you got a lot of cricket poop in your crawl space, you probably got a lot of moisture in your crawl space. Look at all that back in there. There’s some of that foil I was talking about. We’re going to remove that foil up there in the subfloor, and make sure that the dehumidifier dries all that out, as well. I’m going to show you the dehumidifier we’ve got running. This is the Aprilaire 1830. This bad boy will do up to about a 2,200-square-foot crawl space. Just a workhorse. Pulls moisture out, and moves about 70 to 75 pints a day. If you’ve got a bigger crawl space than that, you want to go with the Aprilaire 1850. Great, great dehumidifier we’ve got sitting up on blocks, drains into the condensate pump right here, and then the condensate pump pumps the moisture out of the crawl space.

We’re going to trench and sump pump this crawl space because they have some standing water coming in. We’re also going to put down an underlayment. That is our platinum package with a lifetime warranty, so that’s what they decided to get with us. We’re going to do the platinum with the lifetime warranty on the encapsulation process. We’re going to have the underlayment with the 12 mil vapor barrier on top. But, this is the first step. We got to get this place dry so that we can soda blast, and that’s why the dehumidifier’s been installed. OK, so this is our R10 termite-resistant foam board. We install this foam board with a Hilti nail.

As you can see, it’s a two-and-a-quarter-inch thick foam board. It’s OK to get wet. That’s the nice thing about this product is that it’s OK to be up against the foundation. You can even have it touching the ground. It’s not going to cause any issues with termites, or be damaged by any kind of moisture, unlike fiberglass insulation, or rock wool insulation. If it gets wet, it has to be removed. Great product. Got a 50-year R-value warranty on it, and we also use the foam board right here to seal up the vents, and we put a little bead of spray foam around it to make sure we try to keep as much humidity out of the crawl space as we can, plus with the borate that’s located inside the foam board, it actually discourages pests, even kills them, so that way we don’t have to worry about pests, and termites, and things like that trying to climb up behind the foam board to get to the wood.

A couple of other things I want to show you. If you look right here, we’ve got some penetrations coming through the subfloor. You want to make sure if you’ve got any major penetrations like this, that you air seal them with a spray foam. If you use the great stuff that is located at Home Depot and Lowe’s, if you’re inverted like this and you’re trying to spray it up here, it’ll actually fall on you, because it doesn’t stick real good, so we use the Fomo product by ICP, so it’s a really good product. Once you put it in, it expands really nice. We also use it to seal our vents. We don’t have to worry about it falling on us, because if this stuff gets stuck in your arm hair, it doesn’t come out. You got to rip it out or cut it out.

Here we’ve got a little bit of subfloor damage. This is the front of the house. They were getting some moisture coming in. There’s actually a really high traffic road in front of the house, so the moisture slopes really nice . . . so the ground slopes really good towards the house. That’s partly why they have this painted right here, too. They were trying to stop the moisture by painting the cinder block, and it didn’t work. Painting cinder block does not work. If you’re thinking about waterproofing your basement or your crawl space using paint, it typically fails. You’ve got to do a lot of prep work, you’ve got to install it right. Anyway, even if it had worked, it’s still not high enough. Look, we’ve got moisture damage up in here in the subfloor, so we’re going to try to get this addressed as well. We’re going to soda blast it first, dry it out, and see if we’re still getting active moisture. This could also be a flashing issue from a deck or something like that, that needs to be addressed, so we’ll take a look at that and see what we can find to make sure we don’t have more moisture coming through. OK, now you can see we got a little bit of raised fungus, mold, whatever you want to call it, right here off the joist. The other thing I want you to notice is to look at how the discoloration is from here down. It’s because the fiberglass was up here, so it was kind of keeping a little bit of that from creeping up, but it still holds moisture up against the wood, so we had more mold growth down at the bottom than we do at the top. We had to remove all that fiberglass in order to soda blast all of this. One other thing I want you to notice, in this corner, this is the area that has the most water penetration.

Do you see the watermarks in the far corner? It was kind of hard to see it because we had a foam board covering it, but this is where most of the moisture was coming in. You can see the ground’s pretty wet, so we’re going to trench all of this, put a sump pump in, make sure in the future when it rains, if the water’s coming through the foundation, that we are redirecting that water through our EZ flow pipe, into the Flotec 1/2HP sump pump. By the way, there’s a great unboxing article about that Flotec sump pump if you want to check it out.

Let’s see what else we can find. OK, they installed these 4X4 posts to help support the foundation. They put these nice pillars and all that. These are pressure treated, which is OK to be touching the ground, as long as they are pressure treated. There’s some pressure-treated wood that is OK to be touching the ground, and then there some that isn’t, so you want to make sure you get the right kind, but typically with this type of install, we would use a post jack sitting on top of a poured footer. As you can see, this is going directly into the ground, so if there was any kind of weight on this, it’s not really doing a whole lot of good, because the ground is going to give way. They didn’t really install this properly, and you never ever want to have any wood touching the soil if it’s not pressure treated, or designed for soil contact. Make sure that if you’re doing something like this with a post jack, or whatever, if you’re allowing it to touch the soil, make sure it’s pressure treated. If you’ve got wood in your crawlspace that’s going from the subfloor to the ground that is not pressure treated, you need to remove it, because it’s a great way for termites to move up into your house.

OK, I want to show you this ductwork. This is a flexible duct, and it’s connected to their metal supply, and the only thing I want to point out is it looks like this ductwork has been done properly, but it’s a little misleading because they taped it up really nice on the outside, but the most important thing is, did they actually air seal it where the metal of the flex duct touches the metal of the supply? If you want to know that, you’ve got to take the tape off and move the insulation bag and make sure those tabs are air sealed. There’s a collar right here that they install on this, so if you’re concerned about your energy, maybe you feel like you’re burning a little bit too much AC and heat, you might want to check this area, because they estimate 25% of your AC and heat is lost in the crawlspace because of leakage, so you want to make sure you check all that out. This is a great place to start. If you got a solid duct, there’s actually about every 12 to 18 inches, there’s a collar that you’re supposed to do, but this one, the only place you have to make sure it’s air sealed is at the boot where it goes into the house, and then here where it touches the supply line. Those are the two air seal points of a flex duct. One of the reasons why I wanted to come here today is to see how to crawl space is actually drying up, how it’s progressing along, to make sure we can soda blast it. I got my meter here, and we’re going to put it on the wood, and it says it’s about 14%, which is pretty good. I think when we were here before, before we removed the insulation, it was about 19, 20%. It is drying out in spite of us not having a vapor barrier installed. The dehumidifier is strong enough to dry out the wood.

Once we get the vapor barrier installed, it’s going to be much better, but this is just part of our process. The subfloor itself is around 10%, so that’s really good. We are low enough, moisture wise, to go ahead and start addressing the mold. OK, this is the Lomanco PCV1 foundation vent fan, and we put this in to put the crawl space under negative pressure, because in our part of the country we have a lot of radon around here, so according to the Environmental Protection Agency, you are supposed to remove one cubic feet of air per minute for every 50 square feet of crawl space, and this basically will do about a 5,500 square foot crawl space based on that calculation. Now, we don’t leave it hooked up to an extension cord. We’re still in the process of making this a platinum package ready for the homeowner so that they have a dry, clean, healthy, and efficient crawl space. We just temporarily hooked it up so that we’re already removing the soil gasses, because we sealed all of the other vents except this one. This is the one that’s going to blow the air out, while the dehumidifier over there in the corner dries up the crawl space. If you’re concerned about soil gasses and radon, this is a great addition to your crawlspace. All right, let’s look at this. One last thing I wanted to show you, I talked about air sealing the boot, basically, is the little metal piece that they use to go through the subfloor into the house. Your register sits on top of it, but I want you to notice that we’re air sealed around the boot.

That is for energy efficiency, but also to help keep the soda from going up into the house, so that’s another energy-efficient tip for you in the crawl space, whether you’re soda blasting or not, if you’ll just spray foam around this boot, it keeps the crawlspace air from going up into the living space, or vice versa. OK, I wanted to show you a rim joist. Some people call it a band board. It depends on what part of the country you’re in. The only piece of pressure-treated wood in most crawl spaces is this piece right here. This is called the sill plate. S-I-L-L, plate. This piece sits on the cinder block, and it’s pressure treated, and then all the other wood in the house sits on top of it. This is where the weight of the house sits along the foundation wall. Now, in Tennessee, you have to leave a three-inch gap between any vapor barrier, or foam board, or whatever, this direction. Our vapor barrier will stop right about here, because the state requires that we give the termite people a viewable area to make sure that there are not termite tunnels going to the sill plate. That’s why you have to leave this gap. Now, if you’re in a part of the country that doesn’t have termites, check with local codes, but chances are you could probably go all the way up with your vapor barrier. But, in the south, where we have termites, we have to leave that gap. That is part of code. If you’re hiring a crawl space professional that is not leaving that gap, you may want to ask them to do that. The other thing is the rim joist right here. According to building science. com, this is called a critical area to insulate, because believe it or not, this gap right up here, air will move through that gap up into the wall of your house.

That will actually stop air infiltration from going up into the house, plus we use an R10 termite resistant foam board on this, in order to thermally insulate. If it’s cold outside, the cold weather will not transfer into the crawl space, because if you got a warm crawl space, and it’s 15 degrees outside, you could actually develop some condensation right here, especially if you don’t have a dehumidifier. If you got a dehumidifier, you probably won’t develop condensation, but if you do not have a dehumidifier, this could condensate if it’s not properly insulated. Anyway, there’s your rim joist, your sill plate, your subfloor, and then the three-inch termite gap right here. OK, now I’m going to show you the door. Now, this is a great door. Not all the crawl spaces we do are this tall. Normally they’re this tall, but no matter if they’re this tall or this tall, you want to make sure that you got some good weather stripping around the door because if we install our platinum crawl space encapsulation system, and there’s this air moving right through here, it’s going to make the dehumidifier work harder. If you can, make sure you weatherstrip around these doors, whether it’s a full-size door like this, or a crawl space door that you decide to build, maybe a 3X2 door. Also, another important thing to do would be to insulate this door.

We could put a piece of R10 foam board right here. This one may already be insulated since it’s supposed to be an exterior door anyway, but most small crawl space doors are not insulated, so you could use the R10 foam board that we used on the walls in order to insulate the door. I appreciate you sticking around. Now I’m going to show you that one tool that I mentioned at the beginning of the article that every crawl space home inspector should have in their toolbox. It’s this, a moisture meter that checks how much moisture is located in the wood of the crawl space. It’s important to know that, because if you don’t get the crawl space wood dry before you address the mold, you’re going to have issues in the future, so make sure you check out this little guy on our DIY store. This would be a great crawl space home inspector gear to add to your toolbox.