Crawl Space Ninja Show
Welcome to "Healthy Home ABCs with Michael Church," where we dive into the essentials of improving indoor air quality. Learn practical tips for fixing your attic, basement, and crawl space to create a healthier home environment.
Crawl Space Ninja Show
Six Insulation Spots for Vented Crawl Spaces
Ever wondered why your floors are cold despite having insulation in your crawl space? The secret lies in understanding exactly where and how to insulate properly. Most builders miss critical spots, leaving your home vulnerable to energy loss, moisture problems, and pest infiltration.
Crawl space insulation isn't just about stuffing fiberglass between floor joists. As Michael explains in this eye-opening episode, there are six specific areas that require attention in a ventilated crawl space: rim joists, sill plates, subfloor penetrations, the subfloor itself, ductwork, and water pipes. Each area demands different techniques and materials to create an effective thermal and moisture barrier.
The rim joist—that wooden frame around the perimeter of your floor system—represents what building scientists call a "critical seal." Yet most homes have this area either completely uninsulated or poorly insulated with compressed fiberglass. Michael walks through the superior foam board and spray foam method that creates a true thermal break. Similarly, the often-overlooked subfloor penetrations from electrical, plumbing, and HVAC installations create significant pathways for air leakage that must be properly sealed before insulation is installed.
Perhaps most surprising is Michael's breakdown of common insulation mistakes, like compressing R19 insulation into smaller cavities (reducing its performance to R13) or creating moisture traps by installing vapor barriers in the wrong locations. These practical insights come from decades of crawl space experience and will help you make informed decisions about your home's insulation strategy.
Whether you're a DIY homeowner looking to improve energy efficiency or simply trying to understand your options before hiring a professional, this episode provides clear, actionable guidance for properly insulating a vented crawl space. Subscribe to our channel for more expert advice on creating healthier, more efficient homes from the ground up.
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Michael Church, crawl Space Ninjas. Today I want to talk about the six places to insulate in a ventilated crawl space. Maybe you're not in favor of encapsulating your crawl space. You want to go the other route. What are six good places to insulate that crawl space? Stay tuned. So, if you're new to Crawl Space Ninja, we talk about everything related to basements, crawl spaces, indoor air quality and, obviously, insulation. We hope you'll subscribe to our channel, ring that notifications bell and follow us on Facebook. Here are the topics we're going to cover.
Speaker 1:What does the Department of Energy say about insulating an open or vented crawl space? Remember, this is for open or vented crawl space. Remember, this is for open or vented crawl spaces. This isn't for crawl spaces with de-hues or sealed vents. So this is if you have your home is built to where you have multiple vents, maybe they're opening in the winter or closing in the summer, or opening in the summer, closing in the winter if they're louvered or vented like that. This is what that topic is about. So what are the ways that you should insulate a vented crawlspace? But first of all, what does the DOE say about insulating crawlspace? We're going to talk about rim joist insulation, sill plate insulation, subfloor air sealing and subfloor insulation, duct insulation and air sealing, as well as pipe insulation.
Speaker 1:So let's see what the Department of Energy says about insulating a crawl space. And first of all, they don't know how to spell crawl space. They make it one word, crawl space is actually two words. But how you insulate a crawl space depends on whether it's ventilated or unventilated. Most building codes require vents to aid in removing moisture from the crawl space. I find that statement to be hilarious because if you live in the South, where it's humid all the time, it doesn't remove moisture. But I'm just reading what the Department of Energy says. Energy says. However, many building professionals like Michael Church of Crawl Space Ninja now recognize that building an unventilated crawl space or closing vents after the crawl space dries out following construction is the best option in homes using proper moisture control and exterior drainage techniques. Again, in the South, if you build a house with a vented crawl space, it never dries out. Okay, humid, hot summers, duct work, all that kind of stuff, but I don't know when this was written. But we've done. We've already proven that encapsulated crawl spaces are the way to control moisture. But that's not what this video is about. Your R value depends on where you live, but ranges anywhere between R13 to R30 in the subfloor. So if you're down in the tip of Florida, your subfloor insulation would be R13. If you're way up in Michigan or in the Great Lakes or Maine places like that, then your subfloor insulation could be R30 or higher. Keep that in mind. I'll put a link to the Department of Energy's website so you guys can check out what R value you need.
Speaker 1:Let's look at rim joist insulation. Buildingsciencecom has claimed that insulating the rim joist is what's called a critical seal. Now your builder whether you have a basement or a crawl space did not most likely insulate the rim joist or if they did, they probably just shoved fiberglass insulation or rock wool or something in the rim joist in order to insulate. That's okay to create a thermal barrier. But it would be better if you used a foam board and spray foam combination and we've got access to those. We even pre-cut the foam board for you on our DIY store and I'll put a link to that below. But if you just go get some R10 foam board, cut it to size and then use a you know one component spray foam with a gun and seal around that, that is what I'm talking about when I say insulate the rim joists. I've done many, many videos about rim joist insulation. If you go to YouTube and type in Crawl, space, ninja, rim joist insulation, you can learn the whys and even see how we've done it and different things like that. So I'm not going to cover that in this video, but that would be a critical step in insulating your home is to insulate the crawl space, rim joists. And again, if you've got a basement maybe it's unfinished and you can see up in the rim joists or a garage I would recommend you insulate those rim joists as well.
Speaker 1:The sill plate insulation Okay, so this is not one that's talked about all that much and we normally do not insulate the sill plate because of the termite gaps here in the south and things like that. But if you're in an area where you don't have termites or you have to deal with termite gaps, you might consider insulating the sill plate. The sill plate is basically the piece of pressure-treated wood that sits directly on the block or the concrete foundation or, if you've got a brick foundation, stone foundation, whatever, so it's that piece of wood that sits directly on that foundation wall and between the wood and the foundation wall, depending on how they constructed your home. There may be a piece of foam insulation already there. There may be a piece of metal there which is an old 60s and 70s termite gap. That obviously doesn't work because they don't use that anymore. But I would only recommend you insulate the sill plate if you've got a lot of gaps.
Speaker 1:If you've got a huge gap, like if it's dark in your crawl space and you can see light to the outside, you may consider insulating that, not necessarily for a thermal break, but it could keep out some cold air. But for me it's more about keeping out the pests. Okay, so you know little bugs and house centipedes and things like that. You want to keep those things out. Even roaches can get in there and infiltrate your crawl space snakes, depending on how big it is. So anyway, that's why I would recommend doing it Now.
Speaker 1:Be careful not to cover the sill plate. Don't cover that piece of pressure treated wood. If you're in a termite area, okay, because your termite, your pest control company could void your warranty. I would recommend, if you're doing it yourself, just get a caulk gun and some caulk and just put a bead of caulk and just make it real thin, just enough, like I said, to keep the pests out. They make some spray foam for pests and different things like that, but spray foam can be a little bit more difficult to do. Neatly, I think caulk is easier and then if for some reason you mess up, the caulk can just come right off. It strips off easier than spray foam does. So that's what I would do is be careful not to cover the sill plate to avoid your termite warranty. But it may not even be necessary unless you've got like daylight that you can see through. All right.
Speaker 1:So air seal the subfloor Now. In order to do that, most likely you're going to have to remove the old insulation or at least move it. As far as I know, building practice does not require air sealing of the subfloor at all, and to me it's just dumb. It should be air sealed. If they put in an electrical outlet or cut in an HVAC boot or plumbing, you know, I don't know if you've ever noticed, but they'll drill four holes and then finally find exactly where the electrical outlet is supposed to go, so they don't plug those other three holes right. So get in there, pull the insulation, move it out of the way. Especially, follow the wires, follow the plumbing, make sure you're air sealing those subfloor gaps and if you come across a big one like maybe you got a jacuzzi tub or perhaps an island where your ventilation for your stove or your cooktop is make sure you seal those.
Speaker 1:Well. Now be careful if you've got some form of pipe that perhaps your furnace is down there and your gas line is going up through the subfloor, make sure you use a fireproof caulk to air seal around those. You don't want to spray spray foam or even use a non fireproof caulk and that fireproof spray foam not working. If you read it, it's actually a smoke barrier. It's not a fire barrier. So don't use that stuff at all. Make sure it's it's approved fireproof caulking okay, for those areas where you've got a heated exhaust okay.
Speaker 1:And also, I don't recommend air sealing the entire subfloor. I've done a lot of videos about that as well. I'm not talking about going in there and getting two component spray foam and air sealing all of the subfloors. I'm just talking about air sealing the major gaps and things like that. You can even use caulk if you want, if it's easier for you to use some kind of caulk versus a spray foam. Just make sure you hit the big gaps and take care of that as well.
Speaker 1:Then, after you do the rim joist insulation and you check the seal plate make sure you don't have daylight shining through and you air seal the subfloor, then you want to install your R-value subfloor insulation. Okay, it could be rock wool. I'm not here to talk about the type. I've even heard of people cutting up foam board and shoving it up in there Again. Whatever you decide to do, just make sure your R value is to code. So do this after you do those other three things.
Speaker 1:If using a craft face now craft face means that it's got paper on it If using a craft face insulation, paper goes to the subfloor or to the living space. So when you're looking up and you're in the crawl space and you're looking up, you will see fiberglass, so the paper goes up. That's the way they recommend. Make sure that you never cover the insulation with any kind of vapor barrier. Or you turn it around and then the craft, or you staple it to try to hold it and you can create moisture problems between vapor barrier or the craft and the subfloor if there's a major air gap. Keep in mind if you have a vented crawl space, chances are you're going to have to deal with more moisture, more humidity, so you don't want to trap moisture between a vapor barrier. Because I've had people ask me should I staple plastic on the bottom part of the subfloor or the joists to hold up the insulation? No, I don't recommend you do that at all.
Speaker 1:You want the vapor barrier on the ground only, okay, and the wrapping pillars if you're going to encapsulate and all that. You do want the insulation to touch the subfloor if at all possible and make sure that you're not smashing the insulation. So these hangers that they use to hold up the rock, wool or the fiberglass, make sure you don't like smash that up against that. Remember, r19, for example, is is six inches thick. So if you smash the insulation to four inches, you're you're about an r13, okay. So you want that insulation as thick as possible to give you the maximum R value, okay. So make sure you don't smash the fiberglass. I've seen people take R19 and put it in a two by four wall, thinking that I'm going to have R19. No, you smashed it to an R13. All right, and then you've got that fiberglass pushing against your drywall and can actually cause issues as well. So the air inside of the fiberglass is also what helps to insulate, ok, so don't smash it in there if you can keep from it.
Speaker 1:You also want to insulate and air seal your ductwork. Now, depending on whether your ductwork is up above, inside the joist, or hanging below the joist would depend on when you do this part. Okay, so if the duct work is up in the joist, all right. If they cut through the joist or they've got duct works running in between the joist, then you want to make sure you air seal and insulate those duct work prior to putting your subfloor insulation in there. But if yours is hanging down below the floor joist, then you can do it after if you like, although you may still decide to insulate those ductwork before putting the fiberglass up, because it's just a lot easier to work around ductwork when there's no fiberglass in the way.
Speaker 1:But huge, huge overlooked problem is leaking ductwork. Now, if you've got flex duct, there's a pretty good chance you're probably not leaking that much. But if you've got an older home or perhaps your builder used the hard duct, the metal piping, then you're probably leaking air like a sieve down there. So 25 plus percent of your air is being lost in that unconditioned crawl space. That's why you want to make sure you air seal that duct work as best you can. Or if your duct work's in an attic, you want to do the same thing. Make sure you're getting the air from the furnace to the register where it's supposed to go, and not losing that air inside the crawl space.
Speaker 1:Last thing I want to talk about insulate pipes. If you've got a vented crawl space and you're in a really cold climate. About insulate pipes if you got a vented crawl space and you're in a really cold climate, you gotta deal with frozen pipes. Now if your crawl space is encapsulated and you're keeping all of the cold air out, you don't have to worry about this. Okay, or maybe you go and you close the vents just in the winter and then open them in the summer. I see people do that all the time too.
Speaker 1:But whatever you do, make sure you're protecting the pipes. They've got some good standard pipe insulation and things like that, and in extreme cases you may need a low voltage pipe heating cable. So if you plan on doing that, if you get pretty cold or you have, like we do here in Tennessee, one every five years, it'll get the teens or the negatives. You can't find that low voltage pipe stuff anywhere. So if you're going to do it, plan ahead, go ahead and get it now, while it's available, and then go down there and wrap those pipes and it just plugs in. What you do is, on those really, really cold nights, you just go down there and plug it in and you don't leave it running all the time. I don't recommend you leave that stuff plugged in all the time. And also remember that a vented crawl space allows air to enter, so you must insulate these pipes to protect them from the outside air. If you have an encapsulated crawl space, I would not worry about insulating your pipes, but if your crawl space is open and vented, you want to make sure you do this as well.
Speaker 1:I'm Michael Church Crawl Space Ninja. Hope you liked this video down below and let us know if you have any questions or comments down below. Also, hope you make it a happy and blessed day and we'll see you later. Sorry, I had a bug flying in my face.