Closed Crawlspace | Construction "Rough-in" 

Thanks so much Terry! Glad the videos are helpful! That's our goal!!! Like and share us to help get the word out. More education is needed in the industry. Sounds like you're doing it the right way and it will pay huge dividends over your lifetime in the house and the life of the home! We run into folks who think its a waste of time frequently but the awareness is building and more folks understand why building better on the most expensive investment most of us make is a very smart decision! Once people have lived in a better built home, they are completely sold on the results. If we can help with suggestions on your build, don't hesitate to reach out!

So glad to have you follow us! We’ve known Matt for years and, like he and the build show team, we enjoy sharing our experiences with the world in hopes that it’s helpful for folks and provides a better understanding on east ways to build better! If you’re ever back in SC, reach out!

Fantastic! Glad to have you following. Matt does a great job and we are trying to fill in some of the gaps unique to the Southeast.

Agreed! We have done it both ways and learned!

We don't currently build in the Lancaster area, but would be happy to speak with you about your project to offer any advice.

Where's the ICF?

Insulated Concrete Form

there is no need for a drain in a conditioned crawl space. a drain is only going to bring more moisture in and be an extra penetration that will add another moisture intrusion point

1) I think you're seeing our foundation "straps" which we use instead of bolts. These are embedded in the foundation and bent around the framing and nailed to the framing in multiple holes. We find that the straps can not only hold the sill plate, but run up the wall and attach to framing as well. 2) We install termite shielding on our insulated stemwall slab foundations which we will be discussing in some upcoming videos, but do not install specific termite shields on our crawlspace foundations. We treat all of our homes with borate termite treatment applied to the wood framing 3 feet in all directions from any contact with masonry or concrete. 3) The waterproofing is a standard asphalt-type emulsion.

Try GMXCO.com

Check out the products at GMXCO.com

Great question! I always use the “think like a shingle” mantra which you have to think about upside down since we are concerned about potential water from underneath. So, the membrane on the floor is lapped on top of the membrane coming down the foundation walls. Laps on the floor membrane will depend on the slope of the Crawlspace floor. If water were to flow beneath the membrane, we want to avoid water “catching” a lap from beneath bringing the water to the tape seam above. Let us know if this makes sense. If it doesn’t, we can make a quick video to illustrate.

This is a pretty common foam fastener for powder actuated fastening guns. A google search brings up several.

Thanks for the comments. Interesting idea to wrap the wall with the vapor barrier. In practice, this would be very difficult to get the vapor barrier of this thickness to "hug" the wall without fasteners. The requirement to have a positive connection between the foundation and the framing would require penetrations through the vapor barrier which could be problematic from a moisture and termite perspective. I wouldn't rely on the vapor barrier with penetrations as an adequate capillary break. Depending on the type of continuous insulation board, if it ran from the exterior framed wall down over the foundation wall to the footer, this would provide a path for termites to move from below grade up the outside of the wall into the framing unnoticed. Of course, termite flashing could be installed at a break in the foam to reduce the chance of this from happening. Another drawback of continuous insulation on the exterior of the foundation is the final exterior finish. The exterior insulation would need to be protected from damage. A common finish over foam board would be synthetic stucco, but it would still be susceptible to damage from string trimmers and other landscaping equipment or activities. Overall, I think the cost and complexity of this approach would be prohibitive. One other option for the membrane would be to wrap the wall with a peel and stick membrane which would eliminate fasteners, but would not address the issue of the foundation connection to framing. This would also be extremely costly. Again - thanks for the comments and ideas. I always enjoy discussing different construction assemblies. Innovation is very important in our industry!

@@AddisonHomes Thanks for the quick reply. I think a peel and Stick membrane would gasket over the J bolts or other foundation connectors. To be sure there wasn't a gap between masonry and sill plate, I suppose you would need a thicker gasket material than just the VB anyway. I was thinking the weight of the gravel for the exterior drain sitting on top of the VB draped over the outside and down onto the footer would pull it tight to hug the exterior wall, then the insulation board would hold it against the wall by the pressure of the backfill the way they do a permanent wood foundation. But not in practice ? Is hugging the wall on the interior important ? I know termites and carpenter ants will tunnel through foam and is one reason I don't like the idea of foam outside at all. What do you think of the Rockwool Board material for exterior insulation and termites ? It doesn't hold water, and termites don't tunnel through it, do they ? You treat the wood within 4' of the piers with boric acid, but not the wood wall framing ? Just the sill plate ? Termites are a big problem in California where I want to build, but I haven't seen this level of precaution out here. I wish it were practical to end up with a box completely wrapped in bug and moisture proof barrier, with all continuous exterior insulation like REMOTE, then control ventilation and humidity with HRV and dehumidifier. Out here, they put continuous VB under slabs but don't then wrap it up the outside of slab onto and under the sill plate. So the concrete is not really isolated from the ground and weather and I've never understood why. Seems like that would work for crawlspace foundations, too, with the VB under all the footings and piers continuous. On a non-VB note, some builders use additional strip footings and short walls rather than piers and beams. Do you prefer pier and beam because it keeps the wood further from the ground for termite reasons, or something else ? Why not short steel adjustable columns instead of concrete piers ? A crawlspace is just a short basement, isn't it ?

Johns Manville CI Max

So glad you’ve found it useful! The exterior foundation waterproofing will be covered by backfill. The foam board used on the interior foundation walls is foil faced polyiso foam.

Thanks. I saw in another comment where you had clarified also that the waterproofing was just up to the backfill level. I had assumed the was not polyiso since that is not rated for ground contact but, then again, this isn’t contacting the ground…that’s kind of the whole point. Thanks again.

BiLar

Great question - not without a moisture barrier beneath the slab.

Glad you enjoyed it! There is no code requirement for capillary break on foundation walls unfortunately. Current code does require a vapor barrier over the dirt in a crawlspace. This can reduce radon, IF there is a radon vent up through the roof.

@@AddisonHomes Thank you for the quick reply! Cheers!

They should be listed in comments on this video but the spray on is a spray applied asphaltic emulsion used by many waterproofing companies.. The membrane is "BiLar" and can be found at www.gmxco.com

I'm always concerned with termite issues with ICFs in contact with the ground in our high termite area.

The waterproofing below grade with a perimeter drain is best practice for any Crawlspace or basement foundation to keep water out of the foundation. It’s not required by code for a Crawlspace, but without, you risk water issues, vented or not. The waterproofing we apply to the top of the foundation wall serves as a capillary break and is also simply a moisture management best practice to eliminate capillary moisture movement up through the foundation into the wood framing regardless of venting a Crawlspace or not.

Do you come back with a brick veneer on the exterior of the foundation to cover the black waterproofed CMU? I’ve noticed most crawls I’ve seen have 0 waterproofing, just the CMUs and raw dirt under the home and some don’t even put a capillary break. I can see what the plastic on the ground does to prevent ground moisture from rising and seems a very minimal cost increase to “sell” to a cost conscious home builder but what does waterproofing the CMUs do? I see you incorporated a capillary break with the waterproofing but want to understand the benefits of waterproofing the CMU. Thanks!

We use the Hilti powder actuated gun with the foam fastener ram and the hilti foam fasteners. Simpson also makes a similar foam fastener for their regular gun I believe. The vendor, GMX supply also makes an adhesive that we use and works great. Its a polyurethane adhesive with good adhesive properties - Its called SealIt XP. www.gmxco.com/products/crawl-space-systems.html

Great question Nick- Its not inexpensive. We were paying around $2.50 / SF of interior crawlspace until the recent supply chain challenges and price increases. Our cost now ranges from $3.10 - $3.95 / SF.

@@AddisonHomes what about issues described in this video? ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-pgA7FqD2IR8.html

A conditioned, sealed crawl needs to be maintained within an acceptable humidity range either by operating the HVAC system or having a dedicated dehumidifier. It is not intended nor designed to be left unconditioned for any period of time. On the other hand, a vented crawl will always have a musty smell like a cooler due to high moisture and condensation on surfaces.

One crew does waterproofing, liner, and foam board. Spray foam would add another crew and it is far more expensive. Many spray foam crews wouldn’t even touch only Crawlspace walls without a hefty minimum charge.

We are on the same page, one crew completes the job. I’ve just seen another builder in Kentucky do spray foam on the perimeter. I like your method, one crew and get it done.

Great question. It definitely an option for an encapsulated Crawlspace. Just need to insure that the vapor barrier is continuous under the concrete and sealed to the foundation walls. The concrete is more expensive but makes for a super nice space! You can actually pour a thinner slab (2-3” vs 4”) since it’s not going to have heavy traffic. Please send pictures if you pour it!!

So, for encapsulated crawlspace, built from the beginning as such, you wouldn't just build it the way a pool is made? I was watching video I took of the construction of my pool. They dug the hole with a skid steer. Put down rock. Compacted it. The put rebar down the sides and across the middle. One giant wire mesh everywhere. Then they started blowing concrete. No barriers! Is that because you dont care about moisture with a pool? Lol @@AddisonHomes

Thank you for responding. I'm exploring all my options and this is very helpful.

@addisonhomes Also, could you use galvanized steel posts instead of concrete & rebar columns? You know, like they have in a warehouse to hold up the steel beam ceilings.

@@user-jw2zk9dt7q would just be an expensive Crawlspace!

BiLar

We've been using this specific barrier for over 14 years and have never had any separation nor odor from the liner. It is a polyolefin polymer which is not reactive to most other materials (think milk jug).

@@michelleusher2355 can the general public purchase this product?

Not talking about crawl space ninja at all.

@@AddisonHomes that would be him yes , he of course I don’t have to tell you that he’s all over RU-vid

@@Bossman_71 I'm not familiar wtih him.

Bi-Lar. Its in prior comments along with the website.

Heavy rain, flooding(raises your home). Plumbing, electrical, hvac, etc is accessible. So, you don't have to break up concrete.

You certainly could use closed cell on the walls and stop short of the top for the inspection gap. Most spray foam contractors will not come out for such a small job and it is more expensive than the foam board. Many spray foam formulations also require an ignition barrier to be applied too. One additional challenge of the spray foam is that many contractors spray the closed cell foam in the band of the floor system, which then makes it impossible to easily inspect the wood framing at the band for termites. We are in a high termite infestation zone, so we terminate our foam board 4 inches below the top of the foundation and use fiberglass batts at the band which can easily be removed for termite inspection. The exterior insulation on the outside of our homes extends down to the foundation, so the band also has an R-5 continuous thermal break on the outside.

@@toddusher2358 Thank you for your thorough explanation! I am in the process of designing our new home in Southern Georgia, and I want to use the pier and beam foundation design. I've researched it done 10,000 different ways it seems! I recently watched a Matt Risinger Pier and Beam build which is why I asked. Here is the video ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-yk0mchsMstQ.html

@@NewVisionLCS No problem at all! I watched Matt's video and just a word of caution - the "pier and beam" foundation that he refers to is quite different than most "pier and beam" foundations here in the Southeast. Are you planning on using poured walls just as Matt did in his video? If so, no worries - just don't want you to get stuck with a local contractor misinterpreting what you mean by pier and beam. It differs even in parts of the Southeast, but in my area, most contractors refer to a pier and beam foundation as one with no perimeter curtain wall - they typically have only masonry or concrete piers with wood beams spanning between the piers, then a non-structural brick veneer around the perimeter. I would consider Matt's foundation to be a continuous concrete stemwall foundation with interior piers. Not trying to be a stickler, but it makes a difference depending on what part of the country you're in! If I can help with any ideas, please feel free to reach out!

@@toddusher2358 Yes, I want an exterior poured wall with interior piers, and I want it conditioned. No slab on grade for me! Have you guys built any homes in Southeast Georgia?

Let us know if we can help in any way!

Hi Cindi- The good thing is that the foundation wall is not sealed on all sides so moisture can always migrate up the wall and to the exterior of the foundation above the exterior waterproofing. The key goal is to prevent moisture from coming into the sealed crawlspace or up into the wood framing. Giving moisture this path to migrate outward of the house is perfect - allowing it to move without coming into the house area.

@@AddisonHomes I'm not understanding... the exterior waterproofing goes all the way up the exterior and over the top. Where can it escape? (You said above the waterproofing, but it looks like only framing is above the waterproofing.) Also can you explain why you installed a sacrificial vapor barrier instead of just installing the good one from the start? If it's super tough and would also keep moisture out?

@@cindianderson9443 Thanks for the clarification questions. We do not run the waterproofing all the way up the exterior of the foundation wall. We only waterproof up to the height where final grade will be around the exterior of the foundation. The foundation wall above final grade is not waterproofed - By code, there must be at least 6 inches of foundation between grade and siding/framing - the only exception to this is in our zero step garages. Sacrificial vapor barrier is exactly that - sacrificial. Even the most robust vapor barrier would be completely abused during construction and would be in no condition to leave as the final barrier for an encapsulated crawlspace. With the red clay in our region, the white heavy duty membrane would be red with mud!

@@AddisonHomes Thanks, that's interesting. I'm used to people putting self-adhered or fluid applied membrane over the whole outside foundation wall, then overlapping the house membrane to that one. But not putting any on top or on the inside. (Usually use other things like sill seal on top.) Lots of different approaches.

Good info Cindy but I’m still unclear on the moisture barrier explanation. In the video I see them spraying from bottom to the top of the wall. Not sure where you have four inches of untreated block to allow moisture to escape . No matter where the grade is the wall is sealed. Please clarify. Thx

2 primary reasons in our market: 1) Cost and 2) Termites. To prevent moisture issues with spray foam in an encapsulated crawlspace, closed cell (2 lb) foam would be recommended. The vapor barrier would need to be extended up the lower portion of the foundation wall so that the foam can be sprayed on top to create a continuous barrier and a 4 inch termite inspection gap would have to be left at the top of the wall - same as with the foam board. The closed cell spray foam is much more expensive than the foam board, so it really doesn't make financial sense. We NEVER spray foam in the rim/band around the floor system in crawlspaces, as this prevents the termite inspector from easily inspecting for termites - the rim/band is where termites are often first discovered. Our termite service partner is ADAMANT that the rim/band is easily accessible for inspection, which for us means batt insulation on the interior and continuous insulation on the exterior.

@Jan Toorop take it from a flooring specialist that has crawled into many nasty crawlspaces. Then you would understand and as a sidenote you breathe that air as well.

So true!!!

In many cases where the slope would work for a walk out basement, you are correct. For sites where a walk-out basement will not work or the client does not need the extra space of a basement, the encapsulated crawlspace still less expensive than a basement.

Its a combination of our rolling topography and relatively high frost line that resulted in crawlspace foundations historically. They still make sense when a lot has some slope but a basement isn't needed by the homeowner. But your observation is on target - if another foundation type (slab or basement) can be justified, it makes far more sense!!!

We considered a basement but it would have added a significant increase in our school fees per square foot. Which our tight budget couldn't afford.

Rock is a factor and older people don’t won’t basement, due to stairs and cost.

Not really - the foundation wall is waterproofed on the exterior and the fasteners are only on the interior side of the 8" thick wall. They penetrate no more than 1/2". We are not relying on the membrane nor the foam board to be moisture barriers on the interior of the foundation wall.