Matt you jsut get it man. Love your info and tutorials. Im a DYI'er and your info helps tremendously. .

Steve seems to be a humble and very knowledgeable architect, thanks for sharing!

About to start work on a basement remodel in mixed humid climate. 50s house no slab insulation. Laying down deltaFL taped air tight - 3/4 iso foam - cement board. Steel studs 1” from wall, 2” closed cell up over band joist. Watching this - sounds like we’re pretty close. Matt and Steve, thank you.

This was great, good to see more about cold climates and more about basements.

I’m a spray foam contractor in Canada and we usually spray foam on top of the grave with closed cell foam it acts as the vapour barrier as well as the insulating factor. The big benefit of spray foaming rather than using insulation board is if there’s any voids it fills them in rather than spanning over

I love seeing smart work done well - really cool stuff.

Good building practice in Finland is to insulate the basement from the outside. We don't have many basements nowadays because it's cheaper to insulate the perimeter of the house with EPS or XPS rather than to build the basement below the frost line. Also post WW2 basements had inadequate drainage so there were a lot of issues with flooding so basements have bad reputation.

Steve at the end made this my favorite episode!!!

I'm building a new house now. We just finished the foundation. My wife's uncle is doing the site work and he's pushing hard for me to insulate under the slab before we pour in 2 weeks. I've been fighting against it thinking its a waste of a few thousand dollars. This video has me re-thinking my position.

Excellent! Love to see these details and hear the the discussion of why and how it integrates into the system. 👍

I know you're from down south but I'm loving these segments about building strategies in the Northern climates, they really apply to me.

This guy Steve, along with you Matt are absolute Geniuses when it comes to building super efficient, strong and safe homes ! I live in Ct and used to do insulation from the age of 18-27, and what a huge difference from then to now. This technique is beyond interesting and valuable and the way this house is being done should be a benchmark for all builders, thanks for showing and if you have anymore videos of this place, please show them. Thank you.

I've never built anything more complicated than a dresser, no idea why I watch this but I enjoy it so much!

I worked making fresh salsa for several years. We ran our production line at sixty degrees and operated out of an old freezer warehouse. We chose the building exactly for that reason. The floor and related substructures were probably a little over four feet thick. Concrete, foam and stone, then another series of concrete, foam and stone. Pretty impressive construction.

Great video!! I have designed basement slab insulation systems and never stopped to consider WHY we put the poly on top of the EPS. Makes total sense! Just say no to "iceberging"!

One of the best builders.. homeowners lucky to have you on the project

Thanks Matt, I already have audible and I ordered the marketing book.

Matt, I don't have a basement, and I'm sure as heck not a construction expert, but these are just so informative that I can't help but watch you ONnn the BUILD SHOW :D

Love your channel, been watching for years! Our 1956 Minnesota rambler has 12" block and we will be insulating the walls with closed cell just like this. We had to install drain tile and a sump system around the entire foundation and the foam will act as a vapor and air barrier for radon and moist. However, I would never insulate under the slab in this climate since the "cold" floor is 50 to 70 degrees WARMER than the winter air outside. Makes it easier to heat the house in the winter and cool in the summer.

interesting twist on closed vs open is if you have a cinder block foundation you should think about open cell. it will potentially allow the moisture to move which could save the block and mortar from deteriorating (assuming a retro fit old block foundation which may not be well sealed on the outside.

On the build show! Love it :-)

Awesome educational material, here given by two guys who are "national treasures" in my opinion. So no disrespect intended by my following comments. I am deeply grateful for EVERYTHING you do, and publish, so the rest of us can WATCH and LEARN. Especially, thank you for the warning of the "iceberg" moment that will wreak havoc if layering of building materials is mindlessly wrong! Meanwhile: 1) There is no mention of how deeply placed, below grade, this basement lies. 2) There is no quantification of the hydrostatic pressure exerted upon anything. 3) Is this on hilly, or flat, terrain? I've seen another of Steve+Matt videos, shot in Texas, where the surrounding land was shown, while a huge ground-water remediation project was poured. Egad that was awesome and mindboggling, to see that such countermeasures even exist. So many people (here in SoCal) just ignore geological issues. Not to mention all the SF-Bay people who live atop a powder keg... the San Andreas Fault. 4) I love the 10 inches of gravel, and the mention of French drains etc., in other words, this is a comprehensive solution; but: 5) If that gravel ever gets silted up, by any means over the next century or two, then really nasty things are gonna happen; so 6) Anyone who believes in, or uses, dry-well-type methods of sub-foundation water removal must contemplate the importance of all those air gaps between the gravel pieces. The gravel might hold up the building, but it's those air gaps that fill with water and allow an underground river to flow. Thank you for considering my comments.

Thank you for insulating houses and basements and putting unfaced insulation in and covering with plastic it will keep my business going forever due to all the mold build-up you builders keep doing her and I'll just keep making my millions thanks

steve knows his shit. thanks Matt

From what i have seen and heard it is best to not have the foam directly to the concrete. They make a special drain mat you are supposed to attach to the wall behind the foam to allow the concrete to breath. The same style drain mat is attached to the outside of the foundation to direct moisture to the drain tile at the footings.

So helpful! Thank you!

I'm planning to (owner) build a home in northern NH next year and want to achieve a very high efficiency level. All these videos are going to serve me well. Very much appreciated.

Matt, love the videos. Q: Is there a separate radon barrier that turns down at footing in addition to that 10 mil turning up the wall? Or does the CCF keep the gasses from infiltrating the basement?

Matt, great video. Do you have a video on water sealing basement walls? Thanks!

Biggest mistake I made in my new house was not insulating under the slab! The tile floors in the bathrooms are uncomfortable in the winter due to cold radiating through the slab. Floor temps get down in the low 60's which makes the heat have to run more often. Great video!

Save so many hours of extra labour and material if you use ICF walls!

German Architect/Construction Engineer/Prefab Construction Contractor here. Your videos are very informative about the US construction scene. But surely we wouldn’t ever do, what u guys are praising here. I advice anybody to check out the Eurocode Building Code on theese issues (available in Eng!). They are mostly created by German universities and Institutes, so they are pretty sound. For example interior insulation is something, everybody try’s to avoid for good reasons. U have literally no active Thermal mass and u will always have a dependency on artificial ventilation/dehydration methods, since there will always be a humidity problem as well. Also nobody is using oil based Foaminsulations in the interiors, for health reasons (except for slabs without possible connection to the air). IF u realy need to have a interior insulation, you always go here for a mineral based insulation like foamglass, which can be plastered with lime-cement plaster (natural desinfection of the wallsurface) and is beeing able to „breath“ humidity in‘n‘out to a certain degree. But if u build new, always try to avoid this stuff by using perimeter insulation on the outside of the basement, incl. a drainage plate and geotextile against the refill.

This concept is awesome, making that basement air tight. Out west here in Colorado and SD we have issues with Radon Gas, I would think this would negate the need for a radon gas removal system saving a ton of bucks.

The poly is also required for radon underslab control. Mass Code requires piping installed under slab

I’ve got 2-3 feet of stone with tile in it , Polly and 6” of concrete on top . My coal stove is in the basement and yes it takes a day or two to heat everything up but one the concrete is warm everything evens out . In the summertime you put a box fan on the floor and it blows across that concrete - your gonna freeze ! Blankets in August !

This is one of the best videos I have seen on basement insulation. Is a sump required with this setup or would it be redundant? How would a French drain be applicable?

Steve knows how to build!!!

I want a slab house where I am in Minnesota and that looks like a great install

I love the budgets Steve has to work with, my clients don't have the $'s for these luxuries also the loss of space would be problem for many referring to the shots of the double framed. I do love all he does, I just wish my customers had the money.

Was hoping ,based on the title this was a renovation. Would be a lot of jack hammering to insulate the floor this way in an existing home unless you had a huge ceiling height and could just cover over the existing. Love Steve both in these videos and in person!

Ooooooooooon the build show!

I'm a big fan of Steve! He seems to enjoy his job so much.

It's wild how Steve seems like he's not going to do well on camera until he starts talking and then is just awesome.

Question on under slab insulation! Where there is a column that is carrying load to a footing, is foam usually capable of carrying through that load from the column to the footing? Appreciate all that you guys do!

Loving that outro

good vid Matt, glad this wasn't another infomercial....stay real , stay unique ..

my slab currently is sitting between 72 and 75, i'm mid remodel and so some portions of my concrete walls are exposed on the inside that are above ground outside on the side that gets afternoon sun, here in the middle of the night that section of concrete is just shy of 79 and I can say for sure that concrete is not insulated on either side. current outside temps around 70, yesterdays high was 90-93 and ground temp for my area is around high 70's at 8 inch deep

Wow, that's some nice Detail! ...but curious about the foam Between the concrete layer? 2" slab, foam, 2" additional slab?

Matt, all great info when $ is not an object on retrofit projects. That’s why the wrecking ball shows up.👍🏻😎

I live in Southern Minnesota and think about foundations and slabs a lot. This video's slab insulation process looks more complicated than it needs to be, at least from my thinking. I've been thinking about a good six inches of sand that is leveled and compacted on top of packed earth. I would then lay down one inch of dense foam and pour my slab on top of that. It's just something I've been thinking about and I'm not sure it's a good idea. What about painting the outside of the poured walls with roofing tar and glue on one inch dense foam board before back-filling with gravel and sand, finished with clay and top soil.

My personal notes: 1: can rebar Concrete foundation walls be poured with the below grade rebar basement foundation slab as a monolithic pour to prevent air gaps? 2: for my 2x8 wall frame beams, I must learn from this video by distancing them a few inches from the concrete wall so I can pour closed cell foam exact same way as is taught to me here in this video. 3: Why does he say the walls aren’t structural? Are the concrete walls the only structural component? 4: Steve also like me thinks it’s a good idea to have a hydro break aka he pours 10 inches of leveled stone with a perimeter drain running around the foundation so that water never is in constant contact with the foundation like most houses. 5: Above the stone but under the concrete he has 4 inches of a special Type 9 EPS styrofoam that is rated for at least 25 PSI so it won’t break when the concrete above it is poured.

keep in mind, a closed cell insulation, below grade, on an exterior wall is illegal in the Midwest which is why it is also illegal to use a vapor barrier or in some cases, not even faced insulation under those circumstances. The moisture needs to be able to evaporate vs. being trapped.

Matt, Can I, or does it make sense in my Northwest Washington state climate, to apply this same system to my workshop/garage/man cave that I'm building? Or is it better to do this system with in-floor heating? I will have a 6" concrete floor and 2x6 advanced stick framing. I love all of your videos and knowledge, I'm learning a lot!

Also see the Insuladd interior paint additive. A guy using it inside a boat told me about it, to take up less space for existing construction. It is made from ceramic beads, a byproduct from burning coal.

Cool stuff

Nothing better than a audio book and good cans to drown out shop noise.

You could also spray foam the concrete walls and the top of the gravel all in one go. Should be more impermeable and air tight. 10" of gravel is pretty nice. I've seen lots of people only use 6". I guess it depends how much sand or clay is in the soil.

Great job.

Just a few comments from living north of 50 degrees latitude: (I'm not really an expert, so please feel free to disagree.) Bat insulation doesn't perform as well in basements as above ground, because the difference in temperature at the top and bottom of the foundation causes vertical air movement within the bat. In the dozen or so basements I've torn up, there are always some spots that have been continuously wet, even with proper vapour barrier & moisture seals, drainage, etc. Any kind of hollow wall construction in an exterior basement wall in a bathroom will cause problems. I prefer to attach foam board insulation directly to the foundation wall and drywall to the foam for these. I've only seen sub-slab insulation when there is in-floor heating, with the exception of one house about five hours north of Toronto that had full-height south windows that heated the slab in the winter.

8:09 wow! Can't get enough of this. he should smile more. GOOD SMILE.

I'm just doing my basement walls. spray foam was going to be about $7000.00. I put R28 batt insulation in for $1200.00. I did get the rim joists sprayed for $1700.00 so it cost me $2900 instead of $8700. The house walls are R24 and the ceilings are R55. We have triple pane windows too. I put rigid foam under the concrete floor which has heating pipes in it. It would have been good to sprayfoam but $5800 will buy a bunch of heat. Sometimes you have to do what you can afford.

Curious if you wanted a cold cellar in the basement would you do this or would you not do the section of the cold cellar?

The rim joist is only the at the top of the foundation wall. Band joists are every where else, connecting framing to framing. The poly is important to also stop radon gas, which is everywhere in the country, though more in some areas and less so in others. Honestly, you only need two inches of foam under the slab. Any more is really a waste of money as there really isn't much heat loss through the slab. My basement, I used two inches of extruded foam (pink/blue) not expanded foam (little white balls), though either is fine. Extruded has a higher R value per inch and holds up much better. The rock fill base is the best part of this video. Most builders use a sand/gravel mix which is inferior to rock, we use limestone around here. Sand/gravel mix holds moisture in it where as rock will not hold water. Dump a gallon of water in your kids sandbox and see how much comes out the bottom, I bet not much. The sand holds onto quite a bit. Rock is also the best to use around the outside of the foundation for the drain tile system.

Matt, I've got to say....I love these northern climate segments! This video was too short! This is some great info on basements and slabs. The only thing I would add is that XPS is a far superior under slab insulation. While his capillary break of 8-10" of free draining stone should keep water away from the foam, the vapor barrier is above the EPS (which I agree is better to prevent "iceberg " affect). The under slab insulation will still be exposed to moisture from the ground that migrates up and will degrade to R value over time. XPS will also hold up better over the life of the slab. I would also add that XPS should be used UNDER the footings and up the sides to meet the slab insulation....it all in the details! I thoroughly enjoyed this segment. Thx!

Steve doesn't like the Outro? Come on that is the best part! I am getting ready to install insulation before my slab goes down. Doing that same technique.

Very well done, I know with the stone, insulation and vapor barrier being under slab there is little chance of capillary wicking of water from slab/footer. My question is since you run the spray foam insulation up into the M joist do you fully cover the M joist or leave some exposed to the inside so that in case any water wicks up in can diffuse though the m joint into the basement so the m joist doesn't rot/mold?

Yeah, Steves awesome BUtT that system is EXPENSIVE.

recently watching your videos..this construction business is like watching lions hunting glues me to the screen nice.detailed technical info which is much appreciated..one single question though, with regards to all sorts of insulation materials (foams, rockwool etc) moisture barrier or sealants etc used extensively in our living spaces, how much of those are we inhaling? cause at the end of the day we become surrounded nothing but all these chemical.syntetic materials how come we can survive in such closed spaces without sustaing long term effects ?? arent there any natural substitutes or technics to build houses as efficient but less poisinous?

For those older homes with slabs and cinder block foundation walls, and an old but apparently functional interior (French) drain to a sump (all working… except during hurricane and freak rain storms, a bit of ground water penetrates between slab and wall plus efflorescence on some areas) what is the recommended way to make them watertight and then insulate? Assuming you have done all you can do to get water away from the foundation on the outside. Also assuming, some of the walls have been painted by previous owners with *terrible* waterproofing paint that failed after about a decade.

Fascinating ! Did I get this right?? 8-10" rock A french drain around the floor edge 4" foam//25 psi rated 10mm moisture barrier 4" concrete pour How deep is the basement?? 10-12'? What about plumbing/sewer? Thanks Matt !!

Great stuff Matt & Crew. Why not spray closed cell foam the foundation before framing the lower level?

Great stuff man, thkx for the video. 2 questions: 1. When you say poly, what king of film you talk about? polyethilene film, right? 2. Is that an air-box/gap between the gravel and the insulation? or is the insulation layed on top of the gravel directly? Could be nice to have some kind of protection so that gravel doesnt ruin EPS foam.

Hi Matt, great video. As I live in a northern climate, and will soon embark on my own house build, I'm curious why two layers of 2" foam were used under the slab as opposed to a single thicker layer?

Two question , CAn I insulate my cold cellar ? It’s under the open porch here in Toronto Canada If so , how ? What is the best option for not to have mold issue in future ? Right now suffering from condesation on cold cellar ceiling & concrete top part which is above the ground

Insulation outside the slab is best, as the thermal mass remains inside the home. It’s why my 3600sqft brick Victorian only need 4 tons of in SE Iowa cooling despite tons of windows and no insulation. It just changes temperature too slowly. Most AC runtime is shifted to nighttime as the brick remains warms for hours. In the hottest part of the day the brick is still warming up.

Alaska requires special foundation insulation detailing so you don't melt your permafrost subgrade. Everywhere else, the basement slab is a nice cool element in the summer and should only need insulation when close to an exterior face (at 2 ft from an exterior face the soil itself will give you an R-value of 12 to 24).

Tell me about the cross section of 2x material under the floor joists above. Where I live, most contractors insulate between the floor joists and drywall directly to the floor joists above (uusing blocking to stabilize the floor joists.). What is the benefit of the 2x lumber attached and running perpendicular to the floor joists I see in most of your videos? I live in NE Pennsylvania.

Does the hydro break extend below the footing too?

Matt, I mentioned a product called Dricore Smartwall a while ago on one of your videos and if I recall correctly you said you'd look into it. It looks like it basically does the same thing as Steve's approach but faster; dricore also makes insulated subfloor panels for basements that add insulation on top of the slab (only major issue is you lose height in the room). Another thought: if you're going to go through the trouble of insulating the underside of the slab (which seems like a good idea) why not insulate the outside of the basement walls? Pour the walls like normal and waterproof them like normal and then put that 4" of EPS on the outside of the waterproofing? If you used a dimple mat between waterproofing and EPS (I'm guessing) that would work even better because the EPS would help prevent the dimple mat from becoming clogged over time

You can insulate after. Insulating pumped screeds are available now. I wouldn't bother personally though. It's much better to pour concrete on grade than foam that will creeep.

Are the walls not insulated on the outside? If they are, is the inside insulation needed or is it just giving you 'extra'? Wish my slab was done like this (or done in any competent way..). For our daylight basemetn foundation walls i used Insofast panels as we weren't going to spray foam and didn't want to use the space to foam panels and stud wall.

How are the horizontal poly seams sealed together below the concrete slab or are they just overlapping?

The one issue with the slab assembly is bringing that vapour barrier up 18" above the floor slab and then spray foaming over that. Closed cell spray foam can't adhere to the vapour. it will actually start to separate and case breaks within your spray foam (which is now the walls vapour barrier). also remember to specify type of spray foam to be 2lb polyurethane spray foam - anything else (0.5 and 1.5lb) are open cell products so there's a higher risk of condensation forming on the assembly (which is why it's also not code compliant in Canada). using rockwool insulation, and continuing the vapour barrier from the slab (with gasket below the parition sill plate), is another effective way to go. just a pain to seal around the joists. great video!

How do you know where the moisture is condensing in between the closed-cell foam and the foundation wall? Seems like trapping moisture in there might cause degradation of the foundation wall over time.

Thank you.

I'm wondering which town outside of Boston. I build in central Mass and in the basement I need a fire break every 10ft to pass inspection. Usually either PT or Roxul. Also we usually have r18 minimum so would need another r3-4 not by choice. And sometimes when using closed cell we get forced to use 5/8 sheetrock or 1/2 blueboard and plaster also for fire. Thanks for visiting the area! 😊

any tips on waterproofing basements, on current homes when remodeling?

Hey Matt! Quick question, what program are you using on 2:20 to edit your videos? Thanks!

What about off-gassing? Long term air quality studies?

My only thought here is that there needs to be some planning for how much vertical space that slab system takes up. If you really want your 8 or 9 foot ceiling then you'd have to account for (conservatively) the 20-22 inches of space used up by a system like that. Really solid and good, but make sure the rest of the foundation is poured low enough to account for this loss of space.

Hy-Tech aluminized paint for concrete along with radiant barrier under the slab keeps my “unheated” basement 6degrees warmer in winter than the main floor, which has radiant heating. My basement is a rectangular pizza box

Matt, would the process change if you are doing Radiant heating in the concrete?

So what is the recommendation for the older house, with the not so insulated slab? How do you get that slab up to a decent insulation?

Mr. Rissinger, I am not a builder, I have been thoroughly geeking out on your channel for the last 6 months trying to absorb everything you share with modern building science. I am curious, since the walls are poured before the slab, how do you moisture/thermal-insulate the foundation walls at the bottom and exterior so they aren't a heat loss/moisture-wick?

How about one of those existing slabs?? Have a method? Thanks!! Great videos!!

thoughts on closed cell foam on 83 year old stacked stone masonry basement walls that get damp somewhat regularly? haven't seen much liquid or pooling water but it's definitely not dry.

Do the basement walls have to be sealed with a hydraulic paint before the spray foam? Or is the spray foam good enough at holding back water under pressure. And is the outside of the wall sealed with anything?

thank you

The slab looks like it's floating. It appears as if there is a small (one or two inch) gap between the gravel and the foam layer, with the concrete poured right on top of the foam. How is this? Or is it that the is foam resting right on top of the gravel and the gravel has been moved away slightly from underneath the foam in the cutout you used to show the layers? I can't figure out why it appears this way, and if there is any significance at all.

Lots of good ideas here. We vary somewhat from what's done here. Poly isn't used because it has permeability. Stego or Husky as vapor barrier has zero perm. When a slab is already in place we use Radon seal for water, radon, eveything protection. No vapor of any kind gets thru. Then, after that with an existing slab we would put 2" of continuous closed cell foam as a thermal break and double layers of 1/2" plywood in opposite directions top of that. This assembly looses 3"