Insulated Slab Foundation

[@Perfectguns89]

We have been insulating our slab with high density foam and laying a vapour barrier on top to stop radon for years in the north.

[@cheeseburger9232]

You in a cold climate

[@christophergruenwald5054]

You should put your vapor barrier below the foam so the insulation is on the dry side. Foam can slowly take on water from hydronic pressure.

[@sommerers2]

@@christophergruenwald5054 The reason he doesn't do that is because the foam will float. I'm pretty sure either Matt or This old house pointed out why you put the barrier on top. You could put another barrier so there is one above and below to accomplish what you are thinking, but then again I don't even working in the construction industry, just enjoy the videos.

[@an7h0ny88]

@@sommerers2 You're right mostly. We put the vapour barrier on top of the foam to prevent water being trapped under the foam. Usually we place the foam, tape seams, then 6mil poly and tape seams. This way if it rains the foam stays dry, water can't get beneath the foam and be trapped between the poly and foam. Otherwise I don't think it matters much.

[@grilledcheeseeater3443]

ive never heard of this turns out its a big deal thank you

[@Firestorm637]

I own a steel frame quad level house with 6 inch commercial floor pours. I love the strength of steel vs wood. Walls are true with no noise with high winds. I wish more steel frame homes that are recyclable. Enjoy your build

[@pcatful]

The detail you go into and the attention to detail is incredible.

[@josephverbosiii5764]

Some crazy money in this project!

[@steveb365]

I suppose anyone that can afford to build right now can also afford $10k to keep out moisture and termites

[@ZeoCyberG]

@@steveb365 Some statistics to consider... According to the United States Department of Agriculture (USDA)... -U.S. residents spend more than $1 billion per year on Formosan termite control alone -Homeowners in the U.S. spend roughly $5 billion per year on combined termite control and termite damage repair costs -Altogether, termites cause damage to as many as 600,000 homes each year in the United States And, according to Texas A&M AgriLife, "Wooden structures in Texas have more than a 70 percent chance of being attacked by termites within 10 to 20 years of construction if they are not properly protected by a chemical or physical barrier" Add, while $1-$2 Billion a year in property damage is caused by termites. Most of this damage is not covered by standard homeowner insurance policies...

[@grahamstefaan]

It's the real rebuild...aka, don't all you simps build like this?

[@rickrudd]

600 yard slab!

[@ProctorsGamble]

A fool and his money are soon separated

[@fernandoserrano9393]

The insulation on the floor will keep the house cool in the summer and warm in the winter. I live near Dallas and the floor is warm in the summer and cold in the winter. The apartment floor was very cold during the February freeze and I had to raise the thermostat temperature as a lot of heat was lost through the floor.

[@joshuaszeto]

That is a really big home! I would love to see regular update videos and see how it progresses.

[@SequoiaElisabeth]

Wow, what an impressive house. I love the decoupled concept for flooring and the heat sink will be a blessing.

[@malavoy1]

That was a house? From the size I thought it was an apartment complex, complete with sheet metal barn 😁

[@ruelsmith]

I work in commercial construction in Ohio/Kentucky and this is the way all slabs are poured. Usually it gets 6 inches of compacted gravel with 1-1/2 to 2 inch pink foam insulation and a plastic vapor barrier on top of it and rebar and a wire mesh on top of all that. They also put foam around the perimeter of the foundation below grade.

[@ncbarndobuild]

Getting ready to do something very similar in NC. Foundation with stem wall and slab poured inside the foundation. Concrete guys here think I am crazy. Glad to see this video. Thanks Matt!

[@apscoradiales]

Double concrete slabs are not really necessary UNLESS you want a ground and polished finish. If you are doing a porcelain tile or hardwood or laminate floor finish, you can easily do a single slab, and will cost you a lot less than double slab. Here is what you do; level off the dirt and make sure that it's proof-rolled, place compacted gravel - thickness and size of gravel, plus compaction as per your structural engineer (don't skip him!!!), put rigid styrene insulation on top of the gravel (two or three inches of Strofoam SM is plenty - has a compressive strength of 25psi), then put 4mil polyethylene vapour barrier on top of insulation, then do the concrete. Don't use 6mil - it's too thin. You can skip the polyethylene if you seal all the styrene joints - the styrene insulation can act as a vapour barrier, but with so many joints and gaps, it does not act as one proper vapour barrier. In terms of concrete slab reinforcing, just use 6x6 6/6th wire mesh. This is a simple slab-on-grade construction. Now, if you have to "reinforced structural slab", then you must talk to your structural engineer. Don't try to save a few bucks by skipping him - he will save your ass from potential future problems. Also, make sure there is some insulation between your concrete slab and the "stem wall" to act as a thermal bridge. If you don't do that, your slab may heave at edges from the frost or the edges will be hotter or colder than the rest of the slab. Reinforce the stem wall too - structural engineer is your best friend here as well. DO NOT depend just on the contractor(s); they may screw you up big time!!!

[@ncbarndobuild]

@@apscoradiales I will only be doing a single 4”slab pour and some other slight differences from what Matt shows. A structural engineer designed and sealed my plans based on what I wanted. I totally agree with you on having plans by a licensed engineer. To expensive to not do it right the first time.

[@HistoricHomePlans]

4:48 Beautiful concrete work! Matt, you really know how to get the best out of your crews and subs. It must be inspiring to work on your projects.

[@nrao8977]

"Board form concrete" is also called "Exposed concrete" - made famous by French architect le Corbusier. Used extensively in Indian city of Chandigarh, Punjab (1951). Indian Institute of Management, Ahmedabad, architect Louis Kahn, also used exposed concrete extensively. Old stuff. Need to treat the surface of exposed concrete so that in humid weather - like Austin, TX - moss, fungus growth is restricted. Else it looks very ugle.

[@buildshow]

Excellent! Thanks

[@bert2754]

@@buildshow do you still recommend Pango Wrap as a physical termite barrier?

[@joepmeloen3373]

I agree, it needs a sealer. Also, be sensible with a powerwasher. Ive seen a few examples were it lost a lot of that nice detail and texture.

[@townsendliving9750]

I'm doing exposed concrete on the interior, all the floors and through the house on the walls

[@nrao8977]

@@townsendliving9750 need to be careful on the interior walls. Exposed concrete takes on the exact surface texture of the forms. If the form is wooden then expect protrusions and sharp edges. Not good if people brush themselves against such a wall.

[@Oldguard_8]

I would love to see the finished build, look forward to you content Matt thank you!

[@apscoradiales]

Matt, do you have a section detail at the intersection of perimeter grade beam and the slab? A picture is worth a thousand words, as they say.

[@SteveP-vm1uc]

Did you say 600 YARDS????????? HOLY SHIT!!!!!!!!!!!!!!!!!!!!!!!

[@davidfleuchaus]

600 cu yards = 16,200 cu ft 1 cu yard = 27 cu ft (3’x3’x3’) If the slab is 12” thick then this is a 16,200 sf house! But I’d guess the two slabs added together are more than 12” thick so, less than a 16,200 sf house but still huge.

[@joev2567]

Looks like about 3 yards per worker on site. lol

[@R2Mike]

In my are that would be a out 154,000 just for the concrete. 257 a yard here

[@eh_bailey]

Great work Matt. I'm loving the details

[@HistoricHomePlans]

Matt - A whole episode on termite strategies would be great. You've covered it in bits and pieces in other videos. With our climate warming we're seeing termites farther and farther north. Soon the entire country will be needing to take these precautions.

[@NSResponder]

9:15 you don't want the rebar in the center of the concrete, you want it about 1/3 up from the bottom. If it's in the center it won't help much to prevent cracking.

[@jpbinva9919]

Center or edge of rebar at the 1/3 point?

[@infiniteadam7352]

These days I think its wise to have the slab at least 2 feet above grade, just incase of flooding. I can't believe they got 17 inches of rain from one storm in Tennessee this week, the weather seems to be getting more intense...

[@antoniotulum4776]

some areas of texas dont get flooded, only in cities and in basins it gets flooded..remember the foundation seemed pretty much high...but yes, always better to play it safe

[@mr.g937]

@@antoniotulum4776 not even during hurricane Harvey?

[@Dudeinator]

@@mr.g937 yes texas is a huge state.

[@antoniotulum4776]

@@mr.g937 did you see the place the property was at? i doubt it gets flooded there, but anyways , the foundation was pretty big... what usually gets flooded in texas are cities due to poor evacuation systems ... even in a tropical storm (hurricanes are hard to get inland (that place looks like austin or some place around san antonio)

[@L0rdEsedess]

@Infinite Adam - I live in TN not to far of a Drive from that Flooding that you spoke of & had family that was in it...Luckily they were O.K. but yeah that was so RANDOM for that have had happened.

[@michaelsites1498]

Like that one time at band camp?!?! We did a slab in Indiana 4” thick poured in on 2 layers of 2” foam running in opposite directions and a plastic 6 mil vapor barrier that was taped all the way around as well as seems.... I don’t know that I’ve ever seen a slab sandwich but hey if it’s out there my man man won’t fail to bring it to you 👉🏼Onnnnn!!!! The Build Sow!!!! In my best Matt Risinger voice ever!!!! 😝😂😂😂

[@pin65371]

I'll have to keep that Milwaukee vibrator in mind come Valentines day.

[@nemo227]

Here, Monterey Bay coast, we bought our new house in 1970, slab floor. It's very quiet, warm enough, never cold, carpeted and it is practically ideal for our climate. If I was going to build a new home I would build with a concrete slab on grade.

[@angeloc700]

Lake Flato is an excellent architect. Lucky clients for sure!!

[@MJ-py3bm]

The house is well built. I’m proud of you. You are building a house best possible way for the client….. they should be very happy.

[@AndrewBuilt]

I though I was just going to see the same old insulated slab. This is on the next level of detail. Glad I took the time to watch it. I don’t think this is the most eco friendly method with all of the concrete. But for a ranch style you are not going to be able to have significant reductions in concrete floor.

[@HistoricHomePlans]

I agree about eco-friendly. Matt did a video last December I highly recommend. It's a project where they put ONLY a concrete perimeter beam. Then in the floor "slab" area they did compacted gravel, carefully leveled, set insulation/vapor barrier over that, then a double layer of Advantech, and the finish floor on top of that. NO concrete slab! I'd like to see building departments all over the country encourage this. Search Matt's channel. The video is called: Slab-On-Grade INSULATED Foundation (NO Concrete?!) - Part 2

[@HistoricHomePlans]

Andrew - I just checked out your channel. Very nice! I'm watching one of your videos now. You've got yourself a new subscriber.

[@AndrewBuilt]

@@HistoricHomePlans thank you. I briefly saw that video with the no concrete slab. It’s an interesting concept, the same way we do brick paver foundations. I’m gonna have to check back in the video and see what the comments say. I think it’s a good idea as long as there are no breaks in the water and vapor barrier. That would be a disaster for basements in the north.

[@Mainetkrause]

Matt, love your videos. Keep them coming. I wanted to ask if you could do in-floor heating, or if you even think it would be necessary with the thermal break, with that type of slab detail for those of us if in the north.

[@UponorNA]

Great project. Can't wait to see the final build.

[@SirPoofyPants]

Having rebar in the center doesn’t add strength. You want it in the tension zone, which will be towards the bottom or top, depending on your loading. Lifting the rebar on chairs instead gives your tensile reinforcement a protective concrete cover from moisture. Concrete inevitably cracks at the tension face. So you want cover so that the micro cracks don’t allow the rebar to become exposed.

[@Witcold]

Exactly. Sometimes there are even two layers of reinforcement for downwards and upwards bending forces. Also there is a minimum distance between the rebar and concrete edge for corrosion protection, as originally mentioned.

[@callmeishmael7452]

@@Witcold there are tensile forces running top and bottom all the time .every time there is a gravity point or spread load the surrounding TOP face ( or steel if it’s there) is in tension. The steel in the centre is very good practice though two chords are better but mostly not necessary. Also concrete has micro cracking through the surfaces which constantly open and close though most are not capillary.

[@altiplanalberto9961]

@Sirpoofypants, your comment is correct. But what I believe Matt meant is that they would have the rebar in the center so that the tensile strengths will be evenly distributed and prevent cracks in the concrete. This top concrete layer is not taking the main loads, remember that underneath the insulation lays the foundation slab.

[@callmeishmael7452]

@@michaelhaidee The second the slab flexes the neutral axis shifts. It is indeed very effective to have steel in the centre of any slab-unless there is zero or negligible load. And in a four inch slab it can go nowhere but the centre.

[@callmeishmael7452]

@@michaelhaidee back to your text books.

[@GoldsConcrete]

Insulated floors of any kind are the best !

[@daniellivingston5168]

Started using Teri-Mesh in Hawaii in early 1990's along with specialized training by Portland Cement. If memory serves, first in Hawaii. Appreciate Matt in keeping up others informed of great products.

[@lyndeesue5607]

Where do we purchase termitmesh in the Midwest area … kansas ? We wanna pour our slab in 2 weeks😬😳 thanks. Or what’s the next best thing to use ?

[@coachhoiidexplains36]

Could you do more cost breakdowns of projects? Like cost to client. There's a lot of variability, but it'd be great to see some real numbers and what can cause that variability.

[@dmitry6472]

Looks like around ~ crazy expensive!

[@davidblalock9945]

That insulation in the slab will be awesome here in Wyoming.

[@enriquealdogarcia4850]

incredible organized & planified!!!

[@roberto3262]

My wife says that she wants one of those Milwaukee backpack vibrators. I don't know why. She doesn't even do concrete work. 🤔

[@mgoren9087]

Funny!

[@snicks50]

LMAO

[@rppvt]

to get the bubbles out

[@LeeYang07133]

🥲

[@christophe3281]

Seems like this method is decades old in Canada. Less the termites of course

[@rajeshkanungo6627]

Curious: how do you handle moisture getting trapped in the foam layer between the two layers of concrete? It could get water logged too.

[@Slowhand871]

There is plastic vapor barrier on the dirt so no water can migrate up.

[@Grunt49]

Nice house! With a roller rink in it!

[@jackzwart8636]

Have you ever considered using a glass fiber rebar? If I'm the client I'm scratching my head at using steel in 2021 when GFRP is cheaper and stronger and corrosion resistant.

[@Prorex1911]

Always doing new things. Love it. Thanks for your information!

[@pulporock]

Great content love the insulated slab. I have only seen Termimesh, on the job site in Oz. The link for Halo is pretty crap. Cheers from Oz

[@jpeterstme]

How good is termimesh? Looking at building and no builder in Melbourne wants to use it. They want to use the chemical barriers around the perimeter.

[@econodrain7075]

Been building those insulated slabs for decades in Europe now

[@apscoradiales]

True. Also, it's in the upper or top layer of slab that you put the heating cables or heating lines in. Lightweight concrete is often used for that top layer. What's also being done is that instead of a top layer being concrete, sometimes people will use cementitious panels such as the Aquapanel by Knauff. It's a dry system, meaning you don't have to wait for the top concrete layer to cure - you start laying floor finished right away.

[@CrustyAbsconder]

Less than 90 years ago, my great-grandparents in deep east Texas where still living in a house of 2 rooms with a central outdoor covered walkway, made entirely of local rough-cut lumber. They had 11 children, and there were often semi-permanent guest, and the pig slept with them on the feather-bed.

[@techone8568]

Let me guess. The house had an insulated slab foundation.

[@YSLRD]

😁Thx My parents (early 20th century) each spent part of their lives in dirt floor cabins. In the 1960's, visiting my grandparents included daytime using the outhouse and a chamber pot for little ones at night. Also a hand water pump.

[@disqusrubbish5467]

You're Eva Gabor?

[@josephmerritt1411]

Curious why there was no insulation for the concrete bath floor? Any thoughts about why they elected to use Halo Subterra versus XPS or EPS or Rockwool?

[@Fredflinstone23]

They should have radiant floor system added,

[@shenoyglobal]

do we need insulation in places like florida before pouring concrete?

[@valdius85]

You do NOT want rebar in the center. This is where it adds almost nothing to the bending strength of the slab. The minimum cover is specified by local reinforced concrete spec and it depends on the usage, concrete mix and rebar diameter.

[@jpconnors8952]

When Matt was talking about locating the rebar at mid-depth he was referring to reinforcement of the topping slab for crack control, not tensile reinforcement for moment capacity of the structural slab. Adding reinforcement in the topping slab is not required structurally but it is best practice to control concrete cracking. ACI 360R-06: Design of Slabs-on-Ground Section 7.5 states “reinforcement for crack-width control only should be at or above mid-depth of the slab-on-ground, never below mid-depth. A common practice is to specify that the steel have 1.5 to 2 in. (38 to 51 mm) cover below the top surface of the concrete. Reinforcement for moment capacity should be at the centroid of the tensile area of the uncracked concrete section.”

[@valdius85]

@@jpconnors8952 Thx for reminding me that!! :)

[@michaelrowley1717]

Really cool project. Great video

[@alexpaden9320]

looking forward to future videos on this build. Looks pretty cool!

[@mcd5082]

Would love to see this house when it’s built

[@jmcdonne]

If you know any astronauts on the ISS, ask them to take a peek while they're over Texas - it should be easy to spot.

[@nashonabo821]

My wife wasn't interested in the video until you mentioned backpack vibrators. Guess shes interested in concrete work

[@ozzmundo1]

Apply high density closed cell spray foam on top of crushed rock and pour your slab on top of that. The inside of block stem walls can also be sprayed with closed cell foam. This method is not without thermal bridging where the slab intersects with the stem wall, but should do a decent job of keeping out termites while keeping your home more comfortable. Obviously its a hack, but if it works it works.

[@dv661]

Stem walls are filled solid with cement so can’t fill with foam

[@Redwingster]

Would spray foam, even closed cell, have sufficient density to bear the load of the finish slap, interior walls, fixtures and furniture, etc? IIRC, closed cell spray foam is typically 2 psi, far lower than the very dense Sub Terra panels.

[@jpbinva9919]

@@Redwingster CCSPF is 2 pounds per square foot, not 2 psi.

[@ozzmundo1]

@@dv661 dude, it’s filled with grout. The foam would be applied to the interior side of the vertical section of the stem wall.

[@ozzmundo1]

@@Redwingster usasprayfoam.com/wp-content/uploads/2018/09/JLC-Online-Article-Insulating-a-Slab-With-Spray-Foam.pdf

[@orthonormality]

Looking forward to seeing the kellered floor.

[@extraart1]

I cannot believe you went to that much effort and cost in preparation for an exposed interior concrete floor and didn't install a hydronic radiant heating system! At some point, the homeowners are going to be in someones home that has such a heating system and wonder why the hell, after all that expense, they don't have the most comfortable heat known to man.

[@i5k-]

Right? even if they didnt want to use it, just future proof. Wasted opportunity...

[@alanswanson5642]

Yep we have hydronic heating basement, first floor second floor and garage. It is silent and draft free. The one down side is you need a separate cooling system

[@ProctorsGamble]

Love mine!

[@jmhowlett]

That's what I was thinking, but they probably wanted to save a few bucks.

[@M1911jln]

Unity Homes / Bensenwood has discussed this in their KZbin videos. Their homes are so well insulated and so tight that radiant heating doesn't work the way it works in a typical home -- the floor would never get that warm because so little heating is required. Also, in a home this large, the cost to install radiant heating would be very large.

[@ImDembe]

Most slab foundations in Sweden have 10-40cm Cellular plastic for it can handle high loads and wont suck up water and then 10cm or more concrete on top of that. Most of the companys sell pre-made sides that look good and is pre insulated for all sorts of walls that you want to build.

[@everycoLor_312]

Nice to see a builder who wants/produces quality😆👍🏼💯

[@rodaliste]

I see you are passing all of that PEX tubing inside the slab. How would you handle any leaks or replacements?

[@eh_bailey]

Jackhammer?

[@DriverDude100]

@@eh_bailey Imagine the face on the repairing plumber when he realizes there are TWO slabs to go through to get to the PEX.

[@lambition]

Would been real nice if radiant floor heating was added to that slab. But, probably not worth in Texas?

[@jackjerryloveify]

I was thinking the same thing. It is super nice to have a warm floor on a cold day. Seems it would have been very easy to add to this particular build.

[@joepmeloen3373]

Floor heating is brilliant.. but what many people dont know is that (water) floor heating also can be used for cooling. Via air/water heatexchanger or with an ground waterloop. I wonder if floorcooling is used in Texas?

[@ToddBizCoach]

Have you ever used Helix Micro Rebar with concrete foundations?

[@Eric998765]

What do you guys do with the boards left over from the concrete forms? Even pre-pandemic prices I'm assuming you wouldn't just throw it all away. A perimeter fence maybe?

[@Thoracius]

In the olden days they went into house framing, e.g. roof deck. Just don't want to have to cut that concrete-impregnated board, as it'll wear out blades. Today who knows. Maybe they're reusable?

[@RR-Alaska]

Light gauge steel framing with aerated concrete filled walls is the future you can literally show up to a job site print out all the framing screw it together place your wall panels and fill the cavities with aggregated aerated concrete. And I believe a underutilized construction resource is sprayable ceramic paint what would give it a super insulating quality

[@fshjdkfhasdkfhsd]

So you only trust under slab insulation in a split slab sandwich, not on gravel or ground?

[@danielcriger9234]

Seeing alot great details on bug and energy solutions on slab on grade. My question is "radon". Is radon even a thing anymore? No one seems to be adding details for it anyway.

[@kc9scott]

I don’t know if radon is much of an issue in Texas (I vaguely recall a video on some other channel saying it was a common problem in Georgia), but it seems to me that having a well-sealed vapor barrier in the floor should go a long way towards preventing radon problems.

[@oldprankster7606]

Your county may have a map indicating radon locations. Where I live, the county does have such a map, and there are areas where radon mitigation would be advisable. If so, I would recommend getting a radon test kit. They are inexpensive, and the cost includes analysis by a testing lab. Radon is naturally occurring, but in areas of concentration, it would be worth the cost of the kit.

[@oldprankster7606]

@@kc9scott You would also need to seal any penetrations in the slab, such as plumbing drainage piping. In areas that are radon concentrated, vents installed in the slab are a good mitigation device. Obviously, that's easier during construction - not so much after the fact.

[@danielcriger9234]

@@oldprankster7606 I see test kits for existing buildings. I am planning on starting a build soon and am trying to address as much as I can on the front side.

[@LogixBrands]

There's some good information here on the test results comparing the Radon-retarding properties of Halo’s Subterra Plus versus the current code requirements: buildwithhalo.com/product-performance-series/controlling-radon-with-halo-subterra-and-subterra-plus/

[@retiredperson4054]

What thickness and R value would be the best for a two car garage where the concrete would be 4 inch thick and the floor heated with PEX Tubing?

[@TheJeffshek]

Thoughts on insulating a slab this way or the way you did your remodel/new build personal home?

[@joepmeloen3373]

Here we insulate the main beam too, then between put a moist barrier on the sand/gravel, insulation, concrete (we call that the workfloor) and on top a dry cement mortar or a self leveling concrete. When radiant floorheating/cooling is installed sometimes an extra thin insulation (or) with a reflective foil is applyed on the workfloor, under the heatpipes.

[@apscoradiales]

In Europe?

[@joepmeloen3373]

@@apscoradiales yes, Netherlands. The newer style of building that is. Traditionally a simpel small slab is poured under the frostline and then up with 2x masonry with insulation and a ventilated airgap.

[@apscoradiales]

@@joepmeloen3373 I knew it! Had a friend in NL, Jeroen as well. We were into Bimmers.

[@brianherlihy3731]

Why did you have bensonwood deliver without doing the walls (insulation) in their factory?

[@marychristenson3913]

Put your vapor barrier over the crushed rock and pour the concrete slab. build the outside walls with a pressure treated bottom plate. Place 1" Halo Subterra over the slab. Install 2x6 or 2x8 joist on top of the outside plate which will be 1/2" over the insulation sheets. Shim between the joist and the insulation where needed. Fill the whole joist cavity with spray foam which will water seal and air seal and add rigidity to the floor. You can now nail floor plywood to the joist and finish as desired. With this method you are not trying to isolate the concrete slab and you have a much more forgiving floor to walk on. What do you think? Would this be viable?

[@antonioelizondo3180]

What are you using for cement forms when you pour foundations on traditional foundations with no basement?

[@ricoludovici2825]

I don't see any fire blocks at 8'. Does your code allow you to count the wall insulation as fire blocking? I know UBC does. I outfoxed a picky inspector with the 1979 UBC. It listed fiberglass as an acceptable fire barrier/block. He wanted there rows of blocks at each turn in a cove ceiling. Like you, I like Rockwool insulation and it is basically fireproof.

[@larrym.johnson9219]

Matt I am a fan of IFC could you use the termite mesh with the IFC, because termites go up the insulation on the outside of the concrete to the roof? I'm also looking into rammed Earth construction could you use rammed Earth on that kind of foundation or would it have to be beefier?

[@dhultgren1]

Hi Matt. Can you tell me about those metal trusses? (The black ones in an X pattern)

[@GrenadierOverlander]

love this idea. Will think about it for my retirement house.

[@andrewzzack92]

Great content as always, and I dig those boots matt, what are they Chippewa? Redwing?

[@gmart225]

I am very detached from the world of building so silly but genuine question: how do brick/concrete walls compare to regular American walls (wood + insulation) - in terms of price and energy envelope? I'd love to watch a video on that!

[@mgoren9087]

Matt, could a substrait insulation be applied on a 6 inch slab on grade after the fact and then use perhaps a sub flooring material finished with tile or stone?

[@townsendliving9750]

Pretty sure he's got a video where he's done it, his personal house might actually be an example you're looking for.

[@smellslikeupdog80]

Can you recommend an architecht / Home Builder out in Southern California that you think does good work? Am looking for a resource in the area for a project. Thanks.

[@VernBigDaddy]

Makes me think of Schluter Ditra. Does the slab insulation provide and isolation of uncoupling benefits? Very interesting stuff sir. I can’t even imagine what a 2 stage pour that size costs. What was the total concrete usage for both pours?

[@oldprankster7606]

Depending on the location, this may make sense in cold climates. However, insulating a slab in regions with milder winters really doesn't make much sense. The soil tends to stay at a constant moderate temperature all year. Where I live in the Mid-Atlantic, it is not required by code, and the payback would probably exceed the useful lifespan of the building.

[@eh_bailey]

It feels cold on your feet here (just north of Matt). That is enough for me. 👍

[@buildshow]

I think Payback is a terrible metric. How about comfort, being a good steward of our resources, or a goal of Net Zero or Net Positive?

[@danielhall5911]

@@buildshow I love your stuff! But...I think this comment is a little out of touch. Payback is THE metric for the majority of households who can't reasonably build to the more sentimental metrics you are mentioning, right? Really, if it was about being a good steward/Net Zero the solution is a comfy pair of organic, sustainably harvested wool socks :-)

[@josecito976]

@@danielhall5911 any pretense of affordability took flight loooooong ago If ya got the cash to splash… do it! Ain’t taking it with ya the day you leave the house feet first

[@BrianKrahmer]

it's a myth that the soil stays at a constant temperature all year. if you go deep enough, it does, but the closer to the surface, the closer it tracks the daily average temperature.

[@erockhefleyjr6852]

There is nobody better bro! 👊🏻

[@ramonbs6075]

I like that rim, that step where the walls have to go, how do you name that? what type of construction is this?

[@d.i.whynot484]

Me too. It’s essentially a stem wall.

[@ramonbs6075]

@@d.i.whynot484 thanks!

[@Jookyforever]

Those hold-downs and interrupted trimmers and jambs look super confusing. I assume there is some structure happening on the other side of that OSB?

[@RBodge1234]

I just was watching this 9/4/2021 and I saw the same thing. Maybe there are intersecting wall panels or posts that align with them on the backside of that sheathing and they used longer screws to make up for the reduced penetration depth due to the sheeting thickness? If not, they are possibly oriented in the wrong direction. Usually, hold downs of that size will be attached directly to solid sawn 4x & 6x members or built up stud groupings that are fastened together along the length of the studs so that the group act like a single solid post. Not having spent any time trying to analyze the homes configuration, I just don't know. But, it looked odd to me as well at first glance. I'm sure if it is incorrect, that when the building inspector does his/her framing inspection before giving the OK to cover and insulate that they will get it straightened out. Right?

[@whiteandnerdytuba]

What do these houses cost excluding land? Seems like all of these houses add up

[@johnwhite2576]

What tape do I use on subterra to join panels?

[@dmitry6472]

Cordless vibrators are the best!

[@L0rdEsedess]

@Matt Risinger - Could this same method work on a wood floor as well?

[@robertdean9392]

Little tip on concrete, when concrete is mixed at.plant, order it with zero injected air during mixing process. We have learned that it pretty much eliminates the need for vibration during pour and creates almost zero air bubbles in slab. It also creates a good environment for finishing the slab with a better look. Take care and see you on the next video.

[@an7h0ny88]

Air entertainment is an important step in creating stronger and more durable concrete. Concrete should ALWAYS be vibrated/consolidated no matter what you're pouring.

[@bmartaggie97]

Matt, in Deep South Texas (McAllen) we seldom see days below 50 degrees. Do you think there is enough benefit for all the days above above 95 degrees to consider insulating our foundations?

[@antoniotulum4776]

majority of mc allen houses dont have a concrete slab big enough to retain and transmit cold in winter..most mc allen houses have carpets, wood floors..... if its in an area like the house showed here, concrete slabs do get very chilly in winter...im from monterrey here where we build w e lots of concrete....

[@eh_bailey]

You might benefit from some passive cooling without the insulation

[@BrianKrahmer]

One can't answer that question without doing a heating/cooling load analysis of the given structure within a given climate and looking at the ROI.

[@bmartaggie97]

It seems that all the conversation has been around cold foundations drawing out heat, I wonder if a hot foundation will drive heat inside my cooler indoor climate enough to make a reasonable value proposition on a new construction project. Our slab will be about 6500 sq ft. I get the cold weather value, temperature delta inside to out of 30-40 degrees. But what about a delta of 20-30 degrees much of the year here?

[@jimpowell4945]

That concrete looked really wet. Were you going for a 7-8 inch slump?

[@ProctorsGamble]

Self leveling lol

[@davidfleuchaus]

After this house is finished and lived for a year or two I think the owners and designers will more easily be able to see two errors: 1. No matter how much insulation is placed under the slab, the slab will always feel cold. If you focus an IR camera on the slab floor and on a rug on the slab floor you would see no temperature change but if you stood barefooted on both portions of the floor you would feel a massive difference in temp. Why? Because of thermal mass. The raw slab floor will absorb a LOT more heat from your foot than will the rug. Although you might feel comfortable at 71F the slab being 71F will suck away heat from your feet at a rate so high that your feet will feel cold. 2. Even a non-heated/cooled building that has a large footprint will keep outside temperatures from reaching the center of the floor. I saw a non-conditioned building in Chicago built over 100 years ago that never needed heat. There was a huge thermal heat sink created by its massive footprint and by its thick walls, massive columns, etc. It never got below 50F. It never got above 78F. Solar gain warmed it and thermal mass laying on the 55F earth kept it cool. No insulation. No HVAC. Crappy old windows. So my point is that the floor insulation in the middle of this house will only be thermally breaking the effect of the 55F ground on the conditioned 71F slab. So, not a mistake per se but an overstatement of benefit. Otherwise, great project. By the way, we have a house up near Chicago that is passively cooled. The house has a large thermal mass first floor floor (6” of concrete with concrete I-beans) that is connected to a 9’ deep basement that is fully below ground. The 55F temp below the frost line cools the basement walls and the basement’s concrete ceiling. All that keeps the house very cool, passively. So next time, grab that earth temp, cool your house with it, bury PEX in the first floor slab for heating. Then all you’d need is a dehumidifier but in TX probably not even that.

[@BrianKrahmer]

I don't consider heated slabs "cold". Having lived in two houses with basement slabs heated with radiant, I find them very comfortable.

[@davidfleuchaus]

@@BrianKrahmer Me neither. The house featured here has no radiant heat

[@OU8Aspark]

Is fiberglass rebar good to use?

[@michaellautermilch9185]

You don't need it most of the time, and rebar likely isn't your main point of failure when things go wrong. In some cases rebar is better.

[@chaseweeks2708]

Kind of curious why you opted to put a ton of those Termimesh's where the pipes are coming out of the slab, rather than just where the pipes are entering the slab. I wouldn't think it would be necessary on pipes that both enter and exit the slab inside the envelope.

[@billmoretz8718]

Seems like too much work. Termites are soft body insects and here we use Duametacious Earth(spelling). It has rough edges that cut into their bodies. Since they need to get back to moisture insides block walls or under bottom plate works well.

[@aleksanteri1234]

Every new construction house in Finland has this.

[@RS-ej9zp]

Does this meet IECC 2021 Residential code for slab insulation for both under slab and slab edge below grade insulation?

[@pcatful]

Yeah, rebar in the CENTER. I see YT contractors showing it on the bottom. Others saying it's in tension there.... I don't think so. You'll demo slabs where the rebar is under the slab, doing nothing. Topping slab also facilitates radiant heating. Heavy reinforcement for the topping slab. I've seen it with no rebar.

[@scha0786]

What is the first interior pour for again? Why not just put down 4” of foam and then pour your finish slab. If it’s because your worried about scratching the finish floor? Seems stupid expensive for that.

[@cmm170526]

I think Texas needs to start considering both cooling and heating 🤔

[@xela158]

Is it really necessary to reinforce the top 4” slab above the insulation? I understand it doesn’t hurt to have it but the base foundation is plenty strong already.

[@WallyGon]

I would think that rebar will help the top slab integrate better with the bottom slab utilities and different elevations on the slab.

[@kc9scott]

AFAIK most builders that do insulated slabs have NO concrete under the layer of insulation, only rock (crushed stone). Lots of care needs to be taken to get the top of the rock layer perfectly flat so there aren’t voids between it and the insulation. The only reason to put concrete under the insulation is to get a more perfectly flat surface, and my guess is that it’d be perfectly OK for that concrete layer to just be a skim coat (without reinforcement) to even out the top face of the rock. The only reinforcement needed is in the top layer.

[@BrianKrahmer]

As an aside, this house will probably have one of the highest loads of CO2 consumption per occupant in the country. I think the 4" top slab is ridiculous. However, in the house I'm building now, I did a lightweight slab on the 2nd floor (2.25") with 6" remesh, and there are cracks radiating from every corner and every couple feet through the slab. They are small, and I expected them, and don't care, but I haven't seen such cracking from a properly prepared 4" slab. So it seems they made the correct decision, and I absolutely would be rebar in there like they did. But the rebar in the top slab has nothing to with structure, but just to limit cracking.

[@replyhere590]

Hi, Matt or anyone who will comment: If we use 5000# concrete (with cylinders, trust but verify) with fiber for our on grade slab (our all above ground 1st floor will my "basement"; size likely approaching 3000 sq ft), do we still need rebar? FYI, central VA, fairly level area for the build. Money must not be an object, with what looks like a very involved multi-step process there on this one.

[@benfowler2127]

Ok, so I have been trying to figure out what psi foam I would need under a garage slab. Foam encapsulated in a vapor barrier, thinking a 4,000-6,000 psi concrete 6” thick with radiant heat just to keep the chill off in the winter. I was assuming a 25 psi would be fine, but since you talked about it here, I’m just curious how the engineer came up with needing a 25 psi foam vs a 10 for an interior since the interior walls are not load bearing? I’m not an engineer, and not trying to cause trouble. Genuinely curious because I don’t want to under estimate the psi foam I’ll need for my garage floor.

[@pnwbuilder]

Keep in mind that it is creep load that is important, not the PSI rating of the foam. check out this page for some good info on this: www.carnationconstruction.com/Materials/07-Materials-ExpandedPolystyreneSheet.html

[@BrianKrahmer]

You shouldn't need more than 4-5" for a garage slab. 25psi will be just fine. Dow Blue Board is the most common product. I'm currently building in a very cold area, and used 2" sub-slab insulation. Vapor barrier may or may not be needed, depending on your soil conditions and climate.

[@benfowler2127]

@@BrianKrahmer Thanks for the reply. We will likely end up having equipment on the floor at some point. A skid steer, potentially a 350 sized backhoe if it was ever needed to have it inside to work on. I’m not building just a typical “attached garage”. It’s not for business so much either as it is for fixing vehicles and smaller equipment we have around. I’m mostly concerned about the concrete not breaking up. I know concrete will crack, but breaking and busting, I want to avoid.

[@mr.wizeguy8995]

You call that insulated floor. Well all new residential house here has under slab insulation usually 8 inch thick EPS. My house is built 1978 and floor has 4 inch EPS. 9:10 Nope you don't want to rebar be in center because there is neutral axis with forces you either want rebar near bottom or top where tensile stress occurs.

[@niklasxl]

damn, i thought all slabs where insulated :D though im from a colder climate :D and the load bearing lower layer being pretensioned hollow core slabs bonded together

[@bahopik]

I'm from Minnesota, and I seen plenty of slabs poured without insulation.

[@niklasxl]

@@bahopik interesting, might then just be more about what the building culture is where you are building more so then what the climate is when choosing how to build