DON'T INSULATE YOUR BASEMENT until you watch this...
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- เผยแพร่เมื่อ 20 ส.ค. 2018
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In this video we will show you how to insulate your basement properly, including the often overlooked under-slab insulation (Did you get the pun over/under...). Anyhow, huge thanks to Architect Steve Baczek for showing off his work and details for the Build Show
Steve's Website and Instagram feed:
www.stevenbaczekarchitect.com/...
/ stevenbaczekarchitect
Builder - www.shorelinebuilders.net
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Steve seems to be a humble and very knowledgeable architect, thanks for sharing!
Extremely lol!!!
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.
Matt you jsut get it man. Love your info and tutorials. Im a DYI'er and your info helps tremendously. .
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.
Always worth insulating
I've never built anything more complicated than a dresser, no idea why I watch this but I enjoy it so much!
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.
same here...
me too, minimum code is R-10 for basements here, and they've already beat it!
Ditto. So helpful!
This was great, good to see more about cold climates and more about basements.
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.
What if you cannot insulate a cold celler from outside? Any possibility to insulate from inside without risks of mould or moisture?
@@vickzin If I had to insulate from the inside I would leave a vented gap between the wall and insulation.
this.
plus...
doing a building with eps around the peremiter now. it's like -10*C for a month now... was sprayed -5*C.
no heating what so ever, and it's been a constant 5*C inside.
i imagine if it was underslab insulation, none of that free geo thermal heat would come through and it would be -10*C inside right now.
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
But can't it get into the gravel and stop the movement of any water.
@@robertgregory2618 I would think it would only makes its way into the gravel by an inch or two before it sets up.
I can't imagine that you would ever recoup the additional cost in energy savings over board insulation.
@@zzzzzzzzzzzzzzzz8635 think about it your right.the company's get the spray foam in large quantities at a discount then stiff the customers because they can.
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.
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.
I love seeing smart work done well - really cool stuff.
Excellent! Love to see these details and hear the the discussion of why and how it integrates into the system. 👍
i would suggest that you watch the whole video. baczek discussed the details and how it integrates into the building envelope system in the video.
I did watch the whole video
Getting some tricks for your property additions?
Thanks David! Hope you are well sir. Enjoy your IG feed and TH-cam channel! Your travels are my daydreams of retirement someday. Best, Matt
Absolutely!
Steve at the end made this my favorite episode!!!
Thank you!!!
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.
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.
sot he house if fucked?
One of the best builders.. homeowners lucky to have you on the project
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"!
So poly on top of insulation and not underneath?
Is this how code wants it?
@@rotaxrider in my area (central canada) I have never seen a code showing specific order... I typically do poly on top for this exact reason... Building inspectors never question it.. they just want to see proof of foam thickness if the plans called for a specific thickness..
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.
Consider insulating OUTside the foundation, That thermal mass can make a much more temp stable living space.
@@joe4324 Excavation is too costly.
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.
Its the sign of a guy who's in his environment, and knows his shit.
@@justinclark216right on. He is a professional
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.
That "interior weeping tile" solution is designed for basement walls that still have some water leakage from outside. In such situations it is better to permanently fix the water infiltration problem on the outside of the wall. When you can't dig up the outside on a cost effective basis, e.g. due to a shared driveway with a nearby neighbor, then the interior weeping system can be used with a connection to a sump pump pit.
@@paulsp6371 I have done a lot of remodeling on houses that have open cell and closed-cell they have been holding water and rotting box plates sill plates top plates and is a climate for post beetles and termites what's on paper is one thing what's going on in the field is completely 100% true Owens Corning opening letterhead stated they will not get involved with spray Foams because they feel that it's the next asbestos material and we don't have enough technology to understand it at this point
@@gaylehiner9511 I could not find that letter. Do you have a link? I have seen another video where the foam needed to be removed/replaced due to poor application and serious air quality issues. Risky when you see some of the people that are installing this stuff. Not all are quality people.
@@gaylehiner9511 The next "asbestos" is already here it is called "fiberglass"
Thanks Matt, I already have audible and I ordered the marketing book.
Save so many hours of extra labour and material if you use ICF walls!
On the build show! Love it :-)
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
The poly is also required for radon underslab control.
Mass Code requires piping installed under slab
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 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 !
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
Yup...i always groan when I see that in a home. So common.
This basement will not grow mold!!!
So helpful! Thank you!
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!
Thank you sir, I agree, if only the knuckleheads above would listen to reason...
@@stevenbaczekarchitect9431 LOL!
I'm into Monolithic Domes and there the concrete is exposed on the inside. Why? Because of 3" of polyurethane insulation on the outside.
It's like eating a Goose Down jacket to keep you warm... No, you put the insulation on the OUTSIDE.
dig out the perimeter of the slab, and slap some EPS boards around it. it'll do a good enough job, because soil is insulative and a thermal mass. you have infinite insulation on the bottom; it all escapes SIDE WAYS.
the further down you run the eps boards, the more insulative it will be. varies a bit of course. say your soil is sand; sand has a r value of 7 per foot.
run the EPS 4 feet in the ground, and the heat will have to go through R28 on the way down, and then another R28 on the way up to leak out to the surface.
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?
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.
Rob Fischer I noticed that they mentioned NOTHING about moisture barriers in this video...
Yep, that wall has 2 sides, and there is no way to guarantee that they can keep moisture out of the concrete wall, thus it has to be able to dry to the inside.
I wondered about this...check some of the articles Building Science Corp and Fine Homebuilding about why this works. According to Joe Lstibirek, PhD, 3.5” of closed cell still has enough vapor transmission to allow it to dry to the inside. Anything over that could be an issue.
Why is moisture in a concrete wall a bad thing? do you think it is going to rot?
@@Shad0wC0mpany2 That's because I believe in airtightness, water management, and surface temps of condensing surfaces - with that vapor doesn't scare me at all
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.
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.
Great!!
Daniel, tread lightly. Demand MSDS sheets on all foams you consider. Most off gas, killing anyone inside during a fire. Many breaks down from the elements and time, eventually turning to dust. Some shrink as much as 36%. Others detach when sprayed on concrete. In short, if any of these problems concern you, it's best you get it in writing. If they can't show you an "aging test" or off-gassing test or shrinkage test or loss of R-value test, then assume they can't pass one.
@@larrymaloney877 Thank you for that tip, that makes complete sense. I'm guessing that extreme temperature changes like we have, would only worsen those issues. I'm also very suspicious of the tapes being used to seal exterior sheathing/foam. Unless it's chemically bonding with the substrate, I don't see how that could last a century or more.
Matt, great video. Do you have a video on water sealing basement walls? Thanks!
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.
I want a slab house where I am in Minnesota and that looks like a great install
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.
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.
Radon (and radon mitigation systems) is pretty common in Boston area. I'm sure the building the foundation this way is more expensive than radon mitigation. And radon seeping through the concrete so it would need to be installed anyway.
Keep these northern climate videos coming! I love what you do, but I have been dying for some videos that pertain to the "other half" of the country. I think you will really expand your audience.
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.
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?
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.
good vid Matt, glad this wasn't another infomercial....stay real , stay unique ..
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
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!
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.
007vsMagua the roofing tar will eat the foam. The sand will hold water and not have big enough gaps of air to dry under slab which is important.
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.
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.
Todd, it is always a challenge to get clients to see the value. Most of them are not knowledgable. It is our job to make them see the light, and I know this, they ALWAYS have the money
Steve... they don’t always have the money. Not unless they are building custom with a finance of $850,000 CAD or more. To add all that extra care & work would be about $20,000 where I live (on a large home).
On a large addition say 18’x40’ it would be about half that just to start. Basically building costs about $100-250/sq. ft.
And that $100/square is for traditional framing meeting code with cheap Home Depot cupboards.
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.
Wow, that's some nice Detail! ...but curious about the foam Between the concrete layer? 2" slab, foam, 2" additional slab?
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 !!
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.
Entirely depends on where you live and how well you've insulated elsewhere.
The only difference there is particle size. Water will adhere and climb along all surfaces. Smaller particles = more surface area. Rocks do the same thing.
Cool stuff
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.
Ooooooooooon the build show!
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!
Nothing better than a audio book and good cans to drown out shop noise.
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.
Matt, all great info when $ is not an object on retrofit projects. That’s why the wrecking ball shows up.👍🏻😎
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!
Any columns go directly to a footing - structure before energy
Steve knows how to build!!!
Thank you
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.
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! 😊
This was down on the Cape, feel free to contact me thru my website if you'd like to chat more. I'm actually from Western MA
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!
in my area, insulation UNDER the footing would not be allowed because the footing has to bear on undisturbed.
Sonny Lloyd - yes it would be allowed. Very good undisturbed soils are at most 3000 psf, with an average assumed compaction of 2500 psf for residential. XPS foam has a minimum compressive strength of 5000 psf and can exceed 12,000 psf. So XPS foam easily exceeds the soil compressive strength a footing would bear on.
An example is a bridge project on I-5 only 10 minutes from my house where they are using EPS foam to build up 40' of depth for the road bed instead of using compacted structural fill.
understood. but i literally just tried this two months ago with a "frost protected shallow foundation" and inspector didn't allow it. maybe if i had tried your argument and provided some test data from XPS manufacturer i would have had better luck. for me in Canada, under the slab yes, under the footing no.
Micah, EPS foam has a faster wet to dry value than Xps foam, the gravel and venting provide a drying action under the slab, also long term Xps foam releases their blowing agents for ever while shrinking in size. Steve designed a residence based on a styrofoam ice chest which holds your beer cold or chicken wings hot just don't put them in the same chest or you have oven ice cubes.
Rock wool/Roxul better solution subslab - avoids outgassing, moisture damage, shrinkage
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!
I'm a big fan of Steve! He seems to enjoy his job so much.
#lovewhatyoudo
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.
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.
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?
Great job.
Is the perimeter drain that he mentions within the foundation walls under the slab? Or is he referring to a perimeter drain on the exterior of the foundation walls? I was wondering weather outside is enough or should i fit a drainage system under my slab and just below the gravel layer? Seems like a good idea to try to get both in.
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.
Loving that outro
In older New England houses with a rubble or stone foundation rather than poured concrete, spraying foam isn’t recommended. Is there another solution?
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.
Always seal the outside of your concrete walls from water penetrating down to drainage system and sleve drainage piping from sediment buildup.
@@Eger7law011 Doesn't answer the question
Hey Matt, is there any chance you can do a retrofit video for us northern homeowners who want to insulate our basement floors? I think I'm going to end up doing r5 over some seam sealed dimple mat, then a plywood subfloor over that. It should be enough to stop vapor and condensation without losing too much height in a basement without high ceilings.
mikecampanella1990 - I’m an insulation contractor in Cleveland, OH and your approach is one that we recommend and use with excellent results. Don’t know if you’ve seen the articles about this on buildingscience.com but it is well documented. Go for it, good luck with your project.
@@torstenhansen4308 great man! Thanks for chiming in! I'm glad it's a successful option because it's really all that I can do with my current home without spending entirely too much money.
@@nc3826 the only problem is that the house was made already and in 1951. Lol. So, my only option besides digging the entire yard up would be putting foam on the interior. With everything having closed cell foam on it and a full vapor seal, water shouldn't be an issue unless there was a burst water pipe down there and everything is brand new pex, in an insulated space. So, I don't see that happening. Any insulation I use in the actual stud walls will be roxul due to its no mold and fire proofing for against the foam.
@@nc3826 well, I had asked about a retrofit for the house because it's a 1951 and I'm not tearing out the slab and I'm not insulating it from the exterior. I will be putting down a dmx subfloor with 100 percent seal, then foam. The plywood will be tongue and groove and most likely floating, anchored at all wall bottom plates so no shifting will happen. I did not use pex a because I didn't have an extra fee hundred dollars for the machine. All of my own joist are accessible and ran with a manifold. I'm not worried about them at all.
I was wondering the same. I used 2in xps directly onto the concrete walls then framed over that. I was also going to insulate in the studs after running my electric, but the floor is tricky. I found some vinyl flooring that is completely water proof and goes down like a pergo floor. Just curious what i could possibly do for the floor....
How are the horizontal poly seams sealed together below the concrete slab or are they just overlapping?
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?
I was wondering the same thing. If the M joist is fully sealed inside, but not insulated and sealed on the exterior, it will wick moisture and not dry during the northern fall-winter-spring.
Dries to the outside
Check out above Matt at end of video the closed cell insulation is pulling/shrinking away from stud. This would be a major air leak. An issue I always think of where spray foam is applied and soon after gyproc covers the wall and there is over time the shrinking insulation that is allowing the air to enter building. Should a vapor barrier (plastic sealed wrap) be installed and tape sealed as an assurance against this type of incident?
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.
Does the hydro break extend below the footing too?
Yeah, Steves awesome BUtT that system is EXPENSIVE.
So is tearing up old work to do it again.
@@donnievick3076 Here's a thought, if your over 30 and you build something that will be trouble free for 70 years you will never really care when someone complains about your work. "Build and live in a house you can afford".
@@itruck1 I own a house built in 1910. The funny part is the only craftsmanship that requires attention is work done in the 70s and 80s.
HAVE YOU ANY KNOWLEDGE ON THE OUTGASING OF CLOSED CELL MAKING IT ABOUT 4.7 IN A YEAR OR TWO. What do you know about neopor 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?
M M , Two layers with offset joints limit thermal bridging cracks when foam shrinks.
I'm confused about the closed cell on the basement walls. In the floor you have EPS then poly then the slab. Why not have EPS and poly on the outside of the walls to decouple the foundation walls from the earth outside, insulate the walls, and keep the moisture barrier on the outside of the walls instead of the inside. Aside from the thermal issues, it seems that hydraulic pressure from moisture coming through the foundation walls is eventually going to push the closed cell away from the walls, and pool water between the walls and the foam. Looks like the right idea in the floor, but backwards in the walls.
Patrick It's a terrible construction, but the US can't build concrete housings. Look how it's done in Germany, they know how to build massive. Never use sprayed PU foam on the inside. It contains harmful substances. Keep the concrete on the inside, it will hold the temperature and moisture constant for good room climate.
I agree you have to keep the moisture out. With that design the concrete walls will be constantly damp.
My guess is the outside foundation walls were also waterproofed. The issue with eps on outside is in cool climates the earth expands and contracts and eventually will destroy the foam. This is why it is now required in many areas to have a 6 mil Poly between earth and eps to act as a slip but this never works in reality. The technique they are using is a very good and cost effective solution if building this way. I only build with icf which solves all these issues with ease
@@paulnovak833 How is the foam exterior of an ICF block any more resistant to those foam-destroying forces than sheetfoam or sprayfoam applied to a block or form-poured basement wall?
@James Bloom icf block isn't going to move, nor would spray foam fornthat matter
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?
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
Nope, dricore wall panels are pre-built wall sections, basically zero chance of there not being gaps behind them... When do you ever get perfectly straight walls.... Spray foam contours to the surface it's applied to
@@deftdawg When you say gaps behind the smartwall do you mean between the EPS insulation and the basement wall? Because there's *supposed* to be a gap there
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?
Being a remodel of a basement, the closed cell foam makes sense. However, if this was new construction why wouldn't the goal be to apply the insulation to the exterior prior to backfill? This complements the use of insulation under the slab. I plan to use a rockwool product because it also deters termites and does not degrade in the presence of moisture.
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).
is it ok code wise to coat the foundation with closed cell foam all the way up to and onto the sill plate ?? i thought you had to leave a gap there (which sucks) from 3 inches or more away from the sill plate (for detecting termites ? )
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
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?
interesting idea that the spray foam in the walls. But how do you deal with any moisture that's coming through the cement walls? It wouldn'thow evaporate travel down to the floor? We've always been taught to make sure that there's an air barrier between the cement and the insulation specifically for this purpose and it seems like we're totally defeating that by using closed cell foam. Is this a complete Paradigm change?
@Joe Bears yes and if you don't have an exterior one and can't add one, you should put an dimpled mat on the inside wall and an interior french drain. Water management must be done correctly before putting any insulation.
If you use a peel and stick membrane or any membrane for that matter on the interior side of the wall, it won't work. The water will push the membrane from the wall instead of pushing it toward the wall like when you put it on the outside. With enough time and hydrostatic pressure, it will unglue the membrane from the wall and you'll be back to square one.
Well the correct way to do it is to have membrane and drain, AND insulation on the outside of the basement wall. Yes in the dirt. That is how we do it in Scandinavia. But the slab thing is 100% correct and how we do it here.
@@72strand Some people do it this way in Canada too but internal insulation works as well. Plus, it blocks the footing from being a thermal bridge .
You just have to be really careful to not allow your warm air to reach the cold concrete wall and hope that your concrete won't crack after many cycle of freeze and thaw.
Actually, I think the better solution it's to put insulation on both side.
@Joe Bears the only way is too put foam under your footings. Some people do it in Canada but I would be worried about deflection personally. I would prefer to add some interior insulation instead or to not have a basement at all and have a shallow frost protected foundation instead.
I suggest ICF for the walls for that exact reason.. totally agree with slab.. I actually put mat underneath foam but my foam has locking edges to prevent concrete coming underneath...
What about off-gassing? Long term air quality studies?
I suspect that's in God's hands. ;-)
Many homes in New England have issues with radon. It's easily solved with a mitigation system that could have been installed in the basement and home walls before this project was wrapped up. it's basically just a vent tube with an air pump.
@@chrishuyler3580 Thanks. Good info
Would you mind doing a video specifically on slab insulation? I'm especially worried about the detail where the slab meets the foundation. Usually, this joint is separated by insulation (foam/rock wool). How does one prevent termite ingress into the home from this joint? It seems that it gives a direct pathway for termites to enter the home and come up into the framing.
Nunchuck Swordfish, The slab usually goes over the footing when poured so it would be pretty tough for anything to get by that.
Thanks for the reply august. Unfortunately, that information isn't what I'm looking for.
If you look at this image, you'll see that the slab and foundation should be separated in modern builds to provide a thermal break.
In my experience, the 'masticated membrane strip' that Building Science Corporation recommends doesn't work long term.
buildingscience.com/sites/default/files/migrate/jpg/BSI059_Figure_01_web.jpg