Floating An Insulated Sub-Floor On Concrete Floor

[@Pembroke1]

Awesome job, it looks fantastic Rob

[@2chipped]

This would be an excellent bone and joint saver in a shop,and allow electrical to be in/under floor for tooling!

[@doranmcferran9663]

Have been considering this for a renovation project, with an older, cold concrete floor. Can't imagine a better alternative. Big thanks.😊

[@lukehanna7440]

This is a great way of doing it. I’ve done this a few times here in the UK. On renovation jobs where existing room hight allows. We use 60mm to 120mm thick pir board with one layer of 22mm chipboard flooring, or there are t&g concrete boards available which are great to tile to.

[@listonscenic]

What a great idea. Could you also grove and layer pex for in floor heating in this at the same time?

[@TheMixmastamike1000]

This video was awesome. Thanks for sharing this clever and unique solution.👍👍

[@kevinjk27]

Do you think I can get away with only one layer of 3/4 Advantech? I have a garage that was converted to studio a few yrs ago. I put down an epoxy floor at the time. But the floor is cold in the winters. A couch,chair, dresser and refrigerator will go on top. I’m thinking of a low pile rug on top of the subfloor. Cost is a consideration. I will go with the two layers if really needed for the floor to function well. Thanks for the video, appreciate it.

[@khgreenwald]

Excellent video and information. I have a similar situation in my "this old house" basement. I appreciate the product inforomation to help guide me on my project. Thanks again.

[@awac4577]

Great idea. How did you resolve doorways?

[@glen748]

I like the idea of this process. Couple question. What do you think would happen if water would get between the concrete and foam board. Do you think it would cause mold growth? Will it dry out? I would really like your thoughts on that aspect. If that was a concern could you lay down a dimple mat as a barrier to act as a drying plane. Lastly what are your thoughts of using say rockwool comfort board or rocktop instead of the pink foam insulation? Thanks Rob.

[@ConcordCarpenter]

I don’t think either material supports mold growth. The plywood would though. I’m not familiar with rock wood board- does it have an R-Value?

[@nathanlee6539]

I’m looking to do this exact same project on a concrete pad under a covered patio. Was this garage pad sloped? And if so was there any concern with leveling the pad prior to installing the xps and subfloor? Thank you!

[@ConcordCarpenter]

Not sloped

[@bluearcherx]

this is well thought out, but I have to wonder if that Titebond is rated for the foam or if it will eat through it like most non foam board rated construction adhesive?

[@ConcordCarpenter]

No issues - check tech sheet

[@samputrah]

Why wasnt a vapor barrier needed? Over the concrete / under the foam?

[@ConcordCarpenter]

@@samputrah because the XPS board is a vapor barrier when it’s taped and sealed

[@jeffa847]

Couldn't moisture migrate up through the slab and get trapped under the foam insulation unable to dry?

[@kurtzcol]

i was thinking condensation build up and just sitting there too?

[@ConcordCarpenter]

Applying a vapor barrier on top of the slab and under the flooring underlayment prevents moisture (and the alkaline salts that moisture can pull from the concrete) from diffusing through the concrete slab. It slows or prevents water in the concrete from damaging the floor. Moisture can break down the water-based adhesive used to secure costly floor coverings and discolor or deform the flooring products. To avoid moisture imbalance and flooring failure, choose a concrete floor vapor barrier with lower permeance than the flooring cover above the slab.

[@dande19]

Is it critical to have 2 layers of advantech? Could you get away with 1?

[@ConcordCarpenter]

@@dande19 we think so

[@yalondar8957]

Can this be done on a basement floor? I have a sump pump, but I want to make sure no mold grows under the lvp I’m planning to lay down in my basement.

[@crabkilla]

What is the detail for the outside framed walls? I saw that you had double bottom plates 1:58 but those would not be accessible for drywall installation once you stack all this material (insulation + 2x subfloor) on top

[@ConcordCarpenter]

@@crabkilla in that case I guess you’ll just have to make sure you fasten into the studs

[@crabkilla]

@@ConcordCarpenter I suppose you would need to do 3x bottom plates or frame block it.

[@checkfoldcallraise]

Would this work on a concrete floor that was not poured over a vapor barrier? Or would this create a moisture problem?

[@davidbruce5377]

Rob, South Florida here. We have an upcoming podium slab or elevated slab, seaside. What's your take on using this type of floor here? Added note; we are using steel beams and columns with the base plates raised and using non-shrink grout. Clear span beams.

[@ConcordCarpenter]

@@davidbruce5377 not sure, we don’t have those kind of conditions

[@discusthrowerstate]

How did you fasting the framing(bottom plate of walls)? Did you nail/screw that through the foam all the way into the concrete?

[@ConcordCarpenter]

@@discusthrowerstate screw

[@discusthrowerstate]

@ will the foam hold up if it’s compressed? It seems like screwing through foam as a substrate may not be as stable. I’d love to know how it all worked out for you.

[@ConcordCarpenter]

@@discusthrowerstate yes it will hold up It worked amazing.

[@discput]

@@discusthrowerstate You're not screwing into the foam. You're screwing THROUGH the foam into the concrete, making sure the screw heads are recessed, so as to not cause interference with the finished flooring.

[@stevenhelu9157]

Why was Foamular NGX 400 chosen instead of Foamular NGX 1000?

[@justinhaller2055]

How long would it take to recoup the cost of that in energy savings?

[@ConcordCarpenter]

@@justinhaller2055 good question

[@robertm5969]

Compared to what? You do not want bare concrete floors in a conditioned space. I'd be more concerned with preventing mold, wood rot, controlling humidity than trying to save every last dollar

[@millertime4770]

any issues if i put poly underneath the foam? i understand your point about the foam being the vapor barrier but more often then not ive seen it done concrete -> poly -> foam -> plywood then flooring and just would hate to mess something up. great video BTW will likely do it how you described

[@ConcordCarpenter]

@@millertime4770 should be fine

[@vinhtrinh9662]

how much per sq ft installed is it to do this?

[@trevordoherty113]

If you were to do a concrete garage floor would you recommend a dimple mat underneath the foamular board first? And if I was to do rolled rubber gym flooring would that replace one of the advantech sub flooring layers ?

[@scottrellwi]

What happens if the basement floods?

[@robertm5969]

This is a garage not a basement

[@cna5018]

This is a really helpful video. Thank you for making this. Question though. If I wanted to connect my radiant heater system to this and run pec through this. How would you suggest doing that? I was thinking of either running 5/8 plywood rips to channel around the pex pipe (as opposed to buying that crazy priced quik trak stuff) Then cement board, decoupler, then tile. That brings the total height to 4.75 inches above concrete. Is that overkill?

[@BiggMo]

Being a garage, isn’t the concrete floor sloped for drainage? How did this method correct it? (Or is this a Washington St only code)

[@ConcordCarpenter]

this one was not sloped, had it been I'l probably do an SLP

[@AzadLassiter]

I assume the existing floor was pretty flat was there a need to use any self leveling compound to create a flat and level floor to start from?

[@ConcordCarpenter]

@@AzadLassiter correct

[@prototype3a]

Cordless 29oz caulk gun eh? I have a Cox 41002 gun which is pretty nice but with that amount of goop to dispense, I think you're right that a electric tool is the way to go.

[@ConcordCarpenter]

It was worth it’s weight in gold, but it will probably sit in the shop for another year

[@hermenegildoluisgasparotto7881]

Excellent work Rob! I live in a small building with townhomes over a concrete slab with an open garage underground. In the winter my house is always freezing. This method probably would work as a good insulator. Would you mind giving me your 2¢ if installing only the insulation boards and skipping the two layers of plywood would suffice to create a thermal barrier before installing a floating wood floor. I won't have enough height clearance to afford the 2 layers of plywood. Thanks!

[@ConcordCarpenter]

@@hermenegildoluisgasparotto7881 I think you need to have a sub floor under a wood floor you need to have at least one layer

[@prototype3a]

@@hermenegildoluisgasparotto7881 Even just 1.5" or 1" of foam then a layer of plywood/OSB would be better than nothing.

[@fooflateka]

Is the concrete slab all perfect and level? Partitions screwed into the subfloor penetrate below subfloor into concrete or nah?

[@ConcordCarpenter]

@@fooflateka level enough

[@fooflateka]

@@ConcordCarpenter what about the second part

[@ConcordCarpenter]

@@fooflateka We only screwed into the double layer of plywood

[@compton3611]

What was the cost per square foot?

[@POLOLOUS3]

For what they used probably $5.25 sq’

[@ConcordCarpenter]

Great question- I’d have to do the math- our labor rate prob skews that a bit too

[@compton3611]

@@ConcordCarpenter yes. I should have said, DIY homeowner price per square ft. Thanks

[@SupermanTeemo]

@@compton3611I disagree. When asking the installer what his “cost” was it goes without saying you mean materials only. When asking what he “charges” it would mean how much does the customer pay

[@uprightcr2744]

Can you run radiant through the foam?

[@listonscenic]

I had the same question. You could cnc groves for the pex right into the foam i would think

[@ConcordCarpenter]

No but you could’ve installed a radiant ready board under the top layer of plywood.

[@cna5018]

How could you integrate a radiant floor system into this?

[@ConcordCarpenter]

@@cna5018 if electric you could glue down a Electric decoupling mat. If hydronic then you install plywood designed for the hydronic tube

[@cna5018]

@@ConcordCarpenter thanks. Would you sandwich that between the plywood or just go on top of both and then put my walls up?

[@cna5018]

Sorry. I would use hydronic and tie into my current boiler system.

[@ConcordCarpenter]

@@cna5018 either

[@francislevesque1155]

Can we install hardwood floor on this setup?

[@ConcordCarpenter]

@@francislevesque1155 yes

[@SandyEdgley]

How long are the screws for the boards?

[@ConcordCarpenter]

@@SandyEdgley I forgot to click on the link and read the article

[@Pdiddy1026]

how much total height does this add?

[@ConcordCarpenter]

less 1-3/4"

[@vinhtrinh9662]

@@ConcordCarpenter how is that possible if the foam is 2", and 2 layers of 3/4" advantec is 1.5"? that right there is already above 3.5" right?

[@gravenextdoor4706]

Is this more cost effective?

[@ConcordCarpenter]

Than what? Not insulating.

[@thelunatick1993]

Vapor barrier beneath the slab? You mentioned no insulation but I am more concerned with vapor barrier. Need to stop coming up through slab and go where

[@ConcordCarpenter]

The foam is your barrier

[@thelunatick1993]

@@ConcordCarpenter Is there a vapor barrier beneath the existing slab? I am not understanding how this stops or prevents vapor drive through the slab.

[@ConcordCarpenter]

@@thelunatick1993 probably not under the slab - unknown. it prevents moisture from getting in the building space

[@gregorysampson8759]

Nice, should have offset joints 2ft. This us a good system, some install this over compacted stone, no concrete

[@executiveflooring]

That Titebond adhesive is not good for foam. It’s solvent based and will eat that foam. You need something like PL Premium! Other than that, a great install!

[@dfghdfzsd]

What was the purpose of the glue? I’ve read about the floating floor and plan to do it but have never seen the glue detail under the plywood.

[@ConcordCarpenter]

more secure - no squeaks

[@michaelvrbanac6923]

NGX 400 on subfloor? Isn't that overkill? Seems like NGX 250 would be fine unless you have some really high point loads. In that case, why not 600? 800? Advantech is extremely stiff, too, especially two layers. Just saying.

[@KALGSO]

2 layers of advantec!! What did this guy win the powerball? Why didn’t the home owner just use one giant garage size piece of polished marble ?it would have been cheaper!! 🤣😂 ✌💖🗣Mackeater!

[@ConcordCarpenter]

Haha

[@LightGesture]

I'm about to just use radiant and concrete over my slab. More mass. Seem the comparison videos. You won't make your money back n the insulation and plywood for 30 years. Do the math. Mold growth will come from a span that seats, under that thermal break, and paper thin air pockets will continue to breathe that into the building....

[@aravinyard5384]

"promo sm" 😬

[@nickluft6315]

Would I be able to lay one layer of 3/4” subflooring and then cement backer board for tile? Or do you think it wouldn’t be steady enough for the tile?

[@ConcordCarpenter]

@@nickluft6315 I would keep it as is and use a Decoupling membrane for tile

[@nickluft6315]

@@ConcordCarpenter I need the added r value for permitting reasons. So I was going to add 2” of foam board below the subflooring. But I’d like to run tile in the kitchen and bathroom if possible.