Basement floor insulation HELP

[Rory Thornton]

So i have been searching and searching for a code that relates to floor insulation in a below grade, zone 5 Basement finish project. I can’t for the life of me seem to figure this out. The table i found said r10 at 2ft or r10 at 4ft but wtf does that mean. It’s a poured concrete foundation done in 2017 and i have no idea if they poured it on rigid foam or not. If anyone has clarification on this i will forever be indebted to you !!!

thanks

 

[cda]

Welcome to the wide wide world of codes.

Give it a day or two for great answers.

I live down south, no cold no basements.

I am thinking non required??

 

[cda]

While you wait for great answers::

https://www.thebuildingcodeforum.co...ion-requirement-at-unfinished-basement.13944/

 

[Enrgxprt]

Im almost positive slab insulation ( under basement floor) when below grade is only needed if its a heated slab.

The values you mention are for slabs on grade. R10 would be needed for 2' (horizontally or vertically) and 4' is required for zone 6

heat loss is dependent on temperature difference. and adding enough earth ( the slab could be 6'-7' or more below grade ) the temp wouldn't be much different outside or inside.
That said there is no loss. But if the floor is heated to 120 (radiant) than that's a different story...

Out of curiosity, how down far below grade is the slab ? whats the frost line at where you area ?

 

[Rory Thornton]

Im almost positive slab insulation ( under basement floor) when below grade is only needed if its a heated slab.

The values you mention are for slabs on grade. R10 would be needed for 2' (horizontally or vertically) and 4' is required for zone 6

heat loss is dependent on temperature difference. and adding enough earth ( the slab could be 6'-7' or more below grade ) the temp wouldn't be much different outside or inside.
That said there is no loss. But if the floor is heated to 120 (radiant) than that's a different story...

Out of curiosity, how down far below grade is the slab ? whats the frost line at where you area ?

THANK YOU!!! That makes sense to me. Well half of the basement is totally below grade and the other half is 5 feet below grade, I believe the frost line in Massachusetts is 36 or 48 Inches. I really appreciate the feedback.

 

[rogerpa]

Floors 12" and greater below grade are not addressed in the code. The Table is referring to "slab-on-grade" floors. the insulation "depth" starts at the top of the slab and runs down to the bottom of the slab and then either outward or back under the slab (your choice) for a total of 24".
If a heat source is embedded in the slab the R-value of the insulation is increased by 5.

80% of the heat loss in a typical basement (8" concrete exposed) occurs in the top 4'.

R402.2.10 Slab-On-Grade Floors

Slab-on-grade floors with a floor surface less than 12 inches (305 mm) below grade shall be insulated in accordance with Table R402.1.2. The insulation shall extend downward from the top of the slab on the outside or inside of the foundation wall. Insulation located below grade shall be extended the distance provided in Table R402.1.2 by any combination of vertical insulation, insulation extending under the slab or insulation extending out from the building. Insulation extending away from the building shall be protected by pavement or by not less than 10 inches (254 mm) of soil. The top edge of the insulation installed between the exterior wall and the edge of the interior slab shall be permitted to be cut at a 45-degree (0.79 rad) angle away from the exterior wall. Slab-edge insulation is not required in jurisdictions designated by the code official as having a very heavy termite infestation.

 

[Sifu]

As others have said, this is only for slabs within 12" of the exterior grade. If you have a true basement, the walls will be insulated down to a depth of 10' below grade, the earth insulates the floor. See the attached for a visual reference.

 

[ameliasolis]

Floors 12" and greater below grade are not addressed in the code. The Table is referring to "slab-on-grade" floors. the insulation "depth" starts at the top of the slab and runs down to the bottom of the slab and then either outward or back under the slab (your choice) for a total of 24".
If a heat source is embedded in the slab the R-value of the insulation is increased by 5.

80% of the heat loss in a typical basement (8" concrete exposed) occurs in the top 4'.

R402.2.10 Slab-On-Grade Floors

Slab-on-grade floors with a floor surface less than 12 inches (305 mm) below grade shall be insulated in accordance with Table R402.1.2. The insulation shall extend downward from the top of the slab on the outside or inside of the foundation wall. Insulation located below grade shall be extended the distance provided in Table R402.1.2 by any combination of vertical insulation, insulation extending under the slab or insulation extending out from the building. Insulation extending away from the building shall be protected by pavement or by not less than 10 inches (254 mm) of soil. The top edge of the insulation installed between the exterior wall and the edge of the interior slab shall be permitted to be cut at a 45-degree (0.79 rad) angle away from the exterior wall. Slab-edge insulation is not required in jurisdictions designated by the code official as having a very heavy termite infestation.

I am looking for flooring that would do well in basement conditions that also has a really poor heat conductor. I was initially thinking of carpet tile, though the wife is against it I also have heard people recommend against it for basements. Another option that looks nice is vinyl planking, though I am worried that it would feel cold to the touch. I did some research and found out that cement conducts heat away from an object about 7 times the rate of Styrofoam, though Vinyl only conducts heat 5 times, hopefully giving a less cold feeling compared to concrete. I see some of the laminate use a foam underlayment, is it possible to use the same/something similar for vinyl plank? I would prefer to use something cellulose free. Any other ideas or suggestions, the cold feeling on the feet is the main reason why we don't use our basement much.

 

[ameliasolis]

Floors 12" and greater below grade are not addressed in the code. The Table is referring to "slab-on-grade" floors. the insulation "depth" starts at the top of the slab and runs down to the bottom of the slab and then either outward or back under the slab (your choice) for a total of 24".
If a heat source is embedded in the slab the R-value of the insulation is increased by 5.

80% of the heat loss in a typical basement (8" concrete exposed) occurs in the top 4'.

R402.2.10 Slab-On-Grade Floors

Slab-on-grade floors with a floor surface less than 12 inches (305 mm) below grade shall be insulated in accordance with Table R402.1.2. The insulation shall extend downward from the top of the slab on the outside or inside of the foundation wall. Insulation located below grade shall be extended the distance provided in Table R402.1.2 by any combination of vertical insulation, insulation extending under the slab or insulation extending out from the building. Insulation extending away from the building shall be protected by pavement or by not less than 10 inches (254 mm) of soil. The top edge of the insulation installed between the exterior wall and the edge of the interior slab shall be permitted to be cut at a 45-degree (0.79 rad) angle away from the exterior wall. Slab-edge insulation is not required in jurisdictions designated by the code official as having a very heavy termite infestation. metallic epoxy flooring las vegas

I am looking for flooring that would do well in basement conditions that also a really poor heat conductor. I was initially thinking of carpet tile, though the wife is against it I also have heard people recommend against it for basements. Another option that looks nice is vinyl planking, though I am worried that it would feel cold to the touch. I did some research and found out that cement conducts heat away from an object about 7 times the rate of Styrofoam, though Vinyl only conducts heat 5 times, hopefully giving a less cold feeling compared to concrete. I see some of the laminate use a foam underlayment, is it possible to use the same/something similar for vinyl plank? I would prefer to use something cellulose free. Any other ideas or suggestions, the cold feeling on the feet is the main reason why we don't use our basement much.

 

[bill1952]

Cork tiles. Easy, reasonable, shock and acoustically absorptive, decent R value, does well with moisture

 

[Enrgxprt]

As Bill1952 wrote and a great idea Cork may be your best bet. The warm feeling your looking for more than likely couldn't be had by any tile, or vinyl product even if there was substantial insulation under. The materials typically used simply feel cold even when at room temp...
Something you mentioned, 5' below grade with a 48" frost line still can get cold and cause heat loss and cold floors, especially near the exterior walls.
If it were my house and I had the headroom, Id contemplate foam safe adhesive, 2 layers of 1/2" foam seams staggered, taped and glued directly on the slab, with advantec sub flooring glued over the top. At that point Id be pretty sure the 5' depth AND R6 continuous would be much more comfortable.
You could always buy a small amount to do only a 2' x 2' area (without glue) and stand bare foot on it, comparing to the bare floor....
There are other condiserations you may want to entertain, interior perimeter french drains to a submersible pump if there is any chance for flooding, under slab venting to the out doors if radon is a local issue and the list goes on...