# Rigid Foam on floor - ok to walk on?



## Rekonn

I'm thinking of finishing my basement, and putting insulation on the walls and on the floor. The stores near me carry Foamular F250 XPS foam. How strong is it? If I put down 3/4" or 1" foam on the basement floor, will I damage it by walking on it? (230 pounds) Doing things at a DIY pace means I can see myself having to use the basement before flooring is finished.


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## funfool

why would you put the foam on the floor?
I see it if it was trash and you just using it as a walkway, what flooring actually recommends you put it on the floor in prep for their product?


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## Rekonn

I am seeing it as a basement insulation technique, to prevents cold floors.
Link 1 (page 13)
Link 2
Link 3


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## funfool

Ok, I see your point. I am not going to say my idea is the only right one, many ways to do the same thing.
I would lay 2"x4" on the flat at 24" openings between the 2x4, use 1.5" rigid foam inbetween, and then 3/4" plywood subfloor on top. Then install any type of flooring I desired.

Laying the foam down and then 2 layers of 1/2" plywood on top, just sounds wrong. I assure you that it may work, I would never install it that way.
To much bounce and give, to much un needed material with 2 layers plywood, 1 solid layer is better.

So my answer is no, I would not do it that way, others will come by and give arguments why my thinking is wrong.


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## joecaption

I've use 3/4 blue foam then a layer of 3/4 Advantec subflooring.
I used 3" long Tap Cons to attach the subflooring to the slab.
I then installed a floating floor over that.
It's never moved at all.


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## Rekonn

funfool said:


> Ok, I see your point. I am not going to say my idea is the only right one, many ways to do the same thing.
> I would lay 2"x4" on the flat at 24" openings between the 2x4, use 1.5" rigid foam inbetween, and then 3/4" plywood subfloor on top. Then install any type of flooring I desired.
> 
> Laying the foam down and then 2 layers of 1/2" plywood on top, just sounds wrong. I assure you that it may work, I would never install it that way.
> To much bounce and give, to much un needed material with 2 layers plywood, 1 solid layer is better.
> 
> So my answer is no, I would not do it that way, others will come by and give arguments why my thinking is wrong.


Putting only one layer down instead of two would be nice. Wouldn't moisture be bad for the 2x4s laying flat on the concrete?


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## Rekonn

joecaption said:


> I've use 3/4 blue foam then a layer of 3/4 Advantec subflooring.
> I used 3" long Tap Cons to attach the subflooring to the slab.
> I then installed a floating floor over that.
> It's never moved at all.


Cool, I've started looking at advantec too, looks very promising. I like the floating floor method too.

So, when you were working with the blue foam, did you have to be careful with it? Or could you step on it and not worry?

Loctite PL300 says it's good for foam to concrete and foam to wood. Every hear of someone not using tapcons and just gluing foam to concrete and then subfloor to foam?


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## joecaption

It's pretty dence but I would avoid walking on it. Just walk flat footed.


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## midwestcoast

I did what you suggest in a small sunroom several years ago. XPS over slab with seams glued & taped. Edges foamed to XPS on the walls. I was using the XPS as a vapor retarder as well.
Then 3/4" tongue & groove OSB subfloor glued & toe-nailed at the seams. Then laminate floor.
I didn't glue the foam to slab or OSB to foam, it's all floating. Was kind-of an experiment in a small room in my early DIY days.
In the end it worked alright, but there is a little bounce/bubble in one spot that is noticeable by me (cause I know it's there). I wish I'd have Tap-con'd the OSB to the slab. 
I say buy your subfloor when you buy the foam & lay it down ASAP after installing the foam. Even if you just lay it loose where you walk. You don't want to dent all that (expensive) foam.


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## Rekonn

Found a Holmes on Homes vid on this, they walk on it, LINK. Still, the pink stuff comes in different compressive strengths, and I don't know which they used. The 250 stuff they have in stores by me didn't seem that strong when I pressed it between my fingers. I like the idea of laying subfloor over it ASAP just to keep it safe. 

Did you glue the laminate at seams? If it's a click lock type, maybe you can take it apart and tapcon that spot that's bugging you?


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## Gary in WA

At your location, you are thinking correctly using foam under the flooring; http://www.epa.gov/athens/learn2model/part-two/onsite/ex/jne_henrys_map.html

Figure the slab at 6' down is 10*F warmer than surface temps (45*F) or 55*F which could be a problem in the spring with a 1-2 month lag of slab/surface temp for condensation there; http://www.buildingscience.com/documents/reports/rr-0309-renovating-your-basment

Insulating the slab gives about a 37% heat loss reduction, compared to uninsulated; in my milder climate, pp.8; http://webcache.googleusercontent.c...nder+a+basement+slab&cd=6&hl=en&ct=clnk&gl=us

Though keep in mind the temp difference is only 55-68 or 13*F.

Interesting;http://www.google.com/url?sa=t&rct=...sg=AFQjCNFTd1V1OUx_SYg8SFtGAAhpW2MrVA&cad=rja

More, for your reading enjoyment; http://www.google.com/#q=deep+groun...&fp=1&biw=847&bih=483&bav=on.2,or.r_qf.&cad=b

The pink 250 compressive strength of 25psi or 3600# per square foot or one foot at a time; 2.5" x 11" foot (averaging...?) = 27.5sq.in. X 25 = 687+# --- used under 4" concrete all the time, but that's not the point; cover it right away for fire-safety.http://insulation.owenscorning.com/assets/0/428/429/431/7971e6f1-2771-43ba-b1f8-9a35bd858667.pdf Don't leave it uncovered... toxic when burned.

Gary


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