# Foam board and Finishing basement.



## charles3526 (Oct 15, 2015)

Hello 

Im interested in finishing my bsmt to add a playrodom for my kids. I have an above ground waste line that goes to septic tank. I want to install foam board on top of cement walls but the line sits right on the wall can i just cut the boards in half and install them up to the wast line and do the same thing for the bottom? Also i was reading on hd website​ some questions and answers about foam board insulation. Someone said to put the vapor barrier on top of the walls before u install foam board? I though it goes foam board,studs, batt insulation then vapor barrier then sheetrock. Im in NY how do i find building codes for that? Any help would be great 


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## stick\shift (Mar 23, 2015)

Generally speaking, a vapor barrier is not required over the foam since the foam is a vapor retarder.

I like your place for installing around the pipe based on what you wrote, just be sure to tape all of the seams.


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## charles3526 (Oct 15, 2015)

So its ok to cut the board and install right up to the pipe and leave the pipe laying on wall and just spray foam along the pipe where it meets the foam board?

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## stick\shift (Mar 23, 2015)

Maybe I misunderstood, I thought this was a pipe exiting the wall. It is generally not a good idea to have a water pipe (supply or drain) outside of the insulation on a wall.


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## charles3526 (Oct 15, 2015)

No this is the waste line i have a pic here. The lone gets closer to the wall as it gets closer to the outside









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## Flannel Guy DIY (Mar 12, 2017)

what happens if you get moisture between the foam board and the block? I feel like there should be some air between or paint the block with that moisture barrier paint


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## m_jg_2001 (Mar 14, 2017)

From what I've read and understand, you would glue the foam board on the wall, across the top of the block and on the end joist. Foam the bottom that's resting on the slab. The concrete should dry to the outside above grade.

I need to pull the trigger and get mine done and this is how I'm going to do it.


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## stick\shift (Mar 23, 2015)

Exactly the opposite - you want nothing between the block and the foam so it acts as one surface with the foam creating a thermal break to prevent condensation from forming on the inside surface.


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## m_jg_2001 (Mar 14, 2017)

the space the glue creates will provide a small amount of air movement


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## ront02769 (Nov 28, 2008)

The air movement in the space that glue creates is a non issue. Unless you use a fire resistant for am board, you will have to cover it with something that is fire resistant, such as half inch drywall. I don't like just gluing the foam to the foundation and then the Sheetrock to the foam. You can buy (or fabricate) panels that allow you to imbed a piece of firring ever few feel ant nail or tap on that into the concrete. Sheetrock then screws to that. Ron


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## charles3526 (Oct 15, 2015)

Thanx i was actually going to attach tje foam board to the foundation via a ramset then install metal studs then put batt insulation between studs then polysheeting vapor barrier then the sheetrock mold resitant.

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## ront02769 (Nov 28, 2008)

As long as you get the correct ramset fasteners should work. But not to bore you, habitat house I just did we got donated four bye eight two inch thick foam boards.....and donated PT two bye fours....so it was ramset two byes onto the wall at 48" centers, rip the foam to correct width and glue in between, 1/2" ply on the two byes to fir out...caulk seams, .and then 1/2" Sheetrock (also donated) over everything. And although we had that same type of waste line running 28' down one wall, we were able to just slide the panels behind it for all except the last couple of feet...because those hangers just hang it up and down, don't kee it from moving gently in and out. And this will be a rated blower door tested house.


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## hawkdriver88 (Dec 19, 2016)

I just got done doing exactly this with an identical drain line. A lot of research done here's what I did 1.5 in rigid above and below pipe. I had approx half in gap behind pipe I slid in half in rigid where I could. And spray foamed that joint where 1.5 met met.5 rigid where I couldn't fit I just sprayed lightly behind where I could Be very careful spray foam expands and my line was cast iron so expending too much behind pipe ran risk of cracking. No vapor needed with rigid al long as it's tapped and sprayed tight See my insulation help post a few up from this. This is the next problem or concern you may encounter framing infront of that drain pipe.


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## charles3526 (Oct 15, 2015)

I was actually going to use a 3inch nail from the ramset gun 2 inch for the foam and 1 inch to go into the cement wall is that good enough or i need longer? Also i was going to do 2 nails per shee one on top and one on the bottom 

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