I am in the phase of putting up 1" XPS on my poured concrete basement walls but not sure on what way to do this. Do I just use adhesive such as PL-300 or do I use just concrete screws or do I use a combo of screws and furring strips? Since the board is tongue and groove do I still need to tape the seams with Tuck/Tyvek tape? Do I need to spray foam the top and bottom still?
Glue alone is fine. If the wall is not perfectly flat, you can use something heavy to temporarily hold the xps in place until the glue dries (about a day). I used 2x4 and plywood.
I used 2" XPS and found that the tongue and groove do not line up most of the time. For those I ended up cutting the tongues and taping the seams. I did not tape the ones that fit well.
I put spray foam at the top and bottom to seal the gaps, after I put 2x4 frames about 0.5" in front of the xps.
If you plan to finish the basement, check with your town to see if you need fire blocks. If yes, I would suggest to put fire blocks at the top first before doing xps.
I had the same question on glue pattern when I did this. I looked on different forums but didn't find a definitive answer. I might have over-done it but it worked. I did two "S" on each 2x8 panel. If your walls are in good shape, I think you can get by with less. I was able to do about 4 panels for each 10oz PL-300 tube.
I bought the PL-300 from HD. I found some online sites that sell them either in bulk or in 28oz tubes, but after shipping they came out to about the same price.
Thanks for the reply. I have one other question: How much glue should go on the board? Assuming its a pretty smooth wall do you just dab a little in each corner and then the center or do you do long verticals layers? Also is buying the tubes of PL-300 at HD the way to go or is there better/cheaper route?
Leungw,
I am getting people from other sites saying concrete screws are the only way. Did you have any trouble at all glueing these boards to the walls? Any tips? Is your basement now finished?
No, no issue with mine. I did exactly what was posted before. Just make sure that the xps is touching the wall. If not, lean something heavy on it and allow the glue to dry for at least a day.
If screw is the only way to go, I would be reluctant to do xps because of the number of holes needed in the walls.
Yes, I replaced all the fiberglass with xps at the rim joists, then put new fiberglass on the xps.
Yes, bottom plate is treated wood. It's required in my town. I have seen suggestions here saying that a foam sealer should be put under the bottom plate. But by the time I saw it I was already done with the bottom plates so I didn't do that.
My original plan was to just leave it like that and then drywall. The inspector insisted that I fill the voids with fiberglass. He said that xps is highly combustible and requires a thermal barrier directly on top. Having drywall almost 4" away is not good enough. I didn't want to argue with him so I ended up filling all the voids with fiberglass.
What part of the country are you in if I may ask? Have you been doing everything yourself- you do this for a living? What are you doing with the floor- plywood over XPS? What about heating- just opening up some returns/ducts?
I am in NJ. Yes, so far I am doing everything myself, and no I don't do this for a living. It has been a long project. I don't want the basement work to get in the way of my two little kids' activities. Being in IT doesn't really help either. :laughing:
For floor, I already put Delta-FL on the slab, then plywood. I plan to have someone come in to do carpet when I am done with everything else.
I don't know about heating yet. The basement is now the most comfortable place in my entire house, probably because of the XPS and fiberglass. I will most likely try an electric heater first if needed. If it's not enough, I will tap into the HVAC trunks.
I have read suggestions to leave a small gap between the wood framing and the xps on the wall. Putting plywood directly on top of xps on the floor seems to go against the suggestions.
I special ordered Delta-FL at Lowes. I think it's about $160 for a roll that covers 320 sq ft. (Don't remember the exact numbers.)
Check with your local AHJ. You may need fire-blocking every 10' lineally, against the concrete wall, not the foam board, as per code requirements.
The foam board may need to be positively attached (fasteners) to meet code, though local may accept wall touching foam.
I just saw GBR's comment and can't agree more. Make sure to check with your town to see if you need vertical fire block as well. It will be a pain to add later. The idea is to completely block off the wall cavities every 10ft.
This is what I did. If you look at the first picture I posted earlier, you will see a piece of wood stuck vertically between two pieces of xps. It has to go all the way to the concrete wall. Notch both the top and bottom just enough to install top/bottom plates. Then line up a stud in your wall framing to meet the one that's touching the concrete.
I used treated wood since it's touching concrete. Some had twisted a bit by the time I started framing. I used Great Stuff Fireblock to fill the small gaps.
I did not glue/screw the fire blocks to the wall. I notched them just enough so that the top and bottom plates would hold them in place. Then after the studs were attached to the top/bottom plates, I screwed the studs and the fire blocks together.
Treated wood is required on concrete but not against it: “7. Wood furring strips or other wood framing members attached directly to the interior of exterior masonry walls or concrete walls below grade except where an approved vapor retarder is applied between the wall and the furring strips or framing members.”---- http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_3_sec017.htm
Yes I plan on finishing that area. It is in the main room. I sent another picture to show how it is mounted. I plan on building walls around it with a door.
I would leave that area alone and only put xps where there's a wall in front of it.
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