Carpet tile installation over concrete

17 years ago

I'm putting in carpet tiles in my finished basement. These are commercial tiles, not the Flor/Legato "home" versions.

Historically, the basement mildly floods about once every two years. I *think* we have that fixed now, but can't be 100% sure as it is below grade.. so that is an important consideration. The tile I've chosen does have an impervious backing and will be just fine - it's only the adhesive that I'm still at all concerned about.

Other than that, the floor is generally dry. It passes the "tape a poly sheet down" moisture test; would it be a good idea to do a full calcium chloride test?

All of the installation instructions seem to be either for easy-DIY installs ("you don't even need glue") or are the heavy commercial instructions.

I lean towards just using the commercial installation instructions - full spread of adhesive, etc - but can't find any good information on how this performs if the subfloor ever floods. And it sounds like overkill, though maybe that's not a bad thing.

The floor was level enough for the old, heavily padded shag carpet, but there are a couple of rough spots. There's minor pitting where the old tackless strip came up, and what looks like a cut-off, concrete-filled pipe sticking up slightly. I can't puzzle out what it used to be, though whatever it is it's been plugged with concrete for at least 30 years, possibly 50. My understanding is that I really don't need to worry about these spots and can just carpet over them - basically, this isn't ceramic tile or even VCT when it comes to a perfect subfloor.

I will be cleaning the concrete with TSP prior to installation in any case.

I've also considered the double-sided tape, and read about the "5-dot method" of daubing adhesive on the back of each individual tile. How do those methods work? Using tape is certainly appealing if the performance is acceptable.

Also, I do need the adhesive to be releasable. Part of the reason for using carpet tiles is to be able to remove them when they become soiled/stained/wet, so a "releasable" adhesive is a must.

Any thoughts? How should I proceed? Am I missing anything important here?

Comments (4)

steve_o
17 years ago
I can't speak to installation below-grade on concrete, because I didn't have to do that. I can tell you that you need a pressure-sensitive adhesive and that they are somewhat soluble in water until they cure (at which time you would need water and some other agent, like ammonia, to dissolve the adhesive). I went full-spread on mine because those were the manufacturer's (Interface, Mannington) instructions. But other tiles will accommodate different adhesive methods. You're not likely to give your carpet a hard workout unless you're dragging furniture or dumbbells across it, so you may be fine with a five-point spread. You also could look for a carpet that uses a softer backing and gravity to hold (Milliken makes a backing like that, IIRC). Then you don't have to worry about adhesive at all.

AFA the higher points on your floor, yes, you could lay the tile over them, but be aware that they will be wear points at best. The backing won't compensate fully for those.
perel
Original Author
17 years ago
I am leaning towards full spread. However, two things that are particularly important to me are zero-VOC and releasability. Which adhesive did you use? Is it releasable?

Fortunately, the main high point I'm worried about is actually behind a staircase, so it's not a wear area anyway. Hard to get level because it's a cast iron pipe sticking slightly out of the floor, which someone plugged with concrete and carpeted over for some reason.
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steve_o
17 years ago
I used Parabond M-5080. It's solvent-free and pressure-sensitive, so I could pull one of my tiles off the floor right now if I wanted to. There are other similar adhesives out there (Bostik, Henry, and 'most all modular-carpet manufacturers have their own brands). In fact, throughout the carpet-laying, the adhesive was never a distinct odor in the house. The barrier that had to go over the floorboard, however, could not be purchased low-VOC and it stank. I'm glad it was summertime. You won't have to deal with a barrier on concrete.
kksmama
16 years ago
I just did my home office, we're on a concrete slab foundation. I bought NuSpraylok adhesive and some discontinued commercial carpet tile from carpetbargains.com a few months ago, it waited in the garage until yesterday.

I'm delighted with the results and price of this job. It took less than a day. We just took out the old carpet and tack strips, swept and mopped. We taped newspaper all around the bottom of the walls and doors. Then I stood and sprayed the adhesive (backing out of the room to reduce the amount on my feet). Half an hour later I went in and started laying tile. We did the whole floor (only about 110 sq feet) before realizing the pattern called for a 1/4 turn and so then had to go back and turn every other tile - which greatly improved the look, since the seams now look like they are supposed to be there.

Quick, cheap, and it looks great. Thanks to Steve-O who has recommended carpet tile many times in the past!

Here is a link that might be useful: link to info on adhesive