Built-in cabinets in basement: what goes under them?


Old 12-19-18, 12:24 PM
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Built-in cabinets in basement: what goes under them?

Hello -

I'm planning to have a carpenter fabricate and install some built-in cabinets in my basement (made out of birch plywood, poplar, and regular moulding pieces). The basement currently has carpet over a good quality pad. The carpenter wants to install the cabinets on top of the carpet (but will go along with whatever I request). My concern is that if the basement ever floods (a burst pipe?), I'm going to have a moldy mess of carpet under the cabinets that I won't be able to get out without destroying the cabinets. Should I not be concerned because the cabinets will probably be ruined by water too and will need to be repaired/replaced?

If it's better to build directly on the concrete foundation, do I need a vapor barrier between the floor and the cabinets? What do I use for this?

Thanks for your advice!
Old 12-19-18, 12:49 PM
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If it were my home, I wouldn't want them built directly on top of the concrete slab. I think I would have him remove the carpeting and padding from the area underneath, then shim them off the floor about a half inch, either using composite shims or strips of pressure treated plywood. If there is any visible gap along the bottom, it can be concealed with base moulding. A vapor barrier seems like a good idea, but I've never done this type of installation, so this is all conjecture.
Old 12-19-18, 01:22 PM
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I would remove the carpet and pad under the cabinets. Even if you don't flood it makes life much easier when you change carpet. I would also do as Mossman recommended and have a vapor barrier and some shims to prevent the cabinet from touching the concrete. And, I might even consider installing vents in the toe kick so there is ventilation underneath the cabinet to let any water vapor escape.
Old 12-19-18, 02:18 PM
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When I remodel my kitchen I took the old cabinets and installed them directly to the concrete floor in the basement. These included the counter top, sink and drain lines along with being next to the stationary tubs and washing machine. Never any problems. (I have had minor flooding due to sump pump failure.)

That being said I agree with Mossman and PD, remove carpeting. I would not bother with vapor barrier. Would it really make a difference? You are going to use a dehumidifier, right? If you had minor flooding then the carpet will soak up the worst and the cabinets will dry out. Any major flooding and cabinets would be ruined in any event.
Old 12-19-18, 03:28 PM
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I built ours on top of the carpet and pad because I was lazy, but it's just MDF and will have to be ripped out anyways if there's a flood. Something else to consider is that if you build it on the carpet, the carpet beneath will settle with the weight.

I would also recommend removing the carpet first,maybe putting down a thin sheet of rigid foam, then 1/4" plywood, then building a 2 x 4 frame on which to sit the cabinets. That will mitigate moisture and condensation issues from the slab and give a level base to sit the cabinets on. However, I didn't do any of this myself because I was both rushing and lazy. I also only paid about 300$ CDN for mine.
Old 12-19-18, 09:10 PM
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I agree with what the others have said but would potentially go one step further and be looking for a new contractor if mine had advised installing on top of existing carpet.

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