Flooring underlayment
joenorm
| Posted in General Questions on
I am about ready to start laying my flooring. On the upper floor I am using click together Marmoleum. The manufacturer states that on an upper floor underlayment is optional. The subfloor is Advantech. Is there any reason to include underlayment here?
On the first floor will be Doug Fir nailed floor over a ventilated crawl. The subfloor here is 3/4 T&G Plywood. This will obviously have a underlayment.
Any recommendations as to brands, type, anything else?
thanks
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Replies
Joe, if the Advantech is flat and smooth, and if you don't need to worry about the flooring height at transitions to other flooring, there should be no need for underlayment. If the Advantech joints have swelled or if you want to match other flooring heights, you could add underlayment.
Why would you say that the first floor will "obviously have a underlayment"? Is the Doug Fir 3/4" thick T+G flooring?
Maybe I misused terminology. I am referring to a vapor barrier. Like #15 felt or others.
I assumed I would need one underneath a wood floor.
Oh sorry, underlayment has two meanings and I was focused on a rigid product. This is long-debated topic and you won't find consensus on whether underlayment is necessary. I don't think it is, in most cases; the best thing it does it makes it more obvious if the floor is clean as you're laying the flooring, so you don't trap small bits of debris that would lead to squeaks. Some people think that it slows vapor movement but in most cases it does not. Some people think that it reduces squeaks but those come from wood sliding on nails, which underlayment can't help. But it's a battle I don't bother fighting; if someone wants to use it, it won't hurt anything.
Joe,
The manufacturer may be anticipating the first floor being a slab. Statistically, that may be right. You are going over 3/4 TG above a crawl that is ventilated - what kind of climate is passing under you? Plus is it bare ground (common where I am)? I would definitely consider getting a recommendation for a vapor barrier and be a bit concerned for the subfloor.
In the olden days, which I barely missed, the sub flooring would be 1x10s or similar set on the diagonal with a small gap. Oak or whatever wood flooring would be put over that on top of rosen paper or maybe 15 lb felt. The paper kept the air from flowing through. A classy job would add sleepers between paper and flooring. Floating floors don't like sticky things like felt. Nailed fir shouldn't object. Mind the nailer settings and watch out you don't make setting dings on the edge. Saw a bamboo floor once that showed every hit on the nailer.
Upstairs the Marmoleum shouldn't need one though you might want to use foam sheet to keep the foot noise down for those on the first floor. Tap dancing can get quite annoying. Pergo might have optional silencing foam that is more readily available. But do check your warranty requirements before cross shopping.