Home>Discussions>KITCHENS>Caulk gaps in underlayment or not?
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gravyboat
Caulk gaps in underlayment or not?

Hi,

I'm installing sheet vinyl in a kitchen with my neighbor. We removed the old particleboard underlayment and replaced it with 3/4" AC plywood. We left 1/8" gaps at the seams and edges for expansion.

So we were about to caulk these gaps when a friend dropped by and said he read somewhere (?) that caulk will prevent expansion and could be a problem. He said we should leave the gaps open.

We're leaning toward caulking it because caulk seems like it will "give" and allow expansion and 2) if there's a gap, even a 1/8" one, beneath the vinyl flooring it seems like that could be an issue (easy to puncture).

Then again maybe the sheet vinyl adhesive will fill these gaps and make caulking unnecessary?

Thanks for any help on this.

Debra
Re: Caulk gaps in underlayment or not?

I would think that the adhesive filling the gap is going to prevent expansion as well. If you don't fill the gap the vinyl is going to settle in there anyway. My vote is for caulk but I'm not really sure.

gravyboat
Re: Caulk gaps in underlayment or not?

Thank you both for the replies. I appreciate the feedback.

debbysewn,

Caulk makes sense to me too. It seems like it would allow more expansion than adhesive, which in my experience dries harder than caulk. But I don't really know either.

YukYuk,

So you're saying that the gaps should not be filled? Interesting. I've noticed that higher-grade sheet vinyl is much thicker and more durable these days so maybe the gaps are not a big deal.

The 3/4" plywood is due to a change in plans. Originally it was going to be ceramic tile with Ditra, so my buddy put in the 3/4". Hopefully it'll work out okay.

As for not applying adhesive to the entire floor, I've seen some people do that around here and haven't heard of any problems.

goldhiller
Re: Caulk gaps in underlayment or not?

Fill the gaps with floor leveler or similar. If you don't the cracks will telegraph thru the vinyl..and you will not be a happy camper. If you're worried about expansion, then I'd suggest you use a polyurethane caulk and allow at least three days curing time before laying the vinyl. (I have as yet to see a plywood underlayment expand enough to cause problems unless it was over a very wet crawl space....or drenched from a long neglected plumbing leak under a sink, toilet or similar. If that's the case, you'll likely be pulling up the vinyl and underlayment anyway.)

As to perimeter-only adhered vinyl.....never would it be so in my house. I can run over to friend's house and take a couple pics of one of those deals after about 10 years since install. It's a joke, but not really funny. Quality vinyl installed by a true flooring pro. He also advised them against it. The vinyl has shrunk and the gapping at the mid-room seam is atrocious. I'm talking a 3/4" gap or so.

It is not difficult to fully adhere and roll out dead smooth...if you know what you're doing and pay attention. It's done many times...everyday of the week.

canuk
Re: Caulk gaps in underlayment or not?

Yep ... totally agree with goldhiller ... imperfections will telegraph through the vinyl.
The perimeter gluing is used though I don't like the idea ... a good example is a friend of mine has to re-do their kitchen floor because the vinyl has large bubbles in the field areas because only the perimeters were adhered.[COLOR=#323232][/COLOR]

gravyboat
Re: Caulk gaps in underlayment or not?

Thanks to everyone for all the great information. It's very much appreciated.

Just to clarify:

The old underlayment was particleboard. There's a subfloor beneath that made of 3/4" T&G 3" wide planks. The particleboard was removed and replaced with 3/4" plywood.

Given this scenario, it sounds like filling the gaps in the plywood underlayment is recommended.

Here's what I'm not sure about though: If I'm understanding YukYuk correcty, if the subfloor/underlayment is a single layer on top of the joists, then filling is not recommended. Whereas if there's a subfloor layer and underlayment then filling is all right.

Is this because the subfloor reduces the amount of expansion of the underlayment?

To complicate matters further, a friend's floor is bubbling like crazy. He used flooring leveler for the underlayment gaps and also to level various spots. He has a similar subfloor. What's odd is that the floor was fine for almost two years before bubbling, and there were no leaks or water damage or anything.

In other words, I'm still kind of lost. Thanks for the Armstrong links- on page 50 it says lightly butt the panels together but don't fill. Maybe I should fill the gaps in the seams but not at the baseboards?

Thanks again for the discussion. It's both interesting and helpful.

goldhiller
Re: Caulk gaps in underlayment or not?
canuk wrote:

Yep ... totally agree with goldhiller ... imperfections will telegraph through the vinyl.
The perimeter gluing is used though I don't like the idea ... a good example is a friend of mine has to re-do their kitchen floor because the vinyl has large bubbles in the field areas because only the perimeters were adhered.[COLOR=#323232][/COLOR]

No fan here for sure.

Had to run over to that place I referred to this morning cause I look after it whilst the owners are in Arizona for the winter. Luckily it's only about 1/4 mile away. :) So......I grabbed a couple pics while I was there.

And......I was wrong about the size of the gap. My bad. :o

It's actually 1 1/8" or a hair more at the worst spot. Didn't even manage to put the tape down in the worst/widest area. Duh.

(The room is a total of 15' wide perpendicular to this gap.)

Nice, eh?

PS - Pardon the dirt you see on the flooring as that's from me when I installed a new WH over there about a month ago......and from various trips thru the snow and into the house this winter to check on things. They're due back in about a month or so and I'll wipe it up before then......I promise. :D

canuk
Re: Caulk gaps in underlayment or not?

Yikes .... that's some gap :eek:

How good are you with duck tape ? .... they may not even know ;) :D

goldhiller
Re: Caulk gaps in underlayment or not?

Yes......it tis quite the gap, isn't it?

Why...........why............why..... it's almost laughable........as some would say.

Then again, he who laughs last.......laughs best. That would be me, thank you very much. :D

The easiest way to eat crow is while it's still warm, 'cause the colder it gets, the harder it is to swaller.

canuk
Re: Caulk gaps in underlayment or not?

Yep .... I've never see a gap that large .... huge .... more common 1/8 to 1/4.

duck tape ...... duct tape ...... duck tape ....... duct tape

Quote:

The easiest way to eat crow is while it's still warm, 'cause the colder it gets, the harder it is to swaller.

I hear it goes down quite nicely with a pint of Sprucey's fine Pumpkin Ale ;) :D

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