No. You need to allow for expansion and contraction. The 'gap' will be covered by the trim. (I want to say quarter-round, but that's not quite right.)

Thanks, chisue. Drywall expands & contracts? We'll have baseboard but no crown molding at the ceiling . . . I can't remember what it looks like now where the drywall meets the ceiling. Wonder if anyone but us knows that there's no crown; wonder if there's a gap at the top? Gah! will run out there and check!

I've never heard of allowing for expansion/contraction of wallboard. On a standard 8' wall the actual wall height w/ the drywall hung on the ceiling is 8'1/4" leaving a gap at the floor as wall board is 4'x8'. On smaller walls or taller walls, ive always seen the rockers just run it tight to the floor.

You might consider dap low expanding/water based foam,(in the blue can). It stays relativaley soft (doesn't harden), and is easy to work with. Because it stays flexible, it will give should there be any movement of the board, even though i've never heard of that, doesn't mean it does not happen.

What kind of ceiling do you have that has a gap?
By the time you install baseboard, and then possibly quarter round or shoe mold there is not a lot of opening left for dust to go through.

Usually you'll caulk the baseboard if painted white and that would cover the gap. Not sure what you mean with the ceiling and not having crownmolding. There shouldn't be a gap there.

Sealant at that location would be for acoustic separation. Dust in a house comes from what is brought in on clothing or the wind and detritus from skin and hair. The sealant would have no effect on dust or moisture in your house.

You can use acoustical caulking at such gaps. But, as the name implies, it's for reducing sound, not dust. Very messy stuff to work with.

What kind of insulation is that rollie? Cellulose batts?

SHOE! That's the word I couldn't remember.

I was thinking of our wood flooring when I mentioned leaving room for some movement. Missed the part about the ceiling; shouldn't have a gap there.

The insulation above appears to be blown-in fiberglass, or "blowing wool," behind a bib system.

Worthy,

Its stabilized cellulose.

no bib

Ditto on the acoustical sealant, Used that stuff once for the seal between the plate and the floor sheathing. No problems, till the carpet layer was "caulking" in the carpet, and his tool got full of the stuff. which came back out onto the carpet when he retracted the tool.

Black Death, we use to call it. "It" being Tremco acoustical sealant.

Oh my! I hope I don't sound like too much of a groupie, but it's wonderful to see your post, Mightyanvil. I'm a dedicated lurker and have sorely missed your input.

oops...sorry! That insulation looks almost identical to our blown in fiberglass insulation, which is behind a bib. Although, to be precise, we have only managed to insulate one room so far because they cannot get the roof/brick/windows to stop leaking...it's a cat chasing its' tail at this point!

nuther, you don't sound like a groupie at all. It's always nice to see Rollie, Mighty and Worthy around here.

I hope you all have a good 2008!

I second bungeeii and nutherokie!!! I always value their opinions/suggestions along with Sierraeast :-)

I'd do it - it certainly can't hurt. We have a house built in 1998 that has no seal between the drywall and floor - we have hardwoods, not carpet, and in the winter, we can feel significant airflow coming out between the baseboards and the flooring. In fact, we had the house resided (long story, check here if you're curious) and had streaks of drywall dust streaming out from under the baseboards from all the banging on the exterior walls - we could see exactly where the air leaks were by the dust patterns on the floor.

So anyhow, it is now on our list to seal this gap. Because the floor is not even (it is random-width pine) and gappy where it hits the baseboard, caulk by itself is going to look awful, so we either have to remove the baseboards, caulk behind them, then reapply the baseboards. Our other choice would be to caulk then install shoe molding to cover the caulk. We're going to try that first and see if we like the look because we're afraid of damaging the drywall if we try to remove the baseboards. Either way it's a pain in the butt, though, which is why I vote that if you can do it now quick-and-easy-like, do it. What do you have to lose other than the cost of a couple tubes of caulk and a few hours?

Not in the same company concerning building sciences as worthy, mighty anvil, rollie, and others but thanks kelntex. Welcome back to you as well. I've learned a great deal from them, you and others on these forums over the years simply by reading the posts and responses as well as corrections when im wrong!

Here's to a great new year to all on your projects, builds, and life in general!

Geeze! Thanks. And the best to everyone else too. I learn at least as much here as I try to share. Plus I get to see some fabulous homes and rooms!

It would be more typical to have the plate/floor intersection caulked, as this will stop air infiltration that would carry the dust into the living space. If the base/floor gap idea is objectionable, have the base installed 3/8" above the flooring and fill the gaps with medium-expanding foam insulation. This will close everything off, but be careful if the finished flooring is already in. The gap is then covered by shoe or quarter round. We typically do this on old draughty houses. It is quite effective for balloon framing where there are no top or bottom plates to caulk to.
Casey

I live in a desert area of Calif with strong seasonal winds. On the south facing wall significanr amount of dust accumates on top of the floor baseboard....significant meaning in that closet over time will accumulate on clorhing hanging near the floor. This is the side of home facing the wind and this happens in garage wear there is no baseboard but at the drywall floor joint. I also get this dirt type dust at interior bottom of all sliding wind tracks. I feel if i could seal this it would dramatically reduce dust. Even with a smal crack (in between kitchen door weather striping repair/replacement the kitchen will look like it was dust for finger prints. Beside dirt/dust at baseboard the bottom corner of kitchen door is my nemesis....any suggestion...seems removing baseboard and calking would work i guess?

As an FYI... it is now recommended to seal the drywall on exterior walls, too. The material used isn’t caulk, though.

jannicone is doing this now. I can look up the material later. I haven’t yet used or even ordered it.

Good question and comments. This is often the leakiest transition in most homes, mainly at foundation to framing. The typical sill sealer used here is too thin. Best to use thicker sill sealers, gaskets or caulk the top and bottom of thin sill sealer during installation. Since most architects and builders miss this detail, it can help to caulk the sill to the foundation while there is still access from the inside.

If you can't reach the sill plate, it can still help to caulk the drywall to slab, subfloor or finished floor. This can help mitigate moisture, bugs, dust and energy loss. If your wall cavities aren't spray foamed, dense packed, or SIPS, then they are probably acting as air pathways to some degree. Air can be pulled through them from the basement, attic or floor framing cavities and with it can come dust.

Stopping this sort of unwanted air movement is better from a moisture management standpoint as humid air traveling through cold building cavities leads to hidden moisture problems.

Acoustical caulk, urethane caulk or high quality one part spray foam are good materials for sealing. I wouldn't bother with Dap's and other water based spray foam, I've seen it turn to dust with light touch, just days after installing.