Crown molding?

Question

I mitered my corners for crown molding and applied DAP painters acrylic latex caulk (25yr) in the corners. after six months they are starting to separate. Should I have glued befor I caulked?

Answer 1

It is winter time and you have your heat on. The heat rises and dries out lumber, like crown molding, and it shrinks causing the cracks you see. When summer gets here it will probably expand again and the gaps will close. It is especially a problem in areas that typically have high humidity during the spring, summer, and fall months because the materials (crown molding) naturally are at an expanded state but shrink when put into a dry climate. MDF and pine trim all react the same way. I've been battling this reaction my whole construction career. We use the best caulks available and still encounter your situation. My crown is doing the same thing and I built it this past spring and summer. Re Dap if you want it to look nice now or wait till spring.

Answer 2

Tootall11 is on the right track. My inside corners are all coped, and I spring the longest piece into the joint. I get no cracks on inside miters in the winter. That still leaves the outside miters. There is little you can do about those. I have taken to using PVC crown. It is glued together with plumping glue, and is nearly seamless. In this application it is better to cut inside miters for a larger gluing surface.

Answer 3

well that is standard procedure when mitering, gluing them. however, if done right, why do you need to calk in the first place. another question this brings up is why are they seperating? Sounds to me like a botched job or you have other things to be worrying about. i prefer to cope them anyway, it gives a much better appearance if done well and allows for the angles to be slightly off. still, I would be very curious to know the reasons they are seperating. too much moisture in the air, improper sealing,. something. You did paint the back side before you installed it didnt you? or use a sealer on it? if you do not seal the wood properly, it allows moiture to penetrate and or evaporate, causing the wood to swell or shrink. another tip, cut the pieces slightly longer than you measure, and if required shave them down until you get a perfect fit. When i did it all the time, i would always cut them at least a 64th of an inch long, sometimes in hard to measure places leaving as much as a quarter of an inch t allow for fudge factor.

Answer 4

Yes, the caulk doesn't hold it together. The glue, nails, staples will. The caulk will fill in the cracks.

Answer 5

I've seen magazines with similar styles and the cupboards that go all the way to the ceiling would not have the crown molding of the rest of the kitchen.

Answer 6

caulking is a sealant, not an adhesive
you can still put a bead of paintable glue in the gap

Answer 7

This is not uncommon, caulk shrinks after time, just apply somemore, you shouldn't have to do it again.