I need help with crown moulding gaps

[1big44]

It’s not your fault. Years of experience. You can’t stop the movement it’s natural you just learn where to hide it. Biscuit joint and cope the inside corners

 

[El Pablo]

This^

Those gaps do not look structural.

The dry air in the winter causes the boards to shrink and gaps will appear, especially the softer the lumber used for the trim. When the humidity goes back up, the gaps will close.

I have used a silicone caulking on gaps and it will help more than a putty will. Find the stretchiest caulk you can find and fill away.

Ditto

 

[Snattlerake]

It would seem to me that if the cuts were mitered at 33 0r 45 degrees that shrinkage and expansion would not be so noticeable when they occur.

It would seem to me too but...it ain't.

 

[Snattlerake]

It’s not your fault. Years of experience. You can’t stop the movement it’s natural you just learn where to hide it. Biscuit joint and cope the inside corners

I never thought of a biscuit joint. I have a biscuit jointer too. And some biscuits. Taking it down will be a bear because I air nailed it both directions.

 

[steelfingers]

Brilliant white expandable outside window caulk.

 

[Wannabe]

Do your best to sand all of the stuff out that you have put on it and use plain painters calk. Once it dries it will move and expand as the joint fluctuates. Then you can paint. You may have to fill it a second time after the joint expands again but then you should rarely have a problem. Been there many times before and this practice has always served me well.

 

[JEVapa]

This problem has been going on for over a year. I am trying to figure out what I did wrong. I bought wood furring strips and wood finger jointed crown and acclimated them to my house for over a month before I could start. I used the furring strips under the crown as a nailer for the crown. The room was so long I had to splice all four sides of the crown. I used white glue because I couldn't find any superglue spray to use on the joint as they do on youtube. White carpenter's glue was used for years and is still used for crown.

I installed the crown and filled the gaps with regular wood putty as I was painting instead of staining. I found out the wood crown had been pre primed with crappy primer and the paint just peeled off after weeks like poorly applied vinyl. I peeled it all off, sanded, and reprimed with a filling primer called Gripper. After two coats of Gripper, I waited for a week to apply the paint. It worked great. After a few months, the wood putty fell out. I tried slow drying silicone and waited for a week to paint that and it fell out. I applied BONDO and it lasted a month. I was told to use fast dry silicone and it lasted a month.

I'm having trouble with all four splices but only two are really giving me fits.

View attachment 248363View attachment 248364View attachment 248365

This gap has closed up about a 1/16th since last week. It is currently about 1/8th inch.

Are those butt joints or are they cut at a 45?

 

[Shoot Summ]

I never thought of a biscuit joint. I have a biscuit jointer too. And some biscuits. Taking it down will be a bear because I air nailed it both directions.

A biscuit isn't going to keep it from moving(shrinking), it might help align it. Would be tricky trying to cut a biscuit in when you miter the splice...

I will typically splice and glue longer lengths before hand, I use 1/8" or 1/4" ply glued and pin nailed on the back in addition to mitering and gluing the joint. Then cope the corner and snap in place. Glued and nailed in place joints typically separate when the heat in the house comes on.

Gluing end grain takes a little extra effort, it tends to wick the glue, I always apply glue, let it set a couple of minutes, then add more glue.

 

[VTDW1]

When we get some rain, most of that gap will close up. My last house had one section of crown that did double duty as a moisture meter or lack of

And that is why the man suggested snap joints! Makes sense to me. Wood moves and we run into that issue in woodturning especially with segmenting

 

[Snattlerake]

Do your best to sand all of the stuff out that you have put on it and use plain painters calk. Once it dries it will move and expand as the joint fluctuates. Then you can paint. You may have to fill it a second time after the joint expands again but then you should rarely have a problem. Been there many times before and this practice has always served me well.

That was the second attempt.

Are those butt joints or are they cut at a 45?

45

I used this. I didn't cope them because I flunked coping saw. I made a scarpwood jig to mark the ceiling and wall where the crown would fit and the furring strips were "relieved" of stress by cutting relief cuts halfway through all along the strip on both sides. After acclimating the strips, I could only use about half of the bundle because of the crooked bends. That's when I relieved the strips with the cuts. I checked the corners for square and the spring angle was perfect.