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Discussion Starter #1 (Edited)
We recently rehabbed our home. Everything is new except the foundation. We moved in over 16 moths ago. Since then, almost every window wood trim joint has spilt. Every crown molding joint has split. Several crown molding and chair railings are cracking in the middle.

Please could someone help diagnosis why the joints are splitting and why the crown molding is cracking?

How can we repair or replace?
 

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Sawdust Creator
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What kind of moulding? Real wood? Foam? PVC?

You will naturally get some shrinkage with temperature fluctuations, but a few of those gaps are pretty large.
 

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My first thought is that the trim material had a high moisture content, but to see the lengths shrink like that is shocking. I do have to criticize the butt joints. When joining lengths of trim, they should be "scarf jointed" and glued and nailed...over a stud. See this link...
https://www.google.com/search?q=sca...y%2Ftips-techniques%2Fscarf-joints%2F;360;480
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Caulk is not a glue. All the joints should have been glued and pinned together "TIGHT" when installed. Caulking over an open joint is not the way to make a lasting joint. Caulk dries out and lets loose. Beyond those pointers, I have to ask if the house framework got rained on before it was sealed up and enclosed. If it did, when the frame wood dries out and shrinks, lots of cracks can show up, but the drywall would also crack.
 

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Looks like the house was trimmed with no heat in the house, or the trim was stored outside or stored in building with no climate control. This same thing happened to a few house we were called on to trim, the people would not have the heat on. I told them this was for them not us but they still wouldn't turn the heat on, they got the same results as your's. They asked what we were going to do, I told them nothing, we told you what would happen.

When heat is cranked up the wood acclimates to the house and it shrinks. I knew one guy who crank the heat up very high for over a week so the sheet rock and trim would do all it was going to do before painting, high utility bill but the not having to repaint off set that

At this point all you can do is recaulk and repaint, chances are it has shrunk all it is going to, but I could be wrong.
 

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Looks like the house was trimmed with no heat in the house, or the trim was stored outside or stored in building with no climate control. This same thing happened to a few house we were called on to trim, the people would not have the heat on. I told them this was for them not us but they still wouldn't turn the heat on, they got the same results as your's. They asked what we were going to do, I told them nothing, we told you what would happen.

When heat is cranked up the wood acclimates to the house and it shrinks. I knew one guy who crank the heat up very high for over a week so the sheet rock and trim would do all it was going to do before painting, high utility bill but the not having to repaint off set that

At this point all you can do is recaulk and repaint, chances are it has shrunk all it is going to, but I could be wrong.
The house was trimmed in July 2011. The house is located in the Chicago area.
 

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Discussion Starter #8
Backer board

My first thought is that the trim material had a high moisture content, but to see the lengths shrink like that is shocking. I do have to criticize the butt joints. When joining lengths of trim, they should be "scarf jointed" and glued and nailed...over a stud. See this link...
https://www.google.com/search?q=sca...y%2Ftips-techniques%2Fscarf-joints%2F;360;480
___
Caulk is not a glue. All the joints should have been glued and pinned together "TIGHT" when installed. Caulking over an open joint is not the way to make a lasting joint. Caulk dries out and lets loose. Beyond those pointers, I have to ask if the house framework got rained on before it was sealed up and enclosed. If it did, when the frame wood dries out and shrinks, lots of cracks can show up, but the drywall would also crack.
Backer board? Is backer board industry standard? How would I know if there was backer board behind trim and crown molding?
 

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Whenever I do any sort of trim job from casing to crown I always glue my miter or butt joints. Wood will always shrink over time but when you glue your joints it bonds the two pieces together. I've done several remodel jobs where previous trim wasn't glued and it looks just like that That would be my guess.
 

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My first thought would be that they just filled gaps with filler and it shrunk but the consistency in which the joints are failing makes me think A: the wood wasn't properly acclimated to the room or B: The wood is pulling moisture from somewhere it isn't supposed to. These aren't all on exterior walls are they?
 

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There's no repairing that... definitely filler in the joints and no glue.
Hate to see this, and hate to say it... but if it's a big issue, the only thing to do is replace it.
Don't know if your installer offers any warrantee or if you were given that option... might be well past that point now.
As others have said :that is the result of non acclimatization (or a poor install).
 

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+1 on the lack of acclimation. not sure if it showed up sudden like or over time. i've seen seasonal changes cause some issues, especially as new houses settle. you may find the next summer season they close back up. maybe.

if not, it is unfortunate. tear out and redo, or, personally, i would attempt to repair in a few areas. i'd clean the joint, insert big stretch caulk, smooth over and repaint. it is a cheap test, before a redo.
 

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It was probably an MDF moulding, which if not stored correctly will gain moisture. When it got warm it shrank as the moisture left. I did an experiment years ago and floated a 16' piece of base in the swimming pool for a day and installed it in my hallway to see how much it shrank. It took 2 months to stop shrinking and shrank 3/16" in length. Floating it in the pool was overkill but having moulding get rained on for a day would do the same thing.
 

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All of those failures are the result of the wood shrinking in length. Most folks will say that wood does not shrink or expand in length but it does. The movement is minimal but with the relatively long length of moundings, the small movements add up,

It also looks like the installer leaves something to be desired. The joints are not done in the manner that a good and experienced trim carpenter would do them. It looks like the improper joints were hidden by caulk which is doomed to failure.
 

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Looks like the house was trimmed with no heat in the house, or the trim was stored outside or stored in building with no climate control. This same thing happened to a few house we were called on to trim, the people would not have the heat on. I told them this was for them not us but they still wouldn't turn the heat on, they got the same results as your's. They asked what we were going to do, I told them nothing, we told you what would happen.

When heat is cranked up the wood acclimates to the house and it shrinks. I knew one guy who crank the heat up very high for over a week so the sheet rock and trim would do all it was going to do before painting, high utility bill but the not having to repaint off set that

At this point all you can do is recaulk and repaint, chances are it has shrunk all it is going to, but I could be wrong.
I agree, after a similar mishap some years back, I always let wood acclimate to the inside of the house before even using it.
 

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I was an "install and caulk" guy for many years. Had similar problems. Had base molding installed by a contractor last year (I'm tired of bending over :) ). His guys glued all of the miters using a two part adhesive specially made for molding/trim - they described it as a Super Glue variation. Sets up in about 20 seconds while holding it - then install. Couple of weeks ago I saw the stuff in a hardwood supply store. That's what I'll use next time (if there is a next time for me).
 

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I was an "install and caulk" guy for many years. Had similar problems. Had base molding installed by a contractor last year (I'm tired of bending over :) ). His guys glued all of the miters using a two part adhesive specially made for molding/trim - they described it as a Super Glue variation. Sets up in about 20 seconds while holding it - then install. Couple of weeks ago I saw the stuff in a hardwood supply store. That's what I'll use next time (if there is a next time for me).
Was it the 2P-10? That stuff works great...a local millwork company uses it on their installs.
LeoG uses it (or a variant), and I am going to start using a variation as well. I've picked up a cyanocrylate glue from my local tool store and will begin using it in my woodworking and trim projects (where required).
If used in conjunction with a good wood glue like TBII or similar, it can pretty much eliminate the use of clamps.
Leo has a better explanation of the technique...and I'm actually stealing the idea from him...so:shifty:.
 

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Did I hear my name mentioned?
 

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Ya, put yellow glue in most areas of the joint and a drop of 2P-10 or two on the ends. Press together to let the 2P-10 lock up and they act as clamps for the yellow glue. After the yellow glue dries you have a pretty secure joint. I like 2P-10 but it is brittle. If you drop a glued pc on the floor it can break apart from the shock. That won't happen with yellow glue. So you get the best of both worlds. I wish it dries a bit slower at times. Crown work is difficult to get aligned in less than 10 seconds. 20 seconds would do.
 
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