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Field joints in molding..

6196 Views 22 Replies 17 Participants Last post by  ubcguy89
I'm interested to know how you handle field joints when running molding. Particularly, with crown and base. I would also like to know your reasons for "why" you do it a particular way. Performance reasons? Aesthetic reasons? Ease of installation?

(I'm questioning "why" I see mitered field joints)
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If it's tail base I end it on studs . Other wise it's miter and nail to base of walls with small molding .
I roll 22.5 stain grade, 45 paint grade. It's the way I was brought up.
The 22.5 hides the grain transition a bit better, while the 45 add more glue surface with the opportunity to cross pin with the micro if needed.
That is a bit contradictory, but I feel 22.5 works better for non painted.
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45 with glue and 23ga pins. Sand a bit if needed.

IIRC Lone had a thread where he made straight cuts then biscuited and glued the joints. I always wanted to try that but have not yet.
45 bevel cuts usually. If it's large crown, I'll glue and pin an 8-12" long backer board at the joint.
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45 with glue and 23ga pins. Sand a bit if needed.

IIRC Lone had a thread where he made straight cuts then biscuited and glued the joints. I always wanted to try that but have not yet.
Yup. I'm back in that house a couple times a month and still can't find the joints.:thumbsup:

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45 with glue and 23ga pins. Sand a bit if needed.

IIRC Lone had a thread where he made straight cuts then biscuited and glued the joints. I always wanted to try that but have not yet.
I used to butt my joints too, it does work well. A well scarfed and glued joint also works well, but your scarf has to be tight. Glue gets much more strength when you have tight joints vs loose ones. I scarf, sand, prime with spray kilz, sand and prime again. Sanding the primer gives it that seamless look.
I used to butt my joints too, it does work well. A well scarfed and glued joint also works well, but your scarf has to be tight. Glue gets much more strength when you have tight joints vs loose ones. I scarf, sand, prime with spray kilz, sand and prime again. Sanding the primer gives it that seamless look.
The nice thing with square butts is that you can spring the joint tight, which is the next best thing to clamping pressure. I've moved away from scarf joints for this reason. As for Kilz, we have a nickname for it onsite....Magic Miter Paint.lol

After sanding pre-primed joints, we always hit it with MMP and touch sand.:thumbup:
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I use a butt joint with a biscuit. I usually work alone and find fitting the reinforced butt joint easier to fit. I can cut the second piece a hair long and force both my cope on the opposite end and my field joint tight this way.
For crown and moulding I'll do a 45 scarf joint. I always have them pointing away from and as far away as possible from the door opening. My thought is if it ever opens up it would be less noticeable because your looking down the joint instead of into it. It doesn't help in all rooms or hallways but it's worth keeping the most common viewing angle in mind. Lately for square edge base I'll butt joint and use kreg pocket screws from the back. It would take a lot for a glued and pocket screwed joint to open up.
For crown I pre-assemble the whole run on the ground. I cut the joint square, put a biscuit in and then use some 1/2" plywood or something as backing plate screwed to the crown from behind. Then I'll put it into position and having one side coped and the other side square I can pop it into position creating pressure on the joint. Minimal sanding required after.

If it's pre-finished cabinet crown, I like to cut a 22.5* scarf joint, and if the size permits I add a biscuit and a backing plate.

For base I square cut with a biscuit but snap it into place in position. I try to hide the joint behind a couch or bed or something so it won't be seen.

I know a lot of people swear by scarf joints but once I started butt jointing with a biscuit I swear I'll never go back to a scarf joint unless it's cabinet crown.
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Man, you guys make it sound easy....
The nice thing with square butts is that you can spring the joint tight, which is the next best thing to clamping pressure. I've moved away from scarf joints for this reason. As for Kilz, we have a nickname for it onsite....Magic Miter Paint.lol

After sanding pre-primed joints, we always hit it with MMP and touch sand.:thumbup:
Yup. My thoughts exactly. I may go back to it someday but I like what I am doing now. Scarfing is faster, butting takes longer to pull off good results, but once you do, it's golden.
A few years back, I got involved in a thread with Gary Katz about a method he liked to do. I thought it was overkill at the time, but have since decided that it was a very good way to deal with extra long runs. If I remember right, he did scarfs on the flat at maybe 30deg, ca glued joint, & ca glued a backer strip across the back side. I could see this working very well on extra long hallways and such. The hardest part would be handiling a 32' piece in the saw. If it was 20 ft run, you'd glue up a 21ft piece, & do cuts.
Joe
Railman said:
A few years back, I got involved in a thread with Gary Katz about a method he liked to do. I thought it was overkill at the time, but have since decided that it was a very good way to deal with extra long runs. If I remember right, he did scarfs on the flat at maybe 30deg, ca glued joint, & ca glued a backer strip across the back side. I could see this working very well on extra long hallways and such. The hardest part would be handiling a 32' piece in the saw. If it was 20 ft run, you'd glue up a 21ft piece, & do cuts. Joe
It sounds like the method myself and a few others mentioned of butt jointing the pieces and using a biscuit and a backer would be much stronger. I could be wrong though, but do you and why do you think that method is better, stronger?

Particularly, I see a lot of benefit in snapping the piece in so the butt joints get tighter. A scarf joint would slide past each other if it was cut snug.
Mostly butt joints. To make up a really long piece, scarf, glued and reinforced.

Glued scarf joints don't make full strength of the wood until they're down around 10 degrees - not happening, so you need reinforcement.
hmmm spot prime your scarf joints eh after sanding flush.. ill have to do this next time, i have a can of bin spray primer thats nearly empty.. ill give it a go..

might get some extra brownie points with the cute painter lady
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hmmm spot prime your scarf joints eh after sanding flush.. ill have to do this next time, i have a can of bin spray primer thats nearly empty.. ill give it a go..

might get some extra brownie points with the cute painter lady

Kilz works better. It's a higher build primer. Sand, prime and sand again. The primer fills the minor witness line left by the joint. It will take you from a well executed joint to a flawless one. I can't find the joints no matter how hard I look after its painted.

And don't say it's the painters job, you will be lucky if your avg painter can properly fill nail holes.
For crown and moulding I'll do a 45 scarf joint. I always have them pointing away from and as far away as possible from the door opening. My thought is if it ever opens up it would be less noticeable because your looking down the joint instead of into it. It doesn't help in all rooms or hallways but it's worth keeping the most common viewing angle in mind. Lately for square edge base I'll butt joint and use kreg pocket screws from the back. It would take a lot for a glued and pocket screwed joint to open up.
Similar here. 22.5 scarfs, glued & nailed through the joint, bit of blocking behind it, over stud, pointed away from the door. The "why" is so I can nail through the joint.

I scarf the base moulding at 45, too. I don't always glue it together, but I like to nail against the other piece.
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