# How to finish mitered joints w. profile



## karen_b (Apr 16, 2020)

Hello and thank you for this forum!

I have been working on my bathroom reno and have all but completed the baseboard, window casing, and door trim installation. But when I installed the first window casing, I was displeased with how the mitered corner turned out.

I measured the angles to make sure they were a true 90; then made a practice cut to make sure my saw was aligned properly and the 45 joint fit together perfectly. But when I put them up, I'm left with this big gap between them. I did paint the casing pieces before installation (I know some of you will have a preference for and against doing that. But I am super fussy about the paint finish; and I can do a better job on the painting when they are lying flat as opposed to already on the wall.) However, it is possible that any drips that went over the edges may be enough to push the raw edges away from each other. I don't know.

Meanwhile, I need to fill the gap and paint the seams. Any recommendations as to what I should use/how to best do that? Some people (youtube videos) suggest against using Dex (starts out pink, turns white when it's dry) spackle because it is softer than MDF and can shrink like caulking. Oh, and I definitely do NOT want to use caulking. (I'm morally opposed to it and suck at its application anyway.) 

I'm thinking either Dex or wood filler. Or maybe just the paint itself would be enough. If I add material (Dex or filler) then I have to deal with sanding it to the profile ~ which seems intimidating but doable.

Anyway, I'm totally stuck and hoping for some advise. Please see pictures (hopefully I attached them properly). Cheers and hope you are all safe and sound!

Thank you kindly,
Karen


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## sanchez (Feb 18, 2010)

Hi Karen,

Welcome to the forum.

I would rethink your opposition to caulk. A good grade of paintable white caulk is the easiest and best option to fill that gap. It stays more flexible than filler, which is necessary since the framing inside your walls moves.

You'll have to touch up the paint anyway once you set the nails and fill the holes. I use a 3" roller after it's all filled.

Using a wood filler/putty means you'll have to sand right where the profile changes direction and will give you more area to repaint. Filler/putty is used in the nail holes, because then it blends in completely with the surrounding wood after painting.

Those miters look pretty close. Next window, use the pieces already on the wall to mark the actual angles you need to cut. Also check your saw to make sure the blade is exactly 90° to the table.

I paint trim before putting it up too, but I paint the entire stick before cutting.

Here's a picture from one of my basement doors. There's caulk at the miter, and filler over the nail holes.


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## karen_b (Apr 16, 2020)

Thank you, Sanchez, for your response!

The biggest practical problem that I have with caulk is that any bit that doesn't end up IN the gap cannot be sanded down; and so you have an imperfect finish.

I did try painting my baseboard cap all in one piece, prior to cutting; but I use a very precarious paint technique that dries to an almost spray like finish (no orange peel effect or visible brush strokes, yay!). But it is sooooooo difficult to keep my hand that steady for that long of a continual glide across the entire length. 

How do I prevent the caulk from being slide across the finish (just outside of the gap). Even when you wipe it off, there remains a super thin film of caulk that is visible. Albeit, I don't see it on you joint.


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## sanchez (Feb 18, 2010)

Thanks, and you're welcome. But yeah, there's caulk there. Believe me, I showed you one of the best miters. 😁

Here's a picture of another one that's not that good. You don't notice it in normal daily use, but you can clearly see the caulk.

You apply the caulk as thin as you can, then use a wet finger to smooth it and push it into the gap, leaving as little as possible on top. Whatever remains outside the gaps, wipe it off right away.
Don't overwork it. Let it dry, then if it's not good enough add a bit more. You don't have to rush to get it fixed in one application.

After the nail holes are filled, and the gaps are caulked, apply a final coat of paint. This is a non-negotiable requirement for painted trim.

Also, nobody is going to peer as closely at the miters as you do, because they're looking at your entire project, so get them good enough to look at from a normal viewing distance.

Good luck!


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## sanchez (Feb 18, 2010)

Also, I'm not a professional. What I've shared is from a hobbyist perspective. I have done a reasonable amount of finish carpentry, and learned what works for me.

We have some members that are finish carpenters, so they'll probably chime in as well.


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## Frost (Sep 24, 2018)

I measured the angles to make sure they were a true 90; then made a practice cut to make sure my saw was aligned properly and the 45 joint fit together perfectly. But when I put them up, I'm left with this big gap between them.

If the joint fit great laying flat on a worktable and does not on the wall, then any gap would have to do with the piece not sitting flat on the wall. The mitered pieces are hitting on the back side. If you want to put trim up piece by piece then a good, sharp block plane is your friend. Relieve some wood that"s not seen, called backbeveling. That being said, I hate mitered trim as even if it looks great at first, it often opens up over time. I've never done production trim work so time is not an issue for me. When I do a door or window, I like to glue and pocket screw all of the pieces together before putting up ,then I'm nailing up a complete frame. Paint before or after. Joints look good and any caulk goes against the wall, not in the miter. Pocket screws are great for trim, imho. I'm sure others that do this all the time will chime in with other approaches, but this is the one that works for me. BTW, good for you for caring enough about your work to question this. Lots of people would fill it, paint it and move on. Best of luck


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## karen_b (Apr 16, 2020)

That's a good point!

On this window, the gyprock stuck out from the depth of the window frame about 1/4". I did not like the option of tearing away the gyprock; so I added a build out. 

I used 1/4" door stop, cut to match the inside edge of each piece ~ glued with tapered side down and out. The fit was pretty good and the outside edge of the casing sits nicely against the gyprock wall. But there would be some degree of difference ~ causing it to be a trifle out of flush. That could account for the gap.

I still don't know the best way to fill it.


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## JayArr (Sep 18, 2018)

I agree with Frost, backbevelling will help solve this.

Here's a video I quickly found on you tube that explains.


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## karen_b (Apr 16, 2020)

Got it.......love it! That makes perfect sense!

Thank you for your advice and for sharing the video. I will definitely do that tomorrow.

So, now how do I pull off the trim without ruining the casing or damaging the wall?


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## BigJim (Sep 2, 2008)

I didn't watch the video, but you are right. When adding to the jamb it stands slightly proud of the sheet rock, when pushing the outside edge of the trim against the sheet rock it opens the gap. As far as using caulk, use a damp rag to wipe the excess caulk off the trim. Wipe across the joint, not with it. Don't put a lot of pressure on the rag or it will make the caulk recess.

If you have other windows or doors to trim, and the joint opens like that with a test scrap, lay your pencil on the table of your miter saw under the trim close to the cut but don't cut your pencil. This will cause a back cut and make the front edges of the trim to touch instead of the back.

Another way to correct the sheet rock standing proud of the jamb, pound it flat with your hammer, just don't hit out past the trim line or it will show. You can draw a slight line with a pencil and stay inside the mark when hitting the sheet rock.

As for the open joints on the trim already installed, use a very small trim flat bar and pry the trim away from the wall slightly at the joints and it will close the joints. Shim and caulk the wall at the back of the trim. Use a damp or wet rag to remove excess caulk.

Edit*** I watched the video, I could have saved a lot of typing had I watched it first. He explained it better than I did. lol


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## karen_b (Apr 16, 2020)

I appreciate all the added detail ~ like swiping across the seam........I would have intuitively gone with the seam, thinking that it would have "scooped" out a bit of the caulk and left a ditch, had I gone across. But I will be careful about that.

And I will definitely try your trick about pulling out the outside edge of the casing, to see if that does it first, before pulling it completely off and redoing it. But I stared at it again this morning; and I'm thinking with all that extra material in there from the build out, I will probably end up back bevelling it. The cut is fine; the adjacent piece just seems to be "floating" above it.

Thank you all for your help! Much obliged. 
Karen


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## GeorgeC (Jul 30, 2008)

The gap in your joint is even throughout. That makes me think that the error is not in the degrees of the cut, but how vertical the blade is to the surface of the saw table. The error could also be in how long you are cutting the pieces.


George


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## JayArr (Sep 18, 2018)

If you can get just the top piece off you may be able to back bevel it by hand with a sanding block and that may be enough so that you don't have to remove the two sides from the frame.


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## gj13us (Apr 19, 2016)

Putty and paint make a boat what she ain't.


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## ChiknNutz (Apr 22, 2011)

I've generally had the best results using caulk. Have tried other things like wood filler but found caulk simply produced a better look. YMMV.


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## Jared Sankovich (Sep 21, 2019)

Pre assemble the casing on a bench. Biscuits or some other joinery aid at the miters. Then nail in place. 

No need for caulk or filler. If the drywall sticks out in a spot tenderize it with the closest hammer. 

The bid benefit to pre assembled (other than the miters never opening up) is that the casing can be clamped into submission and shot in place tight to the jambs and drywall..(unlike messing with back bevels and nailing up individual peices)


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## JayArr (Sep 18, 2018)

Hi Jared, I'm going to play the devils advocate on this because I've been bitten in the ass by this one...


The disadvantage to pre-assembly is that what you have built will be perfectly square and if the window frame you're putting it on isn't it will look like sh*t. 



It actually makes the trim look bad even though it's the correct part. At this point you'll need to start over and the wasted trim pieces will come out of your wallet. (unless you've also got a smaller window on site you can adapt them to.)



I do agree that pre-assembly is great, when you know the frame is square. Like in new build houses or after window replacement. In an old house when you are just replacing the trim for some esthetic reason it may be better to do it one stick at a time measuring each for a perfect fit.


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## karen_b (Apr 16, 2020)

Follow-up from the mitering saga.......

1.So I tried pulling out the outside edge of the trim to see if that would close the gap. It worked beautifully; but the shims I had were not tapered the right way and I suppose i could have eventually cut a shim a hundred times until I got the right shape. And then cut a whole bunch more for around the four pieces. But instead i opted to remove all of the trim and try the back bevel.

2. This gave me the opportunity to fix something else I had not been perfectly satisfied with.....
When i added the build out to the inside edge of the trim, it slid out of skew slightly on one of the pieces of casing when i had clamped it (i found it difficult to clamp well in the first place because the clamps are flat and the profile isn't. But as it was now glued in place, I was able to sand the overlap to be perfectly flush with the edge of the trim. Big smiley face on that one.

3. My chop saw only bevels 45 in one direction. So I had to create the bevel using the trick with the carpenter's pencil and lying it flat on the "table" of the chop saw. (Haven't learned the terminology yet for all parts of my saw.) That was pretty scary.......How to make sure I'm not cutting any of the length of the face while cutting enough off of the butt to create the bevel. The first cut went okay. But then I screwed it up royally (a few F bombs flew) when I hesitated with my blade and ended up tearing out bits of the face side of the cut. Ugh. So then I alternated cutting the bevel or sanding the bevel depending on how good I was feeling in the moment.

4. The results were "okay". Not great. But definitely a tighter fit than before. But it created some additional problems. First of all, because the build-out was added to the inside edge, the 'lip" of my casing is about 3/8 thick. So you can see a big hold in each corner of the window where the bevel meets. This will have to be filled with caulking, I suppose. One corner just did not fit well at all ~ one piece of casing sticks out noticeably from the adjacent piece. i've tried building up the difference with layers of Dex. I mean, it's probably less than a 1/16", but still quite noticeable. But I'm having a devil of a time using Dex on my nail holes, dents, and joints. It just seems to sand away, even out of where I want it to stay, as soon as I touch the soft sanding sponge to it. Argh!!!

5. The good news in all of this is that I'm becoming less stressed out about making mistakes. I actually learned a lot more from having to correct this than I would have if i'd done a good enough job in the first place.

6. Of note, I did try caulking the back corner of the baseboard where washing machine is going to go (in case it look terrible), and i was pleasantly surprised at what a good job it/I did. I made sure the hole was super tiny and had lots of wet rags on hand to wipe up.

I'll post final pictures when the job is complete (I'm working VERY slowly because I procrastinate terribly when I'm afraid of doing a bad job.). But i have one final question:

Are you suppose to caulk where the casing/baseboard meets the wall? Or do you leave it kinda "floating" along it? And what about at the bottom of the baseboard where it meets the floor?

Thank you all so much!
Sincerely,
Karen


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## karen_b (Apr 16, 2020)

Frost said:


> BTW, good for you for caring enough about your work to question this. Lots of people would fill it, paint it and move on. Best of luck


Thank you, FROST!! That felt very nice!


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## karen_b (Apr 16, 2020)

*** meant to say "hole", not "hold"


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