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drewdin 12-24-2012 08:35 AM

Making a square doorway into an arch
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I want to convert a square door into an archway, i have been doing some google searches and I haven't been able to come up with a really good way to do it. It looks like you can either do it form scratch or buy one of those pre-done archs that you just nail in.

What is everyone experience doing this? I have a 32x80 doorway, What angles to I use for the corners? Is it trial and error? Thanks

I found this, I plan on using it as my template

nealtw 12-24-2012 12:18 PM

Yup, just like that. If you have 2x4 wall nail 2x3s across the top and sides and put up the plywood or ? and then cut a bunch of blocks 2 1/2" long go to between the two sheets around the curve. If you want to make nice angle cuts at the corners just cut the plywood first and mark the angle for cutting. If you are going to drywall the angle isn't that important.

drewdin 12-27-2012 07:23 AM

Thanks Neal, i plan on using drywall. I think I will make a few different angles to see what I like the most. Should I keep the height of the arch the same height as the other 80" door in the room or should I make it the full 8' height of the room? Decisions decisions.

nealtw 12-27-2012 08:10 AM

I would go somewhere in between so you don't interfere with crown molding if you ever want that. I don't like these doorway because most people are not happy with one and when you have different width of doorways. You want to keep the top and bottoms at the same heights and the narrow ones really start to look weard then. We have a peice of aluminium 1/8 x 1 1/2 eight feet long so we can hold it up and bend it until people like the look.

drewdin 12-27-2012 11:29 AM

good point, i do plan on having crown molding, i might keep the height of the doorways the same. I don't have any aluminum but I have plenty of scrap wood. I might cut a few just to see what it would look like. Thanks again

notmrjohn 12-27-2012 12:45 PM

Just personally speaking, I don't like the arch that ends in an abrupt angle, it looks unfinished to me. And if you look at traditional classical arches, you'll see that the diameter of the ach is the same as the width of the opening. In this case the arch would have a radias of 16".

Things to consider in the height: first just the look of the thing in relation to room dimension, ceiling height, other doors, windows etc, and the proportions of opening itself. It could wind up looking too tall and skinny. There's pro'lly some "golden ratio" about arches, but its really just what looks right to you.

Then there's leaving room above for that molding at the celing. neal is gonna put that up, It makes my brain hurt trying to remember to cut the joints upside down and backwards. I can barely miter outside corners much less cope with the inside ones.

Then there's clearance for folks walking thru. If the top of the arch is 80" and you its a full arch half circle, the sides of opening will only be 5' 4" high. Without doin geometry, I think that means you'll have 6' high 8" either side of center.

You might wamt to draw a bunch of arcs on the wall or borrow neal's aluminum strip and see what looks and feels right to you. You can cut a inch wide strip from eighth inch masonite, if you don't bend it too sharp it won't break and should bend evenly. 1/8 masonite can be used to face inside of arch too.

If you have a band saw and spindle sander, it may be easier to build arch as bench work. make your own pre-built instead of buying one. Sandwich 3/4 plywood and cut both at same time. bandsaw will keep edges square, Even best saber saws want to wander off square at bottom cut and more so the thicker the cut. You can make template and cut plywood with router and straight bit. If edges are square you can nail masonite directly to plywood. Lots of glue, nails and clamps.Even better is bending birch if you can find it in your area.Its thin, loosely glued plywood that bends into some relativly sharp curves. By building up a few layers of it, you may not need much blocking directly behind it.

I've made more arches as cabinet maker than as a house builder, but I think that unless the arch is shallow, its gonna be tricky getting dry wall to curve smoothly, flex board is available, if you can find that. Luckily I had a huge bandsaw, 4 foot wheels, watching where i put nails, i could put in solid blocking and cut the entire thing at once then run it past a heavy spindle sander. That don't help you at all but I do like encouraging "tool envy." It makes the adventures I had hauling that cast iron monster 200 miles across country, burning out a trailer bearing just as we reached the city, and watching a wheel croos 4 lanes and the median to go rolling into oncoming traffic worth it.

I probably was no help to you at all, just wasted your time. Mebbe you should ask advice from Robin Hood or william tell or some other famous archer. Don't bother Green Arrow, he's got super powers and his advice for us mere mortals is as useless as mine.

drewdin 01-02-2013 08:04 AM

haha, thanks for the info. I agree with what you have to say, its going to be tough to find the right arch to fit. I plan on cutting a few different types and seeing what is the best.

Having the radius of 16" will definitely shrink the sides so I might mess with the angles and not have a half circle. I am going to draw a few in CAD and check it out first. I'll post a few for comments

drewdin 01-02-2013 09:10 AM

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here are some archway drawings, i like the elliptical better at this point. I planned on doing a doorway but now i plan on keeping the doorway square and converting the entry way into an arch. its much bigger. 92" tall and 63.5" wide, i think it will look better as an arch.

nealtw 01-02-2013 10:02 AM

I agree with the wider opening and I would make it look like the one on the top right but I would just use a segment of a circle.

drewdin 01-02-2013 11:25 AM

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Hi nealtw, here is the standard entry way with 10" and 20" diameter corners, is this what you are talking about?

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