New To Me...arched Opening

alter_ego

Got a call the other day for work I have never done. Wanted to run it buy you guys and check for pitfalls.

H.O. has a single story home built in the late 80’s. Home has 9’ plate except for the living area which is 10’.

H.O. wants to have cased opening between the living area (10’) and the formal dining area expanded from about 36” to about 9’6”. They want the new opening arched and bull nosed with knockdown texture. I will have to remove two outlets (one on each side of the wall to be removed) and remove one switch that is wired with 14/3 to another switch in the kitchen. I am comfortable with the electrical portion.

I don’t have to deal with paint or flooring!

Having never done this I have several questions.

First thing, I am assuming that even though this is an interior wall it bears the weight of the raised ceiling. Should I build a brace in the living area during tear out to support the weight or could I go into the attic and glue and screw plywood to the vertical surface of the studs that extend above the wall I’m demoing?

I plan to use two 2x12’s and ½” o.s.b. glued and screwed and cut to length for the new header. I think this should be more than enough for a span of less than 10’.

Is there a mathematical formula for figuring the arch?

Is it best to frame the arch with osb braced with 2x4?

Is the bull nose going to be a pain in the arse over the arch?

I think I can pull this off in five days or less with one helper.

The customer has a budget of about 2k. My helper will cost me about six hundred for one week. I thing the materials for this will be less than 300.00 though I have yet to price my take off.

Ok that’s it… let the flames begin….

mdshunk

If your helper costs 600 bucks, and you cost maybe 800 bucks, and your material is 300 bucks, your margin is only 300 bucks not even including overhead. I don't think you can do this job for 2K.

alter_ego

Yep! that what I was thinking. I havn't quoted it yet I just asked them what they had in mind to spend on the project. I'll get more or wont do it. I am allowing five days because its new to me, without the arch and the higher ceiling in the adjoining room I could pull this off in two to three days max.

The higher ceiling has me scared....I don't know if it should but it does.

IHI

Glueing your header is a good idea for chits and giggles, but using screws is a no-no....at least here anyways since there is no shear strength to them. We're required in this area to use 16D nails 16" oc all the way across the header-both sides, and if using 2x12 there would be4 nails from top to bottom.

Definately build a temp wall on either side, that span is too wide for some make shift glue and screw method, otherwise this small budget job will cost you money when the ceiling cracks out, or even worse, if it drops...I highly doubt that, but ya never know.

As for the arch, it will depend on how high it will go and if it's a true radius (1/2 round) or more of an elliptical arch. Either way you can use a string and a pencil to draw out a perfect radius. The last ones we did I cheated and used osb and ripped lumber down so total thickness of this archways plus the 1/2" drywall would be existing wall thickness. I then made a template of the ones we were matching since they were kind of arabian looking -arch with a point at the peak. But you could still use this primative methos and a string/pencil anchored off the center of the arch at the bottom and trace it out, then cut it out. Or if your looking for an oliptical radius tie the string off at both ends of the span and leave as much slack in the string as necessary for heigth of arch and then run your pencil down the string...this will allow the string to arch in an oval type pattern instead of perfectly round/half round.

Supposed there's an easier method, but I've never been around to see it done so I just improvised.

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alter_ego

wow... found the math but..... hmmm.... wellll.... uhhhh....hmmmm....

looks kinda complicated to me. I'll try it just for fun.

Thanks for the input humper. I bet yours is the method I'll go with!

check this out...

http://www.builderswebsource.com/_discBT/00000d43.htm


Now for the tricky part. You'll need to draw an arc on the plywood that mathematically conforms to the correct width and depth. That means you need to compute the actual radius of the arch based on a preset width and depth. Using a little math, you can derive the following formula for the radius based on Pythagorean's theorem:

r2 = (r-y)2 + (x/2)2 where: r = arch radius, y = arch depth, and x = clear arch width

Solving this equation for the radius "r" yields:

r = (y/2) + x2/(8*y)

Plugging in hypothetical measurements (let's do it in feet where x = 6' and y = 0.5'):
r = (0.5/2) + 62/(8*0.5) = 0.25 + 36/4 = 9.25 feet or 9'-3"

Teetorbilt

First, you need to determine if the wall is truly load bearing. If you cannot determine this then you are in over your head and should not be doing the job at all.

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747

I know how to determine if a wall is load bearing. You look and see if any load is resting on it above. If there is then good building practices says you need to support the load before you do anything. Furthermore if you want to arch that way out your going to need to rework that load.

Teetorbilt

747, give me a 'heads up' before your next flight into PBI. I'd like to meet you.

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IHI

LOL, well after reading that I guess i did it right according to them

The string deal is the easiest, the radius will be whatever is left over and allowable so you can just sketch it out and see what looks right.

if all else fails always assume the wall is load bearing and always over build no matter what, lots easier to sleep at night that way.

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alter_ego

Thanks guys, I have no doubt that the wall is load bearing. I will brace on both sides if I get this job.
BTW. I shot that formula to a buddy of mine we call "Rain man". He is going to put the formula into an exel spreadsheet so the values can be pluged in and give you the string length. I am still grey on how I am going to draw an eliptical arch with a pencil, nail and a string cut to the length this formula indicates but he assures me he can show me in five minutes. Anyway I'll put this in the fileswap section when I get it and update everyone in this thread when its there.
I think on this one I'll sub out the framing work and watch the pro do it. I'll let him demo the wall and install the header then so I can do it hands on I'll frame up the arch.
If I get the job I'll post some pics here.

Thanks again.

IHI

Drawing the eliptical is the easy part. Once you determine how high you want the leak of the arch. tack your nails at both ends where the arch will start....if you have the piece laying on the ground a nail will be placed in the left and right hand corners where the arch will start. The hardest part is just adjusting slack in the string so when you pull the string taunt smack dab in the middle it comes out exactly on your mark you have for the arch's peak....we'll say 16" higher than the base of the plywood where your nails are tacked, now you have to tie the string off so it retaines the heigth you need but will be able to withstand some force, since now you are ready to take your pencil and place it against the string in the left hand corner. Now with slight tension on the string with your pencil start moving the pencil to the right all the while pushing against the string.

Since the string is tied off at the base, but still has enough slope to reach your peak, the pencil will transfer a eliptical shape onto the plywood. This is very simple and is easily a 3/4 day project if using hot mud to blend back in, I did 2 complete archways in under 4 hours start to finish and ready for paint, granted they were both only 36" openings, but your large opening is no different, either way this should not take more than a day to complete even with an hour of head scratching until the light bulb turns on upstairs and then you'll be like...duh, this is easy and away you'll go. Other than the eliptical shape, the rest is basic cut and dry framing that a moneky could do.

This was at my mom's house, she wanted to close in the basement stairs and add recessed shelving in the wall closing off the basement stairs.


All the other openings in her house are the same design as this, but building the box was still necessary prior to transfering the "arabian archway"


Only way you'll get better is taking a bigger bite than what you think you can handle, and this is an easy project that will give you a great fell good when your done and a big boost of confidence. you do it, and post pictures, then the next one you come across will be a piece of cake

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Teetorbilt

IHI, I've always heard of your arch as 'moorish' altough they used numerous types. Roman arches are more popular here and now.

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alter_ego

Only way you'll get better is taking a bigger bite than what you think you can handle, and this is an easy project that will give you a great fell good when your done and a big boost of confidence. you do it, and post pictures, then the next one you come across will be a piece of cake[/QUOTE]

Wow.... thanks man. Thats how I have learned everything I know. "Fake it till you make it". LOL... There has to be a first time on everything. No one was born with it.

On the time thing, I usually underestimate and wind up shooting myself in the foot so on things I have net done I try to estimate a realistic time line for the process then I add about 50%.

What would you charge in your area for a job like this?

Teetorbilt

"Fake it till you make it". LOL... " alter_ego sure has the ego part right. Maybe he'll 'fake it' and get through as another black eye on our indusrty.

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You can't solve you're problems with the same level of thinking that created the problems.

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alter_ego

Thanks so much for your insight and advice.

alter_ego

Definitions of Elliptical arch on the Web:

An arch formed by mutiple arcs each of which is drawn from its own center. Compare to a roman arch which is a semi-circular arc drawn from a single centerpoint.
pghbridges.com/termsBrg.htm




In the spirit of advancing our industry.....

Teetorbilt

alter, you had advice. Rebounded much too quickly on the supporting wall issue. What can I say?

"Faking it"? Dig your own grave. Here, this would require a contractor, permits and inspections.

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You can't solve you're problems with the same level of thinking that created the problems.

Albert Einstein

alter_ego

I didn't "rebound" on anything, I said in the origional post that I though it was a load bearing wall and ask about an alternate brace system to avoid damaging ceilings in both rooms. I did make the mistake of typing "glue and screw" in reference to building the header when I know full well screws have high tencil strength and little to no shear strength, its was a slip.

The fake it till you make it was fallowed by LOL =laugh out loud. it was a joke nothing more.

On the advice end, yes I did get advice from others and thats why I sought out this board so I could learn and grow and share what I know.

On the permits and inspection, This work will be permited and inspected as is all the work I do. The homeowner works for Verizon and wants to pull his own permit for the electrical, I told him that was fine with me and I would help him pull the wire and make the connections.

Your a mod here and I'm new to the board so I don't know how things work here but I would think personal attacks would be more appropriate in a pm rather than the open forum.

And thats all I got to say about that.