View Full Version : framing a large eyebrow window

Sandy Burke
01-08-2001, 10:29 AM
am an architect who wants to get it right for the framer. Have a 13'w. x 6' (at apex of 1/2 round)window to be framed off a 2x6 exterior wall onto a 10:12 pitched roof framed with 2x12 rafters. What is the most efficient way to detail this framing? Thanks for any input!

Mike Sloggatt
01-08-2001, 08:17 PM
I have uncovered a few of these over the years. Most of them were 'hacked ' out of 2x12's with an adz axe. They were rough but the finished outside & inside were very forgiving- (plaster & cedar shingle)
Today we need to be a bit more precise

I started to describe my method on the post here but it got very convoluted - So I simplified my answer & decided
The best thing I can do is fax you or email you a hand drawing of my method -
Basically I make a plywood truss for the 'gable' end- than project the eyebrow rafters straight back to the main roof. A classical design would be to taper the rafters as if going to an intersection in the room. This makes for difficult sheetrocking - So I keep it level & straight - Running my eyebrow rafters like a barrel roof is framed.

That is perhaps the easiest way - There are others - such as building decending plywood rafters - I find it time consuming & uses a lot of Plywood. -

I'm sure there are a lot of different approaches that framers take - So Lets see what the posts Bring


Sandy Burke
01-08-2001, 08:41 PM
Thanks Mike for the speedy response. I realize a sketch is worth a thousand words-please fax to (360)842-3892.Thanks!

Sandy Burke
01-08-2001, 08:46 PM
Very sorry Mike, the correct area code for my fax is (206)842-3892

Warren Camhi
01-09-2001, 08:52 AM
I was reading your discription and it sounded interesting .... could you e-mail me a copy of that drawing.....Thanks

01-09-2001, 01:19 PM
Slog, you mean you don't taper those rascalls. That takes all the fun out of building one. You should slope the roof up hill and taper them inward or you just have an arched dormer window. You can make either plywood ribs that consistently get smaller or run rafters following a plywood arched form in front. The dormer pitch is usually less than the main roof. If doing a rafter method, creat a plywood form that makes the graceful curve of the front of the eyebrow. Inside it will rest the arched window opening. The plywood patern will help create the eyebrow look as it progresses up the roof.
With the pattern set up plumb on the roof, start in center and establish the top or center rafter. Let it run at its desired pitch till it dies into the roof. To do this set up a rafter that will be short of the intersecting point. Hold it in place so it is plumb at the called out pitch. Extrapolate with a straighedge or string till it hits center and into the existing main roof at the same time. Do this to all the others. You will create a bell type curve onto the main roof. Keep the rafters close on center such as 6" this will deliniate a nice tight curve. Of course this is impossible to do and understand by email.

01-09-2001, 07:09 PM
One of you guys needs to get a picture on the forum for us. Ask ol' "More Than A Carpenter" over on the Trim forum, he's given us drawings in past as I recall.

Others of us would like to see this, I'm sure.


Mike Sloggatt
01-09-2001, 09:23 PM
Dunk -
I prefer to frame them the way you describe... They are the real Mccoys ..
I've done them the real way when they are in an unfinished attic & not too big. There is some convoluted method to laying them out that I can no longer recall where I read or saw it..
I found that the last one would have presented the drywallers with a bit of difficulty & the roofer wanted to roll a copper roof over the top so he needed a flatter surface -
Economics was definately the key here . Let's say I cheated & the roof resemebled an eybrow - Most folks would never know the difference . I suppose thats the New York mentality taking over ..

However to describe this framing method here is downright impossible -- But it would make a great JLC Live presentation ! Who wants to sponsor it !

Gary Hansen
01-10-2001, 10:32 AM
I have 3 "Eye brow" dormers that were designed for two differant jobs. One will be a lay on a 30' side of a hip, the other two will be entry way over hangs. I have three questions, 1) I would greatly appreiate anything that could be faxed to me on this subject @ 952-934-4603. 2) If anyone has any ideas on estimating or even ballparking this type of roof? 3)Can aphalt shingles be applied to this type of roof? Thanks for any info to my questions

01-10-2001, 03:42 PM
Mike, I agree about the economics, authentic eyebrows are about the coolest looking dormer window around but clients aren't always willing to pay the cost to put on one of these jewels in its pure form and usually compromise. Anyway for Gary: I think a competent roofer can do an eyebrow with asphalt composition, just work out a good flashing detail and valley weave the shingles to create the curved valley. Easy to say but of course still is tricky to do. The valley flashing might not be metal, probably a more maleable material like some bituthene stuff. As far as cost, this is a labor bid yes,heres a wild Texas quess for ya. Depending on pitch of main roof and size I wouldn't bid less than four days two men. I wouldn't put more than two guys on it, cost enough for just those two to scratch their heads for several hours each day. That would include creating the supporting main roof structure, building the window dormer wall, setting up all the rafters and sheathing. Add a little more for interior work to create a drywall or plaster frame work. Now of course add two more days to cover your butt. As far as reading material there is something on eyebrows in the roof framing book by Taunton Press. If you read FHB, its advertised in the magazine. The book is a reprint of roof framing articles. The article is titled "raising an eyebrow" The Book is called "Framing Roofs, for pros/by pros, the best of FHB." Check it out.

Gary Hansen
01-10-2001, 08:36 PM
Thanks Dunk, For your response so quickly!!! This is a great site for support and a valuble tool.