We are working with a client to design a shed dormer addition above a 3 car Garage. The Garage has a 12/12 roof. In order to get an 8’0″ flat ceiling the shed roof will be aobut a 2.5/12 which will work because they want standing seam copper for the roofing materials. The client has asked us to find architecture rules of design that state what the ratio between the main roof (12/12) and the shed dormer roof slopes should be. So far we haven’t found anything about this. Any help would be appreciated.
Dennis D. Gehman, CR, CLC, CKBR
President, Gehman Custom Remodeling, Inc.
355 Main Street
Harleysville, PA 19438-2417
NARI National Association of the Remodeling Industry
NARI CR – Certified Remodeler
NARI CLC – Certified Lead Carpenter
NARI CKBR – Certified Kitchen & Bath Remodeler
Office: 215.513.0300
FAX: 215.513.1280
E-mail: [email protected]
Website: www.gehmanremodeling.com
Replies
HEY DENNIS!
Duane Kriebel here! Small world huh?
I am DOING copper roofing here in LEX. KY. Starting 70 sq. first thing in the morning.
We do any pitch to any pitch BUT the flatter the roof gets we go to flat seam..lemme ask the contractor that I sub too..his handle here is "Cu"...if he doen't catch up with this thread, I'll put the bug in his ear.
Honestly, I have never heard of any specific ratio rules, and we do a LOT od Standing and flat seam. As a matter of fact, even standing seam,I did last spring was mebbe a 1/12..
Stick around and stay in touch [email protected]
Man, it has been a LONG TIME buddy. No, I don't have any more wooden snoflakes..(G)
Spheramid Enterprises Architectural Woodworks
Hi Duane,
Wow, it has been a long time. I recently came across some of your snow flakes and wondered what you were up to.
Please accept my apology for the percieved advertisement. That wasn't my intent, rather I get frustrated on these forums by not knowing who is on the other end. My goal is to always be up front and keep the cards on the table.
I have checked out the "Golden Ratio" and have found that it more complex than I have time or interest to pursue at this point. In the business of life and business I was hoping for a reference manual that would say this is how the shed roof should be proportioned to the main roof.
I agree with the comment made that it's really up to the client. I believe the clients are telling us in a round about way that they didn't like what we showed them and that we need to try again. They too aren't sure what they don't like but know that it doesn't suit them and would like some rational reasoning other than personal 'asthetics' to give them comfort that when they see what they like others will like it too.
Builder1
Hello there - just wanted to mention privately that there's a typo in your personal quote. Normally I wouldn't bother, but when somebody quotes the Bible, I always think they want to get it right. Like others have said, welcome and good luck!! Don
I'll email ya when I can cool off a bit, it was a hot one again today up on the copper. Wait till you see this job, it is amazing.
8 barrel dormers from a 12/12...whole job is 70 sq. Be there for a month I bet.
I'll catch ya real soon, stick around here for awhile, it is a great place. Spheramid Enterprises Architectural Woodworks
" it doesn't suit them and would like some rational reasoning other than personal 'asthetics' to give them comfort that when they see what they like others will like it too.....".Have 'em call Martha Stewart (just kidding)
I would think that the function would dictate the form, in this case....i.e. whatever slope gives you the interior headroom(s) you need is the "right " one......"I have checked out the "Golden Ratio" and have found that it more complex than I have time or interest to pursue at this point..."Are you sure you're a builder? (only barely kidding....)
You might try asking your question on the House Chat forum too--they're into house design there. It's a good question. I've thought about the reverse too--how come some Dutch Colonial roofs (barn roofs and there's another name for them too that I can't remember) look good and some don't. Off hand and after some quick sketches I was thinking that dividing the previous slope angle in half relative to a horizontal line and the extension of the previous slope looks pretty good, but it's not a rule that I'm aware of.
I've built several of those Gambrel roof barns in the past....IIRC, starting at the peak, the ratio is 30 degrees to the ridge, then downslope 60 degrees, then 30 degrees at the flare to the fascia.
A lot of them are built to those ratios, but look goofy because the section coming on the ridge is too wide, or too narrow, but, for a farmer, that may be a function of creating loft space rather than being concerned with proportion.
To do one of your own, the best way is to do scaled drawings after boning up on classic barn construction (lots of books available on the subject).
Thanks--"gambrel" was the word I was looking for.
I just started an addition yesterday where the house has a Gambrel roof and I just checked both pitches today and they're 22/12 and 7/12. I have to build the addition roof fascia lines, overhangs and returns to match the existing house. The top view of the plans just call for a 2x8 in between the two roofs. I will call the Architect tomorrow and see exactly what he wants.Joe Carola
22/12 is about 61 1/2 degrees and 7/12 a shade over 30 so maybe my feeble memory still has a spark....
I don't have as strong a background in framing as you so I think I ran across that proportion in a book years ago....it always seem to look good, and gives generous headroom/floorspace in a loft.
That also comes real close to landing everything on a circle, like Mike said.
-- J.S.
I built several of these some time ago, actually before I got into the contracting game....the first was for myself, then Dad, and then assisted some neighbors building horsebarns, with me doing the construction drawings and just giving an assist with the construction.
So I boned up pretty good on the roof layout, and the input here from others, like joe and Mike and you have rattled the memory....the circle thing is beginning to come into focus amid the cobwebs. :-)
I enjoyed those projects...after doing a bunch of timber framing in recent years, I've hoped to land one with that method, but, for most people, it's too labor inten$ive.
I did check out one in Maine a few years ago that a Dentist was building for his horses....the worksmanship was top notch; actually much finer fits than most of the traditional timber frames I've seen in the East.
a gambrel roof has 5 points.... 2 bottoms, 2 breaks, and the ridge..
in a traditional dutch colonial gambrel.. all 5 points will fall on a circle
other types ( like victorian gamrels ) do not follow this tradition
it seems to me that the same thing could be true for the 3 points in this 12/12 / shed combination
the ridge, the break , and the lower roof edge will all lie on a circumferenceMike Smith Rhode Island : Design / Build / Repair / Restore
That's cool to know Mike-thanks for the informative post.
Dustin T
RULE 1............DON"T USE THIS FORUM TO ADVERTIZE YOURSELF OR YOUR COMPANY!
We consider it tacky and lacks class, besides if you were half as smart as you claim to be you would already know the answer, and I think you do.
Gabe
Don't have to shout Gabe. I worked with this fine man way back in '85. We put out a lot of fine work, and he is AS professional as you suspect.
It was his first post, how about some slack for a new potential friend?
Did you know all the unwritten rules on your first post? Spheramid Enterprises Architectural Woodworks
It was his first post, how about some slack for a new potential friend.
We'll see if the advertizing propaganda is edited and removed............and then I'll rethink the welcome.
Too many times people only see this forum as a means to get cheap advertizing and it demeans this gathering of brothers and sisters with real questions.
Gabe
Trust me, he doesn't need to advertise here. He is a booming businessman in one the fastest growing areas in S.E. Pa. An extension of Phila. nowadays. I grew up there, I saw what happened, it just went from farms to a million new homes in a very few yrs.
If I can, I will gladly request kindly. I don't think shouting out is needed.
Do you get a little gavel next to your name soon? Spheramid Enterprises Architectural Woodworks
It was his first post
And very complete, with Profile and everything (if possibly too much info . . . <g>)
No having to call the Profile Sheriff or nothin' . . .Occupational hazard of my occupation not being around (sorry Bubba)
Denny, feel free to take what you want and ignore the rest.
Welcome to BT, hang on, it can be a rocky road.
I apologize for the somewhat rude admonishment by one of our peers. Spheramid Enterprises Architectural Woodworks
a. Welcome
b. Gabe tried to trash me on my first post years agok, but he has mellowed since then. I liked your intro, too many people dont put anything in their profile.
c. The golden ratio and derivatives always work, lots of web site hits on the 1.67 ratio as i recall
d. oldest text I have with a roof solpe proportion discussion is "The encyclopedia of architecture", J. Gwilt, London, 1842, which states in article 2500 ...fitness cannot exist .. without equilibrium.... and goes onto explain the Egyption pyramid ratio (close to 12/12) to the Parthenon (edit) roof ratio (closer to a steep shed) as a good examples of proportion.
The author goes on to say in article 2525 that his ((J. Gwilt) conclusions differ from those of the 1807 work of M. Lebrun, 'Thorie de l'Architecture Grecque et Romaine deuite de l'analyse des Monumens antiques'
There you have it, right up to today - the authorities disagree with each other and it comes down to beauty in the eye of the beholder - your client. The ratio that looks best to your client on a sketch is the correct ratio.
e. Is the client a research librarian that they want to rely on some 'published work' as an authority rather than their own good taste? There sure is plenty of published tripe to choose from.
Art Brockschmidt
. -- In keeping with your intial post with the signatures, and to get another rise out of Gabe?, as Luka once said, Art's the rocket scientist I know - e.g. Tech. Fellow at a large aerospace company.
Edited 7/27/2005 10:50 pm ET by JUNKHOUND
The big pyramids at Giza are about 52 degrees face to base, a tad over 15 in 12. This seems to have been about as steep as they dared go. The collapsed pyramid at Maidoum was 52 degrees, and one theory is that they changed the angle on the bent pyramid of Snefru from 52 to 43.5 degrees because of that. Nobody knows the ancient Egyptian words for "Aw, s--t", but it appears that they learned from their mistakes just as we do.
Here are links to a bunch of pyramid stuff:
http://www.crystalinks.com/egyptpyrindex.html
-- J.S.
and one theory is that they changed the angle on the bent pyramid of Snefru from 52 to 43.5 degrees because of that.
The "bent" pyramid is a hybrid, the lower portion at the steeper pitch has all the courses laid horizontal. What I was taught was that after the collapse of the "fallen" pyramid, the stones were set at an angle to their own center, thus the angle change.
That technique being found effective, all future pyramids were then thus built. (The puposes for doing so being the content of far too many web pages <g>.)Occupational hazard of my occupation not being around (sorry Bubba)
The client has asked us to find architecture rules of design that state what the ratio between the main roof (12/12) and the shed dormer roof slopes should be.
Not sure there are any beyond the ones you have stated. That is, the shed is defined by the peak of the roof, and needed ceiling height(s) within.
Now, it may be that this project needs a "bend" in the ceiling to get a 3/12 roof in. It may not, just as well.
Dennis, a rule of thumb I've used is to make the dormer pitch half of the main pitch. Another "rule" is to hold the eave wall in from the first floor wall, so there's some roof exposed below the dormer. THEN you also drop the ridge of the dormer down the same distance from the main ridge. That keeps the dormer looking centered on the roof, and keeps the scale of the dormer second to the scale of the main roof.
Mike