I would like to add a simple porch roof off of my studio which has a 6/12 slope. Is there a formula for determining the porch roof slope so that it remains in keeping with the slope of the main roof. Something along the lines of ” if the main roof is 12/12 then the shed/dormer roof would be 4/12″ (I just made that up)
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I find that halving the main pitch often looks good on dormers and porches. So for your 6/12 you might try a 3/12. There's really no way to know without drawing it out though.
If you split the pitch in half, then you doulble the new run to find the intersection of the two roofs. With a 12' addition, you need at least that distance back so as not to overshoot the existing ridge.
That's assuming both plate heights are equal. hope this helps.
Half the existing slope makes sense. thanks.
"half the existing slope make sense"
Except in your case it gives you a 3/12 pitch---- which you DO NOT WANT !
aethetically-the difference between a 3/12 & 4/12 will be minimal---- but the 4/12 is vastly better if you are looking for a dependable roof.
the 3/12 will take you into the realm of flat roofing, necessitating material compromises. If you DON'T make the material compromises, be prepared to keep buckets handy LOL
Best wishes, Stephen
He is not in a snow/ice location, so 3/12 is very common and acceptable down there. If he wants overkill, he can still add ice and water shield.My thoughts for finding what looks good is to shoot a photo, print a few copies, and sketch right on the print at a few different angles, pick one and figure back from there. This is about appearance and proportion as well as about materials. I think materials and technique are easily adapted to a pleasing design.
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Hi GuysThanks for the feedback. I appreciate the comments re: 3/12. Actually it is a metal roof so a bit less of an issue. Snow is seldom a problem where I live, though at 3/12 should be easy to shovel off.Piffin, sounds like you and I have a similar approach. I was just wondering if there was a more "scientific" approach besides what "feels" and looks right to my eye. Some of the additions around here look right and some just don't. I kind of am seeking the farm house wrap around porch look off a steeper pitched upper if you know what I mean.Cheers, Greg
I do. Those are often limited by needing to fit in under a window at dormer, so they get shoved down less than 3/12 a lot of the time, but as a roofer, that is also unappealing to me. I've moved from roofer, to renovator/remodelor, to designer in 35 years. Well, going on 38 yeaars now.Balance is important. The more unique a project is, the more time planning and drawing it needs
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British Columbia is "down there"?
down there--from Where?
Interesting though---- you seem to agree that from a roofing standpoint--the 3/12 is somewhat less than preferable----- but you would accept it for aesthetic reasons?
Intriguing--because I would think the ROOF would be the place Function would always out rank form. Form should certainly be considered--- but not to the extent of allowing a 3/12 LOL.
BTW---I understand that YOU are well aware of these things-------- but I wouldn't recommend anyone depending on icegaurd for long term protection from ANYTHING. If You start reading the fine print---- you are going to find a lot of the brands are only warranted for 5 years(lifetime shingles with 5 year icegaurd--something doesn't add up !)
British Columbia--isn't that like seattle?---constant, un-relenting,torrential rain in the great "northwet"------I have never been there---but I would think a LOT of buckets would be handy there---under a 3/12
Now---considering the guy is going with a METAL roof----well that would have been handy info> to have had YESTERDAY before I started my long-winded,gasbag "anti-3/12" rant.!--LOL
Best wishes,Stephen
LOL,
I thought his profile said Carolinas location. Down there.Yes, 312 is less than preferable for shingles, but my experience roofing is probably almost as much on "flat" roofs as on pitched roofs, so I dont fell unconfortable with either in the right place.
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Assuming you want to roof with regular asphalt shingles, Hazlett, being one of our resident professional roofers is right. 3:12 is minimal at best. Even 3 1/2:12 would be better. A 4:12 would give the reasonable performance and roof life you want.