Size of roof overhang for the south
My first house in NY was built in the 60s and had large overhangs. My house here in SC was built around 2000 and has small overhangs. Not sure of measures, but clearly noticable from the street.
I am custom building a home and the posts on this forum point to green building techniques and recommendations to use large overhangs (2 or 3 feet). The benefit being solar management and protection from the elements.
I spoke to my builder and he states that 1 foot is the standard; soffit is sized for a 1 foot overhang; the gutter will extend out some additional distance; wind driven rain will get to the walls no matter what. Anything larger is not needed.
Questions: is larger better in the southern parts of the US? If not 1 foot, are there other standard sizes with readily available soffit materials? how large would you go? Would it be worth it? Any benefit?
Thanks, Ted
Replies
an over simplified answer...
This is one of the most important basic design features to a well designed building. And it is almost always ignored and misunderstood. Probably your builder won't have a real clue.
One easy way to figure it is to draw the window elevations on a scale drawing of the south side of the house. You find the suns altitude angles for your latitude for Dec 21 and June 21 at noon and draw those on your south elevation. You can then see how much overhang is needed to block the rays when you want to. For example here at my 32 N. latitude the angles are 83* summer and 32* winter, a lot of difference. The room I'm sitting right now has sunlight on the floor 10 ' into the room, by July there will be none.
As for the other sides of the house solar shading is less critical but can be a factor on the west, less so to the east and not at all on the north.
Also all sides of the house need a decent overhang to keep the rain off the building, particularly at doors and windows but also off the building proper. How much depends on the wall height and a lot of other things.
My hat's off to you for seeing the design need.
I'll assume you're in coastal SC since that's typically where the soffit size i s a factor. The Code changed after hurricanes
Hugo and Andrew and made it more expensive to use larger overhangs because that's where the roofs came apart. You can go larger but you'll need engineering and lots more wood. Gable ends will be even more difficult.
You gain some protection from the sun with wider overhangs but you get even more return on your efforts with attending to the details of air sealing, and a higher R value in the walls and ceiling or better yet, roof deck.
Unless it's a key architectural elemrent I wouldn't sweat the wider overhang.
there are other standard sizes, 16'' and 24'' being the most common...at least in my part of TN. as stated there are other considerations to sizing the overhang.
12'' is the cheapest of the standard sizes. what soffit material will you be using?
My thought would be that if you want the longer overhang, stick to your guns and tell the builder that's what you want.
from your example, the one thing i would point out would be that with multiple planes and gables your overhang could be limited by the amount of windows in proximity to other gables or plane changes.
no "standard"
There is no such thing as a "standard" overhang.
Soffet depth (roof overhang) is usually dictated by a home's architectural style. The one you picture appears rooted in the closely related Geogian/Federal styles. Overhangs were not typically very deep; usually just enough to proportionally terminate cornice projections. Anywhere from 6" -12" is not uncommon.
Of course you can do anthing you want with your builder, but deviating from architectural conventions is (IMO) aesthetically risky.
the op is not refering to standard overhange. if you ready the entire thread youll see that the topic was brought up. the op asked if there were other standard sizes in soffit material. 12'', 16'', 24'' are readily avaliable here and most would consider those standard sizes since it is what lumber yards and suppliers carry as stock items.
stock material does not
necessarily dictate standards. 4'x8', 5'x10' sheets of plywood, fibercement, & pvc are stocked by lumber yards and used for soffet construction as well. Neither of those dimension are commonly found on overhanges. Just because a particulare size of material is stocked doesn't mean it dictates "standard" architectural details.
"Florida" put his finger on
"Florida" put his finger on it. If you are building in a place with a wind code, those longer overhangs become a problem.
Do some homework
yelkenli wrote:
Here is an example, though there will not be as much second story facing the street; the southeastern exposure will be mostly one story, with the other side being two story:
http://cdn.houseplans.com/product/ofrvqesoq0ap2qveii1qm2quot/w1024.jpg?v=5
For crying out loud... Make another drawing of the building that depicts larger overhangs. One cannot make this mental leap without a direct visual reference. If you or an architect are not drawing plans then you needn't be talking to a builder yet.
The builder's main concerns seem to be 1) there is no benefit; and 2) the larger overhangs would not match other houses in the development. There might be other concerns, but this is what was voiced. As Sapwood stated, a drawing of the larger overhang might help determine if larger is worse or better, or might not.
Thanks for the comments.
Ted
That style of house would not look in proportion with a wide overhang. I'm thinking that 12-16 inches is the max, probably closer to 12.
(Not particularly fond of that style myself, though. I favor more of a ranch look, with 2-3 foot overhangs.)