Rafter tail length

[MarkAndDebbie]

Other than banging my outswing doors against them, are there limitations to the length of the rafter tails?

[Amanda_931]

You could outstrip the lumber size's ability to stay straight.

(that happens not infrequently around here--with porches that have a lower pitch than the main roof and presumably the same rafter sizes.)

[MarkAndDebbie]

You could outstrip the lumber size's ability to stay straight.

(that happens not infrequently around here--with porches that have a lower pitch than the main roof and presumably the same rafter sizes.)

Any guess what might be well within bounds? We'll definately be using Southern Yellow Pine down here. Would changing the pitch (less steep) have any effect? I would also think that the size of the birds-mouth cut would make a difference - though maybe not with sheathing on it.

[glenn kangiser]

A couple feet is very common although if you wanted more you could brace it with a closed soffitt under it.

[PEG688]

Other than banging my outswing doors against them, are there limitations to the length of the rafter tails?

 Could you explain what your looking to achieve :-/ :-/ ?

 #1 House style , <if say your doing a 1 1/2 story like it seems as your interested in the notch / ledger connection > , would help :-/

That would MTL but not surely have  a steeper pitched roof like 8 in 12,  or more.    Which would also lead me to believe a 2 x 12 rafter so you could get some insulation in the rafter bays and have a 1" air space over the insulation .


So in theroy you could have 12' walls and end up with a 6' rafter tail on a 2 x12 rafter if you purchased 20' rafter stock when 14' rafter stock  would have done fine .  Witha 12"to 16" soffit.


#2  If you have a very shallow pitched roof 4 in 12 or under with roll roofing / torch down you'd be able to have long tails up to the point you over spannned the rafter or birds mouth notch, remember what ever you cut out reduces the rafter from that point out once it leaves the bearing point .  Sort of or in short :-/

So in short , [highlight]It Depends on other factors[/highlight] that are  not known by what you have let us in on :-/

 More info is needed

PEG    

[Amanda_931]

I was thinking about the porches we have around here (same problem, but....).

You could, to be safe, pretend you were starting from the begining with rafters the minimum width after the birdsmouth was cut.  Then calculate your length as new.  This would work especially well if you had posts and a plate at the end of your porch, if you wanted to use this for a porch.  You can also calculate your door swings to take account of these.  Which didn't get done with my little log room (sigh).

But I can't imagine having problems with a reasonable pitch ( >4) at 18 inches and solid rafters.  That's pretty standard for a one-story, even for straw-bale or cob.

Sometimes with trusses the tails can be very small--2x4's.  There you might get into a bit of trouble, even with a fairly short rafter tail.

(overhangs can look nice, they're needed in things like straw bale or cob, but the really cheap--cheap-looking for Florida maybe not New England with lots of wind--houses in Florida made with no overhangs did better in Hurricane Andrew--wind couldn't get under the overhang and lever the roof up)

[MarkAndDebbie]

OK. How about some more information...

We are leaning towards (after much discussion) the 14x24 builders cabin. We'll assume that for the moment.

We will be building in NW GA = not much snow load. So I might adjust the pitch of the roof (12:12) to something easier to build (I'll need to get a picture in my mind of what different pitches would look like - maybe I'll googleSketch it.) We still want a sleeping loft in which we can at least stand up. I'm the tall one at 5'5. Again, I'll need to googleSketch or do some trig to see if we can live with less pitch. If not we might sub out the 12:12 roof.

If we lower the pitch we might raise the wall height (12' or 14' maybe?) so as not to loose the headroom. 7' to the loft joists would be plenty of headroom in the kitchen/bath.

We'll be under a mixed pine/hardwood forest.

roof material - metal

no gutters

I like mickey's exposed eaves (i.e. no facia and sofit).

I wasn't thinking I would go crazy with the rafter tails. My original thought was 18 - 24". It would keep a little midday sun out of the windows and rain off someone waiting at the door. I also thought it might look better to have the wider roof if I made it taller.

So I wasn't really thinking porch kind of length.

The other thought I had was that I could start with some easier to obtain/cheaper stock length and then back into a reasonable pitch+tail length combination.

Does that make more sense.

Thanks for the replies.

[jraabe]

What I often do is use 2x12's for roof rafters (cathedral roof). This provides for R-30 insulation and the code required airspace. Such rafters are usually overdesigned structurally so you don't have to worry about snow load. Then I would clip these vertically at the wall line and nail on 2x4 or 2x6's for the rafter tails. These can even be at a shallower angle if you want a flair to the roof.

Standard overhangs are 14" to 24". For low slope hip roofs you can go up to 36" with low loads on the roof. For that width I would build a closed soffit with a triangular frame to put some of the load back into the wall.