What size rafters do I need...
#1
Member
Thread Starter
Join Date: Sep 2004
Location: New York
Posts: 507
Upvotes: 0
Received 0 Upvotes
on
0 Posts
What size rafters do I need...
I just put on a 6X8 addition and need to put a roof on it. It's going to have a 5/12 pitch, what size ridge beam and rafters do I need, 6, 8's?
#2
Depends... how much insulation do you need to get in the ceiling? If you are using 2x12 ceiling joists to get the deepest amount of insulation possible, you would probably also use 2x12 rafters.
#3
Member
Thread Starter
Join Date: Sep 2004
Location: New York
Posts: 507
Upvotes: 0
Received 0 Upvotes
on
0 Posts
My main addition has 2x4 trusses with 8" insulation. The main house runs north and south, the little addition runs off the side of the house east to west. The addition roof will butt against the 5/12 pitch, would I really need 12" rafters over a 6x8 room?
#4
Member
If your insulation is going between the rafters, you need 1½" - 2" of air space in addition to the thickness of your insulation. So if you have 7" of insulation, you'll need 2x10 rafters.
If your insulation is between the ceiling joists, you can get by with 2x6" rafters on 16" centers. Keep in mind, if you get a lot of snowfall and accumulation on your roof, you may want to increase the size of your rafters, to accommodate the extra weight.
If your insulation is between the ceiling joists, you can get by with 2x6" rafters on 16" centers. Keep in mind, if you get a lot of snowfall and accumulation on your roof, you may want to increase the size of your rafters, to accommodate the extra weight.
#5
Member
Thread Starter
Join Date: Sep 2004
Location: New York
Posts: 507
Upvotes: 0
Received 0 Upvotes
on
0 Posts
This little addition roof is only going to have insulation in the ceiling joist and not the rafters. We do get a lot of snow here at times so I think I'll go with 2x8 rafters. Should I also run a 2x8 ridge beam or would I have to go bigger?
#6
would I really need 12" rafters over a 6x8 room?
If you want the rafters to fully bear on the ridge you would use a 2x10 ridge. You will need to clip the ends of your 2x8 ceiling joists at your 5:12 pitch. Don't forget to birds mouth the rafters.