Roof Pitch

[Billisnice]

20' wide, what is the minimum roof pitch for a small up stair if i decide to do one later?

thanks

[Redoverfarm]

Billisnice I would not consider anything below an 8/12 for modest headroom.  10/12 or greater are more confortable.

[poppy]

Don't forget to factor in the sidewall height. Makes a lot of difference between 8', 10', or 12' side walls.  I'm using 10' side walls and 9/12 roof pitch on 16' wide.  That makes a nice loft for me.

[Don_P]

I've been framing a 20 wide with an 8/12 this week so its pretty fresh in my head. With no raised sidewall it won't work. The calc below can give you the headroom between plate and ridge.
http://windyhilllogworks.com/Calcs/ridgehgtclc.htm
For the 8/12 I framed the inputs would be
horizontal span 119.25
unit rise(pitch) 8
rafter depth 5.5
width of birdsmouth 3
height from top of plate to floor -5.5 (the joist is sitting above the plate so is entered as a negative number)
ridge depth 7.25

= 71-3/8" directly under the ridge, step to either side and its sloping down 8" for every foot to each side. Without raised sidewalls this is an attic.

You can enter other pitches, joist depths, etc and see the result. A 24" raised sidewall entered into the "Height from top of plate to floor" makes quite a difference there would then be 7' or more of headroom in a swath 4' wide down the middle.

[John Raabe]

12:12 gives real headroom in a small house (especially with a sidewall at the loft) and makes all those tricky cuts the same angle - 45º.

It is steeper to roof but you need to be just as careful and use much the same procedures for 8:12 and 10:12.

[OldDog]

mine is 13/12 to get the headroom I wanted on 16' wide

[MikeT]

I am really amazed in my place with 12' high walls and a 12:12 pitch, the loft has amazing headroom.  The ceiling rises from the 4' side wall so fast that at 16' wide, it really does feel spacious.   And I have to agree with John on the roofing issues with the 12:12 pitch vs something like 8 or 10:12--it all scares me, but I have used that fear to be very deliberate and cautious.

If I were to do it again, I would still go with the steeper pitch. 

mt

[Don_P]

A gambrel also gives good headroom. I like 12/5 on the sides and 5/12 up top. I think I saw someone else suggest 12/7 and 7/12.