roof pitch

JimC · February 24, 2008, 08:14:51 PM

What's the minimum practical roof slope for a place like Florida with essentially zero snow load? Could I go as shallow as 3/12 or 4/12? I'm trying to envision how just how far I could get away with modifying the roof lines in a set of cabin plans....

n74tg · February 24, 2008, 08:27:29 PM

I think it depends on what type roof you want to use. Composition shingles are I think limited to maybe a 3/12 pitch minimum. Below that you would need either metal or roll roofing.

February 24, 2008, 08:31:00 PM

Anything less than 4/12 puts you in engineered truss territory since your rafters stop being rafters and become joists in a manner of speaking.

MountainDon · February 24, 2008, 08:53:10 PM

As Scott indicated, it's a two part question, the roofing material and the roof support structure.

Not all metal is recommended for very low pitches... If you decide on metal check with manufacturers.

Is this to be a DIY installation? Membranes may require professional installation.

Can you post any pictures, or links to what you want to modify and indicate your desired end result?

JimC · February 24, 2008, 09:24:01 PM

Quote from: MountainDon on February 24, 2008, 08:53:10 PM
As Scott indicated, it's a two part question, the roofing material and the roof support structure.

Not all metal is recommended for very low pitches... If you decide on metal check with manufacturers.

Is this to be a DIY installation? Membranes may require professional installation.

Can you post any pictures, or links to what you want to modify and indicate your desired end result?

I was thinking a galvalume metal roof -- so I'll definitely check their recommendations. I want to do this myself -- I have 15+ years as a maintenance man - plumbing, electrical, carpentry, some shingle roofs, some roll roofs and 2.5 galvalume roofs so far.

I'm thinking I need to order the 20' wide 1-story cottage plans and modify them to my goals. I really want a 5 or 6 foot covered porch on all sides of the house -- I can live without the sleeping loft....

February 25, 2008, 02:48:49 AM

Porch all around like this?

JimC · February 25, 2008, 03:46:08 AM

Same concept but I want the roof line to carry a uniform slope from peak to eves. Also, I want to stay away from features that interrupt the roofline like dormers.

I've seen pictures of a very large log house in Alaska that had the design I'm seeking. If I recall correctly, they used a low hip roof. The house was also on giant log stilts.

glenn kangiser · February 25, 2008, 11:27:31 AM

In that case, then I think you need the 1 1/2 story at least as the continued same pitch roof - even at a low pitch will cover your windows at least partially. You might want to sketch it up and see how it works out.

bobtheengineer · February 25, 2008, 12:52:23 PM

Well, if you are looking for a hip roof, or even dutch hip, I'd just go with pre-fabricated truss's. A lumber yard, or a truss factory would be able to do you pretty good there. Trying to save yourself some money and building the low pitch truss's yourself, would be a mistake in my book. As long as the total span was less than 40' it should be pretty economical too.

February 25, 2008, 05:39:41 PM

ScottA you said a mouthful when you said: "Anything less than 4/12 puts you in engineered truss territory since your rafters stop being rafters and become joists in a manner of speaking. "

some how that made it clearer than it was previously. thanks