Shed Roof Pitch and Rafter Sizing

[jcook5003]

Hey Guys-

I'm sketching up a run-in shed for my horses. ultra simple, pole style, low pitch shed roof. I live in Virginia and in our county the snow loading is 30#.

I need some help choosing a rafter size and pitch to aim for. If I use #1 Southern Yellow Pine, and the distance between headers is 14' I believe a 2x8 on 24" centers should be fine. Thoughts?

Also what kind of pitch should I be using I was thinking 2:12 seemed pretty standard, roofing material will be painted 5 rib metal.

Thanks
Josh

 

[massey990]

I think the minimum pitch for 5v panels is 2.5/12 but I would recommend more...the steeper the better IMO.
If your 5V panels are full length (no laps) lower pitches are OK but on low pitch roofs high winds can more easily force water up under the laps.

You didn't mention how long the building is, if you are going to use 2x4 @16"OC for purlins 2' centers on the rafters is OK, you can use 1x4 purlins if the rafters are spaced 16" OC

Also I've seen several threads on where to place the nails or screws on 5V panels. the manufacturer I have used recommend through the V and not the flat, others say the flat is OK, I check with your supplier and also check with some local roofing contractors (They fix more leaks than the average DIY'er.

 

[BeezFun]

Hey Guys-
I need some help choosing a rafter size and pitch to aim for. If I use #1 Southern Yellow Pine, and the distance between headers is 14' I believe a 2x8 on 24" centers should be fine. Thoughts?

I just built a standalone runin 8'x10' (8' span) and I used 2x6s on 24" centers. We get about the same snow as you (Chicago area).

Also what kind of pitch should I be using I was thinking 2:12 seemed pretty standard, roofing material will be painted 5 rib metal.

I used 2/12 pitch for mine, panels are continuous. I used 1x4 purlins. My building is free standing and is a small investment. If yours is very long, and is actually a pole building, I think I'd be a little more careful so it doesn't blow apart. There's rafter tables online, and the roofing manufacturer will recommend purlin sizing. I got my metal from menards.

Thanks
Josh[/QUOTE]

 

[jcook5003]

The building will be 14x36.

I always install the metal with the screw through the rib, the company I bought mine from (factory direct) said it would void my warranty if I didn't.

I will be using 2x4's on 24" centers for purlins.

Panels will be continuous.

 

[LD1]

Well, according to the tables I am looking at assuming the following:

No 1 grade SYP
L/240 deflection limitation
30psf snow load
10psf dead load
2' centers

the maximum span of a 2x8 is 14'5". So if 14 is all you need, you are good.

If the margin is too close on that for you, a couple of options

19.2" spacing gives you a max span of 15'6"
16" spacing gives you a max of 16'6"
and 2x10's on 24" centers gives you 21'1" max

And only spaning 2' with the 2x4 purlins, if you arent planning already, I'd lay them flat. Because that gives you more margin for error on screwing the roofing on, and yet it will still be rock solid:thumbsup:

 

[Verticaltrx]

If it were me I'd use 2x8's on 16" centers, with 1x6 rough sawn oak for purlins. I saw a lot of sheds with collapsed roofs due to snow two years ago, better to over build than under.

 

[BeezFun]

I always install the metal with the screw through the rib, the company I bought mine from (factory direct) said it would void my warranty if I didn't.

The instructions with mine said to go through rib if the metal is going over an existing roof, but through the flats immediately adjacent to the ribs if it's new installation. I assumed that was to accomodate the irregularity of an existing roof so it didn't show through as bad. I would think going through the rib would reduce potential for leakage.

 

[jcook5003]

Next question. You guys think with my posts on 12' centers a single 2x12 header is sufficient?

 

[LD1]

Next question. You guys think with my posts on 12' centers a single 2x12 header is sufficient?

I would go double just for peice of mind. In the grand scheme of things, it will add very little to the total cost of the project.

But without running the #'s, it is probabally fine, but again, go with two just for peice of mind. One on the inside and onw outside:thumbsup:

 

[massey990]

Next question. You guys think with my posts on 12' centers a single 2x12 header is sufficient?

In a word NO, double them up unless you are using a specific type of fastening system, ie, special metal fasteners to hold the rafter to the single 2x beam.