Rafter size for 16ft Span

[ustmd]

Hiya,

Looking for information/feedback.

Finally, I am going to build the workshop.

I am looking at having a 16 ft span on on a simple shed roof with a 2/12 pitch.

I am in Central texas, so there is no snow load.

I am trying to decide on the size of the rafters and spacing and I am looking for feedback from people who have experience with their buildings.

Depending on the tables, I look at, I can do 2x8, 2x10 or 2x12. My preference would be to stay at 24 oc, but I am willing to drop to 16 oc to add strength and drop to 2x8s (general easy of handling).

Any feedback would be appreciated.

Thanks

 

[/pine]

What are you going to use for decking/roofing?

if I were building it...I would go with 2x8 16"oc...then deck with 1/2" or better plywood and a torch down bitumen roofing...OR...2x8 16"oc with 1x4 lattice 24" oc and use 5V metal roofing...

how do you intend to add an overhang on the ends? hung barge? or do your beams extend ?

 

[Transit]

You may not have a snow load to contend with but don not forget to insulate.

 

[ray66v]

Can you get away with a 2/12 pitch there?

Even without a snow load, I am surprised you can build that flat.

 

[ustmd]

/Pine,

I am thinking about putting Galvalume Metal over a 1/2 radiant barrier sheathing.

Transit,

Definitely on the insulation--I am considering doing spray foamed, but that would be another task I would have to sub out.

Tanks

 

[/pine]

I am thinking about putting Galvalume Metal over a 1/2 radiant barrier sheathing.

sounds good...still curious about the overhangs...
if you can't get long enough material scabbing tails may be your only option ??

 

[ustmd]

That is part of my problem is sizing the materials. To keep it simple, I would prefer to just let the rafter run over for the over hang, but I may not be able to get stock that long.

 

[carpenter383]

I've seen 2x12's in 20ft lenghts, so I assume you could get 20ft 2x8's too. But I bet they're proud of 'em!

 

[boxygen]

2x8 will come in 20' lengths. Ive seen 2x6 in 20 foot lengths. 2x8 may be pushing it for that span. they will definitely deflect but they wont break/fail. In your area they probably have southern pine which is stronger than our spruce/fir we have on the northeast. Doug fir will also be stronger if you can get your hands on that.

 

[bp fick]

If you go 2x8, your OC should be 16" as you stated you were willing to do.

If you go 2x10, your OC would be fine at 24", as 16" would be a bit over build, given you have no snow load. Snow or not, I much prefer a 4/12 for the look. Go 5/15 and it virtually assures the ability to have a storage loft in all or part of the building. What a difference in practical storage space a loft makes. It is about the cheapest square foot storage you can build.

Your plan doesn't call for sheathing the roof, as I understand it. If you decide to sheath, do use plywood/OSB clips for 24" on center to avoid deflection.