Simple Framing Question

[Diggin It]

I'm planning a shed roof/awning, whatever you want to call it that will attach to the existing house roof and garage wall. I need a wider than 8' span between the posts for a variety of reasons. Due to prices of graded, stamped lumber, I'll be using rough cut stuff from the mill guy down the road, either red or white oak. There are no permits or inspections here. Top will be metal roof on purlins, no decking. Rafters will be about 8' long on 24" centers.

Span between posts will likely be closer to 12' which may be too wide for a rough cut 2x6 or 2x8. If I add diagonals as shown to reduce the span to around 10' or less, is it more likely to stay up, or fall down?

 

[PILOON]

For sure diagonals will help.
A lot depends on anticipated loads.
Are U down south? or in northern Maine?
No matter, if 2 X 10's were optional I'd opt for them and feel quite safe, but I'd shy away from 6's.

 

[quicksandfarmer]

The way to get more strength out of less lumber is to use a truss, which is the direction you're heading. What you want is called a box truss, see if you can find plans on the Internet, state extension offices used to put plans like that out.

My back of the envelope is you need a doubled 2x10 for that span if it's just straight lumber.

 

[Hay Dude]

I'm planning a shed roof/awning, whatever you want to call it that will attach to the existing house roof and garage wall. I need a wider than 8' span between the posts for a variety of reasons. Due to prices of graded, stamped lumber, I'll be using rough cut stuff from the mill guy down the road, either red or white oak. There are no permits or inspections here. Top will be metal roof on purlins, no decking. Rafters will be about 8' long on 24" centers.

Span between posts will likely be closer to 12' which may be too wide for a rough cut 2x6 or 2x8. If I add diagonals as shown to reduce the span to around 10' or less, is it more likely to stay up, or fall down?


View attachment 695202

Depends on where you are located (snow loads) for one.
You are better off with a 2x8.
Does the roof have pitch, or is it flat, like shown in sketch

 

[Diggin It]

Still early planning so pitch isn't really defined yet, probably 3/12 or so. We get snow and have had 10-12" a couple of times, but it's almost always gone in a couple of days. Most years, no snow at all, or 2-3" at most in any one snowfall which melts before the next one. In 25 years, I don't think we've had a snowfall over six inches more than a half dozen times.

There are some weird angles involved that I can't draw in with MS Paint, but really it's just a simple shed roof/awning to keep rain away from the doors, windows and foundation.

I'm just trying to figure out if I can do it at all right now or if I have to wait for sanity in the lumber stores .... which might be a while.

 

[Hay Dude]

2x6’s would work, but remember it only takes one heavy wet snow.
2x8’s are a better choice. Whats he want per L.F. for 2x8 compared to 6’s?

 

[/pine]

Adding the angle braces does not decrease the span between load bearing points...use a bigger timber or a flitch plate etc...

 

[jthibodeau89]

Can you consider a 2x8 trujoist? The wooden equivalent of an I-beam. Dont know if the price of enginered lumber has gone up like the dimensional lumber. You can then box it in with rough sawn if you like. Apply blocking at the posts with gorilla glue and screws. Should also apply diagonal strapping under purlins to midpoint of span to prevent outward bow and pull out at wall.

Another option would be to use a steel barjoist at the posts, and 2x8x12 purlins on 24" centers for the 26ga roof deck. no rafters. The comnercial built horse barn on our property was built this way. Posts on 12' centers. This way the end band does not carry roof load between posts. 8' bar joist trusses are not very expensive.

If using redoak, best to build while still green, or you may be predrilling screw holes. I used 1x6 rough sawn red oak to floor a tack room and let it dry first to prevent shrink gaps. Could not drive a single nail once dried. Wound up drilling every plank.

 

[Diggin It]

Two 1 x 8 oak side by side and staggered to emulate engineered beam? Attached to each other with timber-lok type screws.

Two 2 x 8s in Oak would be too heavy to lift into place. Might be able to do 3 1 x 8s though with a lifting sling.

 

[nybirdman]

Put one 2x8" on the outside of your upright post and one on the inside and a another on the top(may need a 2x10").Very strong and do one piece at a time.