Patio roof redo... 2x4 vs 2x6

My house has one of these relics on it.

It is circa 1950, it leaks, and the sharp aluminum dog ears are right at forehead level.

I can easily build what I need.  The existing patio is 8x12 and the awning on it is 7x12.  So, three 4x4s, a ledger on the house, angled joists, fascia, two rafters, plywood, a few bags of shingles, and some T-111 for the ends and I'll be golden.

No permit required, no inspection.

Should I do 2x6 on 24" spacing with 2x8 ledger and fascia, or 2x4 on 16" spacing with 2x6 ledger and fascia?  Some other spacing/dimension?  Central PA, so 30lb ground load, 21 lb live load for reference, but I don't need to conform to that, just letting you know a ballpark.  It will all be PT, and I assume I should do PT ply as well since it will be subject to a fair amount of ambient moisture?

I build sets for a theater, so I never do exterior stuff or roofs.  I always do indoor, temporary, and floors.  I did a roof once for a show.  It was luan and cardboard.

In reply to Curtis :

I can’t answer your questions, but I bet someone would pay good money for that mid-century relic you have. 

I'd do 2x6 16" OC if I had a covered porch.

In fact I do have a covered porch, and it is 2x6's 16" OC.

2x6

Preferably 16” o.c. 

24” is a long span for 1/2” Decking. It’s only 2 more rafters. 

My biggest problem with 2x4's is that I never trust walking on that roof later, no matter what the span tables say. 

I wouldn’t use PT ply. 

Its really crappy stuff, and prone to warpage and delamination. 

CDX should be fine. 

mazdeuce - Seth said:

My biggest problem with 2x4's is that I never trust walking on that roof later, no matter what the span tables say. 

The span tables say 0’ for 2x4. Its not suitable for a rafter (especially with a snow load). 

A reasonable sized knot can compromise 2/3 of the width. 

SVreX said:

(especially with a snow load). 

Snow load was my first thought, but we got a lot of it this winter. I hesitate with PT because it tends to get all warpy twisty, the #x4 stuff anyway. 2x6 seems to be ok most of the time.

mazdeuce - Seth said:

My biggest problem with 2x4's is that I never trust walking on that roof later, no matter what the span tables say. 

Truth, but it's an 8x12 patio roof.  I don't imagine ever walking on it or needing to.  One of my first thoughts was to make it translucent with plastic corrugated roofing, but I couldn't imagine that taking snow loads without a lot of purlins.

So if I do 2x6, would I typically use 2x8 for the ledger and fascia?  Until I cut the angles on the 2x6, the ends will be more than 5.5".  Or do I just use 2x6 fascia and trim off the little nib sticking down?  It won't be a huge deal... Probably only a 3/12 pitch

SVreX said:

2x6

Preferably 16” o.c. 

24” is a long span for 1/2” Decking. It’s only 2 more rafters. 

Ah... for some reason I was thinking 5/8" for roofing.  1/2", yes, I would feel better with 16" OC.

SVreX said:

I wouldn’t use PT ply. 

Its really crappy stuff, and prone to warpage and delamination. 

CDX should be fine. 

Ok.  I do insist on using PT for the framing though.  I know it isn't totally necessary, but it does slow the rot and the boring bees.

Pete Gossett said:

In reply to Curtis :

I can’t answer your questions, but I bet someone would pay good money for that mid-century relic you have. 

Yup.  My theater.... unless you're making an offer 

In reply to Curtis :

Yes, PT framing material is a good idea. But not the PT plywood. 

Yes, you just trim the tips of the rafter tails hanging down. 

It's not that you have to sit on your roof with a drink and watch the world go by, but it's that you can that is important. 

In reply to mazdeuce - Seth :

I think that was a veiled insult to my weight  

Thank you all for the help.  Hopefully I can bust it out with my buddy this weekend... if the weather cooperates

Given that head height is a concern and the area is small, I'd use 2x4s at 12"oc with 5/8" CDX ply.  2x4 fascia with the rafters trimmed, or 2x6 fascia.

https://www.awc.org/codes-standards/calculators-software/spancalc

Not a bad idea Duke.  That would save me a couple inches.  I'm trying to squeeze in a 3/12 pitch and leave 7' of headroom at the fascia - both for comfy walking clearance, and for being able to view my back yard out the window.  Initial calculations suggest that a 2x6 construction would leave me with 6'-8" which isn't bad, and I could step out to 2/12 pitch and get that clearance back.

That calculator you linked suggests I can span 7'-4" on 2x4s at 12" OC.  I think that's close enough to 8' to satisfy me, however there is a possibility of renting this house out in the future.  I would hate for some management company to get in a snit about 2x4s.

Honestly, I doubt they'd even check it.  I ran it using #2 Southern Pine.  If you went to #1 studs it would get a little closer to 8'.  Our you could use doubled 2x4s at 16" oc, screwed together.  It's such a small area that a few extra studs doesn't add much cost or labor.

You could also put a 1/2" ply ceiling on the bottom with plenty of fasteners to act as a stiffening diaphragm and help with deflection.  But I think I would just go with sistered 2x4s at 16" oc.

Duke said:

You could also put a 1/2" ply ceiling on the bottom with plenty of fasteners to act as a stiffening diaphragm and help with deflection.

 

But then, where would my House Finches nest?  

One other query.... what about a gable/joist-thingy on the end.... a board straight back to the wall.  I know it would add load support to the ends if I skinned it with something like T-111, but is there any real reason it is really needed other than a little bit of rain shielding?

Leave it open, or frame it with a joist and skin it?

With the simple span from wall to ledger beam, the gable end thing is not really doing anything structural to brace the rafters.

If you want the gable ends for aesthetics, extra shade, and a little weather protection for your swallow nests, then add them, but otherwise, I'd be tempted just to have the sloped rake board and keep it clean so it looks lighter and trimmer.  It will let more light in your kitchen windows there without the end returns.

I'd be tempted to run 2x8 perpendicular to the house with a 2x8 at the house, 2x6 in the middle, and doubled 2x4 out away from the house parallel to it. Trim the 2x8 for head clearance.  Maybe keep a center post if the 12' span concerns you so the smaller lumber is only spanning 6'. Then you can add a tin roof with 4 pre-cut 8' pieces of tin instead of the plywood and your lumber will already be going the right direction. 

I think I'll do a center post anyway because I want to add a little table for the grill like the picture below.  Just make a little deck out of 2x4 scrap and deck boards.

And now I'm totally in trouble.  Pinterest is giving me too many ideas.

Are you installing the porch roof at the same height on the house as the existing roof?  Looks like you have room to install it higher, even close to the level of the house roof, to gain a few more inches of clearance.  I like the white painted wood/clear pergola on that house.  Do you need shade too or just weather cover?

Yah, Curtis.  As long as you're in there.....

You might as well expand your current patio to several times it's current dimensions and screen/enclose the space, get a nice chimenea and some fabulous patio furniture.  Think of the parties you could throw!