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Daugela 11-24-2013 12:00 AM

Covered patio rafters
Simple question.

What size rafters for a 17' span / 2' on center covered patio? I did a 10 foot span and used 268, but would a 17' require something bigger? 2x8?

No gable - flat porch.


tony.g 11-24-2013 06:29 AM


Originally Posted by Daugela (Post 1270593)
something bigger? 2x8?

And the rest.

PoleCat 11-24-2013 07:04 AM

Snow loads are no issue. I would use 2X8 min. just so I could walk up there though.

joecaption 11-24-2013 07:18 AM

Where do you plan on finding 17' long lumber?
A standard would be 16' long.

PoleCat 11-24-2013 07:24 AM

Menard's has 18'. Bet they aren't that far west though.

Daugela 11-24-2013 09:27 AM

Yeah no snow loads in Phx. We did get record rain though this weekend. It's been raining for 3 days straight here.

Anyways, I could theoretically change my plans from 17 to 16 but would rather not. It's not a deal breaker. I haven't looked at any span charts yet.

Could the 2x8 be used if it's 16" - 0? That way I wouldn't be in the "minimum" area. Or I guess 2x10 at 2' - 0.

kwikfishron 11-24-2013 10:16 AM

199 Attachment(s)
Every lumber yard I've ever dealt with stocked 18 and 20' 2x's. It's only in the box stores I've seen length limited to 16'.

GBrackins 11-24-2013 11:16 AM

it depends on your code requirement for live load and the grade and species of wood selected. these span tables are from the 2009 International Residential Code:

Daugela 11-24-2013 08:07 PM

Im trying to figure these tables out and am having a hard time. I'm looking at Douglas Fir, NO snow load, live load 100p/sft. I can't get a span further than 9 feet for 2x10s. Makes no sense.

Surely I'm doing something wrong…

tony.g 11-25-2013 04:49 AM


Originally Posted by Daugela (Post 1271089)
live load 100p/sft.

Your live load won't be anywhere approaching 100 lbs/sq ft, unless you are using the roof to store your collection of vintage cars.

I wouldn't know your code requirements, but it will be much lower, if only for occasional maintainance, say 10-20 lbs/sq ft? Your dead load (ie the weight of the structure) will be quite low - maybe 5-10 lbs/sq ft.

2x10@2ft centres would be fine.

Daugela 11-25-2013 07:52 AM

A guy on here said 100lbs/sqft. His reasoning was so a person could walk on it for maint, etc…Made sense at the time. Now that you're mentioning it, that is way overboard.

Thanks for the input.

GBrackins 11-25-2013 12:38 PM

live load for living space is typically 40 psf, bedrooms are typically 30 psf. a call to your building department would provide the live load for a roof in your area.

A lot of areas of the country it is 20 psf, my area is 30 psf because of our ground snow load.

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