Lean To Plans

[bad_idea]

I plan to build a back patio on the back of my shop this spring. 14x31 attached to the back wall of the shop (under the eave) supported by posts 14' away from the building, concrete slab with footers under each post poured at same time as slab. I am looking for a set of plans with all of the pertinent details - footer size, rafter size, attachment details, etc. I am not a carpenter, but I can build from a set of plans. I'm willing to pay for a set of plans, just not sure where to go.

 

[olytdi]

I have a 12x36 lean-to (carport) attached to my 36x36 pole barn. The lumber yard from whom I purchased the materials for my build provided the build spec and material list (they specialize in putting pole barn packages together). The guy I had build it just put it up per those plans.

 

[bad_idea]

That's not a bad idea. We have a lumber yard in town that offers that service, though they tend to spec them out undersized. I'll see what they have to say.

 

[Old tool guy]

14 ft rafter span is nothing, 2x6 could do that. The 30 ft length will need at least one center post giving two 15 ft openings, that will be easy to span. Or two intermediate post giving three 10 ft spans. So the above ground framing is going to be easy. Footings and slab details will need some thought, as well as how the roof will tie into the side of the shop building.

 

[bad_idea]

Thank you for your input.

I am planning to attach a 2x12 ledger along the bottom of the eave, lagged into the 2x6 studs (on 16" centers) of the building. The frost line is 12" around here, we don't get snow much. Soil is sandy with a clay pan ~2-3' down. Thinking the footers should be 12" deep and large enough diameter to support the load of the roof at each post, not sure what that diameter is. I plan to have them poured at the same time as the slab. Figure a 4" slab should be sufficient. I would like to have (3) posts spaced 10' apart, also not sure on the appropriate header size - thinking (2) 2x12's, though that is not based on anything of substance. Definitely want to build this once and have it right.

 

[Old tool guy]

. I would like to have (3) posts spaced 10' apart, also not sure on the appropriate header size - thinking (2) 2x12's, though that is not based on anything of substance.

Looks like a typo on the number of posts and spacing.
This is a header span table from the 2018 IRC. Not sure that exactly applies in your state/county but it’s a good start.

 

[billconner]

Based on the 10' post spacing and 14' span, that's about 70 SQ ft per post. Assume 30 psf snow load and 5 psf for dead load, that's 2450 pounds each post footer. It's hot to be pretty bad soil to be under 2000 psf bearing, so a footing that's 1 1/4 SF or 16" diameter. Might be easier to make them 13 1/2" square if forming. If it's windy, you might want a little deeper or bigger just to hold it all down.

 

[bad_idea]

I am in a high wind zone, have to carry wind insurance to prove it. Thanks for the numbers guys. I'll go bigger on the footers for added insurance, shouldn't add too much extra to the concrete bill.

 

[billconner]

I wonder if helical piers would be better for wind. Definitely deeper and wider footing for concrete, but I suspect wood post connections are the primary failure points in wind.

 

[ddurrett896]

Did something similar and for a 16’ rafter, I had to use 2x8.

Double 16” LVL let me span 22’.

 

[mike93lx]

That's not a bad idea. We have a lumber yard in town that offers that service, though they tend to spec them out undersized. I'll see what they have to say.

If you know their spec is undersized, shouldn't you be able to design one yourself?

 

[Old tool guy]

Did something similar and for a 16’ rafter, I had to use 2x8.

Double 16” LVL let me span 22’.

SYP #2 @ 16” is good for 13’-6” … close enough for a shed. Had to do 2 clips because of the size of the table.
… hmm, getting an error message …

 

[Old tool guy]

 

[ddurrett896]

SYP #2 @ 16” is good for 13’-6” … close enough for a shed. Had to do 2 clips because of the size of the table.
… hmm, getting an error message …

2x6x14 = $13.37
2x8x14 = $17.32
31' = 24 rafters. I'm all for saving money on material but $92 wont break the bank.

14' is still above that table AND that's a dead load of 10psf. I'd go with the 20psf side.

 

[bad_idea]

If you know their spec is undersized, shouldn't you be able to design one yourself?

I know they spec undersized because that's what the county told me when I brought a set of their garage plans to get a permit. When I built the garage I ended up hiring an engineer to draw up a set of plans for me. Didn't want to spend that much money again for a simple lean to patio cover.

Thanks for all of the help guys.