Another Lean-To Addition

[wicked_pissah]

Howdy everyone, new guy here. I've been lurking in the shadows and doing a lot of reading and it's about time I joined the community!

I recently bought a new house and it came with a 24x24 horse barn on the property which I plan to convert into a garage/shop/he-man woman haters clubhouse!

<a href="https://imgur.com/xvLQVKJ"><img src="https://i.imgur.com/xvLQVKJ.jpg" title="source: imgur.com" /></a>

My first project is to add a 12x24 lean-to for additional storage. I'm a complete novice when it comes to building/construction but as I mentioned I've been doing a lot of reading and I think that I can tackle this project myself. Anyways, I want to start by attaching the ledger board for the rafter hangers but I'm not sure what the best way to do this is. The only thing to attach to is the 1" wooden siding and the 2x4 wall studs. Here's is a picture of the inside of the wall on the second floor of the barn where I want to attach the ledger board, just below the existing roof rafters.

<a href="https://imgur.com/oFhnqNi"><img src="https://i.imgur.com/oFhnqNi.jpg" title="source: imgur.com" /></a>

It's 18" from the floor to the bottom of the top plate and one idea that I had was to cut 18" lengths of 4x4, place them between the floor and the top plate and screw them to every other stud. Then I could lag the ledger board to the 4x4s. What's everyone think of that?

Couple things to know about the lean-to:
1. Roof will be a 3:12 pitch with metal roofing.
2. I'm located in Maine so there are pretty heavy snow loads.

Looking forward to everyone's input.

Thanks!

 

[cdestuck]

If those studs in the pic run the whole way down to the first floor of the garage, there’s plenty of strength there to lag your ledger board to them.

For your rafters of the shed roof, 2x10s or doubled up 2x8s. 16” centers on either.

 

[wicked_pissah]

Thanks for the reply. Those wall studs do run all the way down the bottom of the wall, 10 feet in length. So if I lag the ledger board (planning on 2x10) directly to the studs what would you recommend for fasteners, 5/16 x 4 or 5 inch GRKs? Two in every stud, more, less? Really just want to make sure this thing doesn't collapse under heavy snow load. Thanks again for the reply.

 

[Git]

When this topic comes up, I always reference some online pdf files that apply to S Cal but will give you some pretty good ideas to get you started. It also has some tables to help you figure out what size lumber for your spans but you will also have to factor in for your snow load

I like the GRK bolts personally

https://www.sandiego.gov/sites/default/files/dsdib206.pdf

https://temeculaca.gov/DocumentCenter/View/258/CD21---Attached-Residential-Patio-Cover-PDF

http://www.cityofperris.org/city-hall/forms/building-standards/PatioCoverStandard.pdf

 

[cdestuck]

Two 5/16 or 3/8 lags would be fine. But with the width of 9 1/4”, you could throw in a 3rd lag. I’m like you, error on the side of caution. How close are you planning to place your posts? And the size of your beam on the posts? 6x6s would be my choice over 4x4s.

 

[wicked_pissah]

I was planning on three 6x6 posts, one at each end and the third directly in the middle. All would have 6x6 bracing as well. For the header beam I was planning on a 4x6. I would use 6x6 post caps to fasten the 4x6 to the top of the posts. Make bird mouth cuts at the bottom of each rafter and use a Simpson Hurricane Tie to fasten the bottom of each rafter to the 4x6. Here are some simple plans that I drew up in CAD.

<a href="https://imgur.com/cDhOQz2"><img src="https://i.imgur.com/cDhOQz2.jpg" title="source: imgur.com" /></a>

 

[cdestuck]

Sounds good but I’m seeing a weak link in using just a 4x6 to span 12’ between each post. I’m certainly no engineer thus I tend to overbuild. Hopefully a builder with better knowledge will chime in on this. If I were doing this for myself I’d be using 3 2x10s with 1/2 plywood glued and screwed between them. Remember that you’re only going to have a 3/12 pitch with no heat at all to help snow melt and slide off your roof. So I see potential for a build up of snow unless you plan on using a snow rake to keep your roof clear of snow.

 

[Git]

Sounds good but I’m seeing a weak link in using just a 4x6 to span 12’ between each post. I’m certainly no engineer thus I tend to overbuild. Hopefully a builder with better knowledge will chime in on this. If I were doing this for myself I’d be using 3 2x10s with 1/2 plywood glued and screwed between them. Remember that you’re only going to have a 3/12 pitch with no heat at all to help snow melt and slide off your roof. So I see potential for a build up of snow unless you plan on using a snow rake to keep your roof clear of snow.

Agreed

If you looked at some of those pdf files I posted, you can see that even in S Cal (no snow) a 12' span between your posts requires a 4 x 10.

Look at Table B

 

[wicked_pissah]

Hmmmm, great info. Thanks guys. I'm wondering then if I should go with five 4x4s spaced evenly with a 4x6 header. My 2x8 rafters would span 12 feet and the 4x6 header would only span 6 feet between each support post. FWIW I do plan on paying close attention to the amount of snow on the roof and clearing it off with a roof rake when it builds up...

 

[wicked_pissah]

Hmmmm, great info. Thanks guys. I'm wondering then if I should go with five 4x4s spaced evenly with a 4x6 header. My 2x8 rafters would span 12 feet and the 4x6 header would only span 6 feet between each support post. FWIW I do plan on paying close attention to the amount of snow on the roof and clearing it off with a roof rake when it builds up...

Updated CAD:

<a href="https://imgur.com/HqIjrxG"><img src="https://i.imgur.com/HqIjrxG.jpg" title="source: imgur.com" /></a>

 

[Farmall450]

Hmmmm, great info. Thanks guys. I'm wondering then if I should go with five 4x4s spaced evenly with a 4x6 header. My 2x8 rafters would span 12 feet and the 4x6 header would only span 6 feet between each support post. FWIW I do plan on paying close attention to the amount of snow on the roof and clearing it off with a roof rake when it builds up...

It'll make things a little tight if you try to go in from the long side, unfortunately. Not sure if that's a plan or not.

 

[wicked_pissah]

It'll make things a little tight if you try to go in from the long side, unfortunately. Not sure if that's a plan or not.

Do you mean if I plan to have an entry on the long side? If that's what you mean it's okay, as the plan is to wall the long side off and have the gable ends open.

 

[Farmall450]

Do you mean if I plan to have an entry on the long side? If that's what you mean it's okay, as the plan is to wall the long side off and have the gable ends open.

That takes care of that. Let's see roughly what you're looking at with a snow load.

 

[wicked_pissah]

Ground snow load for Turner, Maine is 80psf.

 

[cdestuck]

I like your using just 3 posts if possible. Just do the proper beam to allow it.

 

[wicked_pissah]

I like your using just 3 posts if possible. Just do the proper beam to allow it.

Would a 12 foot 6x6 work to span the 12 feet between support posts?

If I go with the beam design that you described in an earlier post (three 2x10s and 1/2" plywood), what type of plywood and glue should be used? Do you know of any references that I can check out to learn a little more about building these types of beams or could you provide some instructions?

Thanks!

 

[cdestuck]

I do believe a6x6 is too small for a span of 12’ That will have an expected snow load. I would stay with the 2x10 or even 2x12 and do a glue up with two pieces of cdx plywood. Use 3 1/2” decking screws and Titebond 3 glue.

 

[Dustball]

To give you an idea of what I did, I used FastenMaster 3-5/8" LedgerLOK screws to attach my 2x10 ledger board through the sheathing into the wall studs (2 screws per stud).

They're also available in 5" lengths since your siding is thicker than my 7/16" sheathing.

My rafters are 2x10s at 24" OC with 2x4 purlins 24" OC.

My posts are 6x6s at 8 feet spacing.

The beam is made of doubled up 2x10s sitting on notches cut into the posts.

It held up fine to nearly 30 inches depth of wet snow this last spring which is a lot of weight.

The roof is 15-1/2 feet total width with the posts 13 feet from the house. Total length of the roof is 27 feet.

Make sure you install blocking between the rafters.

 

[wicked_pissah]

Awesome Dustball! Thanks for the description and the pics, those are super helpful!

 

[Ben W]

Adding width to your beam does not make up for a lack of height. i.e. a 4x6 or 6x6 are not comparable to laminated 2x10s or 2x12s just because they have the same area. Another benefit of the laminated beam is that you can make it continuous more easily than a single 4x6 by staggering the joints.

Plywood is typically used to stiffen the beam or to make it a set thickness. More strength comes from the beam size.

Gluing is a nice option, but it makes the boards slippery when you try to put them together. I like to clamp the boards to get them set perfect before I screw/nail. I wouldn't use titebond (that's good if your two pieces are prepared nicely); i'd use PL Premium - comes in a caulk tube and fills those uneven surfaces between framing lumber.

Personally, i'd build a 3-ply beam as it more closely matches the width of a 6x6. If you want it perfect add plywood. And if you're going to make a solid wall, then the larger post spacing isn't as much of a benefit than if you wanted it open for access. How will you frame those openings off? Tighter post spacing might make your life easier there.