Q&A for How to Add a Lean To Onto a Shed

It would be best to use a metal anchor plate securely installed into existing concrete by drilling correctly size hole for the self setting fasteners and applying the correct epoxy cement to the fastener as well.

It is called 'Tin, Galvanized metal, Sheet metal roofing' and is also sold for side walls. It can be purchased at most lumber retailers and home improvement suppliers as well.

Look up "hip" roof construction. Most of what you will find pertains to homes and full structures but can also be adopted to what I believe you are looking to do.

Use large screws and/or bolt, and use a chalk line or laser to be sure you have it level.

Place one on each corner and one every 8 feet between. Like, a 32-foot long wall would require 5. A 16-foot wall would only need one in the middle. A 16x32, if using my recommendation, would require 12-4x4’s.

You’ll want to locate the structural members to the inside if the building and attach the nailer at those points with either large lag bolts into wooden poles or predrill and use bolts with nuts and washers.

If you are talking about a lean-to that needs more pitch, then you will need to either raise the upper end, lower the outer end or start over all together. You can raise the uphill side by removing the roof material, hopefully Tin, and place a new ledger board, nailer as described here, remove the rafters one at a time and raise it to the desired height and re fasten. This creates a problem though if your overhang isn’t long enough because your boards could come up short. If you don’t have enough pitch, I’m assuming that you have come to this conclusion because of a leaking connection, you may try using some flashing to help with the connection being watertight.

You can most usually place them every 8 feet. If you need to span further than 8 feet make sure to use a span chart to ensure you use the correct size lumber to match the distance needed to span.

You can make notes of where the interior framing members are located and transfer those marks to the exterior wall And this is where you will place your fasteners. In the past I’ve also drive a few screws to temporarily hold the nailer and then drill and use bolts with nuts and washers to get a more secure nailer. Then use flashing on the exterior wall of the barn that is caulked at the barn side, put a bend in the flashing midways, length wise and let it stick out over the roof where it joins. Just picture the direction that water travels And use the flashing to prevent it from flowing underneath it. The caulking helps seal against uneven surfaces.

This would depend on the size of your lean to and the dimension of your joist. If you're using 2x4's and the size is 8 ft or under, 12" may be enough. I would go with the standard of 24".