In the United States or Canada, call 811 toll-free to request this service. [3] X Research source
Also decide how the roof of the lean-to will interface with the roof of the shed.
Concrete blocks Concrete footer with a small stem wall to prevent water from seeping in Concrete pier pads with the top flush to ground level You can use pressure-treated skids for additional support, but do not rely on them as your sole foundation. You can use a 4" x 4" pressure treated post to establish the vertical upright framing.
Other options include shingle roofing, rolled roofing, metal flashing to waterproof the join between the new roof and the existing one, metal studs for framing, and cementitious board or composite sidings. Choose the materials that are suitable for your location and climate as well as materials that will match your existing building. Be sure to plan to use a sheath of CDX plywood on the wall that abuts against the structure. CDX plywood resists indirect moisture.
Poles for supporting the eave framing. 4" x 4" pressure treated southern yellow pine will support a lightweight roof framed with 2" x 4" boards, spanning less than 15 feet (4. 6 m) or so. For a longer, heavier roof span, 6" x 6" timbers or even steel columns may be more suitable. Rafters for framing the actual supporting structure of the roof will need to be strong enough to support the weight of the lathing, the decking and the workmen who will walk on the roof while installing it. A somewhat typical span of less than 10 feet (3. 0 m) may be framed with southern yellow pine if the rafters are free of large or loose knots and are otherwise structurally sound. You may use Douglas fir, hemlock, or cedar instead. Lodgepole pine, spruce and other softer pine species are too knotty and not strong enough for roofing unless the rafters are from large diameter trees. For roof spans 10 feet (3. 0 m) or greater, 2" x 6" nominal framing or larger, should be used. The rafter nailers spanning between the posts on the eave side of your lean-to must be strong enough to support the load of multiple rafters. Use a minimum size of 2" x 6" nominal southern yellow pine or other strong wood. Nailers attached directly to the wall of the building onto which the lean-to is being added can be the same size lumber as the rafters themselves as long as the nailer is attached securely to the wall of your building. Local building code and the existing wall material will determine which anchors to use. These may include lag bolts (to attach to large diameter wooden beams), threaded bolt nuts and large diameter washers (drilled into hollow concrete blocks), or hurricane anchors. Lathing strips, or the framing members that lay across the rafters that the metal roofing is attached to should be sound southern yellow pine or a similar lumber. 1" x 4" lathing lumber is sufficient to support a normal load on spans where the rafters are located at 24 inch center spacing or less. 2" x 4" lumber is easier to fasten to (it bounces less when nails are driven into it), and may not be significantly more expensive than the 1" x 4"s. If you are laying a plywood “roof decking” directly onto the rafters, then you only need lathing to brace between the rafters or to prevent side-to-side movement by cross-tying them to the bottoms of the rafters. Nails or screws to act as fasteners. Nails should be large enough to penetrate the attached member and the supporting member deeply enough to secure the two pieces. Screws may be used to attach dissimilar materials, such as metal framing, roofing, or siding to wood framing, or even for joining two separate wood members.
Make sure the floor material will withstand expected weather conditions year-round.
Measure the distance between the wall to which you will fasten the lean-to and the starting corner. You can start by pulling string lines along the planned addition. Use the 3-4-5 rule to confirm the outer corners are square before you dig the holes. If the outer wall is not parallel to the shed, the rafters will be difficult to place.
Plumb two adjacent sides of the post to confirm the post is level. Secure those two sides with temporary diagonal cross bracing, using two 1" x 4" boards. Drive a wooden stake into the ground next to each board. Fasten each 1" x 4" board to a stake and to the post using easily removed nails or screws. Once the end posts are in place, repeat with the intermediate posts.
If your lean to is small and your area does not experience strong wind or severe storms, you may be able to backfill the post holes with dirt instead.
This line will determine the bearing height of the rafters. Start by marking the end posts, and use either a plain line or a chalk line to mark the intermediate posts.
Draw a notch about 1-1/2" (about 4 cm) deep into your post. Use a circular saw set to a 1-1/2" (about 4 cm) depth to cut into the post at the base of the notch. Set the circular saw to maximum depth. Measure out 1-1/2" (about 4 cm) on the top side of your post and cut into the top of the post on the same side as you made the first cut. When your saw blade meets the first cut, the wood block should fall off, leaving the notch for your nailers. If necessary, finish the cut with a hand saw or a reciprocating blade saw. Repeat the process with each post. If you choose to, you may simply nail directly into the side of the post, but doing so places all the weight on your fasteners. You could also use metal hangers or brackets to attach the top beam or plate to the posts, using heavy gauge TECO nails.
If the nailer is not long enough to span the total length of your shed, make sure any joints are set against a post to ensure maximum bearing potential for the nailer. Nail the nailer into place, making sure the spacing between your posts remains correct.
To attach a wooden nailer to a metal-sided building, use a self-drilling screw with sufficient threads to hold the nailer tightly. If possible, nail through the siding into the building’s framing members. Regardless of what method you choose to attach this member, make sure it is fastened securely. This is critical because the nailer it will support the weight of the roofing, the framing and the person performing the installation.
Starting at 1 end, measure the span you determined to use when you designed the building, and mark each space. Marking the edge of the rafter rather than its center will make the mark more visible when you position the rafter.
Hold a speed square (also known as a rafter square) plumb against the top nailer where your string is fastened. [10] X Research source Read the angle on the square’s angle scale.
Test the cut by holding the rafter in position. If the cut does not fit tightly, adjust it. A good fit will increase the hold of your nails when you attach the rafters. When you have established the best angle for the top cut of your rafters, cut each one using that angle. Unless you are certain both nailers are exactly parallel, do not cut the lower end of the rafter. This can be done after the rafters are installed, if cutting them is necessary.
Use a pencil to mark the position where you want your boards to join at a right angle. Place the rafter about 1/4" (6 mm) in front of the nailer. Place the nail about 1/2" from the connection point and nail it in straight into the rafter. The key to toenailing is to drive the nail in straight and then at an angle. Tap the nail into the wood about 1/4" (6 mm). Pull the nail up at about a 50-degree angle. Drive the nail in until it protrudes slightly from the rafter. Reposition the board to ensure that the angle is exact. Finish driving your nail through the rafter and into the nailer. Avoid starting the nails too close to the end of the board, as this may split it, and make a strong connection impossible. If this is unavoidable, pre-drill the hole at the correct angle first.
For 29-gauge metal roofing, spacing can be up to 30 inches between centers. Nail the lathing securely, with a minimum of two nails at each rafter, being careful to keep them aligned.
Typically, a lean-to roof will lay at a different pitch than your existing roof. [11] X Research source The lean-to’s roofing will need to fit fairly snugly underneath the existing roof to prevent rain from blowing into your addition. You may need to install metal flashing to help ensure water proof joining of the two roof pitches.
The shed in the photos is 10 feet (3. 0 m) wide and 21 feet (6. 4 m) long, so a partition was installed to create a 7x10-foot space on one side, and a 14x10-foot space on the other. This partition was created by installing steel stud purlins between one of the outboard support posts and a nailer fastened vertically to the existing shed wall.
Pay close attention to the screws or nails that attach the roofing components. Also check the siding, if used, and any trim installed on corners or edges. Make sure any metal corners (if you side the lean-to with tin) are rolled or formed in such a way that no sharp edges are exposed.
