How to Add a Lean To Onto a Shed
Know your local zoning laws., Locate underground hazards., Draw a plan for your project., Design the roof to withstand weather., Decide on a foundation., Choose the materials you will use., Calculate the amount of each material you will need, price...
Step-by-Step Guide
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Step 1: Know your local zoning laws.
Consult the local building authorities to learn about code requirements, needed permits and property set backs for storage buildings. -
Step 2: Locate underground hazards.
Most lean-tos will require some digging, whether for a concrete foundation, pier blocks, or postholes.
Always call a utility location service before you break soil.
Digging into a pipe or electric line could cause serious injury or property damage.
In the United States or Canada, call 811 toll-free to request this service. , Plan the length and the width of your lean-to, and where it will attach to the shed. , Angle the roof so rain is directed away from the building's perimeter.
You may need a simple gutter or downspout drainage piping to prevent pooling at the base of the lean to.
If your region receives heavy snowfall, build the roof to withstand that load.
Also decide how the roof of the lean-to will interface with the roof of the shed. , Even though the addition is small, a solid foundation is important.
Use the best materials within your budget.
Here are some solid examples:
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. , Lumber is a fairly strong and inexpensive material for framing, and tin is a suitable roofing and siding material.
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. , Some basic items that a lean-to addition for a tin shed would use include:
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. -
Step 3: Draw a plan for your project.
-
Step 4: Design the roof to withstand weather.
-
Step 5: Decide on a foundation.
-
Step 6: Choose the materials you will use.
-
Step 7: Calculate the amount of each material you will need
-
Step 8: price them
-
Step 9: and purchase them.
Detailed Guide
Consult the local building authorities to learn about code requirements, needed permits and property set backs for storage buildings.
Most lean-tos will require some digging, whether for a concrete foundation, pier blocks, or postholes.
Always call a utility location service before you break soil.
Digging into a pipe or electric line could cause serious injury or property damage.
In the United States or Canada, call 811 toll-free to request this service. , Plan the length and the width of your lean-to, and where it will attach to the shed. , Angle the roof so rain is directed away from the building's perimeter.
You may need a simple gutter or downspout drainage piping to prevent pooling at the base of the lean to.
If your region receives heavy snowfall, build the roof to withstand that load.
Also decide how the roof of the lean-to will interface with the roof of the shed. , Even though the addition is small, a solid foundation is important.
Use the best materials within your budget.
Here are some solid examples:
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. , Lumber is a fairly strong and inexpensive material for framing, and tin is a suitable roofing and siding material.
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. , Some basic items that a lean-to addition for a tin shed would use include:
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.
About the Author
Daniel Chavez
Writer and educator with a focus on practical pet care knowledge.
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