How To Add A Porch Overhang To Your Shed

There are 2 general ways to attach a porch overhang to the shed..

  • Extend the existing rafters or truss ends.
  • Use a ledger.

Your choice will depend on the direction of your roof, where you want the porch, and the height of the roof section and height of the door below.

You can either tie into the rafter ends at the end board or use a ledger.

With either choice make sure you have enough headroom so the door can open without hitting the porch rafters.

There are 6 components to the porch structure

This view shows the various components of a porch.

This view shows the various components of a porch.

  • Ground anchors
  • Uprights
  • Headers
  • Rafters
  • Ledger
  • Roof covering

On a lean-to style shed you can extend the roof line by either using one long rafter or splice them. You can splice them where they both sit on the top plate or splice the ends by overlapping them and securing them together with screws, nails or bolts. Or you can attach them to the end board.

For a gable or gambrel roof you can tie the rafters into the truss end board or sit them on the top plate and eliminate the overhang.

Or you can attach a 2×4 or 2×6 ledger and nail into the wall studs. Then you can attach the rafters to this ledger. If you are extending the existing rafters or trusses you will not need a ledger.

But make sure any doors below can open freely.

Make sure there is enough clearance for the door to open.

Make sure there is enough clearance for the door to open.

Ground anchor

Ground anchors keep the porch from blowing away in the wind. You can simply bury the pressure treated uprights about 3 ft in the ground, or dig a hole and pour concrete around them.

A third option would be to bury precast concrete footers in the ground. These will have metal clips at the top to attach the uprights to.

Uprights

Detail showing upright, header and rafters.

Detail showing upright, header and rafters.

Use pressure treated 4×4’s since they will be close to the ground and subject to water rot and termites.

There should be one on either end and about 8 ft centers or less in between.

Headers

Use a piece of 4×6 wood for the header, or sandwich a pair of 2×6’s around a strip of OSB siding. This will make the final header a full 4 inches to match the uprights.

Rafters

Rafters should be the same dimension as the shed rafters or trusses if you are extending the roof line. This will make it easier to trim and make it visually match the rest of the of the shed .

As long as the span from the porch header to the attachment point on the shed is 8 ft or less you can use 2×4’s. For spans over 8 ft you will need to use 2×6’s.

You can extend the porch up to 24 inches beyond the header without any problem.

You don’t need to notch the rafters where they sit on the header because there isn’t that much weight. Attach them to the header with metal ties.

The the ends of the rafters together with an end board.

Trim the outside with facia to match the rest of the shed.

Ledger

The ledger will be the same size as the rafters and secured to the shed with nails or screws into the underlying wall studs.

The ledger will be the same width as the header and should extend the same amount beyond the walls as the shed overhang.

Attach the rafters to the ledger with metal hangers.

Again, you will not need a ledger if you extend the rafters or truss ends.

Roof covering

If you use a ledger you might need to add some metal flashing where the porch meets the shed to keep the joint from leaking.

There will be too little slope to use shingles so you will have to use rolled roofing or metal to cover the porch.