How to Build a Portico Onto Your Home

Determine the desired height and width of the portico. Measure and mark where the front posts are to be placed. Also ensure that the cement slab being used as a foundation is level. If not, one of the posts should be trimmed so that the roof will be level.

Prime and paint the bottom of each post to protect against moisture. Once the paint is dry, add screening material using roofing nails. Then use 2-inch screws to attach aluminum base stands to the bottom of each post.

Pre-drill holes in the concrete slab base using a masonry drill bit of 5 3/4 inches. Then attach the post anchors to the concrete slab using masonry screws. The posts can now be attached to the post anchors using 2-inch screws.

Measure and cut a trim board so that it reaches one inch past the posts on either side and creates a small overhang. Secure the trim board to the posts using 2 1/4-inch screws.

Attach 2x6 and 2x2 pieces of lumber with sixteenpenny nails in order to create a header. Create a ledger board the same way. Attach the header to the trim board and the ledger board to the house using lag screws in both instances.

The location of the joist hangers must be marked on the ledger board. Firmly secure the joists with joist hangers using all supplied holes. Then nail a 2x6 piece of lumber to the end of the ceiling joists to create a ledger for the rafters and attach it to the house using lag screws.

Measure the angle of the roof pitch and cut the first rafter angle with a circular saw accordingly. The initial rafter can then be used as a guide for subsequent rafters. Attach the rafters to the header and the ledger using sixteenpenny nails.

Place a double layer of plywood sheathing down perpendicular to the rafters so that it is flush on the sides with the one-inch overhang in the front. Secure the sheathing to the rafters using eightpenny nails. Then add roofing felt secured by roofing nails.

Begin laying roofing shingles in an overlapping fashion from the front edge of the roof, working your way back to where the roof meets the house. Cut flashing that matches the portico's length along the house and install it over the last row of shingles. Then cover the flashing with another cut layer of shingles.

Use a pneumatic nailer to attach a piece of plywood sheathing to the underside of the joists, which will function as the portico's ceiling. Also add a piece of plywood trim to the beam right beneath the roof's overhang.

Add a soffitt to permit airflow, and then attach the fascia to the front part of the roof. Also, add trim to the exterior side of the roof and the inside in order to cover the side beams.

Attach siding to the sides of the portico roof using studs and then paint the siding to match that of the house. Prime and paint the ceiling, posts, soffitt and fascia so that it corresponds with the house's trim.