How to Install Mono Trusses on a Patio

Build supports for the trusses with ledger boards attached to the house wall and 4-by-4-inch posts on the patio, at the outside corners and every 8 feet in between if the patio is large. Set posts in holes in the ground at least 2 feet deep, secured with concrete, or with metal brackets, fastened to a concrete slab with concrete anchors. Use a level to set the posts plumb.

Locate framing on the house wall to attach ledgers, one at the top of the mono truss, another along the bottom chord at the end. Remove any house siding and look for nails to indicate rim joists, wall caps, studs or other framing elements strong enough to support the truss. Mark those spots on the wall sheathing. Use a tape measure, level and chalk line to snap lines to mark the bottoms of each ledger, with the bottom ledger the same height as the top of the posts.

Nail 2-by-6-inch ledgers in place temporarily with 16d framing nails and a hammer, fastened to studs or other supports. Use a level and tape measure to make sure the boards are level and spaced the same as the end chords on the mono trusses. Drill pilot holes with a power drill and 3/8-inch bit through the ledgers into every house framing member. Fasten the ledgers with lag bolts with a screw end and bolt head, driven with a ratchet wrench into the framing.

Fasten a 2-by-6-inch framing board across the outside posts to support the outside ends of the trusses. Level it at the same height as the bottom ledger on the house wall. Secure it with framing nails into the posts. Mark spacing for trusses on the ledgers and outside support, 24 inches apart the width of the patio.

Set trusses in place, starting at one side of the patio roof. Lift a truss and erect it, plumb it with a level and fasten it to the ledgers and the outside frame with framing nails. Drive nails through the end bands on the truss into the ledger and diagonally through the truss chords into the outside band, two nails on one side and one on the other of each truss chord.