Installing Trusses Over Flat Roof

These purlins are attached by driving nails through the wide face of the purlin into the tops of the trusses.

Installing trusses over flat roof.

Once in place the workers nail the truss to the wall. A professional roofer will use exact measurements from the home s construction along with framing and truss dimensions to calculate the type of roof over will work best. Homes with flat roofs of bowstring trusses pose a problem because they are not strong enough to withstand the weight of a new roof. Workers manually move the first truss to the end of the roof and stand it up positioning it on the corresponding number on the wall plate.

How to install trusses on a roof. Installing a new roof over an existing one also called a layover or nailover is often possible although not always the best option a properly installed layover roof can look and function as well. If you want to build a flat roof then you will need to build a flat roof truss. This four foot truss spacing allows for 2 4 roof purlins to be placed flat on top of the trusses.

After constructing your trusses now you have to get them safely to the top portion for installation. Or if you want to raise the roof a bit more install fascia around the roof perimeter attached to the new soffit and nail the new roof deck to crown molding above the fascia. These are designed to span the space between two load bearing walls and take the weight from the roof onto these walls. Installing the new roof to provide a framework for the new trusses nail 2 by 6 inch strips of wood around the perimeter of the roof.