In Between Rafters Bridging For Roof

Installing stacks of rigid foam between rafters is slow fussy work but it might make sense for a do it yourselfer.

In between rafters bridging for roof.

Install underlay above the rafters. The snugness of the foam itself should be sufficient to hold the strips. For example with bridging installed between joists a piano leg sitting over one 2 10 is actually supported by several. Fine homebuilding finding effective ways of beefing up under insulated roofs is a perennial problem affecting countless houses built to minimum energy standards.

Insulation between the rafters. For low pitch roofs building codes may require larger dimension rafters. Position the foam board between the rafters and push it upward until it fits snugly against the underside of the roof deck. The roof rafters provide integral structural support to the roof.

Common spacing for trusses on this type of building is often between 2 and 4 feet but trusses built with advanced designs may allow spacing as great as 8 or 12 feet. So the space between rafters can be greater without reducing the maximum span. Rafter span tables use these tables to determine lengths sizes and spacing of rafters based on a variety of factors such as species load grade spacing and pitch. For a ventilated roof structure a traditional high resistance sarking can be used.

Before you cut your boards you ll need to measure the width of your building and calculate the exact length of each rafter. For an un ventilated roof construction a vapour open underlay or breather membrane should be specified. If you re framing a gable roof on a new house or building a shed or even a doghouse with a gable roof you ll need to cut a number of roof rafters. The same concept holds true for roof trusses.

Insulation is placed between and hopefully above the rafters or joists with sometimes extra insulation underneath along the ceiling. The blocking or bridging between joists or rafters also contributes to this phenomenon. Visit the roof framing page for more information on cutting roof rafters and visit the roof pitch calculator for determining rafter lengths based on rise and run. Solid blocking and metal or wood x type bridging do accomplish the same task.

As roof pitch is lowered the weight burden on the rafters increases.