Low Pitch Roof Framing

For a low slope residential roof there are two main options.

Low pitch roof framing.

1 cover the entire surface with a self adhesive flashing membrane such as grace ice water shield there are many equivalent products. For our 4 x8 lean to example using a 2 4 rafter the depth of the birdsmouth is limited by the 1 3 depth of the rafter rule. If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center. As a general rule roofs that have a high human occupancy rate should be framed with rafters every 16 structures such as sheds or barns can be frames with rafters every 24 again make sure to consult local codes.

Then apply standard asphalt shingles over the membrane. Use prefabricated mono trusses for the easiest and best framing on a single slope roof. A 2 4 wall with a 2 6 rafter can be notched for a 4 seat. When design constraints necessitate a 1 4 in 12 design slope be used the framing members should be cambered or investigated for ponding.

At the low end of the valley the subfascias of the two roofs are mitered with a block filling in the roof framing. Mark truss locations on the front and back wall caps of the structure. Use a framing square to help lay out the notch based on the slope of the roof. Standing water is a primary source of roof cover discoloration and deterioration that may result in framing member damage and contribute to premature failure of the structural system on low slope roofs.

Self adhesive flashing membrane under the shingles prevents leakage on low slope roofs. Add the length of the overhang beyond this mark and. The membrane will outlast the shingles and seal around all nail penetrations. In older buildings the usual method is to install fiberglass batts or cellulose on top of the leaky ceiling with a gap of a few inches or sometimes a few feet between the top of the insulation and the roof sheathing.

Position the square at the end of the rafter board with the tongue on your left and facing away from you. Just like any other roofing system low slope roof designs will have several effects on the overall construction of the building including the interior volume the style and design of the house the drainage system and the material used for covering. There are lots of ways to insulate a low slope roof and most of them are wrong. How to frame a single slope roof step 1.

To transition the eaves the horizontal fascia extends to the last rafter tail and a vertical return finishes the transition. Updated on april 8 2016. Erect one truss in. A low slope roof design typically has a pitch of between 2 12 and 4 12.

Curvetech glass or polycarbonate dome. Measure form the top of this line down the board to determine the line length or length of the rafter less the ridge. With a velux flat roof skylight designed to meet the growing demand for skylights in homes with flat or low pitch roofs you can transform and improve virtually any space with daylight. Get on a ladder with a tape measure.