Framing A Low Pitch Roof

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

Framing a low pitch roof. 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. To provide a framework for the new trusses nail 2 by 6 inch strips of wood around the perimeter of the roof. Can metal roofing be used on a low slope pitch roof. This sizing guide for roof rafters will help determine what you need for your small project.

Sunday august 5 2018 the traditional metal roof types such as 5v crimp shown above and corrugated are rated by the manufacturers for use down to a 3 12 pitch three inches of vertical rise for every foot of horizontal run. This is denoted two ways a 1 3 or 1 4 pitch in fractions and a 6 12 pitch in inches which means the roof rises 6 inches for each 12 inches of run. This system can also be used for the steep roofs. On the body of the square the longer side input the 12 and input the 7 on the tongue the shorter side of the square by lining up the stair gauges at the corresponding point on the square.

To transition the eaves the horizontal fascia extends to the last rafter tail and a vertical return finishes the transition. Pitch is the amount of angle or slope the roof has. 1 cover the entire surface with a self adhesive flashing membrane such as grace ice water shield there are many equivalent products. Erect one truss in.

Use prefabricated mono trusses for the easiest and best framing on a single slope roof. Metal panel roof systems for low pitch application this system uses a structural metal panel for low pitched metal roofs due to their ability to form a formidable barrier for water. Self adhesive flashing membrane under the shingles prevents leakage on low slope roofs. 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.

At the low end of the valley the subfascias of the two roofs are mitered with a block filling in the roof framing. A 2 4 wall with a 2 6 rafter can be notched for a 4 seat. Use a framing square to help lay out the notch based on the slope of the roof. There are several variables to consider when determining the proper rafter size.

The membrane will outlast the shingles and seal around all nail penetrations. Weather you re building a shed roof or adding a dormer to your second story it is important to choose the proper size rafter. Get on a ladder with a tape measure. For lower pitches a built up or continuous roll roofing must be applied to keep the roof waterproof.

Mark truss locations on the front and back wall caps of the structure. How to frame a single slope roof step 1. Then apply standard asphalt shingles over the membrane.