How to Convert a Flat Roof to a Gable Roof

What You'll Need
Joist Hangers
Wood screws
Polyethylene Sheeting
Rigid foam insulation
EPDM Roof Membrane
Roof drain or Gutter

A gable roof is one that is built with rafters or boards that angle the pitch of the roof, whereas a flat roof is simply a roof that is built flat on top of the home. A flat roof can be converted into a gable roof by following the steps, tools and materials provided in this how-to article.

Step 1: Purchase Roofing Material

At a home improvement center purchase the materials needed on order to convert your current flat roof into a gable roof. You will need to make sure that the wood you use in the conversion is treated since it will be exposed to the elements. You want to make sure that the materials that you purchase are appropriate roofing material. Ask questions if you are not sure about which specific type of brand of material that you need for the flat to gable roof conversion.

Step 2: Create the Walls and Frame for Gabled Roof

You will need to build the walls and framing for the gabled roof. Working carefully with a partner or assistant, frame the roof using the wood that was recommended to you when you purchased it from the home improvement center. The joist hangers should be mounted to the framing of the roof in order to provide a hanger in which the 2 X 4 boards can be run through for the plywood sheets that will cover the top of the roof.

Although this should go without saying, you need to create the gable roof framing and wall on the ground. It will need to be hoisted in to place using a crane truck or other type of hoist. This will be an item that you will need to bring in a professional in order to ensure that the new frame is mounted properly on the roof.

Step 3: Secure the Frame to the Flat Roof

With the gable roof frame constructed, have it hoisted into place and put on top of the flat roof. You will need to use large bolts or screws to attach the ends of the gable roofing to the flat roof.

Step 4: Attach Foam Insulation

Attach the foam insulation to the boards of the gable roofing frame. The insulation is necessary in order to keep the roof dry and resist any elements that may cause the roof to fail.

Step 5: Place the Roof Membrane on the Gable Roof Frame

Take the EPDM roof membrane and seal all of the roof openings using the bonding tape. At each of the intersection on the roof (where joints come together) install the flashing The flashing is needed to direct water away from the roof and into the rain gutter and downspouts. Also, install the new rain gutters and downspouts to the gabled roof.

Step 6: Shingle the Roof

With the tar paper laid out over the plywood and the nailer board in place, place the shingles on the roof. This will complete the conversion of your flat roof to a gable roof.