How to Build Gable Dormers

By eHow Home & Garden Editor

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A gable dormer lifts out of the normal roof line and sits perpendicular to the existing roof. The dormer's triangle shape creates a sloping ceiling inside of the room. Dormers increase living space on the upper floor of a house. Here is the process required to build gable dormers.

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Instructions

Difficulty: Challenging

Preconstruction

Step1

Choose gable dormers if you have an Arts and Crafts, Federal, Colonial Revival, Georgian Revival, Queen Anne, Gothic Revival, Tudor Revival or Stick style home.

Step2

Decide if you have enough home construction knowledge and experience to handle the project. To build gable dormers you will change the roof line that handles rainwater flow, and this area must be strong and correctly positioned to handle the weight of ice and heavy snow.

Step3

Consult with a structural engineer to insure the construction of the dormers won't compromise the home's load bearing points.

Building Process

Step1

Determine the position of the dormers and work inside before cutting the hole in the roof. Roll double or triple roof rafters between the ridge and outside wall flush to the inside edges of the dormer opening (see Resources below).

Step2

Saw and head off existing common rafters using a reciprocating saw, then frame the dormer walls. Prepare the opening for the window.

Step3

Cut the rafters and prepare the ceiling joists when you build gable dormers.

Step4

Strip back the roofing material. Put the valley frame on top of the main roof sheathing under the shingles.

Step5

Insert the window. Apply the sheeting to the roof and front exterior wall of the dormer.

Step6

Install the roofing material.

Step7

Apply the siding of your choice.