How to Build Dormers

Facing the challenge of building dormers? A do-it-yourselfer must consider the requisite planning, preparation, equipment and skills, as well as the amount of time and expense, in undertaking such a building project. The addition of a dormer to a dwelling unit, whether for the purpose of adding a bedroom, a home office or studio or to add general living space, is a fairly common approach to enlarging the dimensions of a home.

Where are Dormers Placed

Dormers are generally employed, either in original construction or as later additions, with the objective of adding usable space in the top story of a building, by adding more “headroom”. Dormers offer vertical walls and either horizontal or vaulted ceilings, unlike a typical loft extension with diagonal walls. They have the further benefit of providing natural light through dormer windows.

Zoning and Permits

One of the first steps to do is to consult with the local town, municipal or county building and zoning authority with jurisdiction over residential building construction in your area to determine how large and how high a home can be built or expanded on your particular zone and your particular lot.

You will also inquire as to the necessary zoning and building permits that must be obtained and the fees for same. No construction should proceed without the requisite paperwork or one may be faced with a fine and a possible injunction against the project.


The preparation includes the generation of detailed building plans or blueprints to be followed precisely as construction proceeds. Such plans should be prepared by a professional and experienced architect or draftsman.

Typically, such plans are now produced with the aid of home design computer software. Such design documents can be obtained locally or they can be purchased on various Internet web sites. Both stock and custom design plans can be ordered.

Dormer configurations vary from a gable fronted or doghouse design to a shed design to a hipped roof design to a flat roof configuration. The selection of the design should take into consideration the number of rooms to be added and the amount of headroom desired.

Even the addition of a small residential dormer will normally require at least two individuals, with at least one of which being an experienced framer (assuming wood frame construction) having advanced construction skills.

What Tools you will Need

Tools and equipment for the project will include:

    basic carpentry hand tools, a circular saw, an reciprocating saw, scaffolding, framing squares, two and four foot levels, roofing brackets, other safety equipment and hardware.

Construction Steps

Once the planning and preparation has been completed, construction may begin. The major building steps will include:

    • Measuring and marking the location for the dormer walls on the attic floor, ensuring the walls will be square and the top wall level;

    • Removal of the existing roofing shingles and sheathing boards

    • Construction of the framing of the dormer walls;

    • Framing the roof, attaching the rafter to the ridge;

    • Adjusting the interior walls to conform to the slope of the roof;

    • Installation of the roofing shingles, flashing and make the dormer watertight;

    • Installation of any electrical and plumbing work;

    Installation of the insulation and drywall;

    • Beginning the finish and trim work

The above steps are only a very basic outline of the many steps to constructing a well-built dormer.

Your local building authority may require periodic inspections as your work progresses. Very often they require a building inspection upon completion of the framework and before plumbing and electrical work is added.

We hope this article has provided any do-it-yourselfers considering adding a dormer to their home a general scope of what is involved.