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From the Architect's Desk



In From the Architect's Desk

By lthomas

The dos and don’ts of Dormers.

On 02, Apr 2015 | In From the Architect's Desk | By lthomas

The Encyclopedia of Architecture, (Joseph Gwilt), defines a dormer as, “A window placed on the inclined plane of the roof of a house, the plane being placed vertically on the rafter.” More simply, The Oxford Dictionary states it’s, “A window that projects vertically from a sloping roof.”

What these definitions leave out is that dormers are wonderful because they create space. Really. A simple skylight can bring in light, but dormers create a veritable room around that light source.dormersun

So what kinds of dormers are there? Why would you put one in to your home?



Illustration: Home Renovation, F. Ching

To begin, there are two main types of dormers, gable and shed. A typical, single-window gable dormer has a peaked roof and gives you a nook of higher head clearance space. This newly created interior space would be a perfect place to tuck a small dresser or a toilet or pedestal sink. I’ve even used a small dormer to create head height for a new stair.  Sometimes this small dormer has an “eyebrow” curved roof. Adding this curve should be a considered design and proportion choice made after looking at the overall balance of the windows on the exterior.




interioreyebrowA shed dormer can create a large area of space and hold several windows. This new space really adds to the usable footprint and can create enough head height to accommodate a large bedroom or bath where there wasn’t room before.  This dormer can also be curved into an eyebrow if the design leans in that direction.




GabledormerI like to use dormers on new construction or an addition to help keep the overall massing and height of a roof down. Rather than have a full upper level with eight foot ceilings, I can drop the roof a smidge, add some dormers and voila! I have a wonderful upper level room full of light without a tall second story looming over the street or yard. This is particularly helpful when you have a strict zoning height restriction or when the overall house is smaller or “cottage-y” in feel. With guest accommodations or a studio over a garage, dormers are a must! Dormers create better proportions, better spaces, better design.


I typically add dormers to existing spaces as a part of an attic conversion. Many older homes were built with a Dormer-atticgenerous attic. I believe a home should use all available space and work within a small footprint, so I frequently ask my client, “Why don’t we use the attic space?” Indeed, the dark attic, now with the addition of a large dormer or even several, suddenly becomes light-filled, and the new dormer space increases the available head height along the room’s edges (the eaves). Another improvement brought to the attic by dormers is the ability to add true egress windows, the large windows required by code to allow exit in case of fire. Old attics with tiny windows are not where I want children sleeping.


As with all things, there is a right way to add dormers to a home and a wrong way. Here is what you don’t want to do. Remember the Mr. Potato Head house? The poor structure with every kind of appendage tacked on? Well, dormers can be overused in this way. Yes, dormers provide interior space, but indiscriminate roof pitches, sizes and shapes plopped onto a roof can quickly ruin the proportion and beauty of a home. So, don’t forget to carefully consider the exterior of your home, too. As I often tell people, you never want someone to drive by and say, “It used to be such a nice house!”