Rules And Considerations For Dormers:
- Make sure a dormer is what you really want, as compared to an addition. Dormers are much more complex and expensive per square foot when compared to an addition.
- The designers job in evaluating and designing the dormer is critical. The final design can be complex and expensive or can be reasonable in its complexity and expense. Sometimes there will be only one way to accomplish the task and that is complex and expensive, but usually careful study will reveal a fairly reasonable approach to the task.
- Breaking the roof for a dormer changes the roof load dynamics. Because of this, many times a beam will have to be installed to carry a new type of load. A normal roof load is carried by opposing thrust and collar ties. If you no longer have those 2 elements to carry the load, we have to utilize a beam at the roof ridge to carry the load.
- There will have to be a downword path for the load. If there is a new structural beam there will have to be a post at each end to carry the beam load all the way to the foundation. This entails going thru the first floor at some point and may also require the thickening of the foundation to carry the new load.
- All new additions, including dormers, will require seismic lateral bracing on all new walls.
- Some jurisdictions will require complex calculations to determine seismic requirements, whereas other jurisdictions will have very little other than the dormer side wall requirements.