What does the lot allow?

Setbacks, height limits and easements decide where an addition can go. Checking them first saves sketching something that cannot be built.

Up or out?

Building out keeps everything on one level but uses yard. Building up keeps the yard but touches more of the existing house.

The new room should be reached naturally from the old ones. Think about which doorway, hall or stair it will open from.

Most of the work happens outside the existing walls until the final connection. Plan where the family will be for those last weeks.