01
Existing and new
Mark the house as existing and the addition as new. Drawings dimension the new part and show the house for context.
Home addition
Design your home addition to match
Rear addition, bump-out or second story: draw the existing house, add the new part and produce drawings where the addition is clearly shown.
Design my addition
02
Matching heights
Story heights, floors and roof follow the existing house so floors and eaves line up.
03
Permit and zoning
Additions almost always need a building permit. Setbacks, lot coverage and height limits come from your local zoning code.
04
Drawings for the permit
With the paid version you get a site plan, floor plan, elevations and a section through the addition, printed to scale.
THE RULES AT A GLANCE
Setbacks, lot coverage and height
Your local zoning code decides how big an addition can be and where it can go. Check the rules for your zoning district.
Setbacks
Front, side and rear setbacks define how close the addition may come to property lines – commonly 5–10 ft on the sides and 20–25 ft at the rear.
Lot coverage and height
Many zoning codes cap lot coverage (often 30–50 %) and building height (often 30–35 ft). Exceeding them requires a variance.
Matching materials and HOA
HOAs and historic districts may require matching siding, roofing and colors, and an architectural review before you apply.
Building code applies
The addition must meet the residential code adopted by your state (usually based on the IRC) for structure, egress, fire safety, insulation and energy.
THREE COMMON ADDITIONS
More space where you need it
Examples to start from. Draw them in feet and inches and see how they meet the existing house.
Primary suite
A bedroom with walk-in closet and private bath, added at the back or side of the house.
Kitchen and family room
An open kitchen and family room with wide windows and a door to the deck.
Sunroom or home office
A bright room with its own door to the yard, without moving load-bearing walls.
FROM SKETCH TO PERMIT
How it works
- 1
Draw the existing house
Enter its measurements and heights and mark it as existing. A photo gives matching siding and roof.
- 2
Add the new part
Sketch the addition, choose a roof and see setbacks to property lines instantly.
- 3
Produce drawings
Choose Addition in the drawings dialog – the new part is dimensioned, the house shown for context.
- 4
Permit and inspections
Check zoning and HOA, submit the permit application, then book footing, framing and final inspections.
THE DRAWING SET
What building departments usually ask for
Drawings showing what is new and how it joins the house – with the same measurements everywhere.
Site plan
The addition shown against the house with setbacks to property lines.
Floor plan
The new rooms, openings and connection to existing rooms.
Elevations
Every side with grade line and declared materials.
Section
Through the addition with floor levels, ceiling height and roof pitch.
Rules vary by state, county, city and HOA. Always check with your local building department. Structure must be verified by a licensed engineer.