Dormer roof calculator
Estimate dormer side-rafter length and flag valley detailing for review.
What you enter
- Dormer width (in)
- Dormer depth (in)
- Pitch rise (in / 12)
Main results
- Side rafter length
- Valley detailing review note
What it follows
Plain geometry on the dormer's width, depth and pitch; no building-code table is looked up. Valley detailing is marked for review.
Every result is marked REVIEW REQUIRED. Illustrative project-planning values only; jurisdiction, species, grade, loads, wet service and current adopted tables require review. Do not use a result directly for permit, purchase, or field use.
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The calculator opens inside the designer, after you sign in.
Accounts are issued by the DeckAndShed team. There is no self-service sign-up.