Roof area, in square feet
The actual roof, not the footprint. If you only know the footprint, run the cost calculator first — it converts for you.
How old is the current roof?
How long do you expect to own the house?
Assumptions, stated openlyAsphalt $8/sq ft installed (mid of the NH $6–$10 band), service life 22 years (mid of 18–25). Standing seam $16/sq ft (mid of $12–$20), service life 50 years (mid of 40–60). Tear-off and disposal at $1.25/sq ft on each asphalt replacement. Figures are in today's dollars with no inflation applied to either side — inflation raises both, and it raises the side you pay more often by more. Full sourcing on the cost page.
What This Does Not Model
Four Honest Limitations
- Your roof is not an average. Complexity, ventilation and exposure all move service life and cost in ways a single number cannot capture. A well-ventilated asphalt roof reaches the top of its range; a badly ventilated one does not reach the bottom.
- Nobody knows what materials cost in 2050. These are today's dollars on both sides. Applying inflation would widen the gap in metal's favour, because you buy asphalt more times — so leaving it out is the conservative choice.
- It ignores the failing years. The last few years of an asphalt roof are where the repairs, the ice-dam damage and the interior staining happen. Those are real costs and they are not in here.
- It ignores resale entirely. We are wary of anyone quoting a confident figure for what a roof adds to a sale price. What is defensible is the negotiation effect, and that is a different thing from a valuation.
A model you can see the assumptions of is worth more than one that produces a confident number from assumptions it will not show you.