Roof replacement typically costs between $4.50 and $8.50 per square foot for asphalt shingles, $9.00 to $19.50 per square foot for metal roofing, $6.00 to $11.00 per square foot for flat roof membranes (TPO/EPDM), and $11.00 to $25.00+ per square foot for tile or slate.

The 5 biggest factors are total roof surface area (measured in squares), selected roofing material, roof slope/pitch, tear-off requirements of existing layers, and regional contractor labor rates.

A roof usually requires complete replacement if it is 20 to 25+ years old, exhibits widespread granular loss (accumulating heavily in gutters), has curling or missing shingles across multiple slopes, or suffers from sagging decking and multiple active leak points. Isolated storm damage, a few blown-off shingles, or minor pipe boot flashing leaks can usually be resolved with a targeted $350 to $950 repair.

Homeowners insurance typically covers roof replacement if the damage is caused by sudden, unpreventable perils like windstorms, tornadoes, falling trees, or severe hail. Standard policies do not cover normal wear-and-tear, poor maintenance, or gradual aging. Check whether your policy provides Replacement Cost Value (RCV) or Actual Cash Value (ACV with depreciation applied).

Replacing rotten or water-damaged CDX plywood or OSB roof sheathing costs between $75 and $125 per 4x8 ft sheet, including materials and labor. Most tear-off projects require replacing 2 to 5 sheets of decking where leaks occurred around valleys, eaves, or chimneys, adding $150 to $600 to the total invoice.

An overlay saves $1,200 to $2,500 in upfront tear-off and disposal fees, but complete tear-off is recommended by structural engineers and manufacturers. Overlays prevent inspecting the underlying wood decking for hidden rot, trap summer heat that reduces shingle lifespan by 20% to 25%, add heavy dead weight to rafters, and often void shingle warranties.

Roofs steeper than a standard 6:12 slope require OSHA-mandated safety harnesses, scaffolding, and roof jacks, slowing down the crew's pace. A moderately steep roof (7:12 to 9:12 pitch) adds a 10% to 20% labor surcharge, while steep roofs (10:12 to 12:12) or mansards add 25% to 45% due to heightened safety and staging requirements.

The most common surprise costs are rotten plywood sheathing ($85/sheet), rotted fascia or rafter tail repairs ($25–$45/linear ft), deteriorated chimney and wall step flashing ($350–$800), and municipal building permits ($150–$400). Always confirm the contractor's per-sheet decking replacement rate in writing before work begins.

Late winter and early spring (January through April) are typically the slowest seasons for roofers, offering maximum scheduling flexibility and competitive contractor discounts of 5% to 15%. Late summer and fall are peak rush seasons with higher pricing and longer booking lead times.