Tear-off is priced per square and per layer, as labour plus disposal. A second layer roughly doubles the line, because it doubles both the labour and the weight going to the dump — a square of asphalt shingles weighs around 250 pounds, so a 25-square two-layer roof is about six tons.
The Roof Tear-Off Cost Calculator estimates the cost to remove existing shingles, underlayment, and nails from your roof. Enter total squares, number of existing layers (1, 2, or 3), local dump fee per ton, and labor rate per square, and the tool returns a full cost breakdown. Tearing off two layers typically costs 60% more than one layer because of the extra weight and labor. Most municipalities limit the number of layers a roof can have, so check local code before considering an overlay.
Tear-off is priced per square and per layer. It is labour and disposal, and it is the line most likely to change once the crew is on the roof, because nobody knows what the deck looks like until the shingles are off.
Most codes allow a second layer of asphalt shingles over one existing layer, and never a third. Overlaying saves the tear-off cost but it hides the deck, adds weight, runs hotter — which shortens the new shingles' life — and leaves you paying to strip two layers next time. It also makes flashing details harder to do properly.
On a roof where the deck is known to be sound and the budget is tight it is a legitimate choice. On a roof that has leaked, it is a way of covering up the evidence.
Ask for tear-off to be priced per layer and stated separately from the new roof. Ask what the per-sheet rate is for replacement decking and how it will be documented — a photograph of each bad sheet is a reasonable thing to request. And ask whether disposal is included or billed at cost, because the two are quoted very differently.
It is priced per square and per layer, as labour plus disposal. The second layer roughly doubles the line, because it doubles both the labour and the weight going into the dumpster.
Most codes allow one overlay over a single existing layer, never a third layer. It saves the tear-off cost but hides the deck, adds weight, runs hotter and shortens the new roof's life.
Around 250 pounds for architectural asphalt. A 25-square roof with two layers is therefore roughly six tons of waste, which is why disposal is a real line rather than a rounding error.
You do, at a per-sheet rate that should be agreed in writing before work starts. Nobody can see the deck until the shingles are off, so a quote that includes no allowance for it is a quote that will change.