Roof replacement
Two quotes for the same roof can differ by half, and the reason is almost never the shingle. It is what happens underneath it, and what happens if the decking turns out to be soft.
What is actually being priced
Tear-off and disposal, how many existing layers come off, and where they go. Decking repair, priced per sheet, and the number of sheets is unknown until the old roof is off. Underlayment, and whether ice-and-water shield goes at the eaves and in the valleys or only where code requires it. Flashing, and whether it is replaced or re-used. Ventilation. Then the shingle itself, which is the part most homeowners compare and the part that varies least.
A quote that looks low is frequently a quote that assumes the decking is sound and the flashing can be re-used. Both assumptions get tested on day one.
Layers, and why they matter
A second layer of shingle installed over a first is legal in many jurisdictions and it is cheaper, but it hides the decking, adds weight, and traps heat that shortens the life of the new material. It also means the next replacement is a bigger tear-off. If a house is on its third roof and two layers are still up there, that is a different job from a clean single-layer tear-off.
The layer question is close to predictable in places that were built in one push. Through Woodbridge and Manassas, and across the Baltimore County plats around Nottingham and Essex, whole streets took their first covering inside a few seasons and their second one about a generation later. If the neighbours are on their third, the odds are that this house is too, and the tear-off should be quoted accordingly.
Flashing is where roofs leak
Not the field of the shingle, the transitions. Where a roof meets a wall, a chimney, a skylight, a vent, or another roof plane at a different pitch. On houses with attached garages and porch roofs, which is most of the postwar housing across this region, those junctions are numerous.
Ask specifically whether step flashing along walls is being replaced. Re-using it saves a few hundred dollars and is the single most common reason a new roof leaks in its first year.
Questions that separate two quotes on the same house
- How many layers are coming off, and is disposal in the number?
- Code allows two, and the answer decides whether this is a strip or a recover, two different prices for what looks like one job. Ask what the estimator found on the roof rather than what is usual for the development.
- What is the per-sheet price if decking needs replacement?
- Sheathing condition cannot be known until the covering is off, so an honest bid names a rate instead of a total. A quote missing that line has left its largest unknown unpriced, and the conversation about it happens with the crew already on the roof.
- Is the flashing at chimneys, walls and skylights new or reused?
- Roofs in this region rarely fail in the middle of a slope; they fail at the junctions. Reusing old metal and running a fresh bead of sealant over it is fast, cheap, and the leading reason a one-year-old roof leaks.
- What waste factor is assumed on this roofline, in writing?
- On a cut-up roof with several hips and valleys, waste is a real share of the material cost. A bidder who counted the runs is estimating; one who applied a flat percentage from memory is guessing, and the gap between two quotes often lives right here.
- What does the ventilation scope include: intake, exhaust, or both?
- Both, sized to each other. Through a humid Mid-Atlantic summer an unventilated attic bakes the covering from underneath and shortens its life by years, and replacement day is the only time the correction is inexpensive.
- 1 Ridge caps. Thin, fully exposed, and the first course to lift.
- 2 The field. Granule loss is the honest measure of how much life is left.
- 3 Valleys. One channel taking the runoff of two slopes, all year round.
- 4 Flashing. At the chimney, and where the garage roof meets the wall of the house.
- 5 The vent boot. Small, rubber, and on a much shorter clock than everything around it.
- 6 Eaves. Where water that has backed up at the edge gets under the courses.