How to read and compare roofing estimates

The scope is the plain-language description of what will be done. Is this a repair, a re-felt that reuses existing tile, a full tear-off and replacement, a recoat, or a roof over an existing layer? Which slopes or sections are included? A patio cover or garage can be left out without you noticing.

Roofs are usually measured in squares, where one square is 100 square feet. If two estimates list very different areas for the same house, ask how each one measured. A difference in the measurement can explain a lot of the price difference.

On Arizona roofs, especially tile, the underlayment does the waterproofing, so this line matters. A vague entry like underlayment or felt is not enough. Look for the type and weight, such as 30# felt, a two-layer system or a named synthetic product, and how many layers. If one bid uses a single layer of felt and another uses a high-temperature synthetic, they are not the same roof, even if the tile on top is identical.

Many leaks start at flashings rather than in the field of the roof. Look for line items covering valley flashing, wall and step flashing, drip edge, vent pipe flashings, chimney or skylight flashing, and whether existing metal flashing is being replaced or reused. Reusing sound flashing can be fine, but the estimate should say which.

Ventilation affects attic heat, energy use and how long the roof lasts in Arizona. The estimate should note what vents are being installed or replaced, such as ridge vents, off-ridge vents or eyebrow vents on tile, and whether the plan meets code for your attic.

There are usually two kinds of warranty on a roof. The manufacturer's warranty covers defects in materials, and its terms depend on the product and sometimes on registration. The contractor's workmanship warranty covers installation. They are not the same, and one does not replace the other.

Read the actual words, not just a number of years. What exactly is covered? Is labor included or only materials? Is it transferable if you sell? What voids it, such as other trades walking on the roof or adding solar? A warranty is only as good as the company standing behind it, so ask how long the contractor has been in business and how warranty calls are handled. Get the warranty in writing as part of the contract.

A low bid can be low for good reasons, such as lower overhead or a simpler approach. It can also be low because it leaves out tear-off, uses a lighter underlayment, reuses worn flashing, has a small decking allowance with a steep unit price, or skips permits. Those gaps often come back later as change orders or as a roof that leaks sooner.

The best way to compare is to make a simple side-by-side list of every item above and fill it in for each bid. Wherever a line is blank, ask. For a general sense of what drives roofing costs, see our Roofing Cost Guide, and remember every roof is different. To get an estimate from us, call 602-548-3770. If we don't answer, leave a message and we'll return your call within 24 hours.