Three roofers come out. You get three estimates. One is noticeably cheaper, one is in the middle, and one is higher than you expected — and none of them are written in a way that lets you tell whether you are comparing the same job.
That is the actual problem with roofing estimates. Not that homeowners cannot read numbers, but that the documents rarely put the same items in the same terms. Here is what the line items mean and where the differences usually hide.
Squares, not square feet
Roofing is measured in squares. One square is 100 square feet. A 2,400 square foot roof is 24 squares.
Two things make the number on your estimate larger than your house's footprint: pitch and waste. A steeper roof has more surface area than the ground it covers, and every roof requires material beyond the exact measurement for cuts, valleys, and starter courses. A waste factor in the range of ten to fifteen percent is normal — higher on a complicated roof with many valleys and penetrations.
If one estimate lists meaningfully fewer squares than the others, someone measured differently. Ask.
Tear-off and layers
Look for how many layers are being removed and whether disposal is included.
Some estimates quote a roof-over — new shingles installed on top of the existing layer. It is cheaper and it is legal in some circumstances. It also means nobody sees the decking underneath, adds weight to the structure, and typically shortens the life of the new roof. If one bid is dramatically lower than the others, check whether this is why.
Decking is the line that changes after work starts
This is the most common source of a final invoice that does not match the estimate, and it is not necessarily anyone behaving badly.
Nobody can see the condition of the wood under your shingles until the old roof is off. Rotted or delaminated decking has to be replaced, and no honest contractor can tell you in advance exactly how many sheets that will be.
What a good estimate does is state a per-sheet price up front so you know the rate before the discovery happens. An estimate that says nothing about decking is not cheaper — it is just deferring the conversation until you have no leverage.
The components most people never look at
Shingles are the visible part and a minority of what actually keeps water out. These lines are where quality differences live:
- Underlayment. Felt versus synthetic. Synthetic is more durable, handles exposure better, and is safer to walk on. It also costs more.
- Ice and water shield. A self-adhering membrane in valleys and around penetrations. Not required everywhere on a North Texas roof, but valuable where water concentrates.
- Drip edge. Metal at the eaves and rakes directing water into the gutter instead of behind it. Code requires it. Not every estimate includes it.
- Starter strip and ridge cap. Purpose-made products. Some contractors cut them from field shingles instead, which is cheaper and performs worse at the two edges that see the most wind.
- Pipe boots and flashing. New, or reusing existing? Boots fail before shingles do. Reusing old ones on a new roof means a leak in a few years at the exact spot everything else was just replaced.
- Ventilation. Whether existing vents are reused or replaced, and whether the intake and exhaust are actually balanced.
An estimate that says "install new roof" and gives one number is not a bad price. It is an unknown price, because you have no idea which version of the above you are buying.
Warranties: there are two
The manufacturer warranty covers the shingles against defects. The workmanship warranty covers the installation, and it comes from the contractor.
The second one matters more, because the large majority of roof problems come from installation rather than defective product. Ask how long it runs and what it covers.
Also worth knowing: extended manufacturer warranties usually require certified installation and specific component combinations. A contractor offering one should be able to say which certification they hold.
What to ask for
If you want three estimates that actually compare, ask each contractor for the same things: squares and pitch, number of layers being removed, per-sheet decking rate, underlayment type, whether starter and ridge are purpose-made, whether boots and flashing are new, and the length of the workmanship warranty.
Most of the price gap between bids disappears once those are on the page — and what is left is a real difference you can actually decide on.
If you would like an estimate written that way, get in touch and we will walk you through it line by line.
