Overlay or Tear-Off: Ask What Each Quote Leaves Out

An overlay is a new roof installed directly over the roof you already have. The crew puts new shingles on top of the old ones and skips the tear-off, the dumpster, and the labor of prying up asphalt. On a quote sheet that usually shows up as a lower total, which is why homeowners ask about it. The lower number is only true if the roof underneath cooperates, and many quotes do not say what they assume about that roof.

This page is for the homeowner who has two quotes in hand, one that says overlay and one that says tear-off, and needs to know what the difference is actually buying. It is also for anyone whose roofer has suggested an overlay without putting the reason in writing. Keys Roofing can be reached at (314) 220-2333 if you want a second look at what your roof can take.

What the overlay price leaves out

A tear-off price includes three costs that an overlay price usually does not: removing the old shingles, hauling them away, and inspecting the deck once it is exposed. An overlay skips all three, so the quote is smaller for a reason that is real. What it does not skip is the question of what is under the old shingles. You cannot see the deck from the ladder, and you cannot see it through the existing layer. If the decking is soft at a valley or along an eave, an overlay covers that damage and makes it harder to find later.

Ask the roofer to write down the assumption. A line that says the deck is sound is a guess unless someone has checked it. Some roofers will cut a test opening at a valley or near a pipe boot before they commit to an overlay. Others will say they cannot tell without tearing off, and that is an honest answer, but it means the overlay price is a price for a roof whose inside nobody has seen yet.

Count the layers before you accept a number

A lot of St. Louis homes have one layer of asphalt shingles on the roof now. Some have two, often because an earlier roofer put a new layer on top of an old one and left it there. Every added layer adds weight and thickness, and both matter. A roof with three layers sits higher at the eave than the gutter was built to feed, and the new shingles will not lie against the drip edge in the same way. That changes how water leaves the eave, which is where ice damming shows up first in a St. Louis winter.

Ask the roofer how many layers are on the roof now, and ask how they counted. A look from the ground is not a count. A real count usually involves a cut at the eave, a look at the rake edge, or a check where the old shingles were lifted. If the answer is that they assumed one layer, the overlay price is built on that assumption. A second layer changes the job, and the quote should say so before you sign.

Permits and the layer limit

Many local building codes limit how many layers of roofing can remain on a house, often at two, and they can require a full tear-off once the limit is reached. The rule is set by the municipality, not by the roofer, and the rules differ across the county. Some municipal permit desks in St. Louis County can tell you the limit over the phone. Kirkwood runs its own permit process, and Chesterfield handles roofing reviews through its own office, so the answer depends on which city your house sits in. Ask the roofer to name the permit desk they will pull the permit from, then call that desk and ask the layer question directly.

If the permit desk allows the overlay, get the approval in writing, or at least the permit number on the scope. If it does not allow it, the overlay price is not a price you can use, because the crew cannot legally do the work. A quote that depends on a permit answer nobody has checked is a quote worth keeping on file but not yet counting.

Where the overlay savings come back

An overlay can make sense on a house with one sound layer, a deck that has been checked, and a permit that allows it. In those cases the saving is real, because the new roof goes over a layer that still has some life in it. The savings can disappear in three places, and each one should appear on the quote.

The first is the flashing and drip edge. An overlay often leaves the old metal in place at the eave, the rake, and the walls. If the old flashing is brittle, rusted, or the wrong height for the new layer, the crew will either reuse it, which you should ask them to justify, or replace it, which should show up as its own line. Ask whether the drip edge is replaced or left as it is. The same question applies to pipe boots and vent flashings, which are often the first things to crack.

The second is the tear-off that happens later. Some roofers quote an overlay and then find, once the new shingles are going on, that a section of decking is soft. At that point the crew either stops or prices the repair as an extra. Ask the roofer for a unit price per sheet of decking, written on the scope, so the later number is not a guess. This is the same logic as any other change to the roof: the price should be set before the work starts, not after.

The third is the next roof. An overlay is a decision about the roof after this one. A roof with two layers will need a full tear-off the next time, and that removal will be harder and often more expensive than it would have been today. If you expect to replace the roof again within a few years, the overlay may cost more in total, even if the first bill is lower.

What to ask

1. How many layers are on the roof now, and how did you count them?
2. Will you cut a test opening, and where?
3. What is the permit desk's rule on layers, and can you show me the approval?
4. Is the drip edge and flashing replaced, or reused? Which line shows that?
5. What is the unit price for decking replacement if the deck is soft?
6. What is the tear-off price per square, if I choose to remove the old layer?

Ask for both prices on the same sheet. If the overlay and the tear-off are written down against the same scope, the difference is a choice you can see. If the tear-off is missing, you are being asked to compare a complete roof against a partial one.