Peel back the shingles on an older Davis County home and you sometimes find a small history lesson. There’s a layer of brittle three-tab shingles from the 1990s, another layer from the 1970s underneath, and occasionally a strip of cedar shake still clinging to the lowest boards. Each layer reflects a choice some past owner made between stripping the roof to the wood or simply laying new shingles over the old ones.
That same choice still comes up in nearly every reroofing conversation. An overlay is cheaper and faster on paper. A full tear off costs more up front but changes what the new roof can actually do. Knowing where the two really differ makes it much easier to read a bid and ask the right questions.
Roof tear off is one of the named services at Redline Roofing, and that matters for this comparison because the crew also handles siding, gutters and metal trim in-house, so the edges of the house don’t get passed between separate contractors once the old layers come off. A local realtor who works with the team describes them as dependable and knowledgeable, which is the kind of judgment you need from a roofing company in North Salt City when the real condition of the deck is still unknown.
Side by Side Before the Details
| Factor | Full tear off | Overlay (recover) |
|---|---|---|
| Upfront cost | Higher, mostly labor and disposal | Lower, often by a dollar or two per square foot |
| Deck inspection | Every board is visible | Deck stays hidden |
| Added weight | None beyond the new roof | A second layer of shingles stays on the framing |
| Ice barrier at eaves | Applied directly to the wood | Can’t be bonded to the deck properly |
| Flashing | Replaced or reset properly | Often left in place or patched |
| Next replacement | One layer to remove | Two layers, more labor and disposal later |
The table makes overlays look weak on almost every line except price. That’s mostly accurate, but the full picture has some nuance.
The Rule That Settles Many Decisions
Building code takes the choice out of your hands in some cases. Under the International Residential Code, a recover isn’t allowed when the roof already has two or more layers of any roof covering, or when the existing roof is water-soaked or too deteriorated to serve as a base. The IRC reroofing provisions in Section R908 spell this out, and Davis County cities including neighboring Bountiful follow the same limits in their own reroof policies.
So if your house already has two layers, the debate is over. A full tear off is required.
What You Can Only Learn With the Old Roof Gone
The biggest difference between the two methods isn’t visible in the finished roof. It’s what happens to the decking underneath.
A tear off exposes every sheet of plywood or OSB. Crews can spot soft areas near the eaves where ice dams have soaked the wood for years. They can find delaminated panels around old vent pipes and gaps from boards that shrank or warped. Damaged sections get replaced before anything new goes down.
An overlay buries all of that. Soft decking under new shingles can still sag, hold moisture and loosen nails over time. You may not know there was a problem until it shows up as a leak or a dip in the roofline a few winters later.
Weight, Snow and the Framing Underneath
Asphalt shingles are heavier than most people expect, and a second layer adds a meaningful load to rafters or trusses that were never sized for two roofs. Across a full-size home, that can amount to several thousand extra pounds.
Along the Wasatch Front, that weight doesn’t sit alone. Snow adds its own load every winter, and wet late-season snow is especially heavy. On a newer, well-built house the framing usually handles it, but on older homes with undersized rafters or past water damage, an extra layer of shingles takes away some of the safety margin the structure depends on.
Ice Barrier and Edge Details
Northern Utah roofs need an ice barrier membrane at the eaves to stop meltwater from backing up under the shingles. That membrane works best when it’s bonded directly to clean decking, and code requires it to extend at least 24 inches inside the exterior wall line.
With an overlay, there’s no clean deck to stick to. The membrane ends up on top of old granular shingles, where it can’t seal around nails as well. Drip edge, valley metal and wall flashing are also harder to install correctly over two layers, so many overlays simply reuse the old metal. Over time, that often becomes the weak point where leaks begin.
Lifespan and Warranty Fine Print
Shingles laid over an older layer tend to sit less flat. The bumps and curls below can telegraph through, and the extra layer holds more heat, which can age the new shingles faster in strong summer sun.
Warranties are worth reading closely too. Many manufacturers’ enhanced system warranties require a full tear off, and some standard warranties limit coverage on recovers. If a long warranty is part of why you’re paying for premium shingles, an overlay may undercut that investment.
When an Overlay Still Makes Sense
Overlays aren’t always a bad choice. They can be reasonable when the house has just one existing layer, the decking is solid, the roof shape is simple and the owner plans to sell within a few years. A detached garage or shed with a low-slope roof that never shows problems is another case where saving money may outweigh the drawbacks.
Even then, it’s worth asking the estimator to check the attic for staining, press on the deck from inside where possible and look closely at the eaves before agreeing to cover anything up.
The Bill Comes Due Either Way
The savings from an overlay are real, but they’re often temporary. When that roof eventually wears out, the next crew has to remove two layers instead of one, with double the disposal and extra labor, plus any deck repairs that were hidden the first time. A tear off pays the full cost of a clean start up front. An overlay delays part of that cost to a later year when it may be more expensive.