Roofing
Reroof vs. Tear-Off: Which Is Right for Your Roof?
By Noah Spagnotti
A tear-off strips the old roofing down to the deck before the new roof goes on. A reroof, also called an overlay or recover, puts new shingles over the existing layer. Where codes allow it, an overlay is only an option when the roof has a single layer, the shingles lie flat and the deck is sound. In the City of Omaha, the local residential code does not allow a recover at all, so a replacement means a tear-off. Even where an overlay is allowed, a tear-off is the only way to see and repair what is underneath.
Below, we explain the code rules that settle many of these decisions, how the two methods compare on cost and lifespan, and how to decide for your own house.
TL;DR
An overlay installs a new roof covering over the existing one. A tear-off removes the old covering, repairs the deck and installs a fresh roof.
Most codes do not allow more than two roof coverings, so a second existing layer ends the overlay option.
The City of Omaha's edition of the 2018 International Residential Code goes further: a roof recover is not allowed, and a replacement removes the existing coverings down to the deck.
Where an overlay is allowed, it can cost less up front, but it hides the deck, adds weight and typically shortens the life of the new shingles.
Leaks, curled shingles or soft spots in the deck all point to a tear-off.
What each option actually means
The Asphalt Roofing Manufacturers Association (ARMA) lays out the terms most building codes use. A roof recover installs an additional roof covering on an existing one, while a roof replacement removes the existing covering, repairs any damaged substrate and installs a new covering. "Reroofing" is the umbrella word for both, which is why searches for "reroof vs. tear-off" can be confusing. People usually mean overlay versus full replacement.
The practical difference is access. With a tear-off, the crew sees every square foot of decking. With an overlay, the old shingles stay in place as the base for the new ones, and the deck stays hidden.
Can you put a second layer of shingles on?
It depends on where you live. ARMA notes that most local building codes do not allow more than two roof coverings on a building, and This Old House likewise says most building codes allow two layers of asphalt shingles. There is also a physical reason for the limit. Fine Homebuilding explains that two is the limit for most local codes because it is virtually impossible to install a third layer that will lie flat, and that multiple layers put a tremendous strain on framing and sheathing.
Omaha is stricter than the model code. Under the Omaha Residential Code 2018 (Section R908.3), a roof replacement includes removing the existing layers of roof coverings down to the roof deck, and Section R908.3.1.1 states that a roof recover is not allowed. The one exception in R908.3: an existing ice barrier membrane that is adhered to the deck may stay in place and be covered with a new layer of ice barrier. Other cities in the metro set their own rules, so check with your building department, and for an Omaha address check with the City of Omaha Permits & Inspections before you compare prices.
How do you know how many layers you have?
Look at the roof edge, the rake and the ridge, where extra layers often show as a thick, stepped profile. If you bought the house and have no roofing history, do not assume there is only one layer. A roofer can confirm the count during an inspection.
When an overlay can make sense
Where local code permits one, an overlay is a conditional option, not a default. ARMA's guidelines are to confirm that local codes permit another layer, make sure the structure can bear the extra weight and make sure the deck is sound and holds fasteners well. If a roof has only one layer of shingles that lies flat and the deck is in good condition, ARMA says replacement may not be necessary.
ARMA adds two cautions worth knowing before you choose:
Some shingle designs do not lend themselves to recovering. Most manufacturers do not recommend installing new shingles over existing laminated shingles, so consult the shingle manufacturer.
Impact resistance ratings for asphalt shingles may be affected when new shingles are installed over existing shingles.
Warranty terms matter too. Fine Homebuilding's roofing expert notes that manufacturers' watertight warranties apply only to new installations and full replacements, not reroofs. Before you commit to an overlay, read the warranty terms for the shingle you plan to use. Our guide to how roofing warranties work explains what to look for.
When a tear-off is the right call
ARMA lists the conditions under which the existing shingles will likely need to be removed: the roof already has two layers, the structure sags across the ridge or truss lines, the deck has rotted or warped wood or gaps greater than 1/4 inch between boards, or the existing shingles are so uneven and distorted that the new roof could not lie flat. Fine Homebuilding adds that a layer of new shingles won't lie flat over curling ones, so curling shingles should come off even when there is only one layer.
A tear-off is also the better route in these situations:
Leak history. Consumer Reports advises that with a history of leaks or insect infestation, it is probably best to remove even a single shingle layer, so the contractor can check whether rot, mold or insects have damaged the sheathing. Fine Homebuilding puts it simply: when you can't determine exactly what has been causing leaks, it's time to strip.
Hail or wind damage. If a storm is the reason you are replacing the roof, the deck and underlayment deserve a look. Our guides to hail damage roof signs and spotting wind-damaged shingles cover what to look for.
Ice dam history. Repeated ice dams can soak the deck edge, which is worth checking from the attic.
A change of material. If you want a different shingle type or an upgraded underlayment, a clean deck gives you the best base. See our comparison of roofing shingle types and the guide to underlayment types.
What a tear-off lets you fix
Stripping to the deck does more than remove old material. ARMA notes that replacement gives you the opportunity to inspect the roof deck, repair any damage and improve deck attachment to the underlying structure. This Old House quotes a roofing pro who prefers a tear-off even on a single layer so he can find the source of any water damage, upgrade the flashing and install shingles so they lie flatter.
The same logic applies to the weight question. Adding a second layer of shingles will make your roof heavier, and you won't have a chance to assess the roof deck for signs of water damage. On a house that already has older framing, that extra load is worth taking seriously.
Cost and lifespan side by side
The up-front saving is the reason overlays exist. Your actual price depends on roof size, pitch, number of layers, decking repairs and material, and in Omaha the choice is already made by code.
Factor | Overlay (reroof) | Full tear-off |
|---|---|---|
Up-front cost | Lower: less labor and no removal or disposal | Higher, because of removal and disposal |
Deck inspection | Not possible from the roof side | Full access to the deck |
Deck repairs | Hidden problems stay hidden | Found and fixed during the job |
Added roof weight | Yes, a second layer | No |
Life of the new shingles | Typically shorter | Full life on a prepared deck |
Eligible when | One flat layer, sound deck, and local code allows it (not in Omaha) | Any condition; required with two layers and in Omaha |
On cost, This Old House notes that nailing new shingles over existing ones requires less labor, making it less expensive and faster in the short term, while a tear-off costs more because of the additional labor and materials. ARMA adds that a recover saves the cost and inconvenience of removing and recycling or disposing of the old shingles.
Lifespan narrows the gap. Fine Homebuilding's roofing expert reports that, in their experience, a reroof reduces the life span of the new shingles by 20% to 40%, because the old shingles are an uneven surface and fastening through them reduces the nails' pullout resistance. Fine Homebuilding also notes that new roofing applied over old rarely lasts as long as roofing installed on a stripped and properly prepared substrate.
Do the math on a per-year basis. If an overlay saves money now but the new shingles wear out years sooner, a good part of that saving can disappear, and the next replacement means tearing off two layers.
The savings are real, and so is the trade
It is fair to say what an overlay gives you where it is allowed: a lower bill, a faster job and, per ARMA, an existing layer that acts as a secondary backup roof. The key is to confirm the condition first, because you can only see the deck from the attic side or during a tear-off.
Our perspective
A second layer of shingles covers up the deck, and with it any rot, soft spots or old flashing problems underneath. Those problems can keep developing under the new roof, and when it is time to replace that roof, both layers have to come off.
That is why the deck matters in this decision. You should know what is under your shingles before you choose, and a tear-off is the only way to see all of it. In the City of Omaha the code settles the question anyway: replacement means removing the old coverings down to the deck.
How to decide: a five-step check
Check your local code. In the City of Omaha, a recover is not allowed, so plan on a tear-off. Elsewhere, ask your city's building department whether an overlay is permitted.
Count the layers. Check the edges and ridge, or ask a roofer to confirm. Two or more layers means tear-off.
Walk the surface. Look for curling, lifting, bald spots, soft or spongy areas and shingles that will not lie flat. A new layer won't lie flat over curling shingles.
Check the attic. Consumer Reports recommends a thorough sheathing inspection from beneath as well as an assessment during a walk-over evaluation. Look for dark stains, damp insulation and sagging between rafters.
Review your history and warranty. Past leaks, ice dams, hail damage or pest problems each push the answer toward a tear-off. Read the shingle warranty for overlay conditions.
If the roof passes all five and your local code allows it, an overlay is a legitimate option. If it fails even one, plan on a tear-off. Our post on repair versus replacement covers the earlier question: whether a repair might be enough at all.
A note on valleys and leaks
If you already have a leak, find the source before you choose a method. Valleys are a common culprit, and our guide to repeat valley leaks explains safe checks and when to call a pro. Roofing over an active leak seals the problem inside the roof.
Get a roof estimate
Spagnotti Contracting handles roof replacement and repair across the Omaha metro area. Our roofing page lists starting prices: roof replacement at $5.50 per sq. ft. and up for standard architectural shingles, $6.00 per sq. ft. and up for Class 3 impact-resistant shingles and $6.50 per sq. ft. and up for Class 4 SBS-modified shingles, with a $7,500 minimum roof-replacement project. Small roof repairs are $595 and up per repair visit, and standard roof repairs are $995 and up. A roof leak assessment is $195, credited toward an approved roofing repair of $595 or more when scheduled within 30 days.
If you are unsure whether you need a repair or a new roof, start with the assessment. Browse all our residential services or contact us to schedule a consultation.
FAQ
Should you tear off shingles when replacing a roof?
In the City of Omaha, yes: the local code requires a replacement to remove the existing roof coverings down to the deck, and a recover is not allowed. Elsewhere it is not always required, but removal is likely needed if there are two layers, the structure sags, the deck is rotted or warped, or the shingles are too uneven to lie flat, according to ARMA. A tear-off also lets the crew inspect and repair the deck.
Can you roof over shingles, and how many layers are allowed?
Not in the City of Omaha, where Section R908.3.1.1 of the Omaha Residential Code states that a roof recover is not allowed. In places that allow it, most codes cap a roof at two coverings, meaning one new layer over one existing layer. Confirm with your building department.
Does a second layer of shingles shorten the roof's life?
Typically, yes. Fine Homebuilding's roofing expert reports that, in their experience, a reroof cuts the life span of new shingles by 20% to 40%, because the old shingles are an uneven base and nailing through them reduces holding power.
What can a tear-off uncover?
It exposes the deck, so a crew can find rot, moisture damage and weak boards and replace them. ARMA lists inspecting the deck, repairing damage and improving deck attachment as the benefits of replacement. That is the main reason many homeowners choose it.
Is reroofing over old shingles a good idea?
It can be, but only on a roof that is flat, sound and single-layered, in a jurisdiction that allows it, which does not include the City of Omaha. Consumer Reports notes that any savings could cost you more later if the sheathing under the shingles is damaged. Get the roof and attic inspected before deciding.
Sources
Asphalt Shingle Reroofing: Replacement vs. Recover (Asphalt Roofing Manufacturers Association)
Chapter 9 Roof Assemblies, Omaha Residential Code 2018 (2018 IRC), UpCodes
Q&A: Is it okay to put new shingles right over old ones? (Consumer Reports)
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