How To Install Roof Shingles Over Existing Shingles

The answer is yes, you tin lay new roof shingles over old ones. Now that we've taken care of the primary question at hand, we'll consider a couple of reasons why you might want to do this. Then nosotros'll await a lot more reasons why you might not want to do this. Just before we get started, ane thing must be clear: adding new roofing over quondam (sometimes called a "re-roof") is possible but with asphalt shingles (too called "composition shingles"). You tin can't do information technology with woods or slate, for instance, and you should never mix materials, such as laying cobblestone shingles over cedar shakes. Also, the erstwhile roofing has to exist in pretty good condition. Otherwise you're just putting lipstick on a pig.

Why Add New Roof Shingles Over One-time?

Reverse to what might seem like an obvious do good, having multiple layers of shingles does not necessarily brand a roof more waterproof, and it often creates its ain issues. Then why would yous lay new roof shingles over old? Convenience and price. If you go on the old shingles on, you skip the messy, laborious removal step -- called the "tearoff" -- and you'll relieve some money on the roof job.

However, both of these benefits take caveats. It's clearly easier and cheaper to leave the old shingles in identify, only there's some special prep work involved with a re-roof (removing vents, ridge caps and misshapen shingles, among other things) and you still have to supplant or add new flashing, which sometimes can be tricky over old roofing. Eliminating the tearoff can easily save $1,000 or more on a new roof, but you lot're actually just delaying the cost: when information technology'southward time to replace the roof once more and you have no option but to start anew (two layers is the maximum immune in almost areas), yous'll have to pay actress for the two-layer tearoff and disposal.

Why Not Add New Roof Shingles Over Old?

As suggested to a higher place, the potential cons of re-roofing tend to outweigh the potential pros, but it all depends on your state of affairs. The following list includes some universal reasons not to reroof as well equally some considerations or things to bank check out if you lot're seriously considering adding new roof shingles over sometime ones.

1. Shingles are designed for flat surfaces. They don't do a adept job of bridging over gaps, dips or humps, including the stepped texture created past overlapping shingles. Re-roofers have tricks to lay new roof shingles over old so that the same pace-ups between courses are maintained, but if any old shingles are cupped, curled, or otherwise misshapen, those defects will "telegraph" through to the new layer. Many roofers recommend using laminated, or dimensional, shingles for re-roofs because they're thicker than standard shingles and often have a staggered edge profile (for looks) that helps hide whatever dips or loftier spots in the one-time covering.

2. Shingles add together weight. Good-quality composite shingles can weigh 350 to 450 pounds per "square" (100 square feet of roofing, installed). Chances are, your roof structure was designed for a expressionless load of i layer of shingles, plus actress for snow and a prophylactic margin. Installing new roof shingles over one-time effectively doubles the weight of the roofing, so you have to brand sure your roof structure tin handle the extra load. That'southward as well why building codes commonly limit re-roofing to no more than ii layers. On some houses, the extra weight of multiple layer causes the roof capsule (decking) to sag between the rafters or trusses.

three. No visual inspection of roof sheathing. Without a tearoff, roofers can't see what the decking looks like. A good roofer will perform a careful "walking" inspection for spongy areas and other problems, and they tin can brand localized repairs before re-roofing. A not-so-good roofer might be less conscientious.

4. Tin't replace underlayment. The building paper (tarpaper) that'southward laid between the roof capsule and the shingles is at that place for a very expert reason -- because water has a way of getting under shingles, no matter how many layers of roofing you have. If the underlayment is old and deteriorated, it won't protect your roof deck from water that gets past the shingles. In snowy climates, most new roofs these days get an water ice-and-water shield (a rubbery moisture membrane) applied to the sheathing along the eave to protect against ice dams. Adding this membrane isn't an option with a re-roof, and the extra layer of shingles offers little protection against water ice dams.

five. Re-roofing may affect the warranty on the new shingles. Pretty self-explanatory. Exist sure to bank check with the shingle manufacturer regarding all warranty issues and installation requirements earlier re-roofing.

6. Local codes might non allow re-roofing. Ii layers is the maximum in well-nigh areas, but some building codes let simply one. For case, towns in climates with heavy hailstorm activity or significant ice dam problems may not allow multiple covering layers.

7. A re-roof might non look good on an inspection report. Adding new roof shingles over old ones is tempting to a lot of people planning to sell their house in the almost future: why pay for a tearoff if y'all can get away without it? Of course, it'll be the new owners who are stuck with the actress expense of a two-layer tearoff downwardly the road, along with whatsoever problems arising from an improper re-roof task. Because of this, home inspectors often written report double-layer roofs when they notice them, and they may warn the buyers of potential issues associated with re-roofs. If y'all're planning to sell your house subsequently installing a new roof, it'due south a good thought to discuss your options with local real estate pros and/or home inspectors.

Contact a reliable roofing contractor to discuss your options for roof repair or replacement.

Philip Schmidt writes for Networx.com.

Source: https://www.networx.com/article/can-you-lay-new-roof-shingles-over-old

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