Can you put new plywood over old on a roof?

As long as the new plywood itself can span the distance and carry the roof, wind, seismic and snow loads for your region, adding new ply over old is just fine. The new plywood thickness should be at least equal to the exusting plywood thickness.

Is it OK to put a new flat roof over an old one?

If there is no weight issue, you can and should apply a new roof over the existing one. Keep in mind that hot tar systems create heavy roofs. In fact, the roof weight usually becomes excessive after two layers, although I've seen seven hot tar roof layers on a building that was still standing.

When should you replace plywood on roof?

How long does roof plywood last? Roof plywood should last twenty years, so long as it is not exposed to water.

Can you overlay existing roof?

Overlay is the most affordable option for roof replacement. With this method, a roofing professional in your area will cover your existing, damaged shingles with a new layer. This means the cost of labor and materials will be lower than with other methods.

How do you fix rotted plywood?

There are two basic ways of repairing rotten plywood, by replacement or by treating it with epoxy-based compounds. The decision usually comes down to one of cost, with larger repairs requiring replacement, rather than repair. The first thing to do is to identify the extent and source of the damage.

How to Install New Sheathing Over Old Spaced Sheathing for Re-roof Projects

Should roof sheathing replace?

Sheathing is an important element in supporting your home's roof structure and subsequently, the building's walls as well. With the old shingles removed, a contractor can inspect sheathing for damage, rot, or failing fasteners. If any of these are present, it's best to replace the sheathing.

How long will an overlay roof last?

Overlays have a Viable Life

An overlay is a viable option if the existing roofing materials have not already been overlaid. Home Reference.net notes that on average you can expect the overlay to last for fifteen or sixteen years.

Should you tear off old roof?

In most cases, more than two layers of roofing shingles does require a tear-off. Laying new shingles over old shingles is easily prone to leaks and reduces the life of the new shingles. This alone ought to be reason enough to do a tear-off; it's just a bad value not to.

Should I overlay my roof?

A: In general, it is not good practice to overlay a traditional asphalt shingle roof versus a complete tear off and replacement for the very reason you stated: you can't examine the decking to determine if there is any damage that needs repaired.

How do I know if my plywood is bad on my roof?

How do I know if my roof plywood is bad?

If the roofline is in any way wavy, then it means your sheathing is damaged and needs to be replaced. You can also check for sagging from the inside. Go into your attic with a flashlight, and look up. If any areas of the roof appear closer to you than others, your roof is sagging, and it is time to call a professional.

Is it OK to reroof over old shingles?

While a repair job can often be more convenient and somewhat more cost-efficient, placing new shingles over old ones is never a good idea. Whether repairing one section of roof, or a replacing a whole one, it's always best to pull up the old shingles before putting down the new ones.

What is a roof overlay covering?

An overlay roof, or the act of overlaying a roof, is when your roofer puts a second set of shingles directly on top of your existing roof. While this isn't the most common method of roofing, it does happen, especially when homeowners are hoping to save a bit of money on their overall roofing costs.

What is the difference between re roof and new roof?

Roof Recover: The process of installing an additional roof covering over a prepared existing roof covering without removing the existing roof covering. Roof Replacement: The process of removing the existing roof covering, repairing any damaged substrate and installing a new roof covering.

Is it OK to put two layers of shingles on a roof?

In most states, you're only allowed to have 2 layers of shingles on a roof for fire safety reasons. However, you'll still see roofs that have 3 or 4 layers today. If you already have 2 or more layers, a contractor will recommend a full replacement.

Is it cheaper to shingle over an existing roof?

It's more affordable.

Simply adding another layer of shingles doesn't require as much labor as it would take to remove them first. Therefore, labor costs are much lower for overlay roofs.

How much does it cost to add a layer of shingles?

On average, you can expect to pay a contractor $3 to $6 per square foot to install your roofing. Prices can be higher if you choose a unique or complex shingle. The contractor will have to dispose of shingles, which costs an extra $25 to $150.

How long does a 2 layer roof last?

Vented properly and installed correctly, you should get around 80-85% of the life span out of an asphalt roof. That means you can expect to get about 20-22 years out of your 3-tab shingle roof and 25-28 years out of your dimensional shingles.

What is a complete roof tear off?

If you choose to have a complete roof tear-off during your roof replacement project, your roofing contractor will remove your existing roofing system. This means that they will remove your old shingles, dated underlayment and damaged decking with possible mold and mildew growth.

How much does it cost to sheath a roof?

Shingling a roof could cost as low as $5,000—but the top-end for a new roof installation could exceed $30,000 if you opt for high-end materials and have a large roof. This cost guide breaks down the cost of a shingle roof, so you know what to expect.

Should roofs have plywood?

Aside from shingles and underlayment, plywood decking is one of the most important components in your roof. The plywood decking is integral in keeping your home free of unwanted water and mold. If the plywood has gotten wet, it can have a disastrous effect on the rest of your roof, especially the shingles.