What's Under Your Roof Matters

When you’re getting estimates for a new roof, most of the conversation naturally revolves around the things you can see, including the shingles, color, style and, of course, the final price.

There is another part of your roof that deserves just as much attention, even though you will probably never see it once the job is finished: the plywood underneath.

The plywood, also called roof decking or sheathing, is essentially the foundation of your roofing system. The underlayment and shingles are installed over it, so the decking needs to be solid, dry and structurally sound enough to properly support the new roof. The tricky part is that we often do not know exactly what condition that plywood is in until the old roof comes off.

A roof can look relatively normal from the outside while hiding deteriorated plywood underneath. Years of small leaks, condensation, poor ventilation, or moisture intrusion can leave sections of the decking soft, rotten, moldy or otherwise compromised. Once the old shingles and underlayment are removed, the roofing crew finally gets a good look at what has been happening underneath.

Does that mean every roof replacement needs all-new plywood? Not necessarily. If the existing decking is dry, solid, properly installed, and in good condition, there may be no reason to replace it. However, if portions have deteriorated, replacing those sections is an important part of doing the roof correctly.

This is also one of the areas where homeowners can get caught off guard by cost. Plywood is expensive, and depending on how much needs to be replaced, it can add a noticeable amount to the final bill. When you are already making a major investment in a new roof, it is understandable to wonder whether the old plywood can simply stay in place.

Putting brand-new roofing materials over deteriorated decking is a little like installing beautiful new hardwood floors over a damaged subfloor. You may save money that day, but you have not solved the underlying problem.

Weak or damaged decking may not hold roofing fasteners as securely as sound material. It can also contribute to uneven or sagging areas and leave the roofing system more vulnerable to problems in the future. Most importantly, you are installing a product designed to last for decades over a foundation that may already be deteriorating.

There is also the issue of the manufacturer’s warranty. Roofing manufacturers generally require shingles to be installed according to their specifications and over an appropriate, sound roof deck. Installing shingles over compromised or improperly prepared decking can potentially affect warranty coverage. The exact requirements vary by manufacturer and product, which is another reason the condition of the decking should be addressed during installation rather than ignored.

I always encourage homeowners to look beyond the big number at the bottom of a roofing estimate and review what is actually included. Ask your contractor what the estimate says about plywood or roof decking, whether any replacement is included and what the additional cost will be if deteriorated sections are discovered after the old roof is removed.

This is especially important when comparing estimates from different contractors. One contractor may appear considerably less expensive than another, but the two estimates may not include the same scope of work. If one accounts for replacing damaged decking and another barely mentions it, the lower price may not tell the whole story.

Nobody likes unexpected costs during a home improvement project, and contractors do not particularly enjoy delivering that news either. However, when we uncover rotten or deteriorated plywood, replacing what needs to be replaced is usually money better spent than covering up the problem and hoping for the best.

A new roof is a significant investment in your home, and ideally, you should be able to install it and not worry about it again for a very long time. When the old shingles come off, homeowners should understand what is underneath, review the condition of the decking with their contractor and know how any necessary replacement will affect the project.

Saving money is always worthwhile, but cutting a corner that could compromise the life of your new roof rarely is.

Bob O’Donnell is the owner of O’Donnell Bros. Inc., a Bristol-based home improvement company established in 1975. Have a question? Email info@odonnellbros.com with the subject line “Ask the Pro.” For your remodeling needs, call O’Donnell Bros. Inc. at (860) 589-5155 or visit www.odonnellbros.com. Advice is for general guidance only.

When you’re getting estimates for a new roof, most of the conversation naturally revolves around the things you can see, including the shingles, color, style and, of course, the final price.

There is another part of your roof that deserves just as much attention, even though you will probably never see it once the job is finished: the plywood underneath.

The plywood, also called roof decking or sheathing, is essentially the foundation of your roofing system. The underlayment and shingles are installed over it, so the decking needs to be solid, dry and structurally sound enough to properly support the new roof. The tricky part is that we often do not know exactly what condition that plywood is in until the old roof comes off.

A roof can look relatively normal from the outside while hiding deteriorated plywood underneath. Years of small leaks, condensation, poor ventilation, or moisture intrusion can leave sections of the decking soft, rotten, moldy or otherwise compromised. Once the old shingles and underlayment are removed, the roofing crew finally gets a good look at what has been happening underneath.

Does that mean every roof replacement needs all-new plywood? Not necessarily. If the existing decking is dry, solid, properly installed, and in good condition, there may be no reason to replace it. However, if portions have deteriorated, replacing those sections is an important part of doing the roof correctly.

This is also one of the areas where homeowners can get caught off guard by cost. Plywood is expensive, and depending on how much needs to be replaced, it can add a noticeable amount to the final bill. When you are already making a major investment in a new roof, it is understandable to wonder whether the old plywood can simply stay in place.

Putting brand-new roofing materials over deteriorated decking is a little like installing beautiful new hardwood floors over a damaged subfloor. You may save money that day, but you have not solved the underlying problem.

Weak or damaged decking may not hold roofing fasteners as securely as sound material. It can also contribute to uneven or sagging areas and leave the roofing system more vulnerable to problems in the future. Most importantly, you are installing a product designed to last for decades over a foundation that may already be deteriorating.

There is also the issue of the manufacturer’s warranty. Roofing manufacturers generally require shingles to be installed according to their specifications and over an appropriate, sound roof deck. Installing shingles over compromised or improperly prepared decking can potentially affect warranty coverage. The exact requirements vary by manufacturer and product, which is another reason the condition of the decking should be addressed during installation rather than ignored.

I always encourage homeowners to look beyond the big number at the bottom of a roofing estimate and review what is actually included. Ask your contractor what the estimate says about plywood or roof decking, whether any replacement is included and what the additional cost will be if deteriorated sections are discovered after the old roof is removed.

This is especially important when comparing estimates from different contractors. One contractor may appear considerably less expensive than another, but the two estimates may not include the same scope of work. If one accounts for replacing damaged decking and another barely mentions it, the lower price may not tell the whole story.

Nobody likes unexpected costs during a home improvement project, and contractors do not particularly enjoy delivering that news either. However, when we uncover rotten or deteriorated plywood, replacing what needs to be replaced is usually money better spent than covering up the problem and hoping for the best.

A new roof is a significant investment in your home, and ideally, you should be able to install it and not worry about it again for a very long time. When the old shingles come off, homeowners should understand what is underneath, review the condition of the decking with their contractor and know how any necessary replacement will affect the project.

Saving money is always worthwhile, but cutting a corner that could compromise the life of your new roof rarely is.

Bob O’Donnell is the owner of O’Donnell Bros. Inc., a Bristol-based home improvement company established in 1975. Have a question? Email info@odonnellbros.com with the subject line “Ask the Pro.” For your remodeling needs, call O’Donnell Bros. Inc. at (860) 589-5155 or visit www.odonnellbros.com. Advice is for general guidance only.