Replacing the roof of your home and removing old singles is a time-consuming and difficult task. In the case of roof replacement, it is better to take the help of a professional contractor. 

There is some reason for replacing roof sheathing. When these reasons are met, the roof sheathing needs to be replaced.

Now let’s take a look at “when to replace roof sheathing”.

The sheathing is an important supporting material that supports the roof structure as well as the wall of the building. 

Roof sheathing can be damaged when the roof is replaced or at any time. So, the question arises, whether I will save the old sheathing or replace it.

Keep reading to explore more.

What is the function of roof sheathing?

The main function of roof sheathing is to increase the strength of the roofIt acts as a support system when the rest of the roof is made. Some more benefits are discussed below.

Helps to stop roof leaks

Asphalt shingle roof was built before roof sheathing was invented. There was no use of roof sheathing then. Users saw leaks being created in different parts of the roof since then sheathing was invented. 

Today’s asphalt shingle roof users use weatherproof roof sheathing, which gives the roof extra protection as there is an extra layer on top of the roof. 

Since almost all roof sheathing is weatherproof, it helps to extend the life of the roof. When the roof is made, the base of the screws or bolt can leak water. Roof sheathing acts as an extra layer to stop these leaks.

When To Replace Roof Sheathing

Increases the strength of the roof and supports the roof.

Roof sheathing covers the roof by giving equal weight to all parts of the roof. Since sheathing boards fix the joints and tresses of the roof, nothing can enter through it.

Snow or any other heavy object falls on the roof sheathing first, so there remains no damage to the roof. Moreover, the leaves of the trees often fall, or water accumulates on the roof and damages the roof. This damage can be avoided by using roof sheathing.

Fire protection 

And last but not least, it works as a fire protection. Roof sheathing helps prevent fire. Although roof sheathing is not 100% fire-resistant, it has some elements that prevent fire.

In addition to these basic functions of roof sheathing, there are many more functions.

What kind of roof sheathing is better in case of replacement?

Roof sheathing is made with two types of materials, usually made from oriented strand board or plywood. 

Of these two types of roof sheathing, most roofers prefer Oriented strand boards (OSB). The reason is that the OSB is lightweight, and its price is low. 

On the other hand, plywood is durable, but its price is higher than oriented strand boards.

If the roof is made of heavier materials such as slate or concrete roofing tiles, then plywood will be the best option.

When to replace roof sheathing

Roof sheathing is an important material of your total roofing system. If your roof sheathing is old, outdated, or damaged then you need to replace your roof sheathing.

The most common reason to replace roof sheathing is to change your roof. There are also other reasons why you need to replace your roof sheathing. These are discussed below.

It’s broken

You can easily determine if your roof sheathing is broken. Roof sheathing can be broken for various reasons. 

Roof sheathing is a strong board sheet but can easily break down when heavy objects such as tree stalks fall. Moreover, if the roof sheathing is old for a long time, its efficiency may be lost, and it will break down. When your roof sheathing breaks, it needs to be replaced very quickly.

Water damage 

Water damage is a bad sign anywhere on the roof. If you see water leaking or water strains 

from the ceiling, you will need to replace the roof sheathing very quickly. 

Replace the sheathing with the specific place where the water has leaked. Water damage can cause problems with the entire roof structure, so replace the roof sheathing as soon as you see it.

Seeing the decay of sheathing

If you also see that some of the roof sheathings are rotting, then replace them very quickly.

Deterioration of roof sheathing usually happens due to water damage. Rotting may not be found; the best way is to use a flashlight  so that you can easily know where the rot is and how much roof sheathing needs to be replaced.

If light passes

You have installed roof sheathing by spending money. You definitely don’t want sunlight to enter during the day and moonlight to enter at night.

If sunlight passes through the sheathing and enters the house during the day or moonlight at night, then it has become urgent to replace your roof sheathing. If light can enter, water can also enter.

Sagging roofing 

The most obvious way to passes  roof sheathing damage is by sagging through the ceiling or roofing.

If you see in the room that your roof sheathing is sagging, then you need to replace the roof sheathing. Again, if you see from the outside of your room that the roof is sagging then you have to replace the roof sheathing.

Is it mandatory  to replace roof sheathing?

Generally, roof sheathing lasts more than 100 years. But it can be damaged in any way. The good thing is it is easily replaceable and has low-cost materials.

One common question that comes to everyone’s mind is “Does roof sheathing need to be replaced after a certain period of time?” The answer is no. When the above reason comes to light, then you have to replace your roof sheathing. 


Roof sheathing is very easy to replace. The first task is to identify the place and take action accordingly. 

If necessary, you can replace the whole roof sheathing. But considering the cost ,the place where the damage has been done should be replaced. 

Anyway, the content is coming to an end at once. Roof sheathing has its pros and cons. The downside is that you often have no idea when to replace it.

But you know now all the reasons for replacing the roof sheathing as well as you got your answer for “When to replace roof sheathing”.

Best of luck. 


As a civil engineer and roofer, I love to share the experience that I have gained through the last couple of years. In the roofing industry, practical experience is a very crucial fact that can help you a lot. Hence, I want to help you with my blog.

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