Got an underlaid roof or thinking of getting one? You鈥檙e in the right place. Underlayed roofs are one of the most popular solutions in the industry, and for good reason. In this article, we鈥檙e going to look at a few of the issues associated with roof underlayment.
Most importantly, how long does a roof underlayment generally last? And if yours is coming to the end of usability, what can you do about it?The reality in the roofing industry is that the general lifespan of an underlayed roof can vary quite a lot. This will depend on the specific material used, how well it was installed, and your locations. We鈥檙e going to look at a few factors that could affect the durability of your underlayed roof along with what to do if there are any issues.
So let鈥檚 get started with how long does roof underlayment last
What is an underlayed roof?
Roof underlayment is a waterproof membrane that鈥檚 installed as a barrier underneath any other roofing material. While you might look for issues or problems with your slates or shingles, many roofing issues can occur because of problems with the underlayment.
Regardless of what your roof is finished with, it will normally have a layer of underlayment. This helps protect the roof against severe weather. There are generally three main types of underlayment, and these are
- asphalt felt
- synthetic underylayment
- and rubberized asphalt underlayment.
These are either waterproof or water resistant.
Wondering what the difference between waterproof and water resistant is? you鈥檙e not alone. Waterproof means completely impervious to water whereas water-resistant means the material can resist water up to some degree, but maybe not prolonged and heavy water damage. Only rubberized asphalt is completely water-proof, so this might be the best choice in areas that get a lot of rain or other precipitation.
How does a standard roof underlayment last?
The general estimated lifespan of an underlayed roof is normally around 25 years. That鈥檚 the headline quote, but as we鈥檒l soon see, this can vary a lot depending on a number of factors.
What can affect the duration of roof underlayment?
Not all roof underlayment is the same. Even within the same groups of material, there can still be some difference in quality. Generally, you get what you pay for in roofing and that means the more expensive materials will last longer.
As we already looked at, only one type of roof underlayment (rubberized asphalt) is completely waterproof. That means if you have an underlayment that鈥檚 made from the other two materials (asphalt felt and non-bitumen synthetic) it won鈥檛 last as long in extreme weather or when it has prolonged exposure to water.
There are a few other factors that can affect the lifespan of an underlayed roof, too. Aside from rain, other weather conditions like extreme heat can cause issues. The duration of your underlayment can depend a lot on the specific climate and weather conditions of the location of your home.
How well it was installed can also be a factor. While you鈥檇 hope to have a quality roofing specialist, they aren鈥檛 all that good. That鈥檚 why you need to take time and care choosing the right roof contractor in your local area.
If your membrane was installed in a rush, it might not have been put in place securely enough. Poorly installed or cheap flashing and joins could lead to further problems with your underlayment.
How to spot when your underlayed roof needs replacing or repairing
Spotting damage or issues with your underlayment can sometimes be easy 鈥 but it isn鈥檛 always. One common sign of a problem is a leak. Leaks can be for a number of reasons, and while you still might have issues with other layers like shingles 鈥 if the underlayed membrane was intact it wouldn鈥檛 be a problem. That means if water is coming through your roof, at the very least there鈥檚 a hole in your underlay.
To find the hole, simply follow the water stream upwards. This can be a bit harder with a flat roof where streams can form anywhere, but most pitched roofs will have a stream that flows in a direct manner.
Once you鈥檝e found the leak, you can decide what to do next. Repatching is sometimes possible, but isn鈥檛 always the best option. In severe cases, you might have to relay whole sections of the roof, or even the entire membrane. We wrote a guide about how to find leaks so you can check it out.
How to repair an underlayed roof yourself
If you鈥檝e only got a minor issue with your underlayment, you can patch it up yourself. Remember, working on roofs can be dangerous, so you need to be careful. Especially if you鈥檙e getting up on the roof and accessing it from the outside. Make sure you鈥檝e got all the right safety equipment and supervision. If you鈥檙e unsure what to do at any point, leave the job and hire a professional.
For small tears and holes in the membrane, you can apply new patches and use industry-standard sealant to put it in place. This can increase the lifespan of your roof considerably, and solve any minor issues. However, repatching yourself isn鈥檛 always an option. If you鈥檝e got multiple gaps and leaks you might need to hire a professional to relay the entire roof.
Instead of tearing off and replacing the whole roof, you will have the option to overlay. This can only be done once, but is much cheaper and easier. A quality roofing professional will be able to advise you the best way to continue.
How to find the right roof contractor
If your roof problems are too hard to fix yourself, you need a professional roofing contractor to take care of the job. There will be plenty of options in the area you live, but it鈥檚 still a decision you need to take carefully. Ask people you know if they can recommend anyone, and check reviews online. Always make sure you check their portfolio and even check finished jobs if you can. Don鈥檛 take shortcuts with your roof.
Spending a bit more and getting the best job possible could add years to its durability.

