Roofing felt is used to shield your home from any rain, wind or snow that might cause damage. It is a very common underlay material as it is very secure and long lasting, it provides a lot of protection against any weather and is a very good option. It is highly recommended to install as it provides great water protection, it also acts as a vapour resistant underlayment.

What happens if roofing gets wet?

After a while roof felts will start to lose quality and purpose if it’s exposed to a lot of dampness. It is made to withstand any weather but if too much moisture gets to it for a long period of time, it can cause it to crack in the sun or even burst when the roof shingle is installed. Applying roof shingles to a damp sheath can trap the moisture inside of the roof and cause it to rot and mould. Although it shouldn’t matter too much if the felt gets wet as it has water repellent properties in it. Also the roofing is built with a shield from water so it just bounces off preventing any leeks or wood rot in the walls.

When installing a roof you need to be careful it doesn’t rain as it can shorten its lifespan and become more damaged quicker, you should install it on a dry day as it dries quickly and easily. If the air is warm and moist it can affect how the felt dries, it can damage the insulation and cause twisting to the roof assembly. If this happens you will need to replace the roof as it can become dangerous. If the warm air enters the roof through any gaps in the ceiling it can mix with the cold air causing water droplets to form. If this happens the water can run down and create spots on the roof.

Does my roof felt need replacing

If your roof starts to leak after any heavy rain that could be a sign it needs replacing soon, Leaking roof felt can become dangerous if not replaced straight away. If it is doing this a lot it will mean the roof felt won’t provide much protection from the rain which can make your house damp and cold. Repairing it will only be short term and will still need to be replaced. Due to all the weather damage a roof will face cover the years the roof will become more likely to leak and get damaged.

Some roof underlayment things to consider if your replacing it

Roofing felt: roofing felt is most commonly used for underlayment, it is used a lot in homes. It is water resistant and well secure but it can still cause rotting and mould if it gets too wet and does not have a proper airflow. Usually the heavier the felt is the more resistant it is to water and provides more protection against strong winds and rain. If you use a high water vapour resistant felt it needs a lot of ventilation to dry well, also if there is not enough air space in the roof it can cause rotting and mould to create and you will need to replace the underlayment.

Synthetic roof underlayment: this type of roof underlayment is also water resistant slough it can still get wet without much damage. It is vapour resistant which means it’s a lot lighter than roofing felt. This could mean it will deteriorate quicker and need replacing in a shorter period of time. Synthetic underlayment is built with asphalt, also fibreglasses are added to make it less likely to tear and more resistant. It can also withstand heavy duty roofing compared to roofing felt.

Rubberised asphalt underlayment: this type of underlayment is designed with a sticky back, this creates a waterproof barrier. This happens between the underlayment and the roof deck protection to roof from any water that might get through. It also contains rubber polymers and quite a high percentage of asphalt. This makes the most expensive type of underlayment roofing material  you can get.

How long does roofing felt last

Roof felt is expected to last from 10-20 years depending on the conditions it’s in and the grade and quality. asphalt roofing lasts up to 20-30 years, although rubberised asphalt is new it can last a lot longer and provides more protection.  However this all depends on the weather as it can tear it down and halve the lifespan. It can get more damaged in extreme cold and wet climates rather than hot and dry places. It is advised to install a water and ice shield to your roofing as it can be very helpful in colder climates.

Overall roofing felts are very good in protection although they can get damaged over time they are very useful and secure. You should allow the felt to fully dry properly for better results and longer lasting underlayment as if water gets trapped into the gaps it will cause rotting and mould, it will then need to be replaced and repairs will only be short term before it breaks again.