Replacing perished felt under roofing tiles
Posted on 25th October 2021 at 14:33
Do I need to replace the full roof if the felt membrane has perished?
It is important to note, this is not the felt on a flat roof, this is the membrane under the tiles or slates on your main pitched roof.
If you are buying a new home and the surveyor has highlighted issues with the membrane under the roofing tiles or have you noticed there are tears appearing in the felt membrane in the attic?
What is roofing membrane felt used for?
The felt membrane is laid onto the roof rafters and the battens are laid on top of the felt, the tiles or slates are then secured to the battens.
• The felt helps to prevent any shifting of the tiles and slates in high winds and heavy rain.
• The felt also provides and additional layer of insulation in your loft space.
• When putting a new roof on it protects the inside of the property from the elements during the build.
• A membrane can help prevent infestation from pests like squirrels and vermin.
• A breathable felt membrane allows the condensation to escape preventing any mold in the attic.
Why has my roof felt membrane perished, there are tears, splits, and holes?
Generally, a property that is older than 1970 used a bitumen membrane under the battens. This product only had a life expectancy of approximately 30 years, and that can depend on the weather conditions it has been exposed to, the internal use of the loft space and its ventilation.
Eventually the membrane will perish as in these photos, then you will need to replace the full roof felt.
My roof isn’t leaking but the felt has deteriorated, do I need to replace the felt?
If you don’t have water coming into the loft then you can wait, but eventually it will need to be replaced as it can affect the condition of your roof and if a tile or slate slips you will have no protection against water ingression.
It can also be a sign of the age of the roof and the full roof needs to be replaced including the felt, battens tiles of slates.
Is it possible to repair a tear in the felt membrane in my loft?
It is possible to repair a tear or small hole in a felt membrane in your loft, but this needs to be carried out by a competent roofer as the process can cause further issues. A competent roofer will assess the condition of the felt internally and advice if it is possible or if the full roof felt needs replacing.
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