Roofing felts or underlays are fixed before laying any concrete, clay or shingles. This are used underneath the final roof covers. They can be polythene or bituminous in nature. The reason for using them is to prevent any rain water from passing through to the ceiling. The tiles or shingle roof covers may allow water to come through when broken or in a driving rain situation. This work is done by a carpenter and with due diligence the ceiling and entire house is protected from any roof leaks.
The roofing felt should be free from any punctures. Site: https://www.bkgdakwerken.be/dakisolatie/ This are likely points for water to to pass through. Sometimes when people want to adjust aerials on the roof they have to climb up. This also applies when fixing digital satellite dishes or solar water systems. The likely hood of disturbing the mortar on ridges or puncturing a tile is high. It is essential that after works on the roof covers, a thorough inspection is done to check on damages. Any broken tiles should be replaced. The ridge tile and mortar should also be checked after any work above.
The roof underlay or felt is purchased in rolls. When using polythene, this should be heavy gauge and preferably laid in two sheets. This is because the temperature in the roof space may rise thus leading to damages on the felt. The bituminous felt should preferably be the sand blasted type. This is able to take higher temperatures without breaking within the roof space. This felts should be laid smooth from the ridge to the eaves. This prevent them breaking after they become brittle during the cold season.
When laying a roofing felt, ensure the surface is horizontal and level. The roof structure is first completed. The polythene is laid using plastic straps. This are nailed first on the purlins. They should be tight to prevent sagging under water weight. They are laid in a mesh pattern. After completion the polythene or felt is laid n top. The roof battens are then nailed onto the purlins. This are laid according to the roof tile specifications. After laying the tiles, water is poured and tested for any leaks within the felt or any sagging.