When faced with a leaking felt roof the first reaction may be to be attempt to remove the old failing felt sheeting. There are two reasons why this may be both unwise and expensive.
1) Disturbance and Unforeseen Consequences
If a roof covering has failed there may well be consequential damage to the underlying substrates such as the roof boarding, batons, purlins etc.
This may not in itself be serious enough to make the roof structure unsustainable but the uplifting of the overlying felt may cause breakage of joints or laths which then will need to be repaired. In turn their removal, in order to effect repairs, may demand yet further repairs. The cost and time spent can easily spiral out of control.
You can avoid these difficulties by applying Rubba Roof compounds DIRECTLY on to existing roofing – felt. . Rubba Roof has very high adhesion to roofing felt ( See page No …. for instructions on use ) and it will form a 100 % waterproof , flexible coating ….just like sheet of rubber . Cracks, upstands and other detailing are easily resolved using the Rubba Roof Reinforcing Fleece ( See Page No … )
2) Costs of Disposal
Roofing felts contain bitumen and so many Local Authorities regard the materials as “Hazardous Waste”; therefore quite onerous and costly stipulations and charges may apply to their disposal.
By using Rubba-Roof to seal and waterproof leaking felt roofs ,the costs and inconvenience associated with the removal and subsequent disposal of old roofing – felt may be entirely avoided.
Causes of Failure of Felt Roofs
Roofing felts are constructed from a layered combination of a polyester carrier layer and a modified bitumen coating.
The thickness of the sandwich elements vary according to brand and the UV resistance and the mechanical strength of the top surface will also exhibit different degrees of robustness.
Ultimately, however, all felt roofs will degrade due to one or more external factors:-
- Expansion and contraction of the top surface due to the effects of thermal variation in climatic conditions. The movement caused within the weather, or top, layer of roofing felts can cause the surface to develop micro-cracks or larger splits. These can let in rain and condensation which itself may then freeze and thaw in cycles; thus the cracks can become enlarged and draw water further in to the membrane’s structure.
- Movement of the supporting roof structure may cause the felt underlay, or the bottom surface of a felt capping sheet to be stressed beyond its mechanical competence. This can cause the surface to buckle and lift. Moreover joints and overlaps may then peel back or lose adhesion.
- Ultra Violet radiation and temperature fluctuations affect the longevity of even the most modern of roofing felts. Even when small mineral aggregates are embedded in the surface of capping felts as a protection against weathering, the effects of hard frosts followed by periods of strong sunlight may cause significant movement and cracking within the actual matrix of the felt itself.
Repair of Leaking Roofing Felts
Rubba-Roof compounds can be applied directly to existing roofing felt. The unique flexibility and high adhesion of Rubba-Roofs Polyurethane technology ensure resistance to problems caused by thermal shock and structural movements.
Rubba-Roof is easy to apply, saves time,
saves money & lasts longer!
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