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FREQUENTLY ASKED QUESTIONS

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What advantages do Casali roof systems offer over other waterproofing systems?

Using a multi-layer waterproofing system gives the security of a fall-back layer should any feature of the final capsheet fail. Single-ply systems obviously do not have this feature. Casali roof systems have been used extensively on Irish roofs since 1982. This in itself is a guarantee of their suitability and durability.

Are flat roofs prone to condensation problems?

No. A properly constructed warm roof system with sufficient insulation laid above the deck will experience no difficulties with condensation. In the past, many small flat roof systems were constructed where the insulation was placed below the deck. In practice it proved difficult or impossible to provide adequate ventilation between the insulation and the deck.

What are the most important factors in gauging the quality of a bituminous membrane?

Technical data on the membrane provides a range of measurements - most contractors will look at the lower temperature figure first. Holroyd & Jones normally recommend membranes with values between -15 and -25 degrees (Dermaflex/Dermabit 4170, Casali Dermabit Extra, Dermabit Extra) for the Irish climate, although other membranes may be suitable for more basic installations. A comparison of tensile strengths is also useful.

Is it safe to tile directly onto Dermacem Liquid Waterproofing?

Yes. It is best to leave the final coat of Dermacem to cure for at least 3 days before applying the tiles.

What advantages does a warm roof system have over a cold roof system?

Cold roof systems - where the insulation is laid below the roof deck - have historically been prone to condensation problems due to the difficulty of adequately ventilating the roof space. This is why Holroyd & Jones recommend using a warm roof system with the insulation laid above the roof deck.

Can torch-on membranes be used on a curved or pitched surface?

Yes, although some mechanical fastenings may be necessary to prevent slippage.