Slate is generally fixed according to two methods. Both systems have pros and cons.
The Conventional Systems
The Conventional slate system is generally fixed on roof pitches of 30 degrees and higher. A triple layer of slate is used with an underlay only on the ridges and hips. This system of roof will last longer than the Alumaz roofing system, as there is no underlay on 90% of the roof. The slate itself should last for 200 years. Broken slate on the roof, may lead to leaks, so regular maintenance and slate re-roofing needs to be carried out.
Alumaz (Peter-lo) systems
The Alumaz slate system, is normally installed on roof pitches between 17 and 30 degrees. The main benefit of this system is that it has a composite waterproofing membrane between the layers of slate. Even if you have broken slate, the roof will not leak, as the underlay waterproofs the roof. The underlay, however should not be left exposed for too long, as it is a costly exercise to replace the underlay. Originally the underlay consisted of malthoid only, and the life span of the underlay was about 20 – 30 years. The new products for slate re-roofing consist of malthoid, but with an additional layer of aluminium on the exposed underlay. The new underlay should last about 60 years.
Although Peché Roofing would normally suggest re-roofing an existing slate with slate again, some clients prefer changing the roof covering to an alternative covering like concrete tiles or sheeting.
We are known in the industry for being slate re-roofing specialists. It is an art in itself, and great care is taken to re-roof the roof in sections, so that no part of the roof is exposed. We also specialise in replacing old concrete broseley roofs with slate, sheeting or concrete tiles. For a professional assessment of your roof please contact us on 011 708 7411 or fill in the contact form below.