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Metal roof installation
Conventional metal roofing is installed on underlayment over solid sheathing. Underlayment normally is asphalt saturated and coated roof felt. Roof felt functions well in the field, but is problematic at valleys and penetrations; at these locations, prefabricated sheet metal valleys and pipe collars should supplement the underlayment.
Typical underlayment is not adequate for most low slope roofs, the alternative is to apply and underlayment, then a modified bitumen product and then the metal product. While this does improve the viability of the roof, this is basically an installation of two complete roofing products, and is highly expensive. While we do consider metal to be a decent roofing material, we do not install it on low slope roofs for the following reasons.
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• Very limited material warranty available from manufacturer
• Water entry can lead to corrosion of unprotected metal components
• Highly expensive, requires frequent maintenance around penetrations
• Our preferred system installations carry a lifetime warranty on residential, up to 25 year warranty on commercial |
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Corroded metal component due to pooling water from debris build up |
Single Ply Membranes |
People have been given the impression that all single-ply membranes are alike. Nothing could be further from the truth. Just because they are called single-ply membranes does not mean that they will perform the same. For example, a Chevy Sprint will not perform as well as a Corvette or a Cadillac, but they are all automobiles.
The expectations of single-ply membranes should be that the membrane:
• is a waterproofing sheet
• must remain waterproof throughout its service life
• must be non-flammable
• must comply with building codes
• must be easy to work with and repair
• be pliable at different temperatures (especially extreme cold)
• be weldable
Since 1975 a wide range of Thermoplastics and Thermosets have been used for single ply roofing materials e.g. CPE, EPDM, Hypalon, TPO, PVC & CPA are just a few.
TPO's, however, are relatively new and do not have adequate performance history to make a concise judgment. TPO's, as a roofing product, have only been around in the United States about ten years and "As yet, little is known about their durability." Ralph M. Paroli, Technical advisor report Feb/Mar 2000.
Recently GAF (manufacturer) recalled it's TPO2 product. According to a newsletter article from the NRCA dated 6/8/01 "GAF Materials Corp. (GAFMC) has announced that it will discontinue production of its new EverGuard® TPO² Plus product…
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