Los Angeles Home Inspector

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Asphalt Roofing

All things considered, asphalt is the most popular roofing option, and the one we see most on home inspections here in LA. So we thought we would take a moment and discuss asphalt roofing to help our clients better understand this product.

Asphalt roofing includes shingles, built-up roofing, roll-roofing, and modified bitumen membranes. Typically, the shingles will also be asphalt as these are effective and efficient. Nowadays, there are a number of different colors and textures that can be used; the four main types are laminated, strip, large individual singles, or interlocking. In truth, they all provide their own unique advantages since laminated shingles will provide thickness as it is layered. Furthermore, wind resistance will see the use of interlocking shingles whilst individual shingles are larger and come in different shapes.

For residential properties, roll-roofing products are widely used for flashings and underlayment; again, there are four different types; saturated felt, smooth-surfaced, mineral-surfaced, and specialty-eaves flashings. Normally, they will be used together or with something else and it is only the mineral-surfaced option that is used by itself on small buildings or even sheds. To seal the roof at protrusions or intersections, normally smooth-surfaced products will be used as flashing as they also add deck protection for the valleys and eaves. For saturated felt, this is mainly an underlayment between the roofing material and the roof deck. If the climate is particularly cold and ice dams are common, specialty-eaves flashings then play a role.

For commercial properties, built-up roofing (BUR) is the most common process as well as on institutional and industrial buildings. With multiple layers of ply sheets and bitumen, BUR can be found on slightly-sloped roofs in addition to flat roofs. Within the BUR system, there are many different factors including a vapor retarder, roof deck, membrane, insulation, and the surface material.

With modified bitumen-membrane, roofers will build layer after layer of coated felts, saturated felts, mats, or fabrics. Then, unsurfaced or surfaced layers of bitumen are applied in between each layer. If it comes with factory surfacing, this will include aluminium, copper, mineral granules, or slag. In terms of the physical feel and touch of the membrane, this will come from the bitumen whilst providing waterproof protection and adding strength to the complete system.

Have roofing questions? Contact us!