Built-Up Roofing Introduced during the 1840s, built-up ("tar and gravel") roofing remains the predominant system installed on low-slope ("flat") roofs. A built-up roof consists of plies of reinforcing material (organic felts, fiberglass mats or polyester), inter-ply layers of bitumen (asphalt or coal tar) and a finish surfacing, such as gravel or decorative rock, mineral surface cap sheets, or coatings. Owing to energy concerns, many built-up systems today incorporate a rigid board insulation as well. The repetitiveness of a built-up roofing system -- its layer upon layer nature -- provides both flexibility and durability. The number of plies and the materials used for surfacing can be varied to adapt the system to virtually any environmental or aesthetic concerns. For the same reason, a built-up roof is more forgiving of abuse after application than are many other roofing systems.

Cold-Process Roofing An alternative to traditional built-up roofing, cold process roofing gets its name from the simple fact that hot asphalt is not utilized. In place of hot asphalt, "cold" asphalt emulsions or adhesives are applied between polyester mats or fiberglass base sheets. A surfacing is then usually applied over the membrane to provide protection from ultraviolet radiation and to achieve a fire rating.

 

	Green Roof A green roof or eco roof is a roof system which provides waterproofing for the building, plus a substrate and growth medium for plantings on the roof.  A garden roof has advantages such as storm water management, noise reduction, increased energy efficiency of the building, increased useable space for tenants, as well as other environmental and aesthetic benefits.
	Modified Bitumens Polymer modified bitumens were developed in Europe during the 1960s and have been in use in the United States since the mid-1970s. These materials come in rolls and as the name suggests, the idea is to improve upon the natural properties of bitumens by modifying them during the manufacturing process. Typically, this means adding either plastic or rubber. When Atatic Polypropylene (APP) is blended into asphalt it makes it more flexible and increases its resistance to ultraviolet radiation. Some APP modified bitumen materials have granules embedded in the top surface for further UV protection and to achieve a fire rating. Surfacings may be applied for the same purposes. APP modified sheets are usually torch-applied. The other major modifier for bitumen is Styrene Butadiene Styrene (SBS), a rubber-like material which improves the ability of sheets to elongate and recover. SBS sheets are generally mopped down with hot asphalt or cold adhesive, but some can be torch-applied. Unlike APP modifieds, SBS is susceptible to damage from long-term exposure to ultraviolet radiation, so surfacings are necessary to protect them. Because they are so flexible, modified bitumens are commonly used as flashing materials in built-up roofing systems.
	Single-Ply Roof Membranes This class of low-slope roofing materials encompasses a variety of products which share the common characteristic of being designed to be installed in a single layer. Single ply materials are also highly flexible, which is why they are sometimes referred to as "flexible membrane systems". There are two main types of single ply product: thermosets such as EPDM, CSPE and Neoprene are synthetic rubbers; thermoplastics such as PVC and EIP are plastic-based materials. Both types of membrane are highly flexible and resistant to ultraviolet radiation. They are also comparatively easy to install. But they are also generally incompatible with one another and cannot be used in combination on a single roofing system.
	IRMA Roof System In an IRMA system (Inverted Roofing Membrane Assembly), the roof membrane is covered by insulation and a surfacing such as pavers or rock ballast.  This protects the roof membrane from environmental elements and foot traffic.  We are approved applicators with T. Clear Corporation, manufacturers of a light weight latex mortar-faced insulation system for use with IRMA roof systems.  This system is especially useful for situations where ballast weight is a consideration.