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Asphalt Built Up Roofing Systems In St Louis Mo |  Williams American Roofing & Construction Inc
Modified Bitumen Roofing System Installation In St Louis Mo
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Modified Bitumen Roofing Systems St Louis Mo

The two most common modifiers are APP (attactic polypropylene) and SBS (styrene-butadiene-styrene). The APP Modified Bitumen sheets are applied by heating up the underside with of the roll with a torch. The torch applied process creates a fire hazard and there are municipalities that have banned the use of torch applied Modified Bitumen (APP). Both sheet types come in one square rolls for easier handling. The width runs about 40 inches and the lengths are usually 33 feet weighing close to 100 lbs. when the surface of the roll is granulated. The manufacturer’s make a smooth surfaced (no granules added) Modified interply sheet. These modified ply’s are not to be used as cap sheets. They are used as additional interply’s to upgrade warranty’s. When used as a cap sheet the smooth modified membrane sheet must be coated to prevent UV rays from prematurely breaking down the surfacing. The coatings that are applied to the surface vary and are discussed in subsequent flat roof system types under the heading Flat Roof Coatings. A polyester mat is saturated on both sides with the modifiers and the granules are embedded on one side. These types of roof systems are very durable, flexible and easily maintained. The granules can be color coated for a variety of color availability. The SBS Modified is applied with either a cold applied liquid membrane or a mopping down of the sheets with hot asphalt.
The Modified Bitumen roof systems are installed over felt base sheets that are glass fiber reinforced. These base sheets prevent the hot asphalt or cold adhesives from dripping into the building and on retrofit (recovers) applications act as a separator from the existing roof system.

Insulation may be applied on flat roof decking and remove the necessity of using up interior space for insulating purposes.

The most common types of insulation are Fiber Board (glass fiber board or wood fiber board), Expanded Polystyrene and Polyisocyanurate. There are composition types where the manufacturer combines the above types for specific application purposes. 

The choice of insulation is usually based on the amount of R-Factor that is desired. Polyisocyanurate carries the highest R-Factor of an R-6 per each inch. This is notably the most desired but is also the highest priced of the insulations. 
Modified Bitumen Roofing Systems St Louis Mo
Modified Bitumen Roof Systems came to the United States at the end of the 1970’s and early 1980’s after being developed in Europe in the mid 1970’s. Modifiers were added to roofing asphalt to replace plasticizers that had been removed by advanced methods of the asphalt distillation process.
Commercial Modified Bitumen Roofing System Installation In St Louis Mo
Commercial Modified Bitumen Roofing System Installation In St Louis Mo
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