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By russell, June 25, 2009 6:26 pm

Description:

These roofing systems are typically a single sheet, reinforced in the middle with either a polyester or fiberglass mat for strength and modified with rubberized asphalt.  This allows the roof to expand and contract with building movement.  The Modified sheet should be installed over a mechanically fastened base-sheet.  These systems are mopped in place with hot asphalt.  These roof systems are also installed using a cold process called permanent bond.  It is applied with a torch to melt it to the base sheet.  The surfaces of the modified bitumen roof  are either smooth or granular finish that come in a selection of colors.

Uses:

These roof systems are used as an upgrade from built-up roofing systems. 

Life Span:

The expected life span of this system will exceed 15 years.  The roofing industry has seen excellent results from the modified bitumens roof.

Caution:

• Torch applied systems can be dangerous and can cause fires.  Extra attention in the application phase is very important.

Limitations:

Proper installation of this roof system is critical.  Details in the construction and installation procedures need to be planned very carefully.

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By russell,

Description:

Built-up Roofing consists of alternate layers of roofing felt and individual moppings of “Hot Asphalt.”  Built-Up Roofing may include either 3 or 4 piles of roofing felt.  Top surfacing can consist of gravel, smooth of granular surfaces similar to the look of a roofing shingle.

Uses:

A Built-up Roof is the most common type of roof for flat applications.  They can be installed over insulation, on metal roof decks, or directly on plywood roof decks with or without insulation.

Life Span:

A Four-Ply Built-Up roof will last 9 to 11 years and a Three-Ply normally lasts 6 to 8 years.  If the roofs are professionally maintained, they should last another 4 to 5 years.

Caution:

• Asphalt is the waterproofing.  Be sure to install enough asphalt.
• Although over heating the asphalt during installation aids the crews to install a job faster, it lowers the quality of the roof.  Use proper techniques to insure the best installation and quality of your roof.

Limitations:

• It’s recommended that the old roof be removed before re-roofing.
• Proper flashing details are critical to ensure a roof that will last.