Built up roof membranes (BUR) are a common commercial roofing system in Minnesota. These roofing systems have been in use in the U.S. for more than 100 years.  Also commonly referred to as "tar and gravel" roofs. BUR systems generally are composed of alternating layers of bitumen and reinforcing fabrics that create a finished membrane. Built up roofs generally are considered to be fully adhered if applied directly to roof decks or insulation.

BUR utilizes reinforcing fabrics or roofing felts or ply sheets.  Roofing felts are reinforced with either glass-fiber mats or organic mats.  Felts are produced in a standard width of 36 inches and metric width of about one meter.

The bitumen typically used in BUR roof systems is asphalt, coal tar or cold-applied adhesive. 

Surfacings for built up roof systems include aggregate (such as gravel, river rock, slag or mineral granules), glass-fiber or mineral surfaced cap sheets, hot asphalt mopped over the entire surface, aluminum coatings or elastomeric coatings.

Ethylene Proylene Diene Monomer (EPDM) is a flat roofing system, and is the most common thermoset roof membrane. EPDM is primarily composed of two compounds, ethylene and propylene, they are derived from oil and natural gas. The following are some characteristics of EPDM roof membranes:

• Sheet widths range from 7.5 feet to 50 feet wide and are
•  typically 45 mils and 60 mils thick.
•  
• Seams are sealed using liquid adhesives or special formulated tape.
• The membranes commonly are black, but white is available.

EPDM roof membranes can be installed fully adhered, mechanically attached (using batten bars) or ballasted. Most EPDM membranes do not receive surfacings.

EPDM and Polymer-Modified Bitumen Membranes often are confused by consumers because of colloquialisms used by many roofing contractors. They often refer to both of these membranes as "rubber" roofs. However, in most cases, when contractors specify “rubber roofs”, they are referring to EPDM.

Asphalt shingles are composed of: a base material, either organic felt or glass-fiber mat, that provide support for the weather-resistant components and give a shingle strength; asphalt and fillers; and surfacing material, generally in the form of mineral granules, that provides protection from impact and UV degradation and improves fire resistance.  Asphalt shingles are the most common residential roofing system in Minnesota.

The most common form of asphalt shingles are strip shingles and are 12” wide x 36” long.  Strip shingles most frequently have three tabs that are exposed along the length of the shingle for visual effect and are called 3 tab strip shingles.

Shingles may be in a single layer or two or more layers. The latter generally are known as laminated strip shingles, or architectural shingles, and they have a three dimensional appearance.

Both 3-tab asphalt shingles and laminated asphalt shingles contain a strip of factory applied adhesive that is activated by the sun's heat after installation and seals each shingle to the next course. The seal strip also provides much of a shingle's resistance to wind uplift. Shingles with factory-applied adhesive have a strip of clear polyester film applied to each shingle to prevent the sealing strips from bonding the shingles together when packaged. When the shingles are installed, the self-sealing strips will not align with the plastic film strips and will bond to adjacent shingles. For this reason, the plastic film strips do not have to be removed.

While not as common in Minnesota as asphalt shingles, wood shake shingles can give a home a unique and elegant appearance.  Wood shakes and wood shingles are manufactured from western red cedar, cypress, pine and redwood trees. Shakes are split from logs and reshaped by manufacturers for commercial use.  A taper sawn shake has a natural taper and is sawn on both sides. Wood shingles are sawn on both sides and have an even taper and uniform thickness.  

Cedar shakes and cedar shingles are available pressure treated with fire retardants and chemical preservatives for increased fire resistance and to prevent premature rot and decay in some climates.

Pine shakes are made from southern yellow pine and are taper sawn and are available pressure treated with preservatives to protect against decay and insects.