Office Building Roofs
FLAT OFFICE BUILDING ROOFS
Unlike steep-sloped roofs, which rely on gravity to shed water, flat roofs have special requirements in order to function properly, using drains and a waterproof membrane to protect the property. Actually, the term ‘flat’ is misleading here — no roof should be completely flat or you’d find yourself working under a pool of water.
“Low slope” is a more accurate description of what’s commonly called a flat roof. Low slope roofs should have at least a 1/4 inch of slope per foot, allowing the water to flow downhill to the drains and then to the ground.
Polyurethane Foam
This material is sprayed directly onto the roof, where it “foams up” and solidifies before a protective coating is applied. Because of its flexibility, foam is especially useful for roofs with unusual shapes or configurations.
Foam has a number of unique advantages over other types of flat roofing systems. For one, it protects against thermal shock and it can greatly reduce your air conditioning bills. Intrigued?
Built-up Office Building Roofs
Built-up roofing (aka BUR) is what many people call “hot tar roofing.” A century old, time-tested roofing method, BURs are made of three or four overlapping layers of asphalt felts fused together with hot asphalt.
Built up roofs must be protected from weather, sunlight and foot traffic by some kind of surfacing material such as gravel, a mineral granule covered top layer (a cap sheet), a smooth coat of hot asphalt or a special reflective coating.
Modified Bitumen
Modified bitumen’s, like built-up roofing, are made of reinforced asphalt impregnated felts. However, unlike BURs, the asphalt in the felts is modified with plastic or rubber polymers (hence the name) to improve its elasticity, durability, and overall performance.
Because of the added polymers, modified bitumen is often applied in a single layer with overlapping seams. They can be “glued” to the roof with hot asphalt or an adhesive, or by using propane torches to melt the asphalt underside. Some modified bitumen requires protective surfacing materials, usually mineral granules or a liquid coating.
Single Ply
Single ply membranes are made of rubber, plastic or a hybrid of the two. As the name implies, single ply membranes are applied in a single layer.
Installation is simple: the membrane is rolled out, the seams between sheets are heat welded, chemically welded or glued together, and the membrane is attached to the roof with fasteners (usually screws/flat plates), ballast (like rocks) or adhesive.
SLOPED OFFICE BUILDING ROOFS
There are many styles of sloped roofs that rely on gravity to shed water. Plus there are different types of materials that can be used.
Shingle
Shingle roofs are reinforced with organic or fiberglass materials. Although asphalt shingles reinforced with organic felts have been around much longer, fiberglass-reinforced products now dominate the industry.
Tile
Tile, whether clay or concrete, is a durable roofing material. Mission and Spanish-style round-topped tiles are used widely in the Southwest and Florida. Flat styles are also available to create French and English looks. Tile comes in a variety of colors and finishes and, when compared to other roofing materials, tile is quite heavy. If you are replacing another type of roof system with tile, you will need to verify that the structure can support the load.
Asphalt Shingles
These shingles own an overwhelming share of the Valley’s steep-slope roofing market and can be reinforced with organic or fiberglass materials. Although asphalt shingles reinforced with organic felts have been around much longer, fiberglass-reinforced products now dominate the market.
Fiberglass Shingles
These are made up of a fiberglass mat, top-and-bottom layers of asphalt, and mineral granules.
Fire Resistance Ratings
An asphalt shingle’s ability to resist fires, like most other roofing materials, is categorized by Class A, B or C. Class A signifies the most fire-resistant. Classes B and C denote less fire resistance. Generally, most fiberglass shingles have Class A fire ratings while the majority of organic shingles have Class C ratings.
Reinforcements
A shingle’s reinforcement has little effect on its appearance. Organic and fiberglass products are available in laminated (architectural) grades that offer a textured appearance. Zinc or copper-coated ceramic granules also can be applied to organic or fiberglass products to protect against algae attack, a common problem in warm, humid parts of the country. Both types of shingles are available in a variety of colors. Regardless of their reinforcing type and appearance, asphalt shingles’ physical characteristics vary significantly. When installing asphalt shingles, KY-KO recommends shingles that comply with American Society for Testing and Materials (ASTM) standards.
