Commercial roofing are roofs on business & municipal related buildings such as manufacturing plants, strip malls, retail stores, sports facilities, government related buildings, restaurants, etc. While most of these roofs in Chicagoland and north Illinois are flat, some are pitched roofs, or domed roofs, some are low-sloped and some are “hanger-style”.
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Flat roofing materials in NE Illinois come in a a few different types – single ply, built up (made from asphalt or tar), modified bitumen, (SBS / APP), and cold process. Metal roofs are also common with buildings with at least 1″ per foot of roof slope. Flat roofs can last 15 to 45 years, depending upon the materials used, the climate, and the maintenance done while in use.
There are a variety of coatings that are used over existing roofs, but can also be used as a roof in and of itself. It is referred to as “liquid applied roofing”.
The most common single ply roof in NE Ohio is EPDM rubber roof. EPDM , or ethylene propylene diene monomer (M-class) rubber, EPDM is a rubber membrane, like a giant inner tube, that is typically delivered in rolls 10′ wide by 100′ long. There are three thicknesses, of EPDM: .045″, .060″, .090″. Some are reinforced with mesh scrim, some are not. Non reinforced are glued down to the substrate using bonding adhesive, while reinforced EPDM is mechanically attached with screws and 3″ steel washers called “plates”. The sheets are bonded together with a sticky, soft, uncured rubber seam tape with two-sided adhesive and primer glue. “Brooming” is a technique that roofers use to apply pressure to a EPDM membrane that has just been adhered, to allow the membrane to lay flat and become enmeshed in the bonding adhesive. Some times heavy steel rollers are used to get out any stubborn wrinkles in the membrane.
Sometime EPDM is installed as a “ballasted” system. This type of system where no attachments are made from the membrane to the roof deck, except on the roof perimeter. Loose laid river stone is placed throughout the field area as a ballast, keeping the roof membrane from blowing off.
There are various accessories made of EPDM, that complete the system, sealing every curb, parapet, knee-wall, inside and outside corners, pipe boots and pitch pockets that seal penetrations. While most of the EPDM membrane is “cured” – a heat treating process that toughens the rubber, some of the smaller pieces are “un-cured”. Un-cured membrane is soft and stretchable, and is used to form around curbs and penetrations, keeping out water in these difficult and leak-prone areas. “Slip Sheets” are used under objects on a roof that do net penetrate the membrane. Slip sheets are just pieces of loose membrane used to protect the installed membrane from objects such as gas lines, satellite dishes, small HVAC units, pavers, and anything on a roof that could damage the membrane. “Cant Strips” are long, triangular cut pieces used when the membrane transitions from a flat surface to a vertical surface, such as a side wall or “knee” wall. They are typically made from wood fiberboard, but can be made from regular wood or fiberglass. They help the membrane ease the transition and will prevent cracking in those areas as the membrane weathers.
“Water block” is a type of caulking used in single-ply membranes that is used around penetrations, flashings and drains, that remains soft for years, keeping water out in these critical areas.
TPO or thermoplastic olefin is another type of single ply membrane used on flat roofs. This is also used in north east Ohio, but not as much as EPDM. TPO is more prevalent in the southern USA and south western and western regions of the USA.
The thermoplastic properties of TPO allows the membrane to be heat welded at the seams, rather than glued or seam taped. There are hand heat welders and robotic heat welders that blow very hot air into a seam in a controlled fashion that bond the pieces of TPO together, creating a water-tight seam. The seam is so strong that it is considered a “monolithic” system, meaning that it is like having a one piece roof membrane over the entire roof. In fact, the material itself would pull apart during a strength tests before the seam will pull apart like EPDM, TPO can be adhered with bonding adhesive to the substrate, or mechanically fastened with screws and places. TPO accessories include pitch pockets with pitch pour, inside and outside corners, pipe boots, non reinforced TPO, and cover-tape.
TPO can last 20-35 years depending upon the climate, materials thickness, installation and maintenance.
After many years, TPO will show it’s age by becoming brittle, flaking, and showing hairline cracks when walked up and hail will leave circular marks on it.
PVC is another type of single ply membrane, similar to TPO in that it is heat welded to attached seams and accessories, but not used as much. Mostly for applications requiring a highly grease resistant membranes such as restaurants and factories, due to it’s grease resistant properties. / qualities.
Single ply roofs are typically installed over substrates such as Poly ISO rigid foam insulation board, or fiber board. These substrates can be install over existing roofs, when only 1 layer of current roofing exists. Negating the need for a full tear off of the existing roofs. These substrates can be either bonded to the roof deck with adhesives, or , attached using screws and plates.
Screws used can be made for attaching to steel , wood, or concrete roof decks.
Also, poly-ISO rigid foam insulation board not only is a great roof substrate, but is a very effective insulation layer for commercial buildings. Every inch thick of ISO is an R value of 6. It comes in various thicknesses and can be layered to create highly insulated building envelope for all types of commercial activities contained with a building.
POLY ISO can be used to create a roof pitch, to enable proper drainage for roofs that do not have any slope , or are not draining properly. The roof can be pitched in any direction, towards the front or back, either side, or pitch to direct water to drains in various roof areas. Poly-ISO can be used create roof “saddles” or “crickets” for drainage, and drain sumps.
Repairing TPO , and EPDM techniques
Many roofs get pre-maturely torn off and replaced, when some maintenence and restoration work could have been done to save the existing roof instead.
TPO roofs can be repaired with the right tools and materials. Membrane can be cut out or patched over with newer membrane and heat welded with a hand-welder to existing membrane. Pipe boots and flashing around pipes and penetrations can be cut-out and installed with new pipe boots and flashing. Seams can be gone over with strips of TPO or uncured TPO seam tape and cover-tape. Pipe boots can be sealed with water block and hose clamps around the pipe, with the base welded to the field membrane. Care needs to be taken to thoroughly clean the surface of TPO for it to weld properly. TPO can only be cleaned with weathered membrane cleaner. Soap and water or acetone cannot be used because the TPO will not weld properly with these types of cleaners. Even using non-white rags can cause the TPO not to weld. Probes are used to check all the welds to ensure the weld is sufficient and the repair will last. PVC is also repaired the same way TPO is.
EPDM roofs have different methods for repair. EPDM uses seam tapes, adhesives, uncured flashing for repairs instead of heat welding. Cleaning is also important, but not as much as with the heat welded products.
Both EPDM and TPO can be coated with acrylic thermoplatic roof coatings, for repairing and restorations.
Built up roofs, also known as BUR roofs are created by building up multiple layers of asphalt, followed by fiberglass embedded felt paper, a layer of asphalt, then a layer of fiberglass embedded felt. These layers can be reapeated many times, but typically they are two, three and four layers thick After the layering, they are then topped with a flood coat of asphalt. Each layer of BUR changes directions by 90 degree. Sometimes gravel is used over the top of BUR roofs, either loose laid or embeded, to increase the life span of a BUR roof and to provide UV reflectivity, and add extra protection from the elements and foot traffic. Asphalt can be applied hot or cold process and can be built up in many layers, or just one. With 3 or 4 being the most common. Coat tar pitch can be used in place of asphalt for an added durability factor.
BUR roofs are an excellent type of roof and have been proven to last the test of time, having been in use since the 1800’s and are still used today. When they start to wear out, and additional flood coat can be applied or another layer or two felt and asphalt, to enable continuous use for years and years. BUR roofs can last up to 35 years, but begin to show sign of age, deterioration around knee walls, HVAC units, and “field” areas beginning to show the fiberglass strands in the felt.
BUR roofs can be installed over metal, concrete or wood decks, using or existing roofs, using a fiberboard layer or poly ISO first, to create a smooth layer to install the asphalt.
Many roofs get pre-maturely torn off and replaced, when some maintainence and restoration work could have been done to save the existing roof instead.
This can be done with asphaltic based products and cements, being that BUR roofs are mostly asphaltic based. Some BUR roofs are made of coal-tar, but can be repaired in similar fashion. “Spudding” is a process of removing embedded gravel that may be needed if the roof has embedded gravel. Not all BUR roofs use gravel – embedded, or loose laid. It is important to brush off gravel over areas that are in need of repair. SBS or APP roll roofing can be used on BUR roofs as a repair product or just roof cement and fabric, which is also knon as “bull and rag”.
Metal roofs are installed on both commercial and residential building, but more often on commercial. While metal shingles and metal faux “tile” are used on some houses, standing seam metal roofs provide a highly decorative and up-scale look. , Standing seam metal roofs can last up to and over 50 years, when maintained properly. More economical metal panel roofs come in a varieties of rib-styles (post a picture of types of rib patterns) and thicknesses and can be mode in over 25′ lengths. Some have exposed fasteners and some have hidden fasterns. Institutional building often use metal panels roofs. Some that are screws down from the top using self-tapping screws with neoprene rubber washers to prevent leaks. There a high grade industrial metal panels made with standing seam style joints to prevent expose of screws head less leaks over time.
Metal roofs can be repaired in a variety of methods, depeding upon the type of roof and the problem that is causing the leak. Metal roofs tend to leak first at the seams or joints, ridge caps, ridge vents, and at the fasteners, especcially if they exposed. Metal roofs leak at penitrations also, such as vents, pipes, internal gutters, and HVAC units. While individual panels can be replaced, sometimes that is not nessary. Small leaks can be repaired with a quality metal formulated roof coating and fiberglass mesh at the leaking point. Rib-stiffeners and other accories can be used i lieu of panel replacement. Sometime the butyl tape that is used to seal panels to one another can get worn out and needs replaced.
The hazards and dangers intrinsic to the roofing industry must be respected and planned for. A safety plan and safety mentality must be part of a roof company’s policies and a roofer must respect in order to stay safe up on a roof. OSHA standards and guidelines are good to be family with and follow.
Harnesses are used where needed and peritmetor flags help roofs stay aware of the edges of the roof while working. Ladders are raised well above the eave line and bungee cords keep the ladder attached to the building and not sliding around.
Doing work on top of roofs can be logistically challenging. There are various techniques and equipment used to overcome these challenges.
Getting roofing materials on roof: Cranes helps with a lot of the heavier items like 500lb rolls of EPDM rubber or TPO. Also, help with a 10′ high 4×8 stacks of poly-ISO insulation, can be rigged and lifted with a crane to place on top of a flat roof, saving hours of time and workers stamina. Flat roof cutters are gas powered cutting mechanic that splice through multiple layers of roofing to prep for removal. They, along with other equipment can be lifted by crane or by roof hoist. Shingles can be deliver to the ridge board of a steep roof using a conveyor – belted truck, and a couple of strong men. One on the truck loading bundles, and one man on the roof, removing the bundles and stacking on the ridge board.