Built-up Roof Blisters

Flat Roofing Repairs – Built-up Roofing Membrane

Blisters may need to be repaired if

• The blisters occur in areas of high traffic
• Membrane deterioration
• Excessive loss of surfacing (gravel)
• Blisters in laps which have reduced lap coverage
• Blisters have breaks, or cracking

Whether to remove, patch, or monitor blisters is a judgment call. Blisters that are keeping air in will keep water out, if this is the case it may be preferable to leave the blisters undisturbed. Should it be determined that blister removal is necessary, the following steps should be used.

1. Remove all loose debris from the surface of the membrane or flashing to be repaired. The area should extend a minimum of 18 inches beyond the perimeter of the defect.
2. If membrane surface has been flood coated and aggregate embedded, carefully spud the aggregate free from the surface and sweep clean.
3. Carefully cut and remove the blistered material until good adhesion of the membrane is reached.
4. Inspect insulation or deck for damage caused by water infiltration. Remove wet or damaged insulation and repair or replace as required. Properly attach or adhere new, dry insulation (consistent with the thickness of the existing insulation).
5. Prime the surface of the BUR membrane with asphalt primer. Be sure not to overuse the primer, because it may harm the existing membrane and inhibit adhesion of newly applied membrane.
6. Install the same number of plies as were removed in cold-applied adhesive or hot bitumen. Extend the bottom ply at least 6 inches beyond the area to be repaired and each exceeding ply at least three inches beyond the previous ply.
7. Reapply the surfacing. For small repair areas, it is a common practice to apply the coating immediately after the membrane repair is made.

Many Leaks are Caused by Mechanical Rooftop Equipment

Who’s to Blame? Don’t Blame the Roofer

It is estimated that roughly 30% of leaks from commercial buildings originate from HVAC equipment, while only 20% of those leaks are actually roof related.

 Photo cited from – www.cdc.gov/niosh/fire/reports/face200013.html

Common leak spots for HVAC units

Holes and loose edges on HVAC fresh air intake hoods

Holes and poor weather stripping in HVAC air intake panels.

Loose or missing filter access panels on HVAC units.

Poorly designed filter access covers on HVAC ductwork.

Improperly sealed joints, seams and holes on HVAC ducts

The Roof is a Working Platform

For most construction trade – electrical, mechanical, plumbing, etc.

And many times the equipment itself is not waterproof. This often leads to roof leaks. Tenants incorrectly assume that all wet ceiling tiles mean roof leaks, but in reality it is often the rooftop equipment. So guess who gets the blame? Of course the roofer is called, while the mechanical, plumbing, and electrical contractors remain unaware of the equipment problems.

Other Common Causes for Commercial Building Leaks

25% – Skylight Louvers

15% – Windows

10% – Concrete Wall Cracks

Related Articles – Roof Leaks – Major Concern for Business

“Greening of Low Slope Roofing Systems”

For new and existing buildings

Learn:

• What “green” means
  How green roof systems work, and how much they cost
  Design and construction issues and constraints
  About International Construction Construction Code – 2012
  Incentive programs
  Evaluate the benefits, but also the potential for failure
  Determine when these systems are right for your facilities

Topics:

• Advantages and disadvantages of “green” roof technology
  Special design requirements for new construction and existing buildings
  Codes governing design and installation
  Special installation requirements
  Warranty issues
  LEED, Green Globe, other recognition programs

Who Should Attend this Event?

• Building Owners
  Architects
  Engineers
  Designers
  Roofing Contractors

The event is approved by the U.S. Green Building Council (USGBC)

For additional details on the event: Low-Slope Flat Roofing Event

The most common roof decks used on flat roofs are steel roof decks. They are made out of cold-rolled sheets. Cold rolled refers to when steel is shaped into the decking or roof panels at room temperature. There are ribs in each panel that make them strong and rigid.

Ribs are referring to the grooves in steel panels that make them strong.

 The panels come in many thicknesses, sizes, and spacing of ribs.

Many roof decks are used on flat roofs, but steel roof decks are the most popular choice in the industry today.

Other Roof Decks Installed on Flat Low-Slope Roof Systems

Cement Wood Fiber Roof Decks made from wood fibers. These are bonded together with cement and other binders. Then they are pressed together and molded into panels.
Gypsum Concrete Roof Decks made of gypsum material mixed with fillers.
Structural Concrete Roof Decks either poured on site or made into planks and then set in place.

Many types of wood roof decks exist as well, such as wood plank, plywood, and oriented strand board.

Insulating Concretes – light weight insulating concretes can be used as fills or toppings. Insulating concretes can be poured over another surface like corrugated steel or form boards.