Typical Causes of Roof Problems
A. Lack of Maintenance
The failure to find and correct minor roof deterioration in the earliest stages is
probably the greatest cause of premature roof problems. This is particularly true of
roofing materials applied on relatively low-sloped roofs.
All roofing materials deteriorate from exposure to the weather at rates determined largely
by the kind of material and the conditions of exposure. In general, inorganic roofing
materials tend to deteriorate less rapidly from exposure than organic roofing materials.
All types of roofing materials may be damaged by hail. Exposure to air pollutants and
industrial or salt-laden atmospheres may accelerate the deterioration process of some
C. Wind Damage
Roofing materials are subject to damage from strong winds and flying debris. Generally,
roofs are not designed to withstand winds of hurricane and tornado intensity. However,
roofs may also be damaged by winds of moderate intensity, with gust that may reach 50 to
75 miles per hour. The primary cause of wind damage is from the partial vacuum created by
wind blowing over the edge of the roof. Nature tries to neutralize the low-pressure area
by bringing in air from a higher pressure area, usually from inside the building. This air
pushes up on the bottom side of the roof assembly and, over time, loosens fasteners and
breaks the adhesion making the roof susceptible to damage from the next moderate or strong
wind. To counteract the effects of wind-uplift forces, the roofing and insulation should
be adequately fastened to the roof deck, and a securely-fastened perimeter detail should
D. Improper Design
Troublesome and costly roofing problems are often the result of faulty initial design of
the roof system. Design deficiencies are costly to correct, and usually can only be
corrected during roof replacement. However, unless design deficiencies are discovered and
corrected during roof repair or re-roofing, the problems relating to them most likely will
recur. Some examples of faulty design are:
- Weak roof structures that deflect excessively under load, causing splitting of the roof
- Inadequate roof slope, sagging roof structure, or insufficient number or location of
drains, resulting in ponding water
- Inadequate provision for expansion and contraction at changes in deck material or
direction, causing membrane splits.
- Incompatible roof materials - i.e. the use of asphalt to adhere a torch-on material
E. Flashing Failures
The function of flashings is to provide a watertight junction between roofing materials
and roof projections or other parts of the structure, and between roof sections. Flashings
should be designed to furnish service for at least as long as the materials used in the
field of the roof. Flashings are the most vulnerable part of any roof. Their importance
and the importance of maintaining them properly cannot be overemphasized.
Many early roof problems are actually flashing problems. Often, repairing the flashings or
providing new flashings is all that is needed to make the roof watertight again. Most
flashing problems result from inadequate flashing design or faulty construction. Many
flashing problems can be reduced or eliminated by careful examination by competent
inspectors during roof installation, and by regularly scheduled inspection and
In many instances, leaks occur at flashings where there are no flashing defects. These
leaks may be the result of open joints in a masonry wall or coping cap, which permits
water to enter behind the flashings and into the building. This problem may be eliminated
by "through-wall" flashings.
F. Base-Flashing Problems
Some common causes of base-flashing problems are:
- Insufficient number of base-flashing plies.
- Improper base-flashing height.
- Insufficient protective coating, resulting in accelerated weathering and deterioration.
- Omission of cant strips, making the base flashing more susceptible to damage.
- Open vertical end laps or seams caused by insufficient sealing.
- Insufficient adhesion or movement between vertical surfaces and the roof deck, resulting
in separation of base flashings from vertical surfaces.
- Loose insulation, causing base flashings to separate from vertical surfaces.
- Improper fastening of base flashings to walls or curbs, resulting in sagging or
separation of the flashing from the vertical surface.
- Deteriorating substrates, causing base flashings to separate from the surface, or
permitting water to enter behind base flashings.
G. Metal Base Flashing and Bituminous Counter flashing Problems
The use of metal base flashings in the construction of built-up roofs is not recommended.
Metal base flashings easily separate from bituminous materials and stripping felts crack
at the edge of the metal because of the difference in expansion coefficients between the
materials. Open joints between metal pieces and deterioration of the metal are also
sources for water entry. Inside and outside corners are particularly vulnerable areas. For
these reasons, metal base flashings should be replaced with bituminous base flashings
H. Metal Counter flashing Problems
Metal counter flashings protect the top of bituminous base flashings from water entry. The
most common metal counter flashing problems are:
- Counter flashings located too high above the base flashing.
- Metal deterioration caused by a lack or loss of protective coating.
- Cracks and open joints between metal pieces.
- The separation of counter flashings from vertical surfaces.
- Reglets not being sealed.
- Counter flashings not tightly fit to base flashings.
I. Penetration Flashing Problems
Penetrations through the built-up roof membrane are usually flashed in one of two ways.
Individual pipes and small vents usually use flat, metal flange flashings that are placed
directly on the last ply of roofing material and are stripped in with felts and mastic or
felts and bitumen.
Larger penetrations and groups of smaller penetrations usually use curbs constructed of
wood, metal or concrete, flashed with bituminous base flashing and metal counter
Common penetration flashing problems are:
- The failure to properly design the flashing for the penetration.
- Open or broken seams in metal curbs caused by expansion and contraction.
- Standing water behind penetration curbs caused by the omission of crickets.
- Sagging or separating base flashings caused by omission of top wood nailers.
- Missing or deteriorated counter flashing.
- Splitting or separation of the felt stripping over the edge of metal flanges.
- Improper priming and stripping of metal surfaces.
- Fastener backout and separation of the metal flashing flange from the roof around
- Movement between stack vents or pipes and the flashing.
J. Drain Flashing Problems
BACK TO TOP
A roof's drainage system includes the gutters, leaders, drain openings and scuppers, as
well as the slope provided by the structural deck, tapered insulation, crickets and sumps.
The primary function of the drainage systems is to prevent the retention of water on the
roof by removing water from the roof as quickly as possible. Every roof, including
so-called "dead-level" roofs, must have some provision for drainage. Further, it
is important that the drainage system be kept free from debris that might interfere with
the proper flow of surface water.
Many roof problems can be traced directly to inadequately designed or improperly installed
drainage systems; for example, the use of only one drain; the failure to install overflow
scuppers in parapet walls; the placement of drains next to support columns instead of at
points of maximum deflection; loose or missing drain clamping rings. Ponded water is the
principal indication of inadequate drainage, and may indicate the presence of structural
K. Gravel Stop and Metal Edge Strip Problems
The primary function of gravel stops (for aggregate-surfaced roofs) and metal roof edge
strips (for smooth-surface roofs) is to close off the edges of the roof to prevent wind
damage or blow-offs. Another important function of gravel stops is to prevent the loss of
aggregate surfacing near the edge of the roof.
The principal problems with gravel stops and metal edge strips are leakage through open or
broken joints between metal pieces, and splitting of the stripping felts at metal edges.
For these reasons, gravel stops and metal edge strips should be raised out the water line
whenever possible by using raised wood nailers and tapered edge strips. The use of
interior drainage is preferred. However, where water must drain over the metal edge,
scupper cutouts are preferable to continuous edge drainage.
L. Problems with Rooftop Equipment, Signs, Braces and Supports
Often, the rooftop is used as a platform for all types of mechanical equipment, ladder
struts, antennas, flag poles, signs, bracing, etc. These items should not be placed on the
rooftop except when absolutely necessary. They should never be mounted or placed directly
to the top of the roof membrane, as leaks beneath or adjacent to the supports for this
equipment are impossible to repair. Rather, they should be mounted to a support structure
or to raised curb-type supports. Flat flange or curb flashings can then be used to keep
the roof watertight, and roof replacement and recovering can be done without disturbing or
removing the equipment. Pitch pans, however, should not be used to keep supports
watertight, and should be avoided where possible. Refer to the ARI/NRCA/SMACNA Guidelines
for Roof-Mounted Outdoor Air- Conditioner Installations, and the roof membrane
manufacturer for recommendations concerning the proper mounting and flashing of these
Emergency Roof Repairs
(Flat & Low Sloped Roofs)
|Click Here for general
information regarding roof leaks and protocol
Please choose one of the following for
specific emergency repair suggestions:
Click here for Storm Damage suggestions
Emergency repairs may be required after severe weather because
leakage into a building can occur at any time (nights, holidays, weekends, etc.). Caution:
It is generally not advisable to attempt roof repairs until after the severe weather has
ceased, due to the danger of high winds and the possibility of a lightning strike. Caution
should be exercised when inspecting a roof after there has been severe weather, or when
there is suspect damage to the roofing assembly, because storm damage may have left the
roof in a hazardous condition. If the roof condition is questionable, have a
professional roofing contractor perform the inspection and necessary repairs. In the
event a professional roofing contractor is not available, and to minimize damage to the
interior building finishes and contents, emergency repairs may be performed.
Emergency repair procedures should be as simple as possible so they may be performed
safely by non-roofing professionals. These repairs should be considered temporary.
Permanent repairs should be made by a professional roofing contractor as soon as weather
If the roofing system is under a manufacturer's warranty, the roofing material
manufacturer, and the installing contractor should be contacted as soon as possible.
The following are emergency repair guidelines that may be performed by non-roofing
professionals, or by professional roofing contractors.
B. Leak Repair Procedures
There are too many different types of roofing membranes to tailor emergency repair
procedures for each. However, if literature cannot be located and/or if procedures are not
detailed for emergency repairs, the following guidelines are suggested:
Protect the interior: Control the spread of water in the interior by collecting the
water in containers or by using plastic sheeting to protect the building contents.
Remove excess water from the roof: Check roof drains and scuppers to be certain
that they are open and functional. A frequent cause of roof leakage and roof collapse is
excessive ponding on the roof surface due to clogged drains and/or scuppers.
Caution should be exercised when clearing debris from drains. Significant suction forces
can be created by draining water, which can suck tools, hands, or arms placed within these
vortices quickly into the drain.
Locate the source of a leak: In attempting to determine the source of a
leak, locate the point on the roof surface above the area of leakage in the building
interior. From this point, first check the condition of rooftop mechanical equipment, then
check all flashings at terminations and penetrations. Second, if the system is ballasted
remove ballast from the immediate leak area, then check the membrane surface for cuts,
splits, or punctures. Finally, check the seams (laps) in the roofing membrane.
NOTE: In many cases, it can be extremely difficult to locate the source
of a leak on a roof membrane that has been installed over insulation placed on a
structural concrete deck, or over an existing membrane or vapor retarder. If the source of
a leak into the building cannot be readily located, the owner or building maintenance
personnel may have no recourse except to control the spread of water until a professional
roofing contractor can be contacted and arrives at the site.
Perform emergency repairs: Once the source of a leak is located, the materials and
procedures which will cause the least amount of damage to the roofing membrane should be
chosen. Please refer to the following list of suggestions to perform emergency repairs by
roofing system type.
Plastic Roof Cement -
This method is recommended for use on
all Built-Up-Roof systems and Modified Bitumen BUR and Single-ply systems.
An emergency patch can be made using plastic cement and fabric or roofing felt. Permanent
repairs should be made as quickly as possible.
NOTE: If used on single-ply systems, this type of repair may require a larger section
of single-ply membrane (and perhaps the insulation) to be removed prior to the permanent
repair in order to ensure that any of the existing membrane contaminated with plastic
cement is no longer present.
Plastic cement is a trowel-grade product. It is available in rain patch or
"wet patch" grades, which are somewhat easier to apply to wet or damp surfaces.
Avoid the use of a liquid or pourable asphalt repair products. Liquid products do not
usually work well and most often only hinder a roofing contractors attempt to locate the
leak source while performing temporary or permanent repairs.
Prior to making emergency repairs to existing gravel or granule surfaced roofing systems
Remove all loose gravel or granules from the membrane surface. Scrape (spud)
embedded gravel / granules and surface asphalt to the membrane. For ail smooth surfaced
B.U.R. systems including Modified Bitumen single ply, smooth surfaced B.U.R., Cap Sheet
B.U.R. Composition Shingles etc., clean the surface of all dirt, dust and debris.
After the surface has been prepaired, and making sure that the area to receive the repair
is clean and dry, apply a trowel grade asphalt plastic cement to extend beyond the area of
repair approximately six (6") inches. The plastic cement should be applied in a
continuos application over the membrane split, puncture, hole etc. Work the material into
the membrane by applying a constant pressure while trowling.
NOTE: You can test the adhesion of the plastic cement to the membrane by laying the
trowel flat on fop of the applied plastic cement surface and lifting. If the plastic
cement lifts with the trowel, and exposes the membrane, it needs to be worked into the
membrane better. After applying the first layer of plastic roofing cement to the membrane,
embed a strip of fiberglass reinforcing fabric. Over the embedded fabric, trowel an
additional layer of plastic roof cement to cover all exposed fabric. The fiberglass fabric
acts to reinforce the plastic cement and can greatly extend the life of the repair. Some
larger repairs can be covered with a additional layer of Type IV fiberglass felt set into
a continous layer of plastic roofing cement.
BACK TO TOP
Sealant & Roof Tape - This
method of repair can be used on most smooth surfaced systems including Built-Up-Roofing
systems, but is suggested for use on Single-Ply systems such as E.P.D.M. or PVC
To make emergency repairs using a sealant or roof tape membrane, start by cleaning the
membrane surface with alcohol or a household cleaning solution, such as window cleaner.
Then wipe the surface with a clean cloth and "splice cleaner" or white gas (use
rubber gloves and proper skin protection).
After the membrane has been cleaned, apply a butyl or polyurethane sealant (caulking), or
roof tape to the damaged roofing material. (Note: The surface must be clean for the repair
material to adhere.) When using roof tape, pressure should be applied over the entire
surface of the tape to ensure adhesion.
Sealants are available at most hardware, builders supply and home discount stores. A
variety of roof tape products are also available. These products typically have a release
paper on the backside and are a few inches wide. Roof tape products are also available
through membrane manufacturers, roofing materials distributors, and roofing contractors.
Duct Tape - This method of repair is recommended for PVC
(Thermoplastic) systems only.
Make a temporary patch for the roofing membrane using common duct tape. (Note: The surface
must be clean and dry in order for the tape to stick. Cleaning guidelines are described in
the "Sealant and Roof Tapes" section.) Permanent repairs should be done as soon as
possible because the duct tape will not last long.
C. Storm and Wind Damage Repair Procedures
If roof damage is observed during a storm, it is generally not advisable to attempt
repairs or damage control until after the storm because of the danger of high winds and
the possibility of a lightning strike.
In some instances, however, repairs during a storm may prevent or minimize further wind
damage. For example, if a loose metal edge flashing is observed, securing it during a
storm may prevent subsequent lifting, peeling, and blow-off of the membrane. If work is
performed during a storm it should be done by a professional roofing contractor at his
discretion. Work should not be performed during high winds or electrical storms. If a
professional roofing contract is not available, work should not be undertaken unless wind
speeds are moderately low and electrical storm activity has ceased.
Following the storm, loose debris on the roof that could be blown off in subsequent storm
should be removed.
Because some roofs are in a hazardous condition after wind damage, debris removal should
be performed by a professional roofing contractor if one is available within a reasonable
Different types of attachment methods require special considerations, as discussed in the
Ballasted Systems: After high winds, the roof should be inspected to determine if
ballast (aggregate or pavers) has been scoured (scattered), leaving areas of bare,
unprotected membrane. If so, the exposed membrane should be inspected for open seams,
punctures, and tears from flying debris (from rooftop mechanical equipment or from
adjacent buildings). Membrane damage should be temporarily repaired before redistributing
Temporary repairs made to the membrane should be marked on a roof plan to aid in locating
them for later permanent repair. Except for areas less than 50 square feet (e.g. five feet
by ten feet), inspection and permanent repairs should be performed by a professional
Temporary Ballast: On ballasted single ply systems, bare areas greater than 50
square feet should be temporarily ballasted using sandbags, tires, concrete blocks, or
concrete pavers. When applying temporary ballast, use caution to avoid overloading the
structure and damaging the roof.
If lightweight concrete pavers were used for the ballast and were displaced, use concrete
blocks, heavy concrete pavers, or sandbags to achieve a minimum load of about 40 pounds
per linear foot around the perimeter of the bare area. (The width of the temporary ballast
around the perimeter to achieve the 40 pound load will depend on the weight of the ballast
being used.) Place the temporary ballast on top of the remaining lightweight pavers to
provide temporary protection against further wind damage until permanent repairs are made.
In conjunction with setting temporary ballast of 40 pounds per linear foot around the
perimeter of a bare area, also apply temporary ballast to secure the membrane when the
bare area exceeds 50 square feet.
In some instances, insulation boards below the membrane are displaced. Displaced boards
should be repositioned prior to final redistribution of ballast. If membrane cutting is
required to reposition the boards, it should be performed by a professional roofing
When bare areas exceed 50 square feet or when ballast is blown off the roof consult with
the manufacturer because, in either of these cases, design enhancements may be advisable.
Mechanically Attached and Adhered, Single-Ply and Modified Bitumen Systems:
After high winds, the exposed membrane should be inspected for damage from flying debris.
If fasteners have backed out or popped up and punctured the membrane, or if debris has
punctured or torn the membrane, temporarily repairs will be needed.
Mechanically attached membranes should also be inspected to determine if any batten bars
or fastening plates were uplifted, or if the membrane has separated from them. Likewise,
fully adhered membranes should be inspected to see if they separated from the substrate.
If the membrane is unattached from the substrate or fastening system, and the area exceeds
50 square feet, temporary ballasting should be performed as described previously under
If any of the above conditions are observed, a professional roofing contractor should make
the permanent repairs.
If a mechanically attached membrane is observed billowing, consult with the manufacturer
or the installing contractor. While some billowing may be normal, an excessive amount
would indicate that design enhancements may be advisable.
If all or a portion of the membrane is peeled back, the building is vulnerable to water
infiltration. In some instances, it is possible to reposition the membrane to provide
temporary protection. Repositioning should be performed by a professional roofing
contractor if one is available within a reasonable time period. After repositioning, the
membrane should be fastened at the perimeter, the damage repaired, and temporary ballast
If membrane is too damaged to be repositioned for temporary protection, replacement
material will be needed. If a professional roofing contractor cannot provide temporary or
permanent roofing service within a reasonable time period, it may be necessary to utilize
large tarps or sheets of polyethylene secured at the perimeter and temporarily ballasted
as previously described.
D. Installation of New Penetrations or Equipment
ne of the most common causes of leakage is the improper installation of new roof
penetrations or equipment. To avoid roofing problems associated with new penetrations or
equipment, consult with a local roofing contractor qualified to apply the type of roofing
system in place, to recommend temporary tie-in steps prior to the installation of rooftop
penetrations or equipment. This would include such items as TV Antennae. sign or equipment
supports, skylights, plumbing soil stacks, HVAC equipment, and electrical conduits.
If the roof system is under warranty, the name and telephone number of the roofing
membrane manufacturer should be written down and kept in a safe place for future
reference. Notification prior to installation will allow the contractor or
manufacturer to recommend how to incorporate the new penetration or equipment and how to
protect the membrane warranty, if one exists.
The permanent addition of penetrations or equipment to the roofing system should be
undertaken by a professional roofing contractor qualified to perform such work. The name,
address, and telephone number of a roofing contractor qualified to perform the work can
usually be obtained from the roofing membrane manufacturer, or RoofHelp, if the
original roofing contractor is not available. Improper installation of penetrations
or equipment may void the roof warranty. If the building maintenance person is forced to
install temporary flashings, set the flashing flange(s) into a continuous layer of plastic
roofing cement and follow the procedures set forth above.
E. Permanent Repair Requirements
The emergency repair procedures described in the previous sections are strictly temporary
in nature and must be replaced with permanent and complete repairs by a professional
roofing contractor in a timely manner. If the roofing system is covered by a
warranty, notify the manufacturer of the roofing membrane as soon as possible to obtain
instructions and recommendations to facilitate a permanent repair.
Emergency Roof Repairs
(Average to Steep Sloped Roofs)
|The first thing you want to do is protect the interior of your
building. Find something to collect the dripping water. If water is dripping onto some
papers, a computer printer, or some other item of value, then MOVE THE ITEM!
choose one of the following:
- Composition Shingles
- Wood Shingles or Shakes