Cap Sheet Repair

Cap sheet roofs have layers of material glued together with hot asphalt, with a roll of mineral surface glued with asphalt to the top instead of gravel. Their use has decreased with the use of more modern, effective materials.

Intermat Exposed

The asphalt holding the granules on has worn off and the fiberglass intermat is showing. The membrane is now susceptible to seepage. Areas can be coated with materials to seal the membrane. It is past the time for a complete recoat or replacement.

Granules Missing

Missing granules expose the roof membrane to the UV rays of the sun. This can mean the roof is near the end of its useful life. The damaged areas can be coated to protect the membrane and reflect the heat.

Slipping & Delaminating

This roof membrane is delaminating and sliding. It can be caused by improper fastening. On roofs with a slight pitch, it is required to fasten each row. On hot days, the asphalt softens and the cap sheet can delaminate and slide. This can cause separation at the overlap and/or buckling in the membrane. It is impossible to tell if the problem is consistent throughout the entire roof or just the areas visible. There is a good possibility this roof may continue to experience this problem in the future. The roof is open and can allow seepage if not repaired.

Damage Tear in Roof

The roof goes through expansion and contraction on a daily basis – the roof moves. It can bind against itself and is subject to thermal shock, which can break it down. A tree branch, a third party, foot traffic and the UV rays of the sun can all cause damage. This area of the roof has broken down and needs repair. There are several sealants and methods that can be applied, some short term and some that will outlast the roof itself.

Old Repair Deteriorating

The materials used for the original repair were not designed to outlast the roof and have broken down. If not repaired, seepage can result. We almost always recommend using a material that will outlast the roof itself.

Uplifting Fasteners

There are uplifting “high nails” that were not driven flush or are backing out. “High nails” will begin to protrude through the membrane, causing seepage and/or rust.

Improper Number of Fasteners

Cap sheet roofs are designed to be installed over an approved surface and fastened per specific guidelines. If the membranes are installed over a surface without the proper fastening, the manufacturer’s warranty is voided and the roof assembly is not to code. This also leaves the roof susceptible to roof blow-off in the event of strong winds.

Tree/Bush Growing Over Roofline

This can damage the roof, causing seepage. The solution is to trim the tree/bush away from the roof line.

Debris on Roof, at Drains, Scuppers

This can cause water to back up and enter through roof penetrations. If too much water collects on the roof, it can cause structure failure. Remove debris as needed to prevent water from backing up into structure. Install a roof screen to prevent water back-up.

Gaps Between Pipes and Pipe Jacks

To prevent seepage, the intersection of the pipe and pipe jack must be sealed. The original installer used tape which has shrunk and left an opening for seepage. If it is applied correctly, it can last a long time. Some people use mastic, which is good. Tape is better, or an EPDM collar, which is best and is guaranteed for the life of the roof. Reseal the intersection of the pipe and pipe jack to prevent seepage.

Metal Cap Loose, Not Sealed

Original installer did not anchor and seal the joints in the metal cap properly to last the life of the roof. Clean the joint, reseal with a long-term material and anchor the joints together.

No Metal Cap

Sometimes cap metal is not installed on top of the parapet wall. This is a potential weak spot in the membrane and has to be maintained. The initial installation costs less with no cap metal. Install cap metal or apply a long term sealant.

Seam Open

This is an installation error – a lack of asphalt was applied. Clean and apply sealant that will last the life of the roof.

Separated at Duct

Over time, separation can occur at the roof and duct intersection. The duct is metal and expands and contracts at a different rate than the roof, which puts stress on the sealants. The sealants dry out and get brittle over time. The sealant is pulling away from the duct. The intersection needs to be resealed with a long term material so that it will outlast the roof.

Kitchen Grease On Roof

Kitchen grease can deteriorate the membrane. If there is a leak, sealants will not bond on the greasy area unless it is clean. Owner/tenant should clean and maintain kitchen equipment to prevent grease from venting onto the roof.

Improper Materials Used On Repair

Someone has applied spray foam at the pitch pocket to seal a leak. If it works, it is temporary at best. The sun has destroyed the foam and the roof is subject to seepage. Clean and apply sealant that will stretch and move for a long term repair.

Lack of Overlap at Skylight

The flashing does not go up high enough for the skylight frame to overlap the flashing and the wood curb is exposed. This is open and will allow seepage. Remove the skylight and install a counterflashing on top of the curb that overlaps the flashing on the side.

Rotted abandoned “Sleeper” allowing seepage

Equipment on a roof is sometimes placed on a wood support called a “sleeper”. It is usually not just placed on the roof. It should be fastened to framing members below the roof. The fastener is sealed at the time of installation. Over time a separation can occur at the sealant. Remove sleeper, apply a long term sealant that will outlast the roof.

Counterflashing Not Oriented Properly

The membrane was installed over the existing counterflashing, not behind it. There may or may not be sealants between the membrane and counterflashing. If it does not leak now, it will eventually. Take the roof apart and correct the orientation so the membrane goes behind the counterflashing.

Gravel Stop Coming Off/Missing

The gravel stop is not integrated into the roof system. The metal gravel stop expands and contracts at a different rate than the roof. Over time, this can cause separation. When it is made, the gravel stop has a thin layer of oil on it to keep it in “like new” condition. All metal that is incorporated into the roof system should be primed to get proper adhesion. If it is not primed, separation and seepage can result. Reanchor the gravel stop and apply sealant where needed to prevent seepage.

Collar at Vent Not Sealed

Sometimes the collar was never installed. If the intersection of the top of the collar and the pipe is not sealed, seepage can result. Seal the intersection of the pipe and collar with a urethane sealant or another long term caulking material.

Loose Counterflashing

Counterflashing is what bridges a roof to wall intersection, a chimney, etc. If the counterflashing is loose and not sealed, water can get behind it and seepage can result. Re-anchor counterflashing and apply elastomerics.

Vent Flashing Incorrect

The vent flashing was not installed correctly when the roof was installed or it was retrofitted after the roof was installed. The sealant used will not last the life of the roof and needs to be maintained to prevent seepage. The flashing can be installed correctly with a new cap sheet for a permanent repair that will last the life of the roof, or a more permanent sealant can be applied.

Plumber’s Flashing Incorrect

The plumber’s flashing was not installed correctly when the roof was installed, or it was retrofitted after the roof was installed. The sealant used will not last the life of the roof and needs to be maintained to prevent seepage. The flashing can be installed correctly with new cap sheet for a permanent repair that will last the life of the roof, or more permanent sealant can be applied.

Abandoned Plumber’s Flashing

Often during a remodel, when plumbing is moved, new flashings for pipes are installed and the old flashings are left open. Cover hole in old flashings with sheet metal.

No Sealant Applied at Flashing

Flashings bridge the transition in the membrane. However, if they are not sealed, they can allow seepage. This roof repair can be done at a minimal expense.

Blisters

This is typically caused from “vapor drive” – moisture from inside the structure gets trapped in the membrane. When the sun heats it up, it expands and creates a “blister,” separating the plies. If the blister is broken and open to the outside surface of the roof, it can allow seepage and should be repaired with proper techniques. The roof may need roof vents to eliminate moisture. If blisters are not broken and open to the outside surface, they should be evaluated to determine the best remedy.

Roof Open at Gable/Valley

The barge rafter sits on top of the roof deck. The roof should go under the barge rafter. The corner at the valley is open to the weather and can allow seepage. Sealant can be applied but will need to be maintained. The roof should go under the barge rafter for a permanent repair.

Tie In Improper

The intersection between your pitched roof and the flat roof is called the “tie-in.” This area is important because there are two different roofing materials that must be integrated correctly. The top roof must be removed to correct what is underneath, then reinstalled.

Plastic Boots Used

The plastic gasket cracked open or became concave. The sun eventually damages the gasket that is mechanically fastened to the galvanized base, which can leave a large opening for water intrusion. Replace the flashing or reseal with rubberized asphalt.

Not Enough Bleed Out/Minute Cracking

During the assembly of the different plies of roofing material, it is essential the applicator uses enough hot asphalt so that some of it oozes out of the overlapping plies – “bleed out”. If there is not enough adhesive applied, water can seep into the membrane and cause seepage inside the structure. Seal the overlap in the membrane. Also, the “minute cracking” is usually from UV damage. We recommend applying a reflective sealant to prevent premature failure.

Flashing Rusted

Steel metal flashings exposed to the elements can rust over time. This area should have been painted and maintained. Today’s flashings are made out of galvanized metal, a process that protects the steel core from rusting. Rust cannot simply be sealed over; it will continue to grow. The rust needs to be treated chemically, then sealed properly. Since the rust is open to the surface and flashings are vital to the integrity of your roof system, we recommend repairing the rusted flashing areas before seepage causes structural damage.

Improper Overlap

When installing a roof system, it is important to always start at the lowest point and proceed upward toward the roof’s peak. This ensures that each layer of materials overlaps the previous. The flashing is not overlapped properly, which can allow seepage. Reorient or replace the flashing.

Improper Sidelap

The sidelap was improperly installed. Manufacturers require sidelaps to be staggered to prevent a weak spot in the roof, causing seepage. If they are not reinforced or redone, they are prone to allow seepage.

Duct Sealed Improperly

The ducts for the HVAC equipment are sometimes installed on top of the roof. The previous repairman used asphaltic mastic. If it works, it is a short-term solution at best. The duct needs to be resealed with materials designed to work with metal joints that are a long-term product for a more permanent solution.

Chimney Chase Leaks at Top

A chimney chase is usually a wood framed box. The pipe for the fireplace goes through the box and out the top. Typical roof chimney flashings are installed then siding covers the framing and overlaps the chimney flashing. Last a metal top is installed which allows the chimney flue to go through to the outside air. The metal top usually has a metal piece that prevents water from flowing down the opening in the metal top. The flue usually has a collar that overlaps the metal piece on the metal top. The flue usually has a metal top to prevent water from going down the inside of the flue. Any one of these items in this assembly can leak if not done correctly or if it has deteriorated. Invest all the potential issues and effect a repair.

Broken Skylight

The amount of time it takes for the plastic dome to break down depends upon the quality of the plastic used to make the skylight. The dome can sometimes be replaced. It is easier just to replace the whole skylight. Some manufacturers give a lifetime warranty, even for plastic domes. Glass is heavier and more expensive than plastic. Glass has a higher R-value and lasts indefinitely.

Vent Cap Rusted Out/Damaged/Missing

Over time, exhaust from appliances will corrode and deteriorate the vent; damage from termite fumigation people or wind can cause the top to blow off. Repair or replace as needed.

Plastic Gutter

Plastic gutters do not come with a wing. The plastic gutter company makes a plastic diverter to divert the water into the gutter. If it is not installed, the edge of the roof deck will develop dry rot.

Gutter in Stucco

When the house was built, the sheet metal installer put the gutter too close to the stucco paper. When the stucco was applied, it went around the gutter, not behind it. Over time the gutter joint can deteriorate, allowing seepage in the wall. Remove the gutter, cut the end back, reinstall the gutter end, repair the wall with waterproofing materials, then reinstall the gutter.

Ponding Water

When water sits on a roof for more than 48 hours without evaporating or running off naturally, it is called ponding. It is a code violation. Manufacturers exclude ponding areas. Ponding breaks down the asphalt by causing the oil in the asphalt to migrate. A leak in a ponding area can cause a lot of damage.

Skylight/Flashing/No Overlap

The flashing does not go up high enough for the skylight frame to overlap the flashing and the wood curb is exposed. This is open and will allow seepage. Remove the skylight and install a counterflashing on top of the curb that overlaps the flashing on the side.