Roofing tar is not caulking.

  The following three photos are just a small sample of the photos I have taken during home cottage and commercial inspections around Orillia and throughout Muskoka. They illustrate why the old roofers say roofing tar is not caulking!


  Roofing tar/sealant or roofing cement, as the fiber thickened roofing tar is often referred to, can be found on a great many roofs nowadays. It shouldn't be so but it is. Handyman, homeowners, and even well meaning contractors, use roofing cement sold in many home repair stores to "caulk and seal" joints in flashing and seal between and over joints in roofing materials.

As you can see in the first photo, far left, roofing cement/tar shrinks in the sun pulling apart at the seams of flashings. Chances are this sealing job, which I discovered the owner paid to have done only a year before, has been leaking only small amounts into the roof so far as it is on top of the flashing.  Come spring when it is buried in melting snow though, it could develop into a great deal of water intrusion doing sever damage and promoting mould growth.

  The second photo shows what happens when tar/roofing cement is used as caulking to fill a void and seal a flashing to a wall. the flashing doesn't move and neither will the wall so as the roofing cement dries out it pulls away from both leaving large gaps for moisture intrusion.

  The far right photo shows a seam between a low slope roof and a flat graveled roof. The aligatoring that already shows the shrinkage here means not only is this seam due for failure soon from splitting, cracking and tearing along the seam, Moisture will flow from the flat roof directly down into the attic through any of the seam openings. The seam should never be made with just roofing tar there should have been a metal flashing that was caulked in place.

Modern caulking is designed to be non shrink, impervious to uv rays and last a minimum of 30 years in direct exposure to the elements. It does this while remaining slightly elastic to adhere and hold onto many different types of surfaces like siding and glass, metal or roof membrane. Improper use of material for caulking is one of the most common causes of moisture intrusion there is at flashing to roofing or wall to roof joints.  A few 5 dollar tubes of proper caulking once every twenty five years or so sure beats reasealing leaking seams every two or three years ,not to mention the damage the leaks cause.