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Coal Tar Roof Maintenance
Maintaining your Coal Tar Built-up Roofing System

Due to its resistance to ponded water, oxidation, chemical attack and its cold flow, self healing properties, coal tar pitch built-up roofing systems typically require little maintenance. However, to get the most out of your roof, a routine audit is recommended in order to detect problems due to wear and tear, abuse or unusual acts of nature. Building owners, who regularly check the condition of their coal tar roofs and implement preventative maintenance procedures when necessary, often find their roofs lasting 30 to 40 years or more.

Understanding the Value of a Roof Maintenance Program

Although coal tar roofing systems are well known for their long-term performance, their life expectancy can be extended through a preventive maintenance program. This type of program, if routinely followed, can be easily accomplished with little effort. The results, however, can be of far greater value. Based on the life cycle cost of your roof, the money spent on providing routine maintenance will be only a fraction of what is saved by avoiding the cost of premature failure and replacement.

Developing a program takes a fundamental understanding of the roofing system and a few basic products. The following information is intended to provide a general understanding and approach to getting started. Whether the actual procedures are to be carried out by the building owner's personnel or by a qualified roof maintenance contractor, we recommend that a qualified individual be assigned to understand and administer the program on an on-going basis.

Setting Up The Program

Record Keeping: To get a program started properly, develop a historical record for each building/roof area. These records should include installation date, type of roof assembly, slope, warranty, installing contractor, etc. Any information on previous maintenance and repair, including costs, should be documented. This type of information allows the administrator to develop a profile for each roof, which will assist in determining future maintenance, potential problems and accessing cost justification of future work. This information can be kept manually or there are now available, a variety of software programs which make record keeping easier and faster. Some programs offer analytical features as well.

Semi-Annual Roof Audits: One of the biggest problems experienced by all roof systems is neglect. Addressing conditions before they turn into problems is a key factor in long the term performance of a roof. It is far less costly to maintain than it is to replace an entire section of roof, including wet insulation, caused by allowing the membrane to be exposed to destruction. Audits should be performed on a semi-annual basis or after any severe weather by an individual with a knowledge of roofing. A sketch of the roof layout and photographs can also be valuable tools in a project file.

Repair/Maintenance Procedure: When problem areas are identified, they should be addressed immediately. However, before a proper solution can be determined, it's important to know the type of membrane you are dealing with. If it's a single ply rubber or plastic type membrane and you are not certain of its origin, it may be necessary to have laboratory analysis performed. If it's a bituminous based product, there are a variety of field tests which can determine whether the membrane is asphalt or coal tar based. It's important to understand that if the intent is to perform a permanent repair, repair materials must be compatible with the primary membrane.

Material Compatibility: When using asphalt and coal tars in conjunction with each other, they should never be heated or mixed together in a kettle. Their chemical compositions are sufficiently different that the two products will not mix. Asphalt and coal tar can be brought together successfully but it needs to be done in a recommended manner. For example, when mopping an asphalt flashing system to a coal tar roofing system, you are joining the systems together rather than creating a chemical interaction. Generally speaking, the higher the softening point of the asphalt that is to come into contact with the coal tar, the less potential there is for incompatibility to develop.

There are three basic rules that apply when bringing asphalt and coal tar together:

  • Do not try to mix asphalt and coal tar in a kettle.
  • Do not use the same tools to apply asphalt and coal tar unless they are cleaned first.
  • Do not "gravel-in" a coal tar and felt roof with any asphalt.

As a general rule, it is recommended that for the best performance, coal tar roof membranes should be repaired using coal tar based repair materials and asphalt roof membranes should utilize asphalt based materials.

Selecting the Right Contractor: Contact Durapax for additional information if roof maintenance and repair work will be carried out by the owner's maintenance personnel. If the building owner is not prepared to take responsibility, a professional roof maintenance contractor should be contacted. If you are not familiar with a qualified contractor, Durapax can recommend several in your area. Whether the work is done in-house or by a roofing contractor, it is worth the time and expense to carry out preventive maintenance on a regular basis to extend the service life of your roof and to protect your investment.

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