What’s Wrong with Coal Tar Pitch Roofing?

Coal tar pitch roofing example

Keeping our roofing crews safe is always our top priority, so we always keep our eyes open for potential hazards. For example, if the crew’s eyes start to burn from the dust in the air or their skin turns red when working in the sun, we recognize these as the tell-tale signs of working with coal tar pitch roofing.

What’s Coal Tar Pitch Roofing, and Why is it Used?

Coal tar pitch has been used in roofing as early as the 1700s because of its superior waterproofing properties. Today’s version is coal tar pitch built-up roofing (BUR). This material consists of multiple plies of felt with interplies of coal tar pitch, and then embedding gravel in a flood-coat of coal tar pitch.

For more than 50 years, coal tar pitch enjoyed a significant percentage of the roofing market. However, new technologies, the decline of BUR roofing, and the precautions needed when working with it have caused its market share to dwindle and new installations uncommon. Despite its decline, it is still sometimes used for flat or very low-sloped roofs, which are prone to pooling water.

How Do You Know If You’re Dealing With Coal Tar Pitch Roofing?

While working on older homes and small commercial buildings, we can identify a coal tar pitch system when we see: 

      • Lots of small black bumps where the coal tar expands on a hot day and bubbles up
      • Areas where you can see the coal tar pitch has flowed over or around the gravel
      • Pitch dams that are installed at drains and scuppers to minimize the flow of the coal tar pitch
      • Flow down the side of the building, over the edge, and heavily into drains
      • Signs of damage or deterioration, such as punctures or ruptures, bare spots, and deteriorated metal edge stripping

The Pros and Cons of Coal Tar Pitch Roofing

Pros of Coal Tar Pitch Roofing 

While most built-up roofing (BUR) systems today are asphalt-based, many industry veterans still proclaim that coal tar pitch roofs are the best choice for flat roofing. Their self-healing properties make them largely immune to ponding water, plus they are resistant to harsh chemicals and UV. Coal tar pitch BUR systems are highly durable, low-maintenance, and have a low life cycle cost.

Coal Tar Pitch roofing for Commercial and Industrial Flat Roofing, Toronto, Ontario Canada.

Cons of Coal Tar Pitch Roofing

Watch for the burn! As any roofer can tell you, coal-tar-pitch roofing has quite a smell. The dust contains a slew of harmful chemical compounds, including carcinogens such as polycyclic aromatic hydrocarbons (PAHs). Other chemical irritants can cause burning eyes, red or itchy skin, and conjunctivitis. Sun exposure increases the severity of these symptoms.

Coal Tar Pitch Roofing Team members in Toronto Ontario for Elite Roofing.

What to Do When Working with Coal Tar Pitch

Our number one concern is always the safety of the crew and other people around the worksite. Here are our recommendations if you are working around coal tar pitch.

To-Do #1 – Protect the skin, eyes, and respiratory tract

Apply topical pitch creams, gels, or sunscreens containing benzophenones to decrease the amount of UV radiation reaching the skin. Dacron hoods can also be used to fight “the burn.” Tear-off crews will typically wear respirators and safety goggles during cutting operations.

To-Do #2 – Prepare the roof 

Thoroughly wet and dampen the roof with water before and during tear-off operations. Use a vacuum system to remove small debris and dust, plus encourage workers to stay upwind of pitch dust. 

Coal Tar Pitch roofing _ Elite Roofing, Ontario CATo-Do #3 – Wear the proper clothing for Coal Tar RoofingProjects

When exposed, wear long-sleeved shirts that fit tightly at the wrist and long pants that extend to shoes and gloves. Following their shifts, workers should wash thoroughly with soap and water (if necessary, use a waterless cleanser) and change into clean clothing. 

To-Do #4 – Follow Recommendations When Using a Combination of Asphalts with Coal Tar Roofing

Asphalts and coal tar have different chemical compositions that don’t mix well, but they can be used together by following the recommended procedures. First, don’t mix asphalt and coal tar in a kettle. Second, use different tools to apply them. Third, don’t “gravel-in” a coal tar and felt roof with an asphalt material. Finally, repair coal tar roofs with coal tar-based repair compounds and asphalt roof membranes with asphalt-based materials.

Take Caution with Coal Tar Roofing

Coal tar pitch roofing has a long history, and its durability is hard to beat. At the same time, working with coal tar pitch requires a professional roofing company that has the right expertise and will take the necessary precautions. To find out what type of roofing assembly is best for your commercial property contact the experts at Elite Roofing in Toronto.