Tarring is one of the most popular solutions among homeowners to protect their roofs.

Sometimes roofing tar that is bought from the market does not come in the consistency that the homeowners want it to be. Again, sometimes the tar becomes too hard and thick if it can remain open for a long time.

In this type of situation, the worker or homeowner must know how to thin roofing tar to complete his actions.

Let’s briefly discuss the roofing tar thinning procedure to achieve desired consistency. 

Roofing Tar

Roofing tar is a long-lasting product consisting of petroleum, asphalt (or bitumen), and hydrocarbons. 

Required Tools

Some tools are required while dealing with roofing tars. These are:

  • A Ladder
  • Roofing Tar
  • Roller
  • Face Mask
  • Gloves
  • Boots, Etc.

How to Thin Roofing Tar: Step by Step

Roofing tar is a thick material. Sometimes your roof does not need that thick layer of tar. In that case, you can thin your roofing tar before applying it.

Thinned tar is easy to apply, spread, and is most appreciated by the roofers. Often when the lid of the tar can is opened but not sealed properly or remains open for a long time, tar can become thickened. Then, the tar must be made thin before using it.

Steps To Follow:

Step 1: Warm-Up:

It is always recommended to use some heating technique to warm up the tar before starting the procedure. The temperature should be near 100 degrees Fahrenheit. This will help to minimize the viscosity and make it spreadable, easier to apply, and deal with.

Step 2: Prepare the tar:

Take a small amount of tar from the can and add a quarter part of the water into the tar solution. Stir thoroughly with a brush until the mixture becomes smooth. 

Step 3: Test on a small surface:

Apply on a small surface and check whether the layer is mildly viscous and easily spreadable or not. If not, add some more water to achieve the required texture and consistency. Repeat the whole process until you achieve your desired consistency.

Step 4: Have the right ratio 

Make sure to have the right ratio. For instance, one part of tar is mixed with three fourth parts of water. Sometimes the ratio can vary a little bit, but the standard ratio of tar: water is 1: 0.75.

How To Thin Roofing Tar

Precautionary Steps

While you are tarring your roof or taking steps to thin the tar, it is very important to follow some precautionary steps. 

While adding water to the thick solution, you should be careful so that it can not splash into your skin. As tar is a poisonous material, it can cause great injury to your skin. So, make sure to wear gloves, boots when you are applying them.

It is highly encouraged to wear masks because of the fumes, smoke, and smell of tar. Make sure to maintain the ratio accuracy among all the batches, which will give you an even consistency.

Again, when heating the tar, be sure to maintain a safe distance. Avoid overheating the tar as it can make the solution bubbly, splashy, and cause accidents.

Ideal Conditions of tarring

Roofing tar secures small holes and leakage preventing your roof from any kind of water damage. 

You must make sure to start the tarring procedure on a hot sunny day. The standard temperature is 70 to 80 degrees Fahrenheit. If you choose to tar your roof in rainy or snowy weather or a more humid climate, then the tar will not harden properly.

Again, while thinning your tar, always keep in mind the ratio you need. Otherwise, if the tar is too thick, it will not spread evenly. And if it becomes too liquidy, it will drip down the ceiling which will create a mess everywhere. 

However, tarring is considered to be a temporary repair. If you have larger leakage problems, eventually, you need to fix roofs in this case.

The necessity of applying tar

Initially, roofing tar seals and secures plane roofs. It also gives protection from the sun, UV rays, temperature, water, snow, and many more.

Roofing tar is most popular for its durability and resilience. Roofing tar is low maintenance and if your roof is tarred properly, it can last 25 to 30 years.

Tar may seem to be a temporary solution but for small holes and leakage, it is quite a long-lasting, cost-effective, and relatively cheap option for water leaking solutions.

Merits and demerits of tar

Plane roofs are susceptible to dirt, rainwater, snow, heat, and wind. Also, help in the growth of molds and rust on the roof, reducing the longevity of the roof. Serious damage can happen if your roof is directly exposed to these factors. 

Tar protects your roof from ultraviolet radiation. Slanted roofs have slopes, so the elements either slip away or cannot stay on the surface. But that cannot happen on plane roofs, so dirt, snow stay for a long time. 

On the other hand, roofing tar is a chemically poisonous product. All the fumes and smoke of tar can be very detrimental to health. It is recommended to use gloves and boots so that splashing of tar can not burn your skin. 

Again, if the outside temperature is not hot enough, roofing tar will not harden properly. Or if your tar is too thin, it will not last for a long time.

Sometimes too thin or too thick a roofing tar layer can show a small flick or crack. If the roofing tar is too thick, then while applying tar, you should be careful. So, always keep in mind not to make your solution too thin or too thick. Otherwise it will break down into pieces.

Final Words 

I hope this article will help you with your queries related to roofing tar.
However, how to thin roofing tar is a common question among beginners. If you want to do it yourself, make sure to consult a professional before starting the process.


As a civil engineer and roofer, I love to share the experience that I have gained through the last couple of years. In the roofing industry, practical experience is a very crucial fact that can help you a lot. Hence, I want to help you with my blog.

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