How Much Coating Do I Need?

How Much Coating Do I Need?

If your RV or home improvement project requires silicone coating, you’ll obviously have to buy a certain amount of silicone. But the No. 1 question we hear from many potential customers is, “How much coating do I need?”

This week’s blog will answer that question and show how Countryman Coatings can help.

Differences in Substrates

A substrate, in its simplest definition, is the surface upon which you apply a new roofing system or coating.

However, not all substrates are created equal. There can be variations from one roof to the next in how a silicone coating project should be done because some substrates need more coating than others.

The reason is that some substrates are more porous than others. A metal roof will need less coating than a mod bit roof because more of the coating will find its way into the small cervices that are part of a mod bit roof.

That’s why it’s crucial to know your roof substrate before you begin. if you do not know the type of roof you have, it will be a challenge for you to give it the best care.

For example, there are four types of materials used in RV roofs:

  • Ethylene Propylene Diene Monomer (EPDM) Rubber
  • Thermal Poly Olefin (TPO) Rubber
  • Fiberglass
  • Aluminum

Coverage Guide

You can use this Silicone Top Coat Coverage Guide to determine how much material you'll need for your project.

The guide lists most standard roof types and the amount of coating needed for each one.

Our guide also shows measurements for a marking square, which can be another helpful tool when applying coating.

A marking square will ensure you put enough Countryman Coatings material on your project. Mark out a square on your roof with the dimensions listed on the guide for your roof type, then pour five gallons of top coat into that square. Spread the top coat evenly throughout the square, and you will have applied enough material.


You are now ready to move forward with your project, and CMC’s 100% silicone roof coatings can completely seal and restore aging residential flat roofs, sheds, garages, RVs, campers, and more. As an added benefit, the application process usually takes less than a day.

Thank you for reading, and good luck on your next project.

If you have any questions about our silicone coverage guide, please visit us here: