Liquasil roof coatings manufacturer
Contact Liquasil

Moisture tolerance on metal roof substrates

by | Jan 22, 2026 | Bitesize CPD

David Carter

David Carter

Technical & Managing Director

Image depicting a wet/dry metal roof for CPD

Silicone coatings have been specified for use on  metal since the 1980’s and that is still the case today. The reason for this is because it works!

Over the years, other coating technoligies have been tried, for example, reinforced polyurethane and even polyurea, but in most cases, these have proved to be too expensive and have not always been successful.

More recently, we have seen the introduction of hybrid technologies that aim to provide the flexibility and water resistance of silicone, along with application tolerance to moisture.

These are usually marketed as being “moisture tolerant” or “hybrid” coatings and they probably have a place in the market, but they don’t have the longevity to demonstrate that they will last the distance.

Liquasil formulates coatings from scratch and have access to all of the latest hybrid technology, along with the recipes to introduce hybrid metal roof coating systems.

This allow us to offer two metal roof coating systems:

However, our view is that the technology remains problematic in a few key areas.

For this reason, we have so far resisted the temptation to introduce something that could prove to be inferior to our proven silicone roof coatings.

 

This Bitesize CPD note examines how the term “moisture tolerant” is commonly used in relation to roof coatings, and why its interpretation on steel substrates matters in professional specification and defect assessment.

Bitesize CPD – Technical Context

The term “moisture tolerant” is frequently used in relation to roof coating systems, but its meaning on steel substrates is often misunderstood. Unlike porous materials, steel does not retain internal moisture; it is either wet or dry at the point of application. This distinction has a direct bearing on adhesion, inter-coat compatibility, and long-term performance at laps and day joints.

When you see the terms “moisture tolerant” on manufacturers’ web sites and social media posts, it’s easy to conclude that the coating can be applied in wet conditions. That’s simply not true.

For a detailed technical explanation of how coating chemistry, substrate condition, and certification scope interact on metal roofs, refer to the following technical guidance note:

Silicone vs STP Technology in Roof Coatings
https://liquasil.com/roof-defect/silicone-v-stp-technology-in-roof-coatings

This reference material supports informed specification and defect assessment in the context of cut edge corrosion, overlaps, and dilapidations reporting.

CPD learning outcome

After reviewing this material, practitioners should be able to:

  • distinguish between environmental moisture resistance and surface condition at application

  • understand how different polymer technologies behave at joints and day interfaces

  • apply this understanding when assessing coating suitability on steel roofs

Reflective question

How does the distinction between moisture tolerance and dry-substrate adhesion influence your approach to specifying or reviewing roof coating systems on metal roofs?

You may also like…

Bite-Size CPD – Roof Fixings

In this bitesize CPD article, we look at roof fixings. Ignoring the fixings means that you could be leaving money on the table with your dilapidations claims. If you are preparing a condition schedule, identifying faults prior to lease agreement, you could be protecting your client from a big claim later.

read more