How Does Liquasil Prepare a Metal Roof Coating Specification?
Roof coating specifications informed by a building surveying background, not simply product selection.
A specification is more than the name of a coating
A metal roof refurbishment specification should describe what needs to happen to the roof.
Simply stating a manufacturer’s name, a product and a coating thickness is rarely sufficient.
The performance of the finished system depends just as much upon assessment, preparation and detailing as it does upon the coating itself.
Our specifications therefore begin with the existing roof.
Establishing the roof condition
Where we are involved at survey stage, we first identify the conditions relevant to the proposed coating work.
This may include the existing surface finish, adhesion and degradation, corrosion, cut edges, fixings, sheet laps, penetrations, rooflights, gutters and previous repairs.
We also look for details that might require further investigation.
A specification should be based on what is actually present rather than what somebody assumes will be present.
Preparation comes before coating
The most sophisticated coating system available will not compensate for inadequate preparation.
The specification therefore needs to establish how contaminants, loose material, corrosion and unsuitable previous repairs are to be dealt with before the main coating is applied.
Different areas of the same roof can require different preparation.
Cut edge corrosion is one obvious example.
Fixings are another.
Existing plastisol finishes may require specific preparation depending upon their condition.
Previous coatings or repairs can introduce additional considerations.
These details matter because they affect adhesion and long term performance.
Details are considered separately
We do not regard an industrial roof as one large surface waiting to be painted.
It is a collection of different details.
Sheet surfaces behave differently from cut edges.
Fasteners create different risks from rooflights.
Penetrations, gutters and previous repairs all need to be considered according to their function and condition.
Lap joints also require particular care.
For example, sealing a joint simply because it exists is not necessarily good practice. An inappropriate repair can prevent moisture from escaping and create a different problem.
The specification should explain what is required and, equally importantly, avoid unnecessary work that could make matters worse.
Selecting the system
Once the condition and preparation requirements are understood, an appropriate Liquasil system can be selected.
Metalseal provides our BBA Approved specification grade metal roof coating system.
Liquasil Lite provides an alternative where the requirements and commercial priorities of the project differ.
Both are single coat silicone systems and both can form part of a properly considered roof refurbishment specification.
The system should be selected because it suits the project.
The project should not be forced to suit the system.
The Importance of Film Thickness
Coating consumption and film thickness form part of the specification because insufficient material can directly affect performance.
Application therefore needs to be capable of being checked rather than judged solely by appearance.
Wet film measurements can be used during application and appropriate dry film measurement can form part of subsequent inspection.
Liquasil has coating inspection capability within its technical team, including ICorr Level 1 qualified personnel.
What about the things we cannot see?
A visual inspection of the top surface has limits.
It cannot necessarily establish the condition of every concealed component.
The underside of roof sheets, insulation, structural members and concealed corrosion may require separate investigation where there are reasons for concern.
A manufacturer specification should not pretend otherwise.
Where an independent building survey is appropriate, we are happy for that work to sit alongside our own assessment.
A specification should also help contractors price properly
A good specification protects more than the eventual coating performance.
It allows contractors to understand what they are pricing.
That helps produce comparable tenders and reduces the temptation for essential preparation or detailing to disappear when quotations are being compared.
If cost savings subsequently become necessary, the specification can be reviewed properly rather than individual elements being removed without understanding their purpose.
The objective
The objective of a Liquasil specification is simple:
To describe a system that reflects the actual condition of the roof, deals with the defects that matter and gives the contractor clear requirements for carrying out the work.
The coating itself is only one part of that.