SprayGrade on asbestos roofs: what you need to know

SprayGrade on asbestos roofs can be an effective way to waterproof and encapsulate an ageing roof, but only when the substrate is asbestos cement, the sheets are still sound, and the work is planned to avoid fibre release. In UK terms, that means proper assessment, compliant preparation and the right weather window. If the roof is badly damaged, friable or leaking because the sheets have failed structurally, a coating system is not the first answer.

Is SprayGrade on asbestos roofs suitable?

In many cases, yes - but suitability depends on the type and condition of the asbestos roof.

The important distinction is asbestos cement versus more fragile asbestos-containing materials. Asbestos cement roof sheets, often found on garages, farm buildings, workshops and older industrial units, are lower risk than friable insulation products because the fibres are bound into cement. Where those sheets remain intact, a liquid-applied coating can help:

• seal minor surface porosity
• reduce further weathering
• improve waterproofing performance
• encapsulate the surface to help minimise fibre release from ongoing deterioration

However, SprayGrade on asbestos roofs should not be treated as a fix for every asbestos problem. If the sheets are extensively cracked, soft, delaminating, or the fixings and structure are failing, you may be looking at overcladding or replacement instead.

SprayGrade on asbestos roofs: UK legal and safety checks

Before any coating work starts, the roof should be assessed by a competent person. In the UK, asbestos work is governed by the Control of Asbestos Regulations 2012. Even where work on asbestos cement is often classed as lower risk than licensed asbestos removal, it is still controlled work and must be risk assessed properly.

Key points to remember:

• Do not drill, grind, abrade or mechanically sand asbestos sheets.
• Do not use aggressive pressure washing that can damage the cement matrix and release fibres.
• Use a suitable asbestos survey or condition assessment before specifying repairs.
• Ensure any contractor has a clear method statement, PPE and waste handling procedure.
• If debris, moss or damaged fragments are removed, disposal must follow UK asbestos waste rules.

For many domestic and light commercial roofs, the goal is encapsulation of existing asbestos cement, not disturbance. If the roof condition suggests more than low-risk surface treatment, stop and take specialist asbestos advice. Contractors should also check current HSE guidance for task-specific requirements, including whether any work falls into notifiable non-licensed categories.

How SprayGrade on asbestos roofs should be applied

A good result depends more on preparation and process than on the coating alone.

1. Survey the roof condition first

Check sheet integrity, laps, fixings, flashings, gutters and penetrations. Confirm whether leaks are from surface weathering, failed laps, loose fixings or underlying structural movement. A coating system works best when the roof is basically sound.

2. Clean the roof with low-disturbance methods

This is where mistakes happen. Asbestos cement must be cleaned carefully, typically with low-pressure wet methods and controlled removal of biological growth. The aim is to create a sound surface for adhesion without scouring the sheet.

3. Detail repairs before the main coat

Lap joints, fasteners, cracks around fixings and local defects usually need attention first. Depending on the specification, this may include reinforcement on vulnerable details before the full SprayGrade application.

4. Apply in the right weather

UK weather matters. Avoid application during rain, standing water, frost, or when temperatures are too low for proper curing. In Lancashire and across the North West, persistent damp, overnight condensation and sudden showers can all affect adhesion and cure times. Plan for a stable weather window, and always follow the product data sheet for minimum and maximum application temperatures.

5. Build the correct film thickness

A liquid system only performs as specified when the right coverage rate and dry film thickness are achieved. Too thin and the membrane may not bridge minor porosity or provide long-term waterproofing; too thick in one pass and curing can be affected. Professional spray application gives the most consistent finish on large roof areas.

SprayGrade on asbestos roofs vs replacement

For many property owners, the real question is not whether a coating is possible, but whether it is the best option.

When coating is often the sensible route

SprayGrade on asbestos roofs is often a good fit where:

• the asbestos cement sheets are weathered but still structurally sound
• the roof has minor leaks rather than widespread failure
• the aim is to extend service life and improve weather resistance
• disruption needs to be kept low
• full asbestos removal would be costly or operationally difficult

In these cases, coating can be more economical than replacement and far less disruptive to day-to-day use of the building.

When replacement or overcladding may be better

A new roof system may be the better investment if:

• sheets are badly cracked or degraded
• the purlins, fixings or supporting structure need repair
• condensation, insulation or profile upgrade is part of the brief
• planning, insurance or lender requirements push you towards replacement

In short, coating is a refurbishment strategy, not a structural rebuild.

Practical advice for homeowners and contractors

If you are a homeowner, do not assume an old corrugated garage roof can simply be cleaned and coated as a DIY job. The asbestos element changes everything. Get the roof identified and assessed first.

If you are a contractor, specify the system around the substrate condition, preparation method and weather exposure - not just the leak location. Ask for confirmation of compatibility, preparation requirements and any primer or detailing components needed for the job.

At Forti Nova, we regularly help customers think through waterproofing options in practical terms. If you want to discuss Liquid Rubber SprayGrade, project suitability or coverage planning, you can speak to the team or visit the Blackburn depot and showroom to talk through the specification before work starts.

FAQ: SprayGrade on asbestos roofs

Can you coat an asbestos cement roof in the UK?

Yes, an asbestos cement roof can often be coated in the UK, provided it is in suitable condition and the work is carried out with controls that prevent fibre release. Assessment and safe preparation are essential.

Is pressure washing an asbestos roof allowed before coating?

No, aggressive pressure washing is not recommended because it can damage the cement surface and release asbestos fibres. Use low-disturbance cleaning methods and follow HSE guidance.

Is SprayGrade cheaper than replacing an asbestos roof?

Often, yes. Where the roof is still sound, coating is usually less disruptive and less expensive than full replacement. If the sheets or structure are failing, replacement may be better value long term.

If you need clear advice on whether SprayGrade is right for your asbestos cement roof, call Forti Nova on 01254 433987 or visit the Blackburn showroom for expert help with the right waterproofing specification.