Fire-Rated TriRoof FLEX Overlay for Finol Oils

Fire-Rated TriRoof FLEX Overlay for Finol Oils, Installed in One Week

This project involved the installation of a 240m² liquid overlay roofing system onto an existing concrete and asphalt flat roof. Completed by Connolly Fibreglass, using the TriRoof FLEX Roofing System, the refurbishment provided a seamless, durable waterproofing solution with minimal disruption, extending the service life of the roof while avoiding the need for a full roof replacement. The installation was completed with the assurance of a 20-year materials guarantee.

Date Published

October 14, 2026

Reading Time

6mins approx.

Sector

Roofing

An Overlay, Not a Strip-Out

Finol Oils needed an ageing flat roof brought back into serviceable condition, and the replacement had to be fully fire-rated. The existing roof was a concrete and asphalt build-up that had reached the end of its serviceable life.

Rather than strip the roof back, Connolly Fibreglass was contracted to overlay the full 240m² using the TriRoof FLEX liquid system. The existing substrate was retained, removing the cost and disruption of a tear-off.

What the project delivered

Customer
Finol Oils

Roofing contractor
Connolly Fibreglass

Project
240m² liquid overlay to an existing concrete and asphalt flat roof

Requirement
A fully fire-rated roofing system

System
TriRoof FLEX, reinforced with 225g chopped strand mat

Programme
Completed over the course of one week

Why a Fire-Rated System Was Specified

The customer required a full fire-rated system. TriRoof FLEX was selected on that basis, for its BROOF(t4) fire rating.

Because FLEX is applied as a liquid, it could be laid straight over the prepared substrate. The existing build-up stayed in place, there was no tear-off to remove from a working site, and the roof was reinstated as a single continuous reinforced membrane rather than a set of jointed sheets.

Roof-mounted equipment and cable runs crossed the area to be covered, so every upstand, parapet and penetration had to be brought into the new waterproofing rather than worked around.

The existing concrete and asphalt roof prior to preparation.

Preparation and Installation

The existing substrate was jet power washed and cleaned, with all necessary remedial works completed prior to application. Once primed and cured, FLEX was applied and reinforced with 225g chopped strand mat.

STEP 1

CLEAN

Jet power wash and full clean-down of the existing concrete and asphalt substrate.

STEP 2

REPAIR

All necessary remedial works completed to the substrate prior to application.

STEP 3

PRIME

TriRoof Primer applied across the full area and left to cure.

STEP 4

WATERPROOF

TriRoof FLEX applied and reinforced with 225g chopped strand mat.

“I’ve been using the FLEX overlay for years — whether it’s overlaying over felt, asphalt, concrete, commercial or domestic, or a new roof, it’s my go-to liquid roofing system.”

Alan Connolly
Connolly Fibreglass

The System Specification

Products supplied for the 240m² overlay.

Product	Role in the System
TriRoof FLEX	Liquid-applied overlay membrane, selected for its BROOF(t4) fire rating.
TriRoof Primer	Applied to the prepared concrete and asphalt substrate and left to cure before overlay.
225g Chopped Strand Mat	Full reinforcement throughout, forming a single continuous membrane across the deck, upstands and parapet.

Why Specify TriRoof FLEX for an Overlay

Fire rated

BROOF(t4) classification, which is why it was specified on this project.

Download the BROOF(t4) Site Checklist >>

No strip-out

Applied over the existing concrete and asphalt deck, with no tear-off to remove from site.

View Installation Manual >>

Fully reinforced

225g chopped strand mat throughout, not a surface coating.

Seamless detailing

Deck, upstands, parapet and penetrations sealed as one continuous membrane.

Fast on site

The full 240m² installation was completed over the course of one week.

20-year guarantee

The completed roof is backed by a 20-year materials guarantee.

TriRoof FLEX 20 Year Material Guarantee >>

Liquid Overlay Compared With a Full Strip-Out

How the two approaches differ on a roof of this type.

Consideration	Liquid overlay	Full strip-out
Existing build-up	Retained and overlaid	Removed from the deck
Waste from site	None from the existing roof	The removed build-up must be disposed of
Finished membrane	One continuous reinforced surface	Depends on the replacement system
Detailing	Upstands and penetrations sealed in as part of the same application	Detailed separately as the new system is laid
On this project	240m² completed in one week	Not required

Note: An overlay suits a deck that is structurally sound and can be prepared to receive the system. A survey establishes which approach applies.

A Roof Sealed as One Continuous Surface

Coverage

The full 240m² reinstated as a single reinforced membrane, with upstands, parapet and penetrations brought into the same system.

Fire performance

The customer’s requirement for a full fire-rated system met through the BROOF(t4) rating of TriRoof FLEX.

Guarantee

Backed by a 20-year materials guarantee.

Programme

The full installation completed successfully over the course of one week, with the existing substrate retained and no tear-off to remove from site.

“We look for quality that lasts in everything we invest in, and TriRoof FLEX was no different. It’s a genuinely robust system, backed by a serious guarantee, and the finish speaks for itself. It was a straightforward, well-managed job from a team who clearly know what they’re doing.”

Sean Holland
Managing Director, Finol Oils

Planning a Flat Roof Refurbishment?

TriRoof liquid systems are designed to overlay existing flat roofs where a strip-out is not practical. Speak to our technical team about your roof condition, fire-performance requirements and specification options.

Frequently Asked Questions

What is a liquid roof overlay?

A liquid overlay is a waterproofing system applied in liquid form over an existing roof surface, rather than in sheets. On this project TriRoof FLEX was applied over the prepared concrete and asphalt deck and reinforced with chopped strand mat, curing into one continuous membrane across the deck, upstands and parapet.

Can TriRoof FLEX be applied over an existing concrete or asphalt roof?

Yes. On the Finol Oils project the existing concrete and asphalt build-up was retained. It was jet power washed and cleaned, all necessary remedial works were completed, and the surface was primed before the overlay was applied.

What fire rating does TriRoof FLEX have?

TriRoof FLEX carries a BROOF(t4) fire rating. This was the reason it was specified for Finol Oils, whose requirement was for a fully fire-rated system.

Does the existing roof have to be stripped first?

Not where the deck is sound and can be prepared to receive the system. Retaining the existing build-up removes the cost and disruption of a tear-off and means no waste from the old roof leaves the site. A survey establishes whether an overlay is suitable.

What preparation is required before application?

The substrate is jet power washed and cleaned down, and any remedial works are completed before application. TriRoof Primer is then applied across the full area and left to cure before the FLEX overlay goes on.

What reinforcement is used in the system?

225g chopped strand mat, applied throughout rather than only at details. This is what makes the finished surface a fully reinforced membrane rather than a surface coating.

How long does an installation of this size take?

The full 240m² installation at Finol Oils was completed over the course of one week. Programme on any project depends on the substrate condition, the amount of remedial work required, the detailing involved and the weather.

What guarantee comes with the system?

The completed roof at Finol Oils is backed by a 20-year materials guarantee. Guarantee terms for a given project are confirmed by the technical team as part of the specification.