Strip & Removal of Existing Asphalt System

The existing mastic asphalt membrane, bituminous patching, and all failed insulation were mechanically stripped and removed. Critically, all stripping was carried out by hand and with hand tools — no angle grinders or mechanical equipment that could transmit vibration into the historic Victorian masonry. Waste was carefully bagged and removed from site via the rear access without routing through the listed interior. The original concrete screed deck was left intact, inspected, and confirmed sound.

Deck Preparation & Breathable VCL Installation

The exposed concrete deck was swept, primed, and allowed to dry fully. Given the history of moisture within the roof build-up, a breathable vapour control layer (VCL) was installed across the full deck area prior to insulation in compliance with Building Regulations Approved Document C (Site Preparation and Resistance to Contaminants and Moisture). This allows any residual moisture vapour within the concrete substrate to dissipate upward through the system over time, preventing future blistering or delamination in the new membrane — a critical step on older buildings where the substrate cannot be guaranteed bone-dry.

Tapered Firestone ISO Board Insulation

Firestone-specified ISO board insulation was laid in a tapered configuration, purpose-cut to restore a consistent 1:80 fall across the full roof area towards both drainage outlets. The insulation specification was designed to achieve compliance with Building Regulations Approved Document L (Conservation of Fuel and Power), improving the thermal performance of the roof build-up and reducing heat loss through the flat roof section — a requirement on any roof replacement or re-roofing project under current UK building regulations. The tapered layout was modelled prior to ordering to ensure the correct fall was achieved without raising the finished roof level significantly — a specific concern on this project as the roof abuts historic window reveals. All boards were fully bonded to the VCL using Firestone bonding adhesive, with no mechanical fixings penetrating the structure whatsoever.

Firestone RubberGard EPDM MAX Membrane — Fully Bonded

The Firestone RubberGard EPDM MAX membrane was rolled out across the full prepared deck in a single piece where possible, minimising the number of seams in the field of the roof. Firestone BondCote bonding adhesive was applied to both the insulation board surface and the underside of the EPDM, allowed to flash off to the correct tack, and the membrane was then carefully rolled in from one edge to eliminate air entrapment. The membrane was then rolled with a weighted roller across its full area to ensure 100% adhesion contact. All laps and seams were sealed using Firestone QuickSeam splice tape, pressure-rolled to manufacturer specification.

Parapet Upstands & Termination Bars

The EPDM membrane was dressed up all four parapet walls to a minimum 150mm upstand height, bonded to the masonry face using Firestone Water-Based Bonding Adhesive to avoid solvent contact with the historic brickwork. Firestone aluminium termination bars were fixed to the masonry at the top of each upstand and sealed along their upper edge with Firestone Lap Sealant, providing a mechanically secure, weather-tight termination that does not rely on mastic alone. Firestone pre-formed inside and outside corner pieces were used at all parapet corners, eliminating the most common point of failure in flat roof upstands.

Drainage Outlets, Parapet Repointing & Final Inspection

Both roof drainage outlets were cleared, re-sleeved with Firestone-compatible EPDM outlet flanges bonded directly into the membrane field, and new grating covers fitted — all drainage works executed in compliance with Building Regulations Approved Document H (Drainage and Waste Disposal) to ensure adequate and unobstructed roof drainage. All parapet coping joints were then repointed in NHL 3.5 natural hydraulic lime mortar, matching the historic specification of the original brickwork and complying with conservation area requirements. A full final inspection was carried out by our lead roofer, checking all seams, termination bars, upstand heights, outlet flanges, and lap sealant runs before handing over the completed roof.