UPGRADING EXTENSION, DORMER & GARAGE FLAT ROOFS IN FINCHLEY
From 1930s semi-detached family homes in Finchley Central (N3) and North Finchley (N12) to large detached residences around East Finchley (N2) and Hampstead Garden Suburb, flat roofs play a vital role in protecting rear kitchen extensions, loft dormers, and integral garages. When old bitumen felt blisters or timber decking sags, water quickly tracks through to interior ceilings. London Roofing Specialist strips failed coverings back to the joists and installs engineered warm roof systems built for Barnet weather.
Tapered Timber Firrings, OSB3 Decking & Drainage Falls
Standing water is the primary enemy of any flat roof in North London. Before laying new waterproofing membranes, our carpenters inspect the structural joists, fit precision-cut timber firring pieces to establish a positive fall towards the rainwater outlets, and lay 18mm structural tongue-and-groove OSB3 or marine plywood decking.
MINERAL FELT, SIKA SARNAFIL & EPDM SYSTEMS IN N2, N3 & N12
Every flat roof has different thermal, foot-traffic, and budget demands. Our NFRC-accredited installers fit manufacturer-approved waterproofing assemblies tailored to domestic extensions, mansion block roofs, and commercial premises along Ballards Lane and the High Road.
Reinforced Multi-Layer Mineral Felt
High-tensile elastomeric cap sheets with a charcoal or grey mineral finish, providing tough, puncture-resistant weatherproofing for extensions and bay roofs.
Sika Sarnafil Single-Ply Membranes
Hot-air welded thermoplastic membranes engineered for clean architectural detailing, UV stability, and zero-maintenance longevity.
Seamless EPDM Rubber Sheets
One-piece synthetic rubber membranes cold-applied to garage roofs, garden rooms, and box dormers to eliminate vulnerable joint laps.
Cold-Applied Liquid Polyurethanes
Fibre-reinforced resin coatings moulded seamlessly around complex skylight kerbs, soil vent pipes, and balcony thresholds.
Part L Warm Roof Insulation
High-density rigid PIR insulation boards installed over a continuous vapour control barrier to cut winter heat loss and prevent internal condensation.
BRICKWORK LEAD FLASHINGS & 10-YEAR INSURED GUARANTEES
As shown in our Finchley project photography, a flat roof is only as watertight as its perimeter junctions. Where a flat extension roof meets a rear brick wall beneath sash windows, water will seep behind the membrane if the upstand is poorly sealed. Our tradesmen chase Code 5 milled lead cover flashings directly into the brickwork mortar courses, securing them with lead wedges and breathable weatherproof mortar.
Vetted In-House Technicians & Full Public Liability Cover
We never subcontract flat roof installations to unvetted casual labour. Every project across N2, N3, and N12 is carried out by our own trained operatives under full commercial and domestic liability insurance, backed by a 10-year insurance-backed workmanship guarantee alongside manufacturer material warranties.
Frequently Asked Questions: Flat Roofers Finchley
Should I choose reinforced mineral felt, EPDM rubber, or Sika Sarnafil for my Finchley extension?
Modern three-layer elastomeric mineral felt is exceptionally tough and ideal for roofs that may occasionally be walked on for window cleaning or maintenance. Sika Sarnafil single-ply offers a sleek, contemporary finish with hot-air welded seams and a 35+ year lifespan, while one-piece EPDM rubber is a cost-effective, joint-free choice for smaller garage and dormer roofs. Our surveyors bring material samples to your site visit so you can compare them firsthand.
Do I need Building Control sign-off when replacing a flat roof in Barnet?
If we are stripping and replacing more than 25% of a flat roof above a heated living space, UK Building Regulations (Part L) require the thermal insulation to be upgraded to current U-value standards. We build the required rigid PIR warm roof assembly directly into our specification so your property remains fully compliant when you come to sell.
