Case Study · External Works & Roofing
North West London Built Up Felt Balcony Waterproofing & Lead Work
Built up felt balcony waterproofing and leadwork across three North West London balconies by J&H Spaces.
Project Overview
Built up felt waterproofing and lead work across three residential balconies
This North West London project involved remedial external works to three balconies on a residential block in North West London. The works covered separate balcony areas of approximately 12m², 23m² and 26m², where rainwater ingress was tracking beneath the existing felt waterproofing system.
J&H Spaces stripped out the defective areas, prepared and primed the balcony deck substrate, installed a new fully bonded built up felt system, chased the brickwork to receive lead cover flashings and completed the exposed perimeter edges with dressed lead capping. The detailing around balustrade posts, upstands, corners and rainwater outlets was central to the job.
- Built up felt waterproofing across three balconies: approximately 12m², 23m² and 26m²
- Defective felt areas cut out and deck substrate prepared
- Bituminous primer, 4mm felt underlay and 4mm mineral cap sheet installed fully bonded in hot bitumen
- Brickwork chased to receive new lead cover flashings
- Dressed lead capping to exposed balcony walls and perimeter edges
- Copper clips, welted edge and patination oil finish where specified
- Careful detailing around balustrade posts, upstands, corners and rainwater outlets
The Brief
Make the balconies weather tight and properly detailed
The priority was lasting weather protection. The original balcony coverings had allowed water to track beneath the felt, with vulnerable junctions around upstands, rainwater outlets and exposed perimeter edges. The solution combined a new built up felt waterproofing system with properly formed lead detailing where the balcony edges needed better protection.
Rather than presenting this as a small roof repair, the page shows what the project actually was: technical external works on a residential block, with waterproofing, leadwork and detail focused finishing carried out across multiple balconies.
Finished Works
Dressed lead capping, perimeter edges and balcony junctions
Additional Balcony
Additional balcony remedial waterproofing
This additional balcony followed the same remedial approach: defective felt areas cut out, deck substrate primed, 4mm felt underlay and 4mm mineral cap sheet fully bonded in hot bitumen, with brickwork chased to receive new lead cover flashing.
Additional Balcony
Second additional balcony remedial waterproofing
The second additional balcony increased the scale of the works again, with the same fully bonded built up felt system and new lead cover flashing formed into chased brickwork. The finished photos show the completed waterproofing surface, dressed lead edges and clean perimeter detailing.
Before & During
The problem areas before the remedial works
These images show the existing felt covering, balcony perimeter edges and outlet areas before and during the remedial works. They are included as evidence of the condition rather than as the main visual story.
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