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Flat roofs · Sheepmoor, Dublin 15

Flat Roof Repair & Insulation Upgrade in Dublin 15

Flat roof repair in Sheepmoor, Dublin 15 to address poor drainage and standing water. We removed the ageing felt covering, improved the roof fall, added insulation and new plywood decking, and then waterproofed the completed roof with a seamless Mariseal 250 liquid-applied membrane.

Completed flat roof finished with grey Mariseal 250 liquid waterproofing, including sealed perimeter edges and wall-junction detailing.
Completed: seamless Mariseal 250 waterproofing installed across the repaired flat roof and carefully detailed around the perimeter and wall.

What needed attention

The existing flat roof was showing its age and had a drainage problem, with water tending to sit on the roof rather than run off cleanly. The old mineral-finished felt covering and roof build-up also needed upgrading. The aim was not only to waterproof the roof, but to improve the fall, upgrade the roof build-up and add insulation before installing the new waterproofing system.

How we approached it

We stripped back the old flat roof covering and adjusted the roof build-up to create a better fall for rainwater drainage. New insulation was added to improve the thermal performance of the roof, followed by new plywood decking and careful detailing around the perimeter and wall junctions. The prepared roof was then waterproofed using Mariseal 250, a premium liquid-applied polyurethane membrane. Because the membrane is applied as a continuous liquid system, it provides a seamless waterproof finish across the main roof area, edges and detailed junctions.

The finished work

The completed flat roof benefits from improved drainage, additional insulation and a new seamless waterproofing system. Correcting the fall helps reduce standing water, while the Mariseal 250 membrane provides a continuous weatherproof finish across the roof and its junctions. This project is a good example of addressing the underlying flat roof drainage and build-up before applying the final waterproofing system, rather than relying on another temporary surface repair.

The job, in photographs

From first look to finishing details

Ageing mineral-felt flat roof beside a rendered wall, with moss, debris and signs of water collecting on the roof surface.
01 / BeforeBefore: the existing flat roof had poor drainage, with moss and debris collecting in areas where water was sitting.
Close-up of the old mineral-felt flat roof at the junction with the adjoining tiled roof, showing moss and weathered surface detailing.
02 / BeforeBefore: close-up of the existing felt and adjoining roof junction prior to the drainage and waterproofing repair.
Wide view of new plywood decking with perimeter trims and wall-junction detailing prepared for the flat roof waterproofing system.
03 / Work in progressWork in progress: the roof build-up was adjusted to improve the fall before new plywood decking and edge detailing were installed.
New plywood flat-roof deck with grey perimeter and wall-junction detailing beside a container of Mariseal 250 waterproofing membrane.
04 / Work in progressWork in progress: new decking and detailed roof junctions prepared ahead of the Mariseal 250 liquid waterproofing application.
Completed flat roof finished with grey Mariseal 250 liquid waterproofing, including sealed perimeter edges and wall-junction detailing.
05 / CompletedCompleted: seamless Mariseal 250 waterproofing installed across the repaired flat roof and carefully detailed around the perimeter and wall.

Your roof, our next conversation

Planning similar work?

Tell us what needs attention. We’ll explain the next step and arrange a roof assessment.

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