Grand Designs: Green Roof Project

Project Size: 350m2

Approved Contractor: Gables UK Ltd

Location: Lake Windermere

Project Type: New Build

Sector: Residential

System Installed: Protec System

Grand Designs: Green Roof Project

The Protec System was used to waterproof the domed green roof areas of this striking, sustainable house development which was featured on Chanel 4’s Grand Designs. With an ambitious vision and a tight budget, Robert and Milla Gaukroger set about transforming a dated 1980’s house overlooking Lake Windermere into a state-of-the-art, eco-conscious home.

Since the house lay in beautiful hillside surroundings, in order to blend into this setting, the domed roofs of the house were to be covered with a wildflower meadow mix to provide a green roof construction.

The Solution

The Protec System was chosen as a waterproofing membrane for the roofs as it is ideally suited for green roof applications. Lightweight, flexible and highly durable, the system can easily accommodate structural expansion movements and is tough enough to resist root penetration. The Protec system was applied to over 350m2 of domed roof to provide a long-lasting waterproofing membrane.

The key reasons why Eastleigh chose Protec are the same reasons that has seen it become one of the fastest growing cold-applied liquid roofing systems in both the new build and refurbishment markets. Combined with the timber cladding to the verticals of the building, the finished aesthetics of the development blended seamlessly with the surrounding areas.

A warm roof build-up that can be made waterproof at multiple stages:
For larger projects the Protec system can be made temporarily waterproof at two stages prior to the application of the full waterproofing system. The first stage is upon installation of the sealed, aluminium-faced vapour barrier. The second phase follows the reinforcing of the foil-faced insulation board joints with Protec resin and taping mat. This enables a much more controlled approach to the installation with a greatly reduced chance of rain causing disruption and damage during the works.

Highly flexible membrane:
Regardless of the size of the roof, Protec forms a homegenous membrane, without a single joint or seam and without the need for any expansion joints.

RapidCure technology for quick installation:
The application of Protec as a liquid, through to the curing process where a solid, tough membrane that can be walked over, takes only 30 – 60 minutes. This enables large sections of the roof to be fully completed in a short space of time.

Installing the Roofing Systems
The Protec System provided waterproofing to all flat roof areas as well as the extensive parapet wall sections. The roof areas were made up of two designs: the Protec Warm Roof System (approx 7,500m2) and Protec applied to concrete as part of an inverted roof design (approx 1,000m2).

The roof installation was carried out with a planned, phased approach that was synchronised to the wider construction schedule. For the warm roof areas, the first stage was to fill the troughs of the structural metal roof deck with acoustic insulation infills that will dampen external noise within the leisure centre. Next, the crowns of the deck were primed ready to receive the self-adhesive vapour barrier.

The use of a high-performance aluminium vapour barrier not only eliminates the risk of condensation within the roof, but also provides temporary waterproofing protection, which is extremely useful on larger works such as this.

The Polyroof RES Insulation boards, which comprised of a two layer system totalling 170mm to achieve a U-Value of 0.14 W/m2K, were bonded using high-performance PU adhesive to the vapour barrier. Following the wind uplift calculations it was determined that mechanical fixings were not required for this application – making for an extremely rapid installation. As you can probably imagine, fixing through 170mm of insulation into the crowns of the metal deck can be a tricky and time-consuming task.

A key advantage of using a tongue and groove insulation system is that the finished surface of the roof is smooth and level without any unsightly board steps that can also lead to standing water issues. The insulation board joints were sealed using Protec resin with Polymat Taping Mat 450 which, in addition to providing additional strength to the joints, also creates a temporarily waterproof layer.

For the inverted roof sections, Protec was applied directly to the primed concrete/screed surface. The membrane was inspected by Polyroof Technical Services, signed off and then covered with inverted roof components. An interesting fact when using Protec in inverted roof situations is its incredible durability performance – as tested by the BBA, Protec “can provide an effective barrier to the transmission of liquid water and water vapour for the design life of the roof in which it is incorporated”.

Monitoring and Completion

Throughout the duration of the contract, Polyroof Technical Services carried out regular site visits that were reported back to Interserve as part of Polyroof’s free-of-charge contract monitoring service. This enabled the client to keep up-to-date with the progress of the roof installation in detail and also provided peace of mind that the original specification was being closely followed and implemented.
Polyroof worked closely with the Roofline Group during the installation, enabling the challenges were identified and solved in an efficient and coordinated manner – saving the client time and money.

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