What is a Ballast Roof?

A Ballast roof installation involves the membrane being loose laid, but all the components are still heat welded together, then having a ballast placed on top (ie timber decking, flags or stones).

What are green roofs?

Green roof construction is designed to reap the benefits that green roofs offer but at minimal cost and with minimal maintenance. During green roof construction, we ensure that an appropriate drainage/retention medium is used in combination with a layer of growing medium to support low growing, stress-tolerant plants such as sedums, mosses and grasses and self-sustaining plants. In addition to being cost effective their low weight means they are suitable for new build or refurbishment projects.

Thermal Benefits

The thermal mass of a green roof provides additional thermal benefits over and above the roof insulation: delivering additional insulation value in winter & summer thereby reducing heating and cooling (air conditioning) costs. Numerous worldwide studies demonstrate the actual benefits but due to continued variations in moisture content levels throughout the year it is currently not possible to include these benefits in thermal calculations.

Acoustic Benefits

The mass a green roof provides above the roofing system provides acoustic properties to the building, reducing transfer of noise pollution into or out of the building and eradicating any drumming during rainfall. The planting will also reduce the passage of airborne noise which, as noise travels in straight lines, is broken by the variable heights and mass of the plants.

Increased Waterproofing Lifespan

A green roof prevents the waterproofing material being degraded by UV light and stabilises the temperature of the waterproofing, avoiding the thermal processes (expansion and contraction) that contribute to waterproofing failure. As a general rule of thumb the addition of a green roof to a suitable waterproofing material will double the life of the waterproofing:

avoiding the cost and disruption of replacement and reducing whole life costs.

Improved BREEAM/Code for Sustainable Homes ratings

A green roof can make a significant contribution to the points scored in a BREEAM or Code for Sustainable Home assessment. Points can be accrued under a variety of headings including POL5, LE4, LE5, LE6 and others.

Planning Permission

With increasing constraint demand for green roofs being part of planning legislation, Local Authority planning departments are looking favourably at developments that include a green roof. The UK is yet to reach the position of some European Countries – some German regions allow for an increased building footprint, and Basel in Switzerland requires green roofs on all new construction. Green roofs are required within the London Plan and in other regional planning guidelines.

Green roofing is a great system. It is aesthetically pleasing on the eye. It also offers much better drainage of water. It also improves the longevity of the roof itself. It improves drainage because once the flat roof is done, you clean it off, put a fleeceback down to protect the roof, then you put foam down that comes in 1 meter squares that look like egg shells, these allow rainwater to settle in them and allow it to constantly feed the sedum grass. When the water has to go through all these processes only clean water gets to the outlet, meaning it will not get blocked and offers easy maintenance.

It offers longevity to the roof because the main cause of failure on all roofs is sun exposure, by being completely covered this stops that from happening.

For further information on green roof construction or ballast roof installation please feel free to contact us