Ask the Experts: What is Blue Roofing?

‘What is blue roofing?” is a question that the PermaRoof UK experts are being asked more and more when discussing sustainable roofing projects. Let’s take a look at it in more detail.

What is a blue roof?

Blue roofing is a complex temporary water storage solution installed above the waterproofing membrane, most commonly on flat roofs. There are several design options for this type of roofing, which releases the stored water back into the local surface water drainage system at a pre-determined rate and capacity.

Some types of blue roofing (subject to some local authority permissions) can be utilised in rainwater harvesting projects. This can reduce the reliance on the mains water supply for flushing toilets or for keeping a green roof watered, for example.

Waterproofing a blue roofing project

The waterproofing layer on a blue roofing project is arguably the most important. By design, blue roofs hold a significant amount of rainwater at certain times. It makes sense to ensure that the waterproofing membrane is highly reliable, long-lasting and fitted correctly. Getting this part of the project wrong could prove a costly mistake.

Two options to consider are an EPDM membrane and liquid rubber waterproofing:

Waterproofing membrane – choose the waterproofing membrane carefully. Once the blue roof system is installed, membrane failure may prove disastrous to the project. Membrane will require some form of protection from the system installed above it. It is wise to seek professional advice to ensure a reliable, long-term solution.

Choosing a high-performance membrane such as EPDM can bring a range of benefits:

• Service life expectancy of more than 50 years
• Typically laid in a single sheet with no joins
• Faster to install due to the size of sheets available – up to 15.24m x 60m
• Remains durable and flexible throughout the exceptional lifespan
• High UV resistance and ozone stability

Fleece backed EPDM membranes have a high puncture resistance and are the ideal waterproofing layer for blue and green roofs. These will still require protection. Talk to us and let us help you plan your blue and green roof systems.

Liquid PU waterproofing – liquid roofing can become an ultra-reliable, high performance base layer for waterproofing beneath a blue roof system. Find out more about P500, PermaRoof’s liquid waterproofing solution here.

Further reading:

Design and construction considerations

Successful construction projects require careful planning in advance. There are a few considerations to add to the planning list:

Structure integrity – blue roofing is heavy. It is much heavier than most flat roof systems available, including green roofing. Because of this, the roof deck must be inspected to ensure it is suitable to hold the additional weight required.

Consideration should also be made regarding the fall of the roof. Blue roofs require precise calculations to avoid issues handling the potential volume of water. Some additions may need to be made in zero-fall roofing, for example.

Planning – while blue roofing is not a new concept, it has been steadily growing in popularity in some form over the past 15 years. There are British Standards and guidelines that apply to several aspects of the project, from collection to discharge, outlets and accessibility. Speak to the local planning authority to find out more about the permissions needed for a blue roof.

Water harvesting – if you’re considering a blue roof for a water harvesting project, bear in mind that some regional authorities have restrictions. Blue roofs can potentially provide water for use within the home, garden or for irrigating existing green roofs and terraces.

Related products to buy online:

Here at PermaRoof UK, we support all our customers and answer a variety of flat roofing questions every day. If you have a question, please visit our FAQs page, give us a call on 01773 608 839 or use the live chat for a quick query.

Other articles about flat roofs:

PermaGroup has established links with some of the biggest names in our industry thanks to our reputation of excellence. Read more about becoming a supplier or stockist here.