Mastic asphalt screeds offer a variety of benefits that make them a preferred alternative to traditional concrete screeds.
Screed specification will depend upon the requirements of the individual project. There is not only the basic performance characteristics of the screed material to consider but also how the preparation and installation of the screed fits into the project timeline. Durability and load-bearing performance are important factors, especially if the screed is intended as a wearing surface.
Using Screed Materials in Flat Roof Build-Ups
A significant challenge in the design and construction of flat roofs is ensuring that they shed rainwater as effectively as possible. BS 6229:2018, the code of practice for flat roofs, has heightened awareness of roof drainage and correct falls. It recommends deflection analysis on flat roof decks to establish whether any areas are at risk of becoming non-draining low spots.
Designing a roof to achieve the correct falls is one thing but constructing it in accordance with the design is another. Movement in the building structure or poor construction can mean the finished roof deck is not in accordance with the design. Traditionally, a tapered concrete screed would have been the remedy on a roof where timber firrings were not feasible.
The flat roofing industry has witnessed a trend of screeds being omitted to save time and money. Although a concrete screed can accommodate variations in an uneven deck, it contains a lot of water and must be allowed to cure before installing the roof system on it. Many projects may not be willing to allow that time for curing.
Mastic Asphalt as an Alternative to Concrete
If traditional screeds are unpopular, or unlikely to address the issues of ineffective roof drainage, then a better solution is required to help ensure falls are provided as designed. The advantages of mastic asphalt are particularly well suited to screeding in flat roof build-ups and highway repair work.
IKO Permascreed is a levelling screed based on a mastic asphalt formulation rather than the traditional mix of sand and cement. It is lighter and cures quicker than wet screeds, and can be laid to a minimum thickness of 10mm (compared to 40 or 50mm for a concrete screed). The roof can be trafficked quicker and means any excuses for omitting a tapered screed are redundant.
Suitable for both warm and inverted roofs (including green and blue roof variations), IKO Permascreed provides both drainage falls and a stable substrate for the chosen waterproofing. It is also capable of providing temporary waterproofing to the roof structure prior to installation of the final waterproofing.
Mastic Asphalt as an Alternative for Highway Repairs
Longevity is an essential quality for any product used in road repairs. Without it, the repair fails too soon, leaving road users frustrated. With the number of vehicles using the nation’s roads on the increase keeping highways in the best possible condition is essential for smooth-flowing roads and reduced risk to the vehicles using them.
Mastic asphalt’s service life of at least 50 years is in excess of other road repair solutions, including concrete based products. Speed of laying keeps disruption to a minimum, while the durability of the wearing surface means whole-life costs are kept to a minimum as well as initial installation costs.
IKO Permatrack is a mastic asphalt patch and crack repair solution. It is able to bond to different substrates, accepts differential movement and can bear standing traffic quickly thanks to the speed with which it cools.
Sustainability Benefits of Mastic Asphalt
Whether for flat roofing or highway repair projects, mastic asphalt also offers substantial environmental benefits over concrete products. As well as being durable and offering excellent longevity, mastic asphalt is completely recyclable at the end of its useful life.
On a broader level, in 2008 the entire mastic asphalt industry became carbon neutral by achieving the CarbonZero standard.
At IKO we demonstrate our sustainability credentials through our membership of CO2balance’s scheme, meaning that every tonne of mastic asphalt produced is offset by internationally approved carbon credits. Highway projects in the UK contribute to humanitarian and environmental projects such as providing boreholes to communities in Uganda, and stoves to families in Kenya.
To find out more about IKO mastic asphalt products, contact us for advice on the best IKO solution to use on your project, and for comprehensive technical support.