One size waterproofing will not fit all
Liquid waterproof membranes have improved beyond all recognition over the last 20 years and are today considered to be one of the most effective and versatile of all waterproofing systems. Seamless application means that liquids are good at problem solving, but one size does not necessarily fit all according to Justin Pitman, sales director at Proteus Waterproofing.
There are probably more types of waterproof membranes available to UK specifiers and contractors than ever before. They all claim to do the job better than anything else and while they will all waterproof, you have to ask the question – have I chosen the right membrane and is it right for the job I want to do?
All waterproofing system types have a place in roof and structural waterproofing. Not all are best suited to all projects even if they can be installed. Some projects also require a more specialised waterproofing solution because if it is going to fail, it will nearly always happen around the most difficult part of the installation.
Like everything else, the devil is in the detail which accounts for 80% of all roof failures. Upstands, areas around roof lights, covers, maintenance equipment, stairs, ramps etc are all prone to movement, poor craft skills and outside damage which is why Liquid Systems which provide more flexibility than most have become increasingly popular and continue to increase market share.
They also deliver high fire ratings, offer a light weight solution, are great with awkward detailing and because of their seamless application they can be designed to be fully trafficked. Fully bonded systems are also incredibly effective against wind up lift.
Until fairly recently, most installers looking for a seamless application would choose a more traditional waterproofing such as mastic asphalt, which is heavy and not as flexible as alternative waterproofing solutions or hot rubber melt. Both continue to provide a major role in the marketplace.
Felt, historically is also well understood and has a great track record but typically requires hot works for some or most of the installation. This has altered more recently with the introduction of self-adhesive felt which can be used in areas not deemed safe to torch.
In spite of the rise in liquid systems, felt, of course, still remains a massive market and is a trusted and tried material which delivers exceptional value for money, but like all types of roofing, you have to make the decision – is this the right material for the job?
There are, of course, many other issues to consider when choosing the right material. More recently there have been major concerns about naked flame or molten materials at roof level. Insurance companies are increasingly more reluctant to sanction such materials following a series of disastrous fires. As a result, there has been a growing move to cold applied products.
So, let’s compare systems. Every membrane will do the job if it is expertly installed according to manufacturer’s specifications and will perform and provide longevity as long as it is not subject to conditions it was never designed for.
However, not all membranes offer the same longevity or performance and this is when you have to decide what is best for you, so let’s compare some of the different types of membrane, the benefits they offer and some of the downsides, starting with felt.
Most felt applications require huge amounts of heat in order to make it usable and from a health and safety point of view, it can be dangerous during application. Because it is very susceptible to ultra-violet light, it must also be protected with chippings, a mineral surface or solar reflective paint. It can also be affected by hydrocarbon solvents and oils and creates noxious smells and smoke.
Mastic Asphalt also has many excellent qualities such as seamless application, is highly versatile, is good in heavily trafficked situations, is usually installed by the best craftsmen and will last for a very long time. On the flip side however, it is more expensive to install than other membranes, requires application using molten material with many similar disadvantages to that of bitumen and there are large limitations on colour.
Single ply faces similar challenges even though it is widely regarded that most major waterproofing projects – particularly those on large lightweight metal decks – use this particular membrane. They require skilled roofing contractors to seal laps and take care of the detail. On the downside, not everyone is always that careful and single plys also have a poor track record in trafficked situations and in the case of PVCs, there is the risk of longer-term polymer migration.
Waterproofing is of course not all about roofing. Most membranes will also work on structural decking, balconies and green roofs but do not have the versatility of liquid solutions. Most are limited by type of application, climatic conditions and design restrictions.
So, we get back to liquids, but how will they solve your waterproofing problem? For a start, no other membranes can compare with liquid solutions for sheer flexibility and versatility. Solutions are good to waterproof guttering, balconies and much more and will take care of the detail. They work just as well with other types of membrane and they can be laid cold.
At Proteus, we have one of the largest ranges of liquid waterproofing systems in the country with products such as Cold Melt® that can be laid over three-day old green concrete, has virtually no odour and is BBA certified to last for the life of the substrate on which it is installed.
We also offer a huge range of other liquid systems especially developed for balconies, car parks, stairwells, walkways and much more. So, you can see, that one size does not fit all – but whatever membrane you choose – make sure that it is designed to fit the application.