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What Is Liquid Applied Roofing?

Liquid applied roofing is the process of applying a liquid waterproofing membrane as a roof coating on to a new roof or to make a defective existing roof waterproof. The process of using a liquid applied roofing system to make an existing roof waterproof is referred to as a "liquid overlay". Whether a liquid applied roofing system is used to waterproof a new or existing roof, this type of system comes with a number of excellent benefits.

The Benefits of Liquid Roofing Systems

The benefits of liquid roofing systems when compared against other roofing systems include:

It is suitable for virtually any roof design or function. Be it a green roof or a blue roof or anything in between. A key benefit is that it is installed as cold applied liquid so is completely flame free. This makes it a very safe option for both the specifier, contractor, installer and, in the case of refurbishment, the building occupants. Risk of fire is minimal.  Also, Mariseal 250 liquid waterproofing has one of the highest fire ratings for roofing liquids available Brooft4. This means it has been independently tested and shown not to promote the spread of fire. This is a vital part of any installed building system which was proven to be a major factor in the tragic Grenfell fire disaster for example.

Liquid applied waterproofing systems also provide a completely seamless solution. It is installed as a continuous coat and has no areas where water access and get under the skin. Systems such as single ply, bitumen felt, and EPDM all tend to fail at the seams. This is an obvious weak point, and every seam is a possible area where water can attack and finally penetrate. Regarding sloping surfaces on flat roofs, although liquid waterproofing can withstand standing water, normally this is called ponding, minimum falls of 1:80 should exist so as not to promote water remaining on the roof. This means that the roof would come within current building guidelines in the UK mentioned in BS6229. Falls are even more important if the roof faces north as obviously it receives less sunlight and is therefore more prone to suffer from standing water, which over time encourages organic growth.

Another positive thing about some liquid roofing systems is the lack of strong odour. The smell that emanates from some systems can and do make people nauseous and can even provoke asthma attacks. The Mariseal 250 liquid waterproofing has a low odour compared to many other systems and makes it more suitable for working in built up areas. Some systems are simply too smelly to be installed in crowded or occupied areas.

There are four main reasons that have caused the recent move in favour of liquid applied waterproofing systems:

• The need to reduce risk, in particular flame/heat whilst installing a waterproof membrane.

• Any system with seams and laps on roofs has these as weak points – seamless systems do not carry this risk. Liquid roofing systems encapsulate the entire roof.

• Modern building designs using curves and angles means that the ability of liquid to shape perfectly around any shape makes it a perfect unique solution.

• Skill levels in other parts of the roofing industry are at an all time low. There are simply not enough trained and skilled installers to meet demand.

Advances in polymer chemistry mean that liquids are evolving with the times and are a perfect solution to waterproof modern buildings. And the safety challenges they present. Liquid waterproofing is growing in popularity as a construction solution.

Some key advantages liquid roofing systems have over seamed products:

• Cold applied so no hot works

• Seamless and fully bonded

• UV Stable

• Allows intricate detail works to be formed on site. Liquid roofing systems encapsulate the most complex roof details.

• Suitable for new build and/or refurb works

• Lightweight as no heavy rolls to transport

Liquid Waterproofing is a fast and easy system to install. Therefore, site disruption is greatly reduced accordingly. The substrate should be prepared correctly and primed if required. A peel test should always be carried out and left as long as possible to inspect that adhesion is good. A week is ideal, but a minimum of 48 hours is required to check this. Once this has been completed to satisfaction the liquid waterproofing is applied by brush or roller to the surface. No other tools are required and also, the Mariseal 250 liquid waterproofing is self-terminating, so upstand areas which are a notorious weak point in any seamed system have no entry points where the water can access behind the finished surface and work its way into the building.

Inspection and walkway anti slip areas are easy to install. Simply tape off the relevant areas, put a thin coat of liquid onto the substrate and sprinkle quartz or hard chip into the wet coat. Once the surface is dry, simply sweep off any loose materials. You can recoat lightly if required. A different colour can be used if required to make the designated areas even clearer.  

An accelerator can also be added to Mariseal 250 liquid waterproofing which means it cures faster. The obvious advantage here is that work can continue to take place in conditions not always suited to some other waterproofing systems. It enables the contractor to take advantage of narrow weather windows, typically in the winter months which always have cold temperatures which can shorten the working day or finish a project before expected wet conditions.

Due to the anti-root accreditation that Mariseal 250 liquid waterproofing has, it is a perfect system for providing the waterproofing under a green roof. It is seamless and therefore there is nowhere for any water to access the roof. Which is why Mariseal 250 liquid waterproofing is perfect for green roof systems. Unlike single ply and felt, where every lap is a potential weak point. Only a small part of any weld or lap has to fail to render the whole roofing area a failure.

This can have disastrous financial and logistical consequences. If there is a failure the whole green roof area normally needs to be removed before the leak can be located and repaired. The financial cost of this can be very high and the whole process is time consuming and can cause disruption to the building. Best to avoid the risk and specify a Mariseal 250 liquid waterproofing system under a green roof.

Unlike some other systems, liquid waterproofing specifications can be very flexible and can be designed to reflect exactly what the roofing requirements are, both in use and life expectancy. For instance, a refurbishment requirement may vary from just a straightforward coating onto an existing GRP substrate that only requires a ten-year warranty, right through to a multi layered, fully reinforced system, complete with a hard-wearing trafficable topcoat designed to give maximum protection from UV attack that can be expected to last for up to twenty five years.

The coating thickness could vary depending on the warranty required or the function of the roof. So, for instance, typically a single ply roof that has failed at the laps or is coming to the end of its expected life cycle, normally no more than 20 years in the UK, even less in hotter climates. can easily be refurbished. The entire roofing area, including upstand areas, needs to be cleaned and dry, jet washed if required. A peel test would confirm the necessity of if a primer is required. It isn’t always, but it is considered good working practice to apply a primer.

Certainly, if there is any doubt use a primer. The Mariseal Aqua Primer is suitable for most substrates, is easy to use,  and cures very quickly. PVC roofs under five years old should always be primed. Prior to priming a PVC roof, the Mariseal 9010 activator product could be used. This opens up the PVC and enables it to absorb liquid more thoroughly, thus giving the ultimate adherent result.  For a 25-year warranty typically 2kg/m2 of liquid is then applied in two coats. Once cured, a further thin third coat may also be applied if walkway or inspection areas are required. This can either be a clear coat that is available within the system (Maritrans) or Mariseal 250 liquid waterproofing.

This operation would take place within a taped area and whilst the liquid is still very tacky a quartz or chipping material would be broadcast. Once cured any loose particles would be swept off. This provides the client with a safe anti-slip area suitable for walking on. The procedure for asphalt and bitumen felts is much the same, but the Mariseal 9010 activator is not required on these kinds of substrates. It is important to any specifier, client, and contractor alike, that a liquid system offers a full tested system.

This includes various primers, reinforcement material to be used where the roof design requires it, the liquid waterproofing system itself, ideally complete with a catalyst option to speed up curing where required, plus various topcoats that can add further integrity depending on the roofs design and usage.

Training available for installing liquid waterproofing can vary depending on the system. All professional training often takes place under site conditions as this is deemed to be the most worthwhile and realistic scenario. It can take between one to two days and is normally undertaken by installers with experience of numerous other liquids. Often this training is ongoing and permanently reviewed as liquid waterproofing methods and options are permanently evolving and improving. New products are added that can bolster the system, making it even more cost effective to install.

Get In Touch About Liquid Applied Roofing

If you would like any further information about liquid roofing systems, whether for a new or existing roof please contact us or call us now on 01277 375 511. One of our friendly team of liquid waterproofing specialists will be delighted to help.

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