Liquids in a metal gutter
Before I start this article, I want to be clear that my intention is not in any way to discredit liquid waterproofing, those who know me will testify that I’m a great ambassador of the benefits of liquid roofing and that one of my favourite sayings is “horses for courses”. I really do believe that the right product correctly specified in the right environment and installed by competent installers will stand the test of time. I have objectively formed the opinions in this article through decades of practical experience in the liquid waterproofing market combined with hands-on experience to date in the metal gutter market.
When it comes to heavily detailed areas, there is no doubt that liquids are the best choice in the flat roofing environment. I have seen some wonderful examples of workmanship that simply could not be replicated by a sheet membrane but the metal gutter environment is a completely different animal and I think that if they were honest, manufacturers of market leading liquid systems would say that they found their way into the metal gutter environment almost by accident. It is not uncommon in the metal gutter market for a paint type application to be used as a temporary repair and this leads me to believe that liquids, which are intended only as a short- term repair, have inadvertently become specified as a long-term solution to leaking gutters.
A pitched metal roof is designed to shed the water to the gutter and, in reality, most gutters are permanently under a large amount of standing water often on top of silt and all other types of debris. Couple this with the amount of details, number of joints and the additional thermal movement of a metal gutter and you start to understand the harsh environment we are talking about.
As a consequence, most liquid manufacturers will either increase their coverage rates or lower the length of guarantee in the commercial gutter environment and I can completely understand the reasons why. Under permanently ponded areas, liquids have a water uptake factor which, can be argued, will weaken the membrane and therefore shorten the life expectancy. The amount of water uptake can vary between different liquid chemistries and the quality of the finished membrane. Liquids are also heavily reliant on the preparation of the area and attention to detail of the installer and the metal gutter environment is not the easiest of areas to work in. At every gutter joint, a bond-break needs to be formed to stop the liquid bonding in these areas and allowing the gutter to continue to move without splitting the membrane. When you add up the number of intricate details, the consideration of permanent standing water and the time and preparation needed, for me, the risk of using a liquid is too high.
Liquid systems are well suited to the flat roofing environment as well as successfully adding to the life expectancy of pitched metal roofs with robust coating and cut edge corrosion systems. However, their third-party accreditation, longevity statements and single point guarantees don’t seem to be replicated in the gutter environment for the reasons outlined above.
In addition, the biggest risk for a contractor tendering for any project is in the labour time. The cost of the materials, once tendered, are largely set in stone but the labour cost is dependent on many factors with the weather being the biggest threat. This is perhaps a liquid estimator’s biggest headache as a few days of bad weather can push the timescale out. This will have a knock-on effect to access systems and claims for not completing the works in the programmed timescale.
In a metal gutter, the weather is even more significant as this is ultimately where the water is going to end up. Liquid systems should not be installed in the wet and therefore work must stop. When you consider the amount of detail in a gutter and the fact that most liquid systems comprise of two coats or more plus any primers needed and multiply that by the amount of preparation necessary before and work can commence, again, you have to question whether this is the correct product for the environment.
As a final observation, when it comes to specifiers obtaining the correct advice, I think it is fair to say that manufacturers who mainly deal in the flat roofing market are experts in their fields but may not specialise in the design element of the gutter environment giving the correct advice for drainage calculations, syphonic systems, gutter capacity expectations, etc.
When I sat down to write this article, I wanted to give the best advice to both the specifier and the contractor. As I said, I think that liquids are fantastic products, as are felts, single plys and a lot of other solutions. Providing that they are used in the right environment and specified by experts in their field.
So what is the solution?
A system that is manufactured for the metal gutter environment would need to be: non-bonded, fast to install and unaffected by weather and specified by experts.
I feel that the Sharman’s Plygene Gutterline system is correctly suited to this environment because:
- It is non-bonded and allows the gutter to move freely without putting stress on the product
- It is a single operation, creased to the profile of the existing gutter for rapid and easy installation
- All details are bespoke manufactured off-site meaning they cloak the existing detail, minimising labour time and reducing risk
- The system is not affected by weather resulting in peace of mind for the estimator
- HD Sharman have been installing their system for over thirty years, therefore we know the system has passed the test of time
- The system is BBA accredited specifically for use in the gutter
- Technical expertise is at the heart of the business so the necessary factors for the gutter are considered at specification stage
We would welcome the opportunity to discuss technical aspects of the gutter environment or to arrange to present our latest CPD “Why gutters fail and the options to repair, replace and refurbish: A specifier’s guide”.