How Do You Guarantee Leak Prevention in Commercial Gutters?

Gutters

Author: Josh Hamer, Specification Manager at HD Sharman

LEAKING GUTTERS are a common commercial property concern, and one that should be dealt with as soon as it is noticed. You may carry out an inspection, realise that that its more serious than you thought and knowing that there have been several repairs already, it is essential that you decide on a solution to repair the damage and reline the gutter.

Many people will naturally turn to Google to carry out research about solutions or find a reputable roofer or surveyor to carry out a professional inspection and put forward recommendations. In this instance a specialist will offer their recommendations based on their own experiences or products they are familiar with, but how do you know that what you are being offered is the correct solution for you? We’re here to break down everything you need to know about how to guarantee leak prevention by using the right gutter refurbishment solution which is a gutter lining system.

What you need to know about different gutter lining systems

Firstly, there are four main types of gutter lining systems: a liquid applied membrane, a bonded membrane, a fold-out rigid system and a loose lay system. Choosing the appropriate system will depend on several factors, and which works best with the existing gutter condition or situation.

These factors include: what caused the failure in the first place, construction of the existing gutter, its condition and how it is detailed with the roof construction, gutter capacity, and what components are there within the gutter system, such as outlets, corners, transitions.
Matching the correct system to the requirements to restore the gutter to full working order and prevent leaks and water ingress for the long term is more complicated than simply plugging a leak.

During the selection process, it’s important to remember these facts:
• Gutters are not laid to falls, so constantly contain water between outlet points, not just when it’s raining
• Maintenance or rather the lack of it, allows debris to build up in the gutter system. This build up traps and holds water and promotes plant growth which can cause further issues as decaying matter produces a mild form of acid.
• The gutter is a much more aggressive environment than that of the roof, which is designed to shed water. Any system that is continuous or seamless, is going to be more reliable than one that is joined.

What makes each system different?

Liquid Coating:
Coating technology has come a long way in the last few years. The main thing to understand about liquid coating is that it has been developed predominantly as a roofing membrane. Because liquid coating systems are inherently waterproof, easy to apply and cope well with intricate building details, they are a popular choice for gutter relining. However, their suitability needs to be questioned when the aggressiveness of the gutter environment is taken into consideration.

Firstly, the condition of the existing substrate is critical as the coating relies on successful bonding. This means that the substrate needs to be structurally sound, corrosion free, entirely clean and completely dry. Existing repair systems will need to be removed, or at best a barrier or primer layer will be required to well adhered repairs. Whilst application is relatively easy, the preparation for these systems is absolutely crucial and labour intensive, as are the conditions it is applied in as coatings have temperature and humidity parameters in which they have to be applied.

Secondly, building movement should be considered. The reason repairs to section joints of gutters is common, is due to building movement, and any flex or movement will become apparent at the weakest point. Gutter joints work and flex along with the building and sections are bolted together with a flexible seal (usually butyl or silicone). When this seal breaks down, water ingress occurs. Subsequently, any coating that is bonded to these joints is going to be subject to the same structural and thermal movement.

Bonded membranes:
These are very similar to liquid coatings, in that they are roofing membranes that have become recommended gutter solutions. The level of preparation for bonded membranes is the same, too, as the systems rely on successful bonding of the membrane to the substrate, but also to themselves. Whilst the membranes are strong and reliable, particularly PVC and EPDM, they are a roofing membrane which is designed to shed water and they rely on adhesives for bonding. This leads to real issues when it comes to components such as outlets, stop ends, transitions and boxes as many of the joints are site formed and consistently under water. In reality, there are not many full gutter refurbishments that use a bonded membrane, and they tend to be used as a repair system, particularly the hot melt bitumen systems.

Fold-out systems:
A fold out system is a factory engineered system. When a detailed survey of the existing gutter and its components is required, the factory then produces the system to suit.
Fold out systems are formed of a steel tray with either a PVC or EPDM membrane bonded to it, usually in 2.8 or 3m lengths and the joints in the membrane are either welded or bonded. Being a rigid system, this is very good for gutters that have lost their structural integrity, however due to its rigidity, it struggles in gutters that are uneven or not consistent in profile along their length. The bolts joining the sections of the original gutter have to be covered, so the solution is to install a sole board to give the new gutter a base to sit on which compromises the profile. When it is installed into a gutter that has roof overhangs or is uneven in profile, the sections have to be manufactured so it will fit.

In order to get this system in, it has to be smaller than the original gutter. This can compromise the capacity of the gutter and lead to a risk of overflowing. Although less preparation is required than a liquid or bonded membrane, installation times are longer due to the number of joints needed between the sections. Detailing between the new gutter and the existing roof is also crucial, as the runoff from the roof needs to be contained within the gutter and not be allowed to track behind it.

Loose lay systems:
The same is also true for a loose lay system, but an advantage of this system is that it is flexible and easier to detail, as opposed to a rigid system. Because looselay systems are flexible, they are a jointless pre-creased lining which copes easily with uneven gutters. The components within the gutter are single moulded units that are hot air welded to the lining to form a continuous membrane, as opposed to a jointed section of the ridged system. Non-bonded membrane systems are a continuous roll, with all the components being factory formed, which reduces complexity and labour time on site. Preparation works are also greatly decreased as the existing gutter just becomes a carrier which needs to be structurally sound and have all sharp edges removed to maintain the capacity of the gutter.

Balancing quality and cost

At the end of the day, a key factor in considering what type of gutter lining system you need is how much you want to spend vs. the level of quality and durability it will give you. Site applied or created systems will have lower material costs, but much greater labour costs, and rely heavily on the workmanship and conditions they are fitted or applied in. They also tend to have shorter guarantees. On the other side, factory manufactured systems will have higher material costs but lower labour costs as the time required on site is much less. The consistency of these systems is also much greater as they are less dependent on the skills of the installer. Subsequently, these systems will have longer guarantee periods.

Making the final choice

Let’s put these factors into a realistic scenario. If I had a gutter with issues, that was in need of repair or leaking, I would assess how long I need it to perform for and the gutter’s current state.

I would dismiss the bonded membrane as these are not reliable as a long term solution and are only really a repair system. If I had structural failure, where I would require a total replacement but this option wasn’t practical, I would choose a rigid system. In doing this however, I would have to accept that the high material costs would still be more cost effective than a total replacement and all that the process would involve with the level of disruption to the building. Using it for a lining system where my existing gutter is still structurally sound would have too many compromises in terms of capacity, number of joints and costs.

In practical terms, the most effective choices are either a liquid or loose lay system; they are both seamless, maintain capacity and can be used in a large range of gutter constructions. Loose lay systems are good long-term options as they have a robust membrane and usually have the longest guarantee.

For a short-term solution, I would favour a quality liquid system like silicone that can cope better than other systems with movement, however I would note that a system like this would need careful maintenance as the membrane is easily damaged, and failed areas would need re-coating. Another facet of liquid systems is that regular inspections would be required to check for delamination areas.

While the overall view is that because material costs are the lowest for a liquid system it is the best when compared against the higher material costs for the loose lay, labour costs are usually forgotten. In reality, when both are compared with the labour costs included, the cost differential is probably only 10% for a complete installation. When factoring in the life expectancy and robustness of the systems, where the loose-lay is going to be at least 50% greater, then I would brave the extra initial cost in exchange for the long-term reliability and more importantly the guaranteed leak prevention that comes with this.

To find out more about HD Sharman’s gutter & roof refurbishment systems, please visit the website here. 

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