The number of roof penetrations on commercial buildings has increased dramatically in recent years. This is particularly evident on mission-critical buildings such as data centres, hospitals and airports. These buildings tend to have more services such as HVAC systems, plumbing vents, electrical conduits, smoke vents, data and comms systems. Add to that green technology, such as heat pumps and building management systems, and not only are there more penetrations, but they’re often extremely complex too.
High-quality weatherproofing of these roof penetrations is essential due to the UK’s variable and often harsh conditions. This should be designed to prevent water ingress, which can cause mould growth and structural damage, and ensure energy efficiency, air tightness and occupant comfort.
DON’T COMPROMISE PERFORMANCE
There are a variety of off-the-shelf roof boxes (also known as dog, roof or junction boxes) available for building services penetrations. They’re factory-made and come in different sizes and specifications to accommodate multiple pipework and duct runs. It’s easy to fall for the trap of the convenience of ‘othe-s-helf’ solutions. The requirements of the building service design are rarely known during the early stages of a project. So, roof boxes are marketed for their ability to accommodate more services than might be anticipated.
Bigger is better, the marketing tells us, but space on commercial roofs is at a premium. Additionally, while building services roof boxes are insulated, when compared to modern roof U-values they are still a comparatively weak point in the thermal envelope. The larger the box, the larger the penetration through the building envelope and the more significant the thermal bridge.
If they’re not installed to the manufacturer’s specifications (and they often aren’t), then the weatherproofing, energy efficiency, air tightness and comfort are all compromised. Furthermore, building services roof boxes are not designed with the aesthetics of a specific project in mind. They are, of course, well finished, but designed to be a universal solution to an issue unique to each building. They are purchased to perform a function; not to align with the architect’s vision for the finished building.
PERFORMANCE AND AESTHETICS
Involving a specialist weatherproofing contractor at the concept stage means they form part of the design team. They can work closely with the architect, M&E consultant and principal contractor to design, manufacture and install a high-performance weatherproofing system that works with the building.
One of the key benefits is adaptability. A bespoke cold-applied liquid solution can be designed to accommodate any type of roof system, which helps to prevent design conflicts between building systems. The solution can also be tailored and refined as the build progresses, ensuring it can cater for the vast and complex array of penetrations that will be needed even as building services requirements change.
Bespoke weatherproofing solutions require no fixing joints – traditionally a weak point in off-the-shelf solutions. This helps to mitigate risk and ensure that the building delivers its theoretical performance when built.
Early involvement means the contractor can offer a dependable schedule of service and a high degree of installation flexibility that works with the sequencing of the project, helping to deliver on time and to budget. This gives principal contractors reassurance that their programme schedule is less likely to be disrupted.
Cost may also be worth considering. Off-the-shelf solutions are generally assumed to be cheaper than a bespoke weatherproofing service, but this may not be the case. Once you factor in the purchase of the product, the delivery and installation of the roof cabinet, the overall cost is comparable to a bespoke solution. Additionally, roof boxes usually come with a five-year warranty as standard, while many bespoke solutions are backed by more robust warranty periods, which offer significant benefits and highlight the confidence a bespoke solution can afford a project.
So, while off-the-shelf building services roof boxes may seem to offer a short cut to convenience, they fall short of delivering the performance and aesthetics that modern buildings require. Working with a specialist weatherproofing contractor to develop a bespoke solution offers a smarter and adaptable approach to weatherproofing penetrations. One that complements the design vision and helps to safeguard building performance – something that is essential when it comes to the Great British weather. www.jones-weatherproofing.com