Technical Butyl

Gloomy economic forecasts coming out from the Treasury and industry analysts are making all buyers look very closely at the products they source. It is now becoming even more vital that the correct product is used in the correct place.

Despite its low cost in the overall spend, butyl strip sealant is no different in this respect to any other product used in the construction of a roof.

Preformed butyl strip sealant is a highly technical, engineered product vital in a componented roofing system yet it is often grossly undervalued. Butyl sealant has been specified and used by the industrial roofing sector for many years and has more than demonstrated its longevity and ability to complete the building envelope. Part L of the Building Regulations requires buildings to meet demanding standards of air tightness and thermal performance and butyl sealant plays an important role in ensuring compliance.

As the leading UK manufacturer of butyl sealant, Hodgson Sealants Limited makes an enormous range of butyl sealant at its state of the art production plant in Hampshire. Produced to stringent quality standards, Hodgson can offer the butyl best suited to a particular application and supplies preformed strip to many industries in the UK and throughout the world. Recent investment of £1.5million in a state of the art continuous butyl-mixing machine demonstrates the commitment of Hodgson Sealants not only to the roofing and cladding industry, but also to a reassurance of quality and a long-term involvement.

Alongside this production facility and based at the plant is our Technical Department, providing experienced and professional help to all users and specifiers of Hodgson Sealants’ butyl. Well-equipped laboratories allow on-going research and development and provide a technical back-up service. Off-site third party testing is provided by independent, accredited establishments with which Hodgson Sealants’ technical officers have established links over many years.

Hodgson Sealants’ GCA butyl was developed as a result of development work that led to the NFRC Class A standard, a benchmark also endorsed by the MCRMA. This Class A certification was awarded by an independent testing house. GCA carries a 12 year Warranty and remains the workhorse butyl for sealing end and side laps on built-up and composite roofing systems. Installed correctly and used in association with Polyband to seal the side laps of liner sheets, it will help to ensure that the roof is both weather tight and airtight.

In order to meet the on-time demands of the industry, Hodgson Sealants works alongside a distributor network that is professional, knowledgeable and reliable. These distributors hold stocks of core size product so that the supply chain to site is as smooth as possible.

However, do you know what is actually being supplied to site? Hodgson Sealants’ GCA for example, is easily identified as the removable backing paper on the reel is printed, boxes are clearly labelled and every batch is traceable, but as costs increase and budgets shrink there is a temptation to cut corners where they will not be seen. It is ever more important that sourced material comes from a reputable manufacturer and partner Distributor, backed by a stringent quality standard.

Increasingly however, the ability of a butyl strip sealant to meet the Class A standard should be the starting point, the entry level of quality for a butyl to be used in this application.

The evolving design of roofs, changing roofing systems, longer roofing sheets and panels and not least, the increasing demand for long-lived building envelopes have contributed to greater demands being made of all the components within the roof. The most obvious of these has been that sometimes guarantees are expected that exceed the normal “service life” of a component. In these cases, one has to look higher.

This has been reflected in the availability of higher performance butyl strip within the roofing and cladding industry. Products are now supplied with Warranties of up to 25 years, originally designed to meet the need of PFI and higher specification contracts. If the specification being looked at calls for a higher performance butyl, then either the manufacturer or the distributor network should be consulted.

Working together in this way means that the correct product is supplied for the project in hand.

The roofing and cladding industry makes many demands of the products used within it. They are expected to perform in a wide variety of environmental and climatic conditions for varying periods of time.

The range and grade of butyl sealants traditionally supplied to roofing contractors has been doing and continues to do a very good job and this should be recognised. The greater emphasis on cutting cost has tempted some to look for a sealant product that was recently described to me as “sticky stuff”, but attitudes have to change.

Joint designs are being revised and sometimes product is specified in an application that has not had any real-time or “live” data gathered. This, combined with development work within the laboratory and growing experience of what actually happens to a roof over time, has led to a growing realisation of how important the performance of the building products used within the construction are.

Callbacks to site are always inconvenient and incur a cost, but product failure can be catastrophic. It is worth remembering that “best” is not necessarily cheapest, nor is cheapest necessarily “best”. To explain, there are many different formulations to make butyl but there is no “best” formulation, there is simply the formulation that is best for the job in hand.

A butyl designed to work in the automotive industry for example, will not be the same as a butyl intended for pond liners.

Development projects currently under way are examining the sealing of end laps and revisiting earlier work done. This work is throwing up some very interesting data and forcing us to re-consider some practices that appear to be in need of revision. What is becoming ever more apparent, however, is that the correct installation of the butyl sealant strip is crucial to the integrity of the building envelope. Unless the butyl sealant within the joint is put under positive pressure by the fixing method the seal will not be intact.

Research shows that along an average end lap joint, this compression can vary enormously. In this scenario, this means that along the finished joint the sealant will vary in compressed width and thickness and also in adhesion to the panel surfaces. Basics such as using the correct number of fixings and the spacing of fixings are, at times, neglected.

The many millions of metres of butyl strip sealant used on the many millions of square metres of roofing panels demonstrates conclusively that butyl can help to provide a trouble free componented roofing system.

MCRMA Technical Paper No 16 Guidance For The Effective Sealing Of End Lap Details In Metal Roofing Constructions should also be consulted. New ideas are leading to new products, which will compliment and enhance new specification design and we at Hodgson Sealants are there to assist.