Sixty years on from the construction of its first UK factory, Professional Builder looks back at the development of H+H and its iconic Celcon Block in the UK.
2018 is something of a landmark year for aircrete manufacturer H+H. Sixty years since work began on the construction of its first UK factory the company has just unveiled the multi-million pound rebuild of its Borough Green plant in Kent.
That’s a pretty sustained record of investment in the UK market, and one which has helped the familiar grey block become an everyday feature of sites across the country. But what is its main appeal and what’s changed over the last six decades?
Of course the essential characteristics of aircrete haven’t changed a jot. It remains a robust building block which is lightweight and easy to handle – used for internal and external walls, foundations, floors in beam and block construction, party walls and spandrels.
Back in 1958, aircrete became popular for just that reason: easy to lift, easy to cut, easy to use. In the 1980s a dramatic Celcon video, introduced by the presenter of BBC Tomorrow’s World, illustrated the point by throwing a Celcon Block into the Thames and filmed it floating. All those air bubbles make for a block that, despite its strength, is light and buoyant.
It wasn’t until the fuel crises of the 1960s that building regulations started to consider the thermal insulation of houses
and first introduced a maximum U-value requirement for external walls (1 W/m2K at the time). Suddenly the insulating properties of aircrete became as interesting as its light weight.
In 1981, Building Regulations tightened (maximum U-value now 0.6 W/m2K) and the proposal that cavity walls could be built to this performance using an aicrete inner wall, brick outer leaf and no insulation at all proved extremely appealing.
Move on to the 2013 revision to Part L of the Building Regulations and H+H was busy demonstrating that an external wall with a 100mm fully insulated cavity could meet the tighter performance requirements. The Government-funded AIMC4 project also proved that a “fabric first” approach, using aircrete, could provide homes to meet the (then) Code Level 4 standard and be cost effective when compared with other building methods.
It would be great to think that innovation alone changes markets – but H+H’s experience is generally that real innovation only takes off when external factors force the industry to consider new solutions.
Consider Thin-Joint as an example. Thin-Joint methods produce more airtight, more dimensionally accurate houses that can be built at much higher speed than standard block structures: the method is also proven, having been available for decades across Europe. H+H introduced the system at the Interbuild exhibition in Birmingham in 2000, yet still the method tends to be seriously considered only when very high performing structures (such as Passivhaus or the AIMC4 project) are required.
It took the NHBC, reporting on a worrying rise in claims on faulty foundations, to change the way foundations were designed in the late 1980s. Suspended foundations with beam and block floors came into the mix and H+H was ready with its foundation blocks and High-Strength Blocks for three-storey constructions.
The same may prove to be true of Celcon Elements – our storey-high aircrete panels. It was in the early 1980s that H+H began building using a panelised system in Europe but there was little interest in the UK.
Move the clock forward to the present day and the I-House system, based on a combination of Celcon Elements with prefabricated timber floors and roofs, is now generating huge interest as a means to build masonry homes fast using components that have been fabricated offsite.
H+H has certainly never lacked imagination. Its Jamera house system, unveiled in the early 2000s, provided a package-build solution for new homes. This was the ultimate aircrete demonstration: aircrete foundations, solid aircrete floors and even an aircrete roof structure offered a high performance, high quality build method. Welcomed for its technical performance, Jamera just proved too expensive for the volume housebuilders at the time.
Unfazed, H+H went back to the drawing board and introduced the Rå Build Method. Based on the Thin-Joint system, it’s a package offer providing ground floors, exterior walls, upper floors and partitions. To keep the cost down floors and roofs are timber but technical specification and design support are still provided by H+H.
While the design teams have focused on providing system solutions, the product development team at H+H continues to push the envelope. Standard Celcon Blocks remain the single most popular product in the range, but it is just one product in a family.
Looking for higher compressive strength? Go for the Super and High Strength Celcon Blocks.
Tight dimensional tolerance for accurate (and Thin) joints? Choose Jumbo Blocks and Multi Plates which give greater speed of build too as they are larger than Standard.
Longer blocks? Celcon Plus Blocks are the answer
Finally, for foundations (unsurprisingly) the Celcon Foundation Block.
Whatever developments in the UK housebuilding sector, H+H is confident that it will have an answer – and probably one that has already been tried and comprehensively tested somewhere in Europe.
With such a strong focus on new housebuilding, H+H is looking forward to the next decades with confidence. Whatever the outcome of the current Brexit debate, local sourcing is the name of the game and demand for resilient, fireproof and long-lasting construction materials looks very positive indeed.