After considerable research, Ian was fortunate in tracking down 750 Hi-Strength 7N Thermalite floor blocks for his extension project

As far back as Autumn 2013, worrying rumours were starting to circulate about supply problems with building materials, particularly bricks and blocks. The blame for these shortfalls was generally laid at the door of firms who’d mothballed factories after the 2008 downturn and had been slow to ramp up production as demand soared in line with a resurgent housing market.

To make matters worse, the press was full of reports to the effect that skilled brickies were becoming an endangered species. However, there was a distinct sense of déjà vu about all this.

The building materials industry has long been notoriously prone to ‘roller coaster’ volatility, suffering periodic shortages that somehow don’t seem to afflict other products and markets. What’s so surprising this time round is that a full three years later problems have stubbornly persisted, with supply and demand frustratingly failing to realign, a phenomenon economists refer to as ‘market failure’.

The Impact on your Project

It’s hard to think of a component that has greater importance for the majority of residential construction projects than aerated concrete blocks. Also known as ‘thermal blocks’, or simply referred to by brand names, such as ‘Thermalite’ or ‘Aircrete’, they are favoured principally for their excellent thermal insulation properties which go a long way to helping designers meet demanding Building Regulations U value targets.

With a major extension project about to commence on site in a matter of weeks, alarm bells started ringing in my ears when a delivery driver for a national builders’ merchant commented: “We just can’t get Thermalites anywhere at the moment — no one can.” The prospect of a deepening famine of thermal blocks could not have come at a worse time for me, with decision time beckoning for placing large orders.

As with most building materials, the ‘shopping list stage’ for bricks and blocks comes after many months of deliberation on matters such as aesthetics and cost as well as structural and thermal performance. All the various planning hurdles will have been navigated with additional input provided by structural engineers and building control. Blocks are specified in terms of density, load-bearing strength and thermal efficiency (known as K value or lambda), so any changes at this stage can mean going back to the drawing board.

Another consequence of the recent block famine is that trying to order large quantities at low prices isn’t easy when you’re lucky to get any supplies at all. Yet, with labour rates having recently rocketed to over £200 a day, keeping a lid on material costs is more important than ever.

Although shortages don’t seem to have driven up headline prices, the collapse in global oil, gas and commodity prices over the last couple of years should, in theory, have driven prices down, with big savings both in manufacture and transportation. Suppliers are naturally reluctant to ‘give away’ precious stocks at deep discounts, however.

To be fair, builders’ merchants have had a tough time in recent months, with supplies of bricks and blocks rationed, put on meagre ‘allocations’ or worse, let down at the last minute with cancelled deliveries, prompting flurries of flack from irate customers further down the line.

What’s Behind the ‘Famine’?

The big question, of course, is what lies behind this extraordinarily longstanding supply shortage? Stories abound of housebuilding giants renting entire fields to stockpile huge volumes of blocks. Manufacturers tend to prioritise major housebuilders who order in quantities of millions and are supplied direct. But ‘panic buying’ and stockpiling are really only a secondary cause.

The key problem has been a paucity of pulverised fuel ash (PFA), a by-product of coal-fired power generation and a vital raw material. This is partially an unforeseen side effect of government policy to reduce the number of coal-fired power stations in favour of ‘greener’ methods of energy generation such as gas, nuclear or renewables. The problem of dwindling supplies of PFA has been hugely exacerbated because last winter was unusually warm and oil and gas prices were exceptionally low, with the net result that our few remaining coal-fired power stations were under-utilised.

When you factor in sharply rising orders for PFA-rich aerated concrete products as well, you have a perfect storm of enhanced demand at a time of reduced supply. There are other possible contributing factors, such as a leading block manufacturer deciding to temporarily shut down a major plant for maintenance in May 2016. Some also point to the fact that nearly all large UK manufacturers of building products are now part of international groups based abroad, perhaps making them less responsive to the UK market.

What are the Alternatives?

If you can’t get hold of the blocks you need, what options are open to you? The obvious danger with projects already on site is that out of sheer desperation anything that comes to hand might be used, resulting in a building that doesn’t comply with Building Regulations, leaks heat or is prone to structural problems.

Although far from ideal, there are reported instances of designs successfully changed mid job, substituting ‘colder’ dense blocks, which in turn necessitates wider cavities with thicker insulation to make up for their inferior thermal properties. But this can have potential implications for internal dimensions, fittings and floor space, as well as possibly adding to labour costs.

A possible solution for my own extension project presented itself thanks to a local structural engineer who was familiar with a lesser-known type of block. Plasmor’s Fibolites, despite sounding vaguely reminiscent of a 1960s soul group, are dense blocks made from expanded clay aggregate, popular with brickies because they’re extremely low weight (the manufacturers claim ‘one-hand-lift laying’) and resistance to shrinkage.

Although not quite up to Thermalite standards they still achieve an impressive K value of 0.025W/m2K, which can easily be accommodated by upgrading cavity insulation slightly in order to exceed the U value target of 0.28W/m2k for main walls.

Unfortunately, I wasn’t the only one to select Fibolites as an alternative, so supplies were limited too, although still obtainable. After a spot of due diligence it transpired that builders’ merchant Huws Gray in North Wales had large stocks at reasonable prices. But the cost of long-distance delivery (I’m based in the south-east) coupled with restricted site access for articulated trucks knocked this idea on the head.

Taking the bull by the horns and phoning the manufacturer paid dividends, helping to ascertain which local merchants already had bulk deliveries earmarked. As luck would have it my nearby Buildbase had two artic deliveries scheduled (25 packs — with 96 blocks per pack). The upshot is there’s a pile of 2,400 blocks now on site.

We also had to adopt a flexible approach when it came to ordering the specified Thermalite trenchblocks (300mm wide for use in foundations), which were also in short supply. Thankfully it was a fairly straightforward process to substitute these with standard concrete blocks and Class B engineering bricks, with no significant increase in labour costs.

Moving Forward

Every shortage has a silver lining for manufacturers of competing products who stand to benefit from a windfall. Suppliers of alternatives to conventional blockwork construction such as timber frame, SIPs (structural insulated panels) and ICFs (insulating concrete formwork) may have enjoyed a consequent boost (with the proviso that many of these wall structures are clad with a masonry outer leaf).

Smaller UK manufacturers like Besblock and Plasmor have similarly benefited from a corresponding surge in demand. Block shortages have also prompted interest in related materials such as the Porotherm clay block walling system, and may even spawn a revival of traditional limecrete or natural hempcrete blocks.

Probably the most obvious solution, however, is for block manufacturers to identify a suitable replacement raw material. Firms like H+H Celcon are modifying their manufacturing processes to use stockpiled PFA (which apparently has different performance characteristics from the fresh stuff), and have negotiated purchasing contracts to secure future supplies of imported PFA (although the weaker GBP post-Brexit is likely to make imports dearer). And if the British winter this year reverts to ‘normal’, power stations will burn more coal, increasing the volume of ‘home-grown’ PFA.

There is however one cloud on the horizon. In July 2016 brick-making giant Forterra (formerly Hanson) announced it was planning to mothball two plants in Lancashire, both of which were closed between 2010 and 2014. It’s claimed that production can be brought back online in a short period of time.

So what does the future hold? When it comes to crystal-ball gazing few people are better placed than Steve Kendall, brand stock controller at one of Buildbase’s biggest branches in Cowley, Oxford. According to Steve, things are starting to pick up after a dry spell in May and June when all the big merchants found it virtually impossible to source thermal blocks.

“Bricks are not as bad as blocks — two years ago bricks were on a six-month delivery. The picture is now improving with more imported blocks and ships coming over loaded with PFA from coal-fired power stations in countries like India and China.” If problems continue, builders’ merchants are increasingly prepared to source products from far flung countries such as Dubai. Not great news for the UK trade deficit, but at least it will keep Britain building!

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