Having tracked down a missing piece of the jigsaw puzzle, I thought it was worth updating and re-posting this post from 2016 about Dorran Construction and W, T & H Dye Builders. By accident, it’s begun to evolve into a snapshot of housebuilding in Tayside during the 1960’s and 70’s.

During the 1950’s, the Hull construction firm of R.G. Tarran, builder of the Tarran Prefab, adapted the former dyeworks of Pullars of Perth to produce the Dorran House, a single-storey bungalow built from precast panels.

Dorran houses are like Structural Insulated Panel Systems or SIPS houses, but pretty much without the “I”. The Dorran system consists of storey-height precast panels which are 16 inches wide, which seems an odd width for a structural module, but we now live in a world which has the luxury of setting out in metric, usually on multiples and fractions of 2.4 or three metres.

Whether Dorran licensed the system from Tarran, or the company was a direct subsidiary, isn’t clear – but during the 1950’s, they sold to the public sector with houses for the Forestry Commission in outlying parts of the Highlands, small developments of social housing in rural counties such as Argyll and Caithness, and even domestic accommodation at RAF Saxa Vord on Shetland.

Dorran Construction later offered a range of bungalows to private buyers; the housetypes had couthy names such as The Glen Shean, The Glen Varloch, The Glen Frugart and The Glen Clova. By the 1960’s they were fabricating around ten houses each week at their precast factory in Perth, and a total of 2500 had been erected by 1962.

According to the Building Research Establishment (BRE) report I consulted, two-storey Dorrans have a characteristic protruding band at first floor level, like a string course, formed by a precast ring beam. Timber floor panels were strapped to the ring beam with joist straps, and the precast panels were tied together using steel bolts. Some Dorran bungalows appear to have a concrete ring beam at ground level, too.

For vapour control, the concrete panels were lined with 2-ply bituminous felt as a damp-proof membrane. When the wall was erected, the joints were filled with gunned bitumen, then pointed up in cement mortar. Interestingly, a newspaper article from the 1960’s notes that one of their outstanding features was the level of insulation in the walls and ceilings. A half-inch-thick internal layer of expanded polystyrene sat between the concrete panel and its plasterboard lining … half an inch, which is laughable nowadays, but better than nothing.

By the 1970’s there was disquiet about non-traditional methods of construction, and two of the Dorran houses’ failings were shared by several other systems. The panels’ lack of decent, continuous insulation led to condensation problems, and serious corrosion of the steel ties between the panels was a by-product of that.

The BRE diagnosed the problems during the early 1980’s, which eventually led the designs to be designated under the Housing Defects Act 1984, which effectively condemned them and made them un-mortgageable. However, the 1984 Act was soon consolidated into the 1985 Housing Act, which provided grant assistance for people who had unwittingly bought former council houses constructed using problematic systems.

Perhaps if the Dorran system had been constructed using stainless steel fixings, and with effective insulation, the design might have succeeded. As it is, the remedial works entailed in fixing the problems range from adding a masonry skin outside the precast panels, to propping the roof then demolishing the panels and building a brand new external wall. Instead, many chose to demolish the existing house and start again, often building a timber kit on the site instead.

While it’s true that we probably won’t make exactly the same mistakes again in future, we may make slightly different mistakes in pursuit of the same goals. A few years ago, I worked on a project with some of the first zero energy houses in Scotland, built using a SIP system comprising JJI joists skinned with OSB board, and a cavity filled with injected cellulose fibre.

There have been no insulation or corrosion issues that I’m aware of – but the high degree of airtightness meant that when tenants switched off the whole house ventilation system (because they were concerned about running costs) they suffered from condensation problems in kitchens and bathrooms.

A different kind of prefabrication, a new type of problem, caused partly by a novel approach to design and more so due to poor communication between the landlord and tenant about how the house worked. The other lesson of Dorran Construction Ltd. lies in how we may try to meet today’s unmet demand for housing by using “off-site construction”, which is the new, untainted name for system building, a.k.a. prefabrication.

In the early 1960’s, Dorran looked southwards and after 1964 during which it made a profit of £96,000, the firm opened a precast factory in Consett, and another in London. By 1967 the firm had built 4000 houses across Scotland, but by signing up to fixed price contracts in England during an era of rampant inflation, Dorran committed its fatal mistake.

The company lost money on its English contracts, the factories in Consett and London closed, and the parent firm in Perth struggled to survive. By the time that Dorran Houses began displaying the first symptoms of structural corrosion, the firm was no longer producing them – and the post-war housing boom was over. As demand slackened, the industry pulled back from mass produced housing.

“House factories”, the dream of technocrats and Le Corbusier alike, are much trickier to achieve in practice than you might think. Dorran Houses have been condemned, both literally and metaphorically, as a failed experiment in mass production. After the 1984 Act, mortgage lenders viewed precast panel houses as “Non-Traditional” and as far as most buyers were concerned, that euphemism was the kiss of death for prefabrication.

Another name from Tayside during the 1960’s and 70’s is W, T & H Dye Ltd. which was founded in Dundee around 1959 and fell into liquidation in 1988. In the intervening thirty years, William, Thomas and Harry Dye were less radical than Dorran, and they targeted a different market. If little has been written about Dorran, I’m not aware of anything at all about the Dyes.

Their family-run business generally built their own developments. They concentrated on small sites in the West End of Dundee, Broughty Ferry and Monifieth, and their houses were thought of as better quality than run-of-the-mill bungalows built by other firms of the time such as Interbuild, Pat Dempsey or McCabe. Dyes typically built cavity wall detached and semi-detached houses, with harled walls and panels picked out in Fyfestone. The 1960’s houses between Victoria Street and Grange Road in Monifieth are typical of their output.

The Dyes didn’t attempt to compete directly with Bett Brothers of Downfield, who were Dundee’s largest housebuilder for several decades. Betts built thousands of houses in the western, northern and eastern suburbs of Dundee – plus Perth, Fife and Aberdeen too. Before they were taken over by Gladedale, they were Scotland’s biggest house developer north of the Central Belt.

Betts employed their own architects, including Bert Stevens and the late Ron Valentine who later worked in partnership together. While I was preparing a portfolio for my architecture school interview, Ron Valentine kindly set aside a morning to chat about the course, show me his own drawings from Duncan of Jordanstone, and offer some pointers.

A year or two after I published this piece, the son of one of Dyes’ directors, also Harry Dye, got in touch. He was generous with his time and very helpful in providing more background about the family firm, but he pointed out that some of the developments I highlighted in Barnhill – including a couple of dozen houses on the Dalhousie Feus in Ardmore Avenue, half a dozen in Holly Road, and a couple in Navarre Street – weren’t actually built by Dyes at all.

As I’d relied on anecdotal information, I held my hands up and promised to track down whoever did build those houses in Barnhill. Their facings in Leoch stone, harling and natural slate roofs combined to create what one ambitious estate agent described as “Voysey-style” bungalows. Not quite, but some of their larger houses were vaguely Arts & Crafts in a watered down fashion. While a Bett bungalow in the area we’re talking about now sells for upwards of £200k-£250k, the houses in question are now worth at least £300-£350k.

People notice the difference in quality, and there’s a reason why many homebuyers are conservative. Most have little say in what their house looks like or how it’s built, yet they tie up most of their wealth in it and sink much of their sense of self into it, too. “Traditional” housing has always been popular: partly because it’s time-proven, and also because it doesn’t lose its value in disastrous ways, like Dorrans’ houses did.

The developer of those houses in Barnhill built in the spaces left behind by other developers – they were evidently happy to achieve a slow and steady rate of sales on gap sites. They built on ransom strips, backlands, landlocked plots and spaces left over after planning. The rising tide of land values means that the quarter- or fifth-acre parcels they used are now only a seventh- or even an eighth-acre in area!

Nowadays, small-scale developments avoid Planning Gain and Section 75 agreements (providing parks, playgrounds, contributions to roads schemes and primary schools), and the complexity of SUDS systems using swales and constructed wetlands. The developer in Barnhill avoided those too, but one giveaway is that some streets have unmade pavements and unadopted roadways: they were “unbonded” developments. In other words, there weren’t financial bonds in place for the roads and sewers when the development was completed, so the local authority wouldn’t touch it.

On reflection, “barriers to entry” for this type of housebuilding seem low. Many joinery firms entertain the idea that if they can build houses, they should also be able to put together developments of houses. But the functions of a developer – land acquisition, finance, project management, marketing – are very different to those of a builder, and for the past thirty years they’ve become ever more complex.

Similarly, with the coming of the timber kit from firms like Interbuild and Stewart Milne, cavity walls with stone facings became an anachronism. Also virtually gone are the “All Trades” building contractors who directly employ their own concrete workers, bricklayers, masons, workshop and site joiners, roofers, painters and decorators. Likewise firms with joinery shops which can manufacture their own doors, windows and stairs: the best you can ask are Howden kitchens, Magnet doors and kit panels rattled together with a Hilti gun.

As a consequence, houses are built to meet the ruling standards of the day, but the construction is less robust with gang-nailed trusses rather than couple roofs, and timber kit walls versus cavity masonry. They’re generally finished to a lower standard, with flush ply versus panel doors, and MDF rather than hardwood facings.

Traditionally-built houses from the 1960’s and 70’s would be tricky to procure in large numbers nowadays, but they’ve proven to be a remarkably good store of value over the past half-century. Perhaps, depressingly for those with a “social” model of housing in mind, that’s the real message.

Meantime … the final piece of the jigsaw? A few days ago, I discovered that the houses in Ardmore Avenue, Holly Road and Navarre Street were developed and built in the early 1960’s, by Hills Brothers of Brechin. That firm wasn’t even on my radar, so there’s another rabbit hole to disappear down. Perhaps they were designed by a local practice, in the same way that the now-forgotten architect James A. Fraser of Blairgowrie designed houses for A&J Stephen of Perth during the 1960’s…?

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