Think there's nothing new and different about building a masonry home? You'd be wrong. Brick, block and concrete manufacturers are rising to the challenge to innovate. As Building Homes next month hosts its own conference: The future for masonry-built homes, We tour some of the innovations.
Hit the walls on the inside, they sound hollow. They have done for 20 years on Persimmon Homes' product. But now if you hit the walls on the outside they may sound hollow as well. Yet here is a company that remains wedded to masonry build. "We still think brick and block is the best way of building homes," says Persimmon's construction director Don Mason. But the house the company has just completed in Milton Keynes' Emerson Valley is hardly brick and block as we know it: bricks slips and 215 mm aircrete blocks, all held together with glue.

Superficially, the house looks much like its neighbours: plastic windows, concrete roof tiles and a weathered brick exterior. This look is important to Persimmon. Mason comments: "We find that people are scared of unusual appearances. These systems give us the scope to build differently while maintaining the style of an ordinary home."

There are two elements to the construction of this house which are new to British homebuilders. The first is the use of Hanson's TiS brick slip external cladding system. TiS has been supplying brick claddings to the likes of McDonalds and Burger King for some time but since Hanson purchased the company recently the emphasis is moving towards the homebuilding market where skills shortages have roughly trebled the cost of bricklaying in the past ten years. Until now, housebuilders have tended to steer clear of brick slip systems because they perceived them as expensive, but with labour costing three times more than materials, anything affordable that offers reduced labour times is welcome.

Persimmon seemed impressed by the time saved. "The brick slips took six days to install, about half the time it would have taken to lay bricks conventionally," says Jim Annetts, the site manager who monitored construction. "There was quite a bit of head scratching initially. I feel sure if we undertook more schemes we could reduce the time still further." The 25 mm thick brick slips were each individually glued onto the supporting panels and then mortar was gunned into the joints and pointed.

The other innovation being trialled here was H+H Celcon's Jamera system. This is a marriage of thin-joint or glued blockwork with reinforced aircrete floor and roofing planks. In Finland, where the system originates, Jamera is used extensively for upmarket houses at block widths of up to 375 mm, often with very little internal finishing. In the UK, Celcon is investing £25m in a production plant in Yorkshire to supply developers with a simple system that meets the requirements of the new Parts L and E of the Building Regs and crucially reduces on-site labour times. Again, Jim Annetts was impressed: "The floor planks arrived on site at 8.30 one morning and by 11.30 we had them all in place. Beam and block would have taken all day and still needed grouting." The floor planks are all 240 mm deep and can span up to 6 m. They can also be used as roof cassettes though to date no one in the UK has tried. The external thin-joint block walls on this house are 215 mm Celcon Solar, a familiar product to UK builders though not at this thickness. Annetts says his blocklayers had no trouble with the 100 mm Celcon internal walls but struggled to master the wider blocks in the external walls.

The meat in the sandwich between brick slips and blockwork is a panel of 50 mm of expanded polystyrene onto which the slips are glued. This produces an overall wall thickness of 285 mm, just 10 mm more than Persimmon's norm, yet the U value is just 0.27, well in excess of the 0.35 required by the new Part L.

Internally, the house is finished to Persimmon's normal standards, though this design has been tweaked to accommodate two bedrooms in the roof, each with its own bathroom. The Finns like their aircrete raw, either painted or finished with a thin-coat spray plaster, but Persimmon has continued with its time-honoured plasterboard on dabs. But with dryliners commanding rates as high as bricklayers, perhaps this could be the next area of focus for homebuilders.

Whatever happened to Panablok and Quickhome?

It is four years since Marshalls’ Panablok featured in Building Homes’ Innovation Awards. At the time the strutural insulated panel drew a mixed reception from our panel, many of whom thought it was just too radical for the UK, but times change. Panablok consists of two skins of cement particle board sandwiching a phenolic foam core: the edges of the board are tongue and grooved and they slot together with a locking device: the bottom and top edges slot into a steel channel. It comes in standard 1200 mm widths and at three standard heights. Panels can be cut on site with a saw - which is how openings are usually formed. During the last year, Panablok has been used to build around 150 homes in the UK. “I don’t think we’ll ever make a huge impact in the speculative homebuilding market but we’ve found a good niche on three-storey flats where we are competitive with concrete,” says Panablok’s general manager, Wade Rowlett. The system continues to develop and Marshalls is developing a brick slip wall with Taylor Maxwell, the brick factor. The slips, known as Gebrik, are made in Belgium and, when used in conjunction with Panablok inner walls, can produce a fully finished wall with a U value of less than 0.25 and a thickness of under 150 mm. The first Panablok/Gebrik development is on the drawing board and should be completed by the end of this year. Meanwhile Roger Bullivant’s Quickhome, the ultimate precast concrete panel system comprising inner walls, floors and foundations, is still awaiting its first site trial on a 12-unit Manchester scheme for Northern Counties Housing Association. The project is aiming to cut build time by a third, and Bullivant’s objective is to reduce construction cost to £600 per m2.

The low-down on basements

Laing Homes has built homes with basements on one or two sites before, but at its Canons Gate, St Albans site it has used a precast walling system for the first time (above). The walls were made in Suffolk by ThermoneX, a UK company set up to develop a Swedish technique using lightweight waterproof concrete. “Having tried and tested traditional reinforced concrete basements we began searching for alternative techniques which could significantly reduce construction time. Simpler precast foundations mean a single basement can be built in a day,” says Laing Homes North Home Counties MD Stuart Wallace. The eight Laing homes have living areas above basement level. Below ground they follow continental European style with space for garaging, laundry and storage. As the site slopes steeply basements can be accessed from ground level at the front of the houses. Most basements are still built in situ but the installation speed and accuracy of off-site manufacture have seen prefabrication take a significant market share, notably in Germany. Prefab basements have been imported into the UK before but manufacturing ThermoneX’s walling systems in the factory at Brandon, Suffolk will reduce costs. The basement walls can be finished ready for decoration or can be finished with traditional materials such as drylining or render, and electrical boxes and conduits can be cast into the walls in the factory. “By building a basement, most developers can either increase their floor area substantially or reduce the size of the building’s footprint,” says ThermoneX MD David Aulton.

Conference on masonry’s future

Building Homes is hosting a conference on The future for masonry-built homes, next month in Birmingham. The conference will look at amendments to Parts L and E of the Building Regulations, and masonry innovations including Celcon’s Jamera system. To book your place at the conference, telephone JSB Marketing Services on 01793 881946.

Source

Building Homes