The housebuilding market is increasingly turning to engineered floor joists for new builds in favour of ‘traditional’ solid joists. There is limited independent and current research to back this statement up, but few in the housebuilding industry would argue the point.

Certainly the customers I speak to as part of my role at Gang-Nail Systems confirm that engineered joists are increasingly becoming the product of choice. Solid joists have done a perfectly adequate job for centuries, so why are house builders turning their back on them?

Return on investment

One reason for this trend is return on investment (ROI). The initial purchase price of an engineered joist is higher than that of an equivalent solid joist. In the past, this has put developers off the idea of using engineered joists. However, we are increasingly seeing house builders look at the bigger picture when it comes to assessing their ROI; looking beyond the initial purchase price to the overall savings engineered joists can bring throughout, and even beyond, the build.

Advantages

Let’s take Ecojoist as an example. Marketed by Gang-Nail Systems, Ecojoist is constructed from parallel stress graded timber flanges joined together with engineered ‘V’ shaped galvanised steel webs. Unlike solid timber joists, Ecojoist is made-to-measure, so it is quicker, and therefore cheaper, to install and there is no site wastage. The open web system also makes Ecojoist 40% lighter than solid timber joists, resulting in easier handling on site. The open web system enables the easy installation of all services and has the potential to reduce or eliminate unsightly surface-run waste pipework in bathrooms.

The statistics of major housebuilders, based on thousands of houses completed over the past few years, clearly show that Ecojoist is a ‘zero maintenance’ product. The shrinkage problems frequently associated with solid floor joists are no longer an issue. All housebuilders allow a sum of money for post completion maintenance, so the less they have to spend, the more profitable they become.

So there are a number of points that explain the rise in popularity of engineered joists. But what is interesting is that Gang-Nail Systems has witnessed a particularly strong interest in open web systems, such as Ecojoist. A possible explanation for this trend can be found in the latest proposed changes to the Building Regulations.

Internet cabling

If the government gets its way, Part Q of the Building Regulations will soon require that ducting for broadband internet cabling is fitted as standard in all new homes. The government hopes that this will make it easier for homeowners to install broadband services and help it meet the target of getting the ‘UK Online’ by 2005.

If the regulations are passed, housebuilders will have to install an infrastructure of vertical and lateral cable ducting that allows broadband cabling to be distributed within the building to at least one habitable room on each storey.

To fulfil this obligation, risers would need to be installed to carry cables between the floors of the property, while lateral distribution ducts would distribute the cable to the rooms. The ducts would typically run underneath the floordeck. Bends in the lateral cabling ducts must be kept to a minimum and have a maximum angle of 45°. Where more acute bends are required, access points from the floor above should be provided.

Expectations

Meeting these regulations would be extremely difficult using a solid floor joist, requiring a great deal of time and skill to cut passages through the joists along which the ducts could run. Part Q makes it clear that bends in the ducting must be kept to a minimum so specific routes would have to be created.

Open web joists, on the other hand, remove the need to notch or drill for pipes and cables and could make it significantly easier for housebuilders to meet the proposed requirements. If the regulations are passed, or even if the government chooses to publish the recommendations as a guide for good practice, I think we can expect to see a sharp rise in the use of open web engineered floor joists.