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Floor construction

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Adrian Gibney has been working with us in our Truss department for eight years and is responsible for designing and estimating timber floors and roof trusses. Here he tells us about the latest innovations in flooring construction techniques.



Floor construction is not always the highest priority when making decisions about building your home, but it’s an important one that you’ll live with for many years to come. So it’s worth taking the time to look at the various options available to you.

Solid timber joists have been around for a long time and adequately provide what you will need. But new innovative solutions have been introduced to the market called I-Joists and Posi-Joists which provide a range of benefits for the self builder.

From an end user point of view, the main benefit is a more stable floor. Traditional timber joists warp and twist which can cause squeaks and creaks in your floor. Installing I-joists and Posi-Joists will avoid this issue because they are designed for less than 1% shrinkage, as opposed to 3-4% in more traditional methods. This will also avoid any unsightly gaps around your bath or skirting boards.

Installation, however, is where the real benefits can be found in using these flooring solutions.

Here’s a closer look at these innovative products:


While relatively new in Northern Ireland, I-Joists are proven across the world and are being increasingly used in projects across the province.

ggThis small but mighty product is a composite engineered timber joist that is designed to give a superior strength to weight ratio meaning it can hold heavy loads over longer distances. It combines 45mm deep C24 grade softwood flanges with a 9mm thick standard web and comes in 8, 9, 10 and 12m lengths.

Getting the design right is important but even if you are further on with the build, don’t worry as I-Joists are compatible with solid joists meaning you can still incorporate them without the need for expensive drawing changes.

When incorporated into your house plans at the design stage, I-Joists can eliminate the use of internal load bearing walls, immediately cutting costs but giving you more scope for your internal layout.

Another added advantage is the more cost-effective installation time. I-Joists are lighter and easier to install than solid joists and take a third less time to install.

I-Joists are compatible with both ground floor and upper floors and can also be installed in the rafters and stud walls. They can even be specifically designed to suit your requirements for a screed finish and underfloor heating.

Posi-joist is an open web floor system offering the simple solution to the needs of building the modern home. From conventional plumbing and electrical services to accommodating the increasing need for Mechanical Ventilation & Heat Recovery systems, Posi-Joist is the most cost effective Posi joistanswer. The benefits of installing this flooring system are:-

  • Open web design provides easy access for the design and installation of services
  • Improved quality of service fitting, eliminating costly remedial work
  • Engineered and manufactured to consistent standards of quality and reliability
  • Greater clear spans for design flexibility
  • Lightweight, strong and stable, making installation easy and fast
  • Clear profit from savings in labour, time, materials and call-backs
  • Standard depths of 202, 225, 253, 304, 373 and 421m



Utilising either I-Joists or Posi-Joists in your project means you will have tailor-made flooring for your home. The team at Haldane Fisher carry out a free design service using state-of-the-art computer programmes and will work with your architect and contractor at every stage to ensure you benefit from the wide range of advantages these products provide.

Working from your designs, all the I-Joists or Posi-Joists are cut to size in our factory and delivered directly to your site labelled and referenced for assembly.  In essence, this is a giant jigsaw puzzle that removes the needs for extensive onsite work, again saving labour costs.

We have been providing I-Joists and Posi-Joists for many years now and the feedback from contractors, architects and, most important, customers has been hugely positive.  In our experience, I-Joists and Posi-Joists offer versatile and cost-saving solutions, so talk to us to see how we can help.

If you have a specific question or would like further information, contact Adrian on Tel no 028 3031 6651.

Comments (2)

  • At 16.54 on 02 October 2014 - Haldane Fisher wrote

    Hi, itís difficult to comment on this as we did not supply the beams however if you would like to discuss this further with our Truss office in Newry, you can do so on 028 3026 3201

  • At 17.03 on 13 September 2014 - P. Coll wrote

    We have recently completed a kitchen extension the floor of which is supported by 'Eco joists' covered with 3/4in tongue and groove plywood and tiled with ceramic tiles. It's like walking on a bouncy castle. Joists are 5. 4 metres unsupported in the middle. Not sure who supplied said beams. I've read how strong they are but they don't seem to be too stable. Any comment?

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