Space Joist Design

Murdock Space Joists – Newry, Northern Ireland & UK

The popular Alpine SpaceJoist open web joist system for floor (and SpaceRafter roof) applications, comprise of timber chords with steel “V” webs and timber vertical webs. Combining the best features of an I-joist with an open web construction, SpaceJoist delivers a quality product for maximum job site efficiency and overall cost effectiveness. SpaceJoists are available in a range of depths from 195mm as a direct competitor to solid timber joists, up to 424mm – ideal for large spanning commercial applications.

State of the art software

We use Gangnail Software by ITW Industry to engineer SpaceJoists for maximum economy and design turnaround speed – with the improved design method of Eurocode 5 (EC5).

EC5 designs benefit from a more objective, methodical drafting process from scratch. Three specific checks, rather than the blanket 12 /14mm maximum deflection check of the BS standards, have been introduced to limit undue vibration in floors: i) fundamental frequency of vibration, ii) footstep induced vibrations and iii) heel impact checks. Footstep induced vibration checks have received many years of investigation, resulting in more predictable performance. In some cases, greater spans can be achieved as a result. The design method of EC5 is recognised by the NHBC.

Our use of the Gangnail Software an ITW Instinct Residential Design System component, makes us “Instinct enabled”. The ITW Instinct suite of compatible construction software eliminates the laborious practice of redrawing the building envelope – typically 5 to 7 times per building design. Architects, designers, engineers, estimators and managers collaborate data to a shared hsbCAD Building Information Model (BIM), keeping all parties up to date with latest revisions. Endorsed by the UK Government, BIM massively improves project coordination, reduces errors, identifies construction safety hazards at the design stage and ultimately saves money!


SpaceJoist has a number of features that simplify construction, which helps a project to run smoothly, and meet deadlines: The consistent width and depth of the off-site manufactured SpaceJoists provide easier floor material installation, while the open web design allows for service runs without the need for drilling or notching. These benefits reduce the amount of time contractors spend on site, speed up construction, and ultimately save the builder money.

SpaceJoist’s lightweight open web design provides on-site savings in labour. With no need for drilling or notching for installation of services, typical errors that incur costly remedial work are reduced. The long spans that SpaceJoist can achieve eliminate the need for costly intermediate load bearing walls. The bespoke design of each SpaceJoist to fit a particular job reduces the site wastage and pilferage of timber joists. These factors among others translate into an increase in profit for your bottom line.

Open web design – Fast and simple installation of services, without drilling or notching.
Long spans – Longer spans over solid timber can be achieved. This may eliminate intermediate load bearing internal walls, reducing overall cost.
Design flexibility – A number of end conditions are available to the designer, including top chord supported. SpaceJoists can be designed to precisely locate bearing walls and accommodate large services.
Reduced site wastage – Bespoke design eliminates the need for site alterations. Offsite construction also saves timber resources by reducing the amount of waste timber generated on site.
Wide spacing – Fewer joists are required to complete a floor installation (over solid timber for example), reducing labour time.
Light weight – The light weight construction allows makes site handling safe and easy, often without specialist lifting equipment.
Wide nailing surface – Floor and ceiling application are quick and simple.
Save money – Trades can work quickly on site, reducing labour costs. The necessity for intermediate load bearing walls is also reduced.
Engineered – Manufactured off-site ensuring consistent quality and reliability. The Alpine VIEW design software can create SpaceJoist designs to a variety of specifications.


Alpine SpaceJoist engineered timber joists are ideal for the environmentally conscious as timber the only truly renewable building resource. Timber construction also benefits from higher thermal efficiency than alternative materials such as aluminium, steel, or concrete.