• Whitehaven: 01946 518 800
  • Workington: 01900 844 200
  • Calderbridge: 01946 841 122
  • Barrow: 01229 845 300

We are open Monday – Friday 07:30 to 17:00 & Saturday: 08:00 to 12:00

Cumbria's No.1 Timber, Joinery and Tool merchants


Easy access for the installation and maintenance of the services in a floor zone is the clear advantage of the Posi-Joist flooring system. 

With the move towards the building of more sustainable homes, an increasing number of mechanical ventilation and heat recovery (MVHR) systems are being installed in the UK and Ireland, driving more and more architects and specifiers to look for a versatile open web flooring solution.

The system combines the lightness of timber with the strength of the Posi-Strut™ steel web, enabling you to span far greater distances than would be possible with alternative timber products, allowing a variety of internal room layouts within an external shell. This gives you unequaled design freedom across a wide range of applications for both floor and roof in domestic, industrial and commercial applications.

Posi-Joist - The Economic choice

A cursory comparison of two floor quotations often does not tell you the whole truth when it comes to the ecomomics of a floor.  There are many different factors that impact upon the cost of an installed floor. 

With a Posi-Joist floor there are likely to be far fewer components than a traditional softwood or an i-joist floor.  The fewer components in the floor, the faster and cheaper the installation will be.  


Why pay carpenters to spend time drilling service holes in solid joists when Posi-Joists remove that necessity? A floor zone will typically have electrics and plumbing running though the joists and increasingly air ducts as part of Mechanical Ventilation and Heat Recovery systems. Every time the drill comes out it is costing you time and money - with Posi-Joists the installation of services takes minutes not hours once again reducing the cost of the installed floor.


The typical chord width of a Posi-Joist is 72mm or 97mm wide making a Posi-Joist inherently stable. As a result a strongback brace is only required when the clear span of the Posi-Joist exceeds 4m. Unlike other flooring systems, no herringbone strutting is required, once again reducing the number of components in the floor and saving on installation time.


In timber frame construction, Posi-Joists can be top hung from the timber rimboard and in that instance do not require temporary bracing, reducing the installation time and the ancillary materials required for the floor.

Posi-Joists can be designed to include single sided Posi-Strut webbing where appropriate to provide considerable material savings. The use of staggered webs can give as much as a 12% reduction in the amount of steel used in a Posi-Joist™ compared to its competitors once again delivering you the best possible value.

With a range of joist depths from 203mm all the way up to 421mm and with varying timber chord widths, Posi-Joist caters for every eventuality. If you require a rectangular void within the floor zone then a chase opening can be designed into the floor using two timber verticals in the appropriate location.

With Posi-Joist you have peace of mind.  Whilst solid joist alternatives may in some instances allow for the drilling of holes for services, the placement of these holes must adhere to strict guidelines. By its very nature a Posi-Joist does not restrict you in this way, allowing a soilpipe to be though the floor zone close to bearing points and delivering maximum design flexibiltiy.


For more information, please contact our Workington Depot.


Pitwood Road, 
CA14 4JX

Tel: 01900 844 200 

Fax: 01900 844201

E-mail: enquiries@jacksonstimber.co.uk