Clear service routes
Plumbing, electrics and ventilation run through the webs with no on-site cutting.
Products
Posi-Joists
We design all of our Posi-Joist flooring systems using MiTek Posi-Joists.
02 / DETAIL
We design all of our Posi-Joist flooring systems using MiTek Posi-Joists.
Posi-Joists (metal web joists) are another common way to structurally frame an upper floor in a residential building. They are also commonly used in flat roofs for both domestic and commercial buildings.
Donaldson Timber Engineering design and manufacture the MiTek Posi-Joist system. Posi-Joists are manufactured using TR26 structural graded timber for the flange along with the Mitek Posi-Strut Steel Web.
The metal web construction provides clear routes for pipework, ducting and cabling, reducing the need for on-site alterations. Furthermore, by combining the lightness of timber with the strength of the Posi-Strut Steel Web, it creates a joist that is capable of spanning greater distances than a traditional I-Joist.
Easy access for the installation and maintenance of services in the floor zone is the clear advantage of the Posi-Joist system, and with the ever increasing need for MVHR (Mechanical Ventilation and Heat Recovery) systems, Posi-Joist provides a perfect and simple solution that just isn’t possible with alternative solid timber products.
Get in touch with our team at Donaldson Timber Engineering today to find out if Posi-Joist is right for your next project.
03 / POSI-JOIST FLOORS
Floors with services built in
MiTek Posi-Joists use a metal web between timber flanges, so pipework, ducting and cabling pass straight through the floor zone instead of being notched or drilled in later.
Long clear spans
Fewer internal supports, giving more flexible layouts above and below the floor.
Faster on site
Lightweight, pre-engineered and delivered to a cutting list for quick installation.
Posi-Joist span drawing / not to scale
CCPI Approved
Our products are CCPI Approved: clear, accurate, accessible, up-to-date and unambiguous product information.
04 / LOADING OPTIONS
Match the joist to the floor
Pick the loading condition for your floor. The clear spans and depths below come directly from the standard options in our quote calculator.
Unsure of the loading? Send the floor plans and our design team will confirm the right specification.
Selected option
Domestic floor
Metal web, services run through the webs
- Max clear span
- Up to 8.00m
- Depths held
- 225mm · 253mm · 304mm · 373mm · 421mm
Price this option
Larger sizes and bespoke designs are available. If what you need is not shown,talk to our design team.
05 / PROJECT INPUTS
Bring the right information
A floor layout and the loading condition are usually enough for us to design and price a Posi-Joist floor.
Send project drawings01
Floor plans
Plans and sections in PDF or CAD, with bearing walls marked.
02
Clear spans
Longest clear span and any changes in level or direction.
03
Loading + use
Domestic, apartment, office or flat roof, plus any heavy fittings.
04
Service strategy
Main duct, soil and ventilation routes crossing the floor zone.
06 / QUESTIONS
Common questions
Price your floor
Posi-Joist floors, priced in a minute
Use the calculator for standard loading, or send the floor plans for a fully designed joist layout.