Engineered timber Posi-Joists deliver longer spans, faster installation and superior structural performance for modern residential and commercial projects.
MiTek Metal Web C24 Timber Posi-Joists
UAB Eivuda LT has been designing, manufacturing, and installing timber roof and floor structures for more than 15 years, working with advanced MiTek metal web Posi-Joist technology. Produced in a controlled factory environment with CNC machinery and hydraulic presses, each joist achieves millimetre precision and complies with Eurocode 5 (EN 1995-1-1). By using carefully selected C24-certified structural timber combined with galvanised steel webs, UAB Eivuda LT ensures exceptional strength, durability, and long-term performance.
Unlike traditional solid joists, Posi-Joists provide longer clear spans (up to 50–80% greater), reduced timber usage, and open-web zones that simplify the installation of electrics, plumbing, ventilation, and heating systems. This not only saves considerable time and labour costs on site but also minimises structural weakening from drilling or notching.
Delivered off-site, manufactured, dry, and dimensionally stable, Posi-Joists arrive ready for quick assembly, ensuring a faster construction process and improved site safety. The result is a lightweight yet robust system that enhances energy efficiency, reduces long-term maintenance, and extends the service life of both the roof structure and overall building framework.
Metal Web Timber Posi-Joist System from MiTek
The metal web timber Posi-Joist system uses parallel C24 timber top and bottom chords joined by a triangulated galvanised steel web. Depths typically range from 195 mm to 425 mm, with centres set between 400 mm and 600 mm.
Under standard domestic floor loads, spans are generally 4-8 m. Meanwhile, under specific roof or light commercial loading, spans of up to 12 m are achievable.
Construction preparation in factories ensures consistent geometry, low moisture content, and minimal distortion over time. The open-web structure permits continuous service runs, reducing on-site labour and preserving structural capacity.
Each joist is designed to meet specific load cases and deflection criteria, often span/300 for floors and span/200 for roofs, though actual limits are determined via MiTek’s span calculator in accordance with Eurocode 5. This system is used extensively in floors, flat and pitched roofs, and mezzanine applications where structural performance and service integration are equally important.
Why Choose Open Steel Web Joists for Construction?
Open web joists consist of C24 timber chords connected by a galvanised steel lattice, designed and manufactured to MiTek tolerances. They provide longer clear spans than solid timber, which are typically 50-80% greater, while maintaining a high strength-to-weight ratio.
The open lattice allows uninterrupted service runs for mechanical and electrical installations, avoiding the weakening effect of notches or holes. With depths from 195 mm to 425 mm and centres of 400–600 mm, performance is verified against Eurocode 5 deflection and loading requirements, ensuring compliance across both residential and commercial projects.
The combination of efficiency, long and uninterrupted spans, lower weight and higher strength, and reduction of labour costs is why many project developers, contract companies and homeowners rely on open web joists for their construction projects.
How Strong is an Open Web Steel Joist in Buildings?
Open web steel joists achieve their structural strength through the engineered combination of C24 timber chords and galvanised steel lattice webs, designed to Eurocode 5 specifications. Under typical domestic floor loading, these joists deliver 4-8 m spans at depths of 195-425 mm on 400-600 mm centres, with deflection limits maintained at span/300.
This structural efficiency means that where a 225 mm solid timber joist might span 4.5 metres, an equivalent open web joist of similar depth can often achieve 6-7 metres under the same loading conditions, a rather clear proof of structural strength.
What are The Standard Posi-Joist Sizes in The UK?
Typical Posi-Joist sizes in the UK span overall depths of 195-425 mm, set by web module and timber chord options. Chord widths are usually 47 mm (single) or 72-97 mm (wider or sometimes twin chords), with matching joist thickness at bearings. When it comes to spacing in between, joists are commonly spaced at increments of 400 mm, 450 mm or 600 mm centres.
Posi-Joist Cost and Price per Metre – Full Price List | The UK
Indicative Posi-Joist prices depend on the following specification:
- Strength class (C16 or C24).
- Overall depth.
- Chord width/configuration.
- Centres, span, and treatment.
- Delivery region.
For budgeting, Posi-Joist cost per metre (supply-only) at our company typically falls within these ranges, assuming standard measurements:
- 202×47 mm £ X–£ X/m;
- 225×47 mm £ X–£ X/m;
- 253×47 mm £ X–£ X/m;
- 304×47 mm £ X–£ X/m;
- 373×47 mm £ X–£ X/m;
- 421×47 mm £ X–£ X/m.
Allow for extras, such as hangers, trimmers, preservative or fire treatment, cranage, delivery, and VAT. A project should state load category, joist centres (400/450/600 mm), and required spans to provide an accurate Posi-Joist cost.
For an accurate figure in the UK, request a detailed quote from us directly – we work transparently and do our best to provide the most accurate price estimates before starting the project.
MiTek Posi-Joist Cost Calculator
MiTek provides an official span calculator, which helps determine the correct joist size and span according to Eurocode 5 requirements. However, it does not include cost information.
For budgeting, we supply an indicative price table. By matching your required joist depth, width, and spacing to the table, you can easily calculate the approximate cost per metre for your project. This approach combines MiTek’s structural accuracy with clear price guidance, helping you plan both the engineering and financial aspects of your build.
MiTek Posi Wood Strut Cost – Full Price List
MiTek’s Posi strut webs and wood strut infills are priced per length or bundle, varying by module size. Rely on these estimates for approximate material (excluding labour) cost:
- PS8 £ X–£ X each;
- PS9 £ X–£ X;
- PS10 £ X–£ X;
- PS12 £ X–£ X;
- PS14 £ X–£ X;
- PS16 £ X–£ X.
MiTek Posi-Joist Span Table Calculator
MiTek’s tools, which are available on their site, translate your approximate input (roof weight and pitch) into span and maximum height estimates.
Understanding Posi-Joist Load Span Table Values
Posi-Joist load span tables relate maximum span to joist depth, centres, chord configuration, and design load. Each value assumes a load case (dead + imposed), service class, and deflection criterion. The final readings, while not yet accurate, can be generally considered as quite reliable estimates.
Standard Posi-Joist Spans by Depth and Spacing
Posistrut Joist Span Table Specifications
Posistrut web modules govern clearance, stiffness, and connection capacity. A Posistrut joist with wider chords or closer centres increases span at the same depth. Posistrut span tables specify permissible spans by module (PS8–PS16), chord thickness, spacing, and load category, and include bearing reactions, blocking/bridging notes, and hanger compatibility, ensuring selections satisfy strength and serviceability requirements.
Posi Truss Span Table Structural Limits
Advanced Posi-Joist Flat Roof System for Construction
An engineered Posi-Joist flat roof uses open-web members to carry uniformly distributed roof loads while providing clear service routes for drainage, MVHR ducting, and insulation continuity.
The Posi-Joist roof build-up supports warm-roof or cold-roof strategies, accommodates tapered insulation, and simplifies falls formation with firrings. Open webs limit thermal bridges around penetrations, ease plant support framing, and improve access for maintenance.
Why Choose Posi Strut Roof Trusses in Construction?
Cost-Effective Posi Floor Joists for New Builds
Engineered Posi floor joists deliver longer clear spans and faster service installation than solid floor joist timber, reducing secondary beams and drilling. Open webs provide continuous routes for electrics, plumbing, MVHR, and sprinkler pipework, minimising penetrations and preserving capacity.
Factory-controlled moisture and geometry enhance flatness of the Posi-Joist floor, limiting squeaks and remedial work. Design per Eurocode 5 verifies strength, deflection, and vibration criteria; joist depth and spacing are selected using MiTek software and span tables.
Compared with traditional timber, material savings, reduced labour, and predictable bearing reactions simplify procurement and cranage. The result is a lighter, stiffer floor ready for cassette installation and closing of the building envelope.
What Makes a Posi-Joist Floor Better Than Solid Timber?
Compared with solid floor joist timber, a Posi-joist floor spans further at the same depth, offers continuous service routes, and avoids strength loss from notches and holes. Factory accuracy improves flatness and reduces rework. Lighter members lower handling effort and bearing reactions, enabling smaller beams, simpler hangers, and faster programme with consistent, verifiable design data.
When to Use Posi Strut Floor Joists, Trusses in Builds?
Use Posi strut floor joists where long clear spans, heavy service zones, or future service changes are expected: apartments, MEP-dense dwellings, mezzanines, and refurbishments. Posi strut floor trusses suit irregular grids, offsets, or openings around stairs and risers. They reduce drilling, ease sprinkler routing, and maintain capacity where solid timbers would require significant notching or holes.
Can Floor Joist Timber Span Long Distances Safely?
Yes, although within design limits. Solid floor joist timber spans are constrained by strength, stiffness, vibration, and service openings. Open-web alternatives achieve longer spans at comparable depths by using steel webs to increase efficiency and retain capacity without notching. Always verify span, centres, load case
Posi Strut Floor Joists Span Table
A Posi strut floor joists span table lists permissible clear spans for each web module, chord thickness, and joist spacing under specified dead and imposed loads. Read the depth column, choose centres, and match the load row to find the allowable span. Notes flag vibration checks, bridging requirements, and bearing reactions for hangers and supports.
Posi-Joist, Strut Suppliers in the UK
When selecting a Posi-Joist supplier, reliability, certification, and engineering competence are key. UAB Eivuda LT is a MiTek-accredited partner with over 15 years of experience in designing and manufacturing timber roof and floor structures in full compliance with Eurocode 5.
Our clients across the UK choose us because we provide:
- Fast production and delivery lead times.
- Complete engineering support from design through to installation.
- Certified connection systems and structural-grade materials.
- Accurate span tables, sample calculations, and detailed cutting lists.
- Accessories (PS8–PS16 modules, plates, screws) together with full COSHH and CE/UKCA documentation.
By choosing UAB Eivuda LT, you are not only working with a verified supplier but also with a trusted partner who takes care of everything – from factory precision to on-site assembly. Instead of wasting time comparing multiple suppliers, you can order directly from us and be assured of quality, compliance, and timely delivery.
Contact us today – your most reliable Posi-Joist supplier and installer across the UK.
Posi-Joist Installation Guide
We generally recommend refraining from installing Posi-Joists yourself, as this is a matter of high precision and a mistake may be quite costly. However, if you have similar experience and would like to know the principle, we have outlined a brief Posi-Joist installation guide:
Store joists flat, dry, and supported
Fix and install hangers per calculated support reactions
Restrain chords with bracing and blocking as specified
Maintain service clearances, avoid notches
Apply temporary propping until decking is fixed
Perform documented inspections
For full Posi-Joist installation requirements, carefully analyse MiTek instructions and engineer notes at handover.
If you wish for a professional, error-free, and guarantee-backed installation – contact us and we will discuss the details of your project.
Posi-Joist Hangers
Posi-Joist hangers are selected from manufacturer schedules to match reaction, flange width, skew angle, and corrosion class. Options include standard face-fix, top-flange, skewable, and adjustable height types. Specify fixings per data sheets and provide adequate bearing depth and edge distances. Coordinate trimmers and girders so hanger capacities and bolt groups remain compliant on site.
When to Install a Timber Herringbone Joist Strut?
A herringbone strut or timber strut is installed where lateral restraint or vibration control is required between joists, such as long spans, high live loads, or uneven decking. Fit the herringbone joist strut mid-span (or at thirds for longer bays) to transfer load and stiffen the floor, following manufacturer spacing, fixing type, and edge-distance requirements for full compliance.
FAQ
Frequently Asked Questions
How Much Weight Can a Posi-Joist Safely Support?
The load-bearing capacity of a Posi-Joist depends on its depth, spacing, and load conditions, all verified to Eurocode 5 standards. Using MiTek span tables and software, each joist is engineered to safely support the specific weights required for your project.
What are The Downsides of Engineered Wood Joists?
The main downsides are factory lead times, dependence on specialist design, and the fact that on-site alterations (such as cutting or notching) are not allowed. These controls ensure safety and long-term performance but mean less flexibility during installation.
Why Do Joists Ceiling Sometimes Cause Sagging?
Common causes are overspan, centres too wide for the load, creep/moisture, inadequate bracing, or finishes/partitions added post-design. Serviceability limits (deflection/vibration) must meet Eurocode guidance.
How Do Easi Joists Compare to Posi Joist Systems?
Do Posi Strut Beams Reduce Weight in Construction?
Yes – MiTek Posi-Strut beams are engineered to reduce timber volume while maintaining strength, resulting in lighter yet robust assemblies. This not only makes handling and installation quicker and safer on site, but also simplifies MEP integration and reduces the need for additional structural elements. The outcome is a more efficient build process, lower labour costs, and a stronger long-term solution.
Are Posi Strut Truss Joists Sizes Fixed or Custom?
Posi Strut truss joists are not fixed – they are custom-designed for each project. Depths, spans, and spacing are tailored using MiTek software to Eurocode 5 standards, ensuring every joist matches your structural and service requirements.
Which Is Better: Easi Joist Span Table or Posi Type?
While both span tables provide guidance for metal-web joists, MiTek’s Posi-Joist span tables are generally considered more comprehensive and widely used across the UK construction industry. They are developed in line with Eurocode 5, supported by dedicated MiTek software, and regularly updated to reflect current standards. This makes the Posi-Joist option the more reliable reference for designers, contractors, and developers.
Can Posi-Joist Beat Eco Joists Cost Per Metre in Value?
Yes – in many projects Posi-Joists deliver better overall value. While the unit price per metre may be higher than “eco joists”, the open-web design significantly reduces MEP installation time, secondary structure requirements, and on-site labour costs. This means the total programme cost is often lower, making MiTek Posi-Joists the more cost-effective choice in practice.
Is Posi-Joist Better Than Eco Joist Cost, What is The Price Range?
Yes – Posi-Joists generally offer superior long-term value compared with so-called “eco joists”. While prices vary depending on span, centres, and logistics, MiTek Posi-Joists are engineered to Eurocode 5, ensuring reliability, safety, and full compliance. Typical supply-only prices in the UK start from £ X–£ X per metre, depending on specification. The open-web design also cuts labour, MEP installation, and programme time, making them a smarter investment despite a slightly higher unit cost.
Can A Webbed Joist Reduce Noise and Vibration?
Yes – when correctly designed and installed, MiTek Posi-Joists can achieve excellent acoustic and vibration performance. The open-web system is engineered to Eurocode 5 limits, and when combined with the specified floor build-up (such as resilient layers or acoustic decking), it ensures quieter, more stable floors. Always follow MiTek’s design guidance to guarantee full compliance and long-term comfort.
What Is a Joist Web and Why Is It Important in Design?
The web is the triangulated connector between top and bottom chords that transfers shear, stabilises the chords, and enables long spans with service openings. In metal-web systems it’s galvanised steel.
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