Posi-Joists vs. I-Joists: Which One Should You Choose?
Choosing the right joist system for your construction project is a critical decision that impacts structural integrity, ease of installation and overall project efficiency. In this blog we’ll go through both options, compare their positives and negatives, and pick a winner for each category.
What Are Posi-Joists?
Posi-Joists (also known as open-web joists or engineered joists) combine timber chords with metal webs to form a lightweight yet robust structure. Their open design makes them ideal for accommodating utilities such as plumbing, electrical wiring and HVAC systems.
What Are I-Joists?
I-Joists consist of a solid web (typically OSB or plywood) sandwiched between top and bottom flanges made of engineered timber.
Design Flexibility
Posi-Joists: The open-web design allows for seamless integration of services without cutting or drilling, making them highly versatile for complex builds.
I-Joists: While strong and precise, any alterations to accommodate services require careful cutting and reinforcement, increasing labour time.
Winner: Posi-Joists for greater adaptability.
Spanning Capabilities
Posi-Joists: Excellent for long spans with fewer supports, which can reduce material and installation costs.
I-Joists: Also perform well over long spans, but their solid web construction may require additional reinforcement for certain loads.
Winner: Posi-Joists for their no-fuss, long spanning capabilities with few (if any) supports.
Ease of Installation
Posi-Joists: Prefabricated to exact specifications and lightweight, they are easy to handle and install. Their open-web design reduces the need for on-site adjustments.
I-Joists: Heavier and may need trimming or reinforcing for service integration, which can slow installation.
Winner: Posi-Joists for faster, less labour-intensive installation.
Cost Considerations
Posi-Joists: Tend to have a higher upfront cost but can save money overall by reducing installation time and simplifying service integration.
I-Joists: More affordable initially but may incur extra costs for modifications or installation delays.
Winner: Posi-Joists are often more cost-effective for modern builds.
Suitability for Modern Construction
Posi-Joists: Ideal for projects requiring energy efficiency, such as Passivhaus builds, due to their compatibility with airtight designs.
I-Joists: Better suited for simpler construction projects where service integration is less critical.
Winner: Posi-Joists for modern, service-heavy builds.
Final Verdict
If your project involves complex service integration or prioritises sustainability, Posi-Joists are the superior choice. For simpler, cost-sensitive builds, I-Joists may suffice. Although we have the equipment and knowledge to use both, we only supply Posi-Joists for the reasons above. They outperform I-Joists in virtually every aspect and offer greater design flexibility, allowing you to achieve that dream home with less to worry about.
Shop Posi-Joists online, or get in contact for a free design & quote:
📩 enquiries@tailormadedesigns.co.uk
📞 01432 355046