What you need to know.
The clocks go back soon, and the wet, windy months are on their way. For anyone with a floor going in this winter, how you store and handle your joists on site matters as much as the design.
Posi-Joists are tough, engineered products. Look after them for the few days or weeks between delivery and decking, and they’ll go in straight, level and ready for services.
Here’s a practical run-through, based on MiTek’s own site guidance.
Get the timing right first.
Order for when you need them. HETS’ advice is simple: storage on site should be for a limited period before erection. Plan your delivery around when the walls are ready, not weeks ahead. The less time joists sit in the open, the better.
Check your masonry is ready. If you’re using masonry hangers, MiTek’s guide calls for a minimum of 675mm of cured masonry above hanger level (or whatever your hanger supplier specifies). Fresh, wet mortar in cold weather cures slowly, so allow for it.
Storing joists on site.
Keep them off the ground. Store Posi-Joists either upright or flat on level bearers, never in contact with the ground or vegetation.
Bearers in the right places. When stored upright, put intermediate bearers at the node points, not in the middle of a web bay. When stored flat, use enough bearers to stop the joists bending sideways.
Strap, wrap and ventilate. Keep joists strapped together and wrapped in a waterproof cover for short-term protection. Fix covers so air can still circulate, as you don’t want trapped condensation.
Brace your stacks. If you’re storing floor cassettes, add bracing to the ends of the stack to stop it racking sideways.
Lifting and handling.
Sling from the timber, not the steel. When a crane is unloading, slings go on the timber chords or the cassette lifting points, never the metal webs. Use fabric slings rather than chains or wire ropes, near the quarter points, at 60 degrees or less.
No bending, twisting or dropping. Carry joists upright where you can. And never notch or drill the timber chords, or cut a metal web, to make something fit. If something doesn’t fit, call us first.
Once They’re up.
Brace before anyone walks on them. Unbraced joists can be unstable. Oue guides shows 22x97mm binders and diagonal braces, nailed to each joist with 2 No. 3.35x65mm nails, at the ends and midspan (around 2.4m centres on spans over 4.8m).
Don’t overload the deck. Stacked boards on joists are limited to 250kg/m² and 300mm high. That’s about 16 sheets of 18mm chipboard or 13 sheets of 22mm.
Cover undecked joists. If the floor is erected but not yet decked, HETS recommends a waterproof membrane to prevent excessive exposure to moisture.
Pick a weather-tolerant deck. Once decked, check what your board manufacturer allows. For example, EGGER says its Protect flooring can be left exposed for up to 100 days.
Implications for your project
Fewer delays: Joists delivered to programme and stored properly go straight in, with no waiting for things to dry out or straighten.
A flatter floor: Correct bearers and bracing keep joists true, so you get fewer squeaks and less packing later.
Protected warranties: Following manufacturer guidance keeps you on the right side of the joist and decking warranties.
Safer sites: Braced joists and sensible deck loads help keep everyone safe through the darker months.
What does this mean for you as our customer?
We’ll help you plan delivery around your build programme, so your joists don’t sit around longer than they need to. Every order comes with our free joist design, structural calcs for building control and a free interactive 3D model. That way, you know exactly where everything goes before the lorry arrives.
Need hangers, straps or fixings? They’re all available from our online store, so your metalwork turns up with your joists.
Final Thoughts
Hampshire Engineered Timber Solutions (HETS).
Winter doesn’t have to slow your floor down. Keep joists off the ground, covered and braced, lift them by the timber, and get them decked promptly.
Want to know why Posi-Joists make such a good floor in the first place? Read our last blog – Posi-Joist vs I-Joist vs Solid Timber.
Contact us to Get Started for a free quote and 3D design call: 02393 553 509 or email.
Hampshire Engineered Timber Solutions (HETS)
Sources
MiTek UK: Site storage of trussed rafters and Posi-Joists: storage, bearers, wrapping, stack bracing, membrane on undecked joists
HETS / MiTek Posi-Joist install guide (PDF): 675mm cured masonry, lifting and slings, temporary bracing, 250kg/m² and 300mm sheet storage limits
EGGER: Protect exposure rating extended to 100 days: decking exposure example