Joist Timber Connector Bolt Sets for Joist Repairs (12 Sets) DELIVERY to Mainland UK ONLY

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The two 50mm square plate washers play a crucial role in distributing the load evenly across the joist, reducing the risk of localized stress points. They are designed to fit snugly against the timber, providing a stable and balanced support for both the bolt and the joist. I would probably sandwich the damaged section between two 8' boards or even two pieces of OSB or plywood. I'd attach the repair material with nails in a "W" pattern. Actually in this case I might use structural screws since I picture the joist being a pain to nail. Yip! I had a SE do the calcs and all is well - I can put 18mm T&G chipboard directly on these exist. joists.

There are several issues: 1) the roof joists are not large enough to span the 90”, 2) the lower horizontal ties (including the damaged member) help support the 2x4 roof members, 3) the damaged member does not support the ceiling finish below, as seen in the bottom picture. Sandwiching the butt joint of two joists between lengths of similar material will also lengthen a joist to span acceptable distances if longer boards aren’t available or won’t fit. This often requires the use of bolts or lag screws for fastening the sandwiching boards with the joist, especially if the joint is unsupported.I think using a larger number of smaller fasteners in a "W" pattern will weaken what's left of the joist less. The "W" pattern avoids splitting from two fasteners breaking along the same line in the grain.

Likely, you will only be able to partially sister the joist, as LVLs are used primarily in longer spans that dimensional lumber cannot reach. In that case, follow the same procedure as you would when sistering dimensional lumber. ConclusionEnsure your new joist has at least 3’ on either end of the point of deflection – the point where the sag is greatest – to properly support the old joist. 3. Fit the Sistered Joist