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Rotten joist repair

Discussion in 'Wood / Woodwork / Carpentry' started by Swell1, 18 Jul 2021.

  1. Swell1

    Swell1

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    Hello, due to a water leak a small section of joist is rotten. To repair would you recommend chopping out and replacing the section or screw battons each side to strengthen? Or is there another way Many? Many thanks
     
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  3. blup

    blup

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    You could "sister" the joist, and remove any rotten wood.

    Blup
     
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  4. JobAndKnock

    JobAndKnock

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    To get the required strength you normally prop the joist (Acrow) and cut out the affected area. Next double up the joist with a full length new joist which is bolted to the existing joist - something like M10 or M12 coach bolts with dog washers between old and new joists at centres no greatervthan 600mm apart. If the joist ends go into a pocket (or pockets) in external walls it is highly advisable to order pressure treated timber. It is also advisable to envelope wrap the joist ends with good quality roofing felt to protect the timber further. Because this is a structural repair you need to use a structural timber of C16 or C24 grade. Fishplating with any old pieces of timber really doesn't hack it in the longer term and won't guarantee success

    Note: if propping anything structural the top of the Acrow needs to be screwed to the joist. The bottom should sit on a spreader pad of some description e.g. a doubled up scaffolding plank or the like. Screwing to the top ensures that the prop can"t drop acvidentally and potentially injure you

    Note 2: if a new pocket or pockets is required this must be cut out of the masonry (club hammer and bolster, etc) and the joist end(s) will need to inserted into the pockets and the hole(s) bricked up
     
    Last edited: 18 Jul 2021
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