Sistering Joists


namluke

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Hi,

Im sistering joists (7x2) 2.5 meters in length.

I am securing them with around 4 to 6 100mm No.6 wood screws and 4 x M10 Nut and Bolts. 

Would you say i need to use construction adhesive also or do you think that what i have used will be ok.

I thinking the adhesive may help with potential creaking 

Thanks

Luke

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I do this a lot in rehabbing.  The accepted practice here is that the sistered joist extends at least three feet beyond the damaged section, and then secure using adhesive as well as three screws/nails every 16 inches with two 1/2 inch carriage bolts at each end, though that last bit is not as important if the sistered joist extends the whole span and is supported by a wall/foundation on each end.

For a joist that's 8 feet long, I'd be using something around 12 screws or nails. Screws hold the joists together better over time, but nails have much better sheer weight strength.  Personally, I use the carriage bolts and screws, because most of the sheer weight holding is going to be done by those carriage bolts.

Clamps are a must for closing those gaps before driving the fasteners, especially if using screws.

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1 hour ago, wdwerker said:

Yep, nails have high shear strength. Drywall screws are too brittle.  Construction screws do not have a bugle head. If it's getting inspected just use bolts & nails. Nails are cheap so you can use plenty, especially if you have a nail gun !

and it is really fun to pincushion the daylights out of a beam with a nail gun

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