Carpentry & Joinery Question

I need to bolts 6x2 to 4x4 posts,for decking joist. due to weight what bolts would i be able to use that wil be strong enough?? m12 coach bolst1500mm ???

is it best to notch out the 4x4 so the 6x2 sits on it like a halving joit or should it be ok to just bolt stright onto the 4x4 ??thanks for your other answers

4 Answers

Best Answer

M12 coach bolts would be fine. 150mm galvanised preferable.

Answered 21st Jun 2011


Member since 7 Jul 2009

Yes M12 Galvernised but if the depth is 4" =100mm + 2"=50mm overall 150mm then unless your countersinking them i would get 175mm.

Personally i would notch out only 25mm! I built a small decking area outside my workshop and i notched the 100mm x 100mm uprights and sat my frame with the support on the inside of the frame and bolted.

Good Luck.

Answered 21st Jun 2011

Cannon Preservation Ltd

Member since 21 May 2011

M12 bolts are fine, and as PB said, galvanised, you could also put in some timber dog washers.

Answered 21st Jun 2011


Member since 29 Oct 2008

m12 coach bolts 150mm will be adequate or m12 coach bolts 120mm

Answered 20th Jun 2011


Member since 20 Jun 2011

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