Joist sizing

[yorkney]

Hello,

The joists in my front room measure 76mm by 115mm, can I buy some joists and get them cut to those dimensions? Would this compromise their strength?

Thanks in advance

 

[AronSearle]

You can only shave off a few mm from graded timber, otherwise you invalidate the grade.

This is because knots are measured in relation to the cross section, and their position within the cross section, so changing the cross section changes or invalidates the grade.

You would need to find a timber yard that has a someone qualified to grade timber, then they can cut any size you want and grade it.

 

[yorkney]

AronSearle,

Thanks for the answer, much appreciated.

 

[yorkney]

Hello All,

Could I cut a 35 mm notch in 150 mm timber. The span is 4m with support in the middle, will C16 suffice?

Thanks in advance

 

[AronSearle]

Notching rules - 18mm notch on that joist size.

http://www.eastdevon.gov.uk/bc-guidancenote7-notchingofjoists.pdf


For the span, probably, but 150mm by what?

 

[yorkney]

Thanks for response, 75mm x 150mm.