Hole size in Floor Joist

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cldlr76

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#84718 6-Jun-2011 19:27

Hi,

Does anyone know the maximum diameter a hole can be in a floor joist (to be used for cat5 & RG6).

Cheers
Chris

cyril7

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#478293 6-Jun-2011 19:28

Hi, building industry start getting bitter and twisted if you go over 32mm, normally 25mm is fine, otherwise put a couple of 25mm in with a gap between.

How many cables are you trying to put through.

Cyril

cldlr76

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#478301 6-Jun-2011 19:43

The maximum will 3 rg6 and 3 maybe 4 cat5, and then further along the joist will be another 2 cat5

cyril7

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#478307 6-Jun-2011 19:54

Hi, oh, so just a couple of cables, a 25mm hole will start being stressed when your stuffing 10 or so cat6 cables not 6 or 7, cat5e cables are slightly smaller. RG6 and Cat6 are similar dia.

Cyril

apm45

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#478310 6-Jun-2011 20:06

Cyril's advice sounds good to me as a structural engineer. Of course it all depends on the depth of the joist.
Generally penetrations should be less than 1/4 of the depth of the beam. It must also be located at mid-height of the joist.

cldlr76

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#478327 6-Jun-2011 20:32

Thanks guys, the joists at normal 6" joists so 25mm is well under the 1/4 of the depth. I'll test on a scrap piece of wood to work out how small I can go to fit all the required cables through.

cyril7

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#478345 6-Jun-2011 21:04

Just use a 25mm which is pretty much all a sparkie will use for all holes regardless of what he is putting through..

Cyril