"logized" wrote in message
...

I have just looked in a plumbing manual (from 1995) - it says holes cannot
be bigger than 1/4 of the depth of the beam and the zone in which they can
be made is between 0.25 and 0.4 of the length of the beam from wall.
Also,the holes must not be below the centre of the beam or closer than 3
times the diameter to any other holes.

Dave

Thanks for the info. What's the typical depth of a joist? My house was built
in 1995 if it makes any difference.

CM.