"Mike Faithfull" wrote in message
...
"citizensband" wrote in message
...
Taking up the bathroom floor boards in my home, I was somewhat surprised
that the cowboy who had plumbed the bathroom in for the last owners, had
cut
an almost 2 inch deep slot out of the seven inch by three inch joist.
The
slots have been made about 2 feet from the wall supporting the joists.
This
seems excessive to me to run in two15mm pipes
Should I consider re-enforcing the joist in some way, if so, some
suggestions would be welcome?

Completely unscientific response, but gut instinct would drive me to
acquire
a short length (two or three feet) of five (i.e. seven minus two inches)
by
three and firmly attach it in parallel to the existing joist along the
area
where the slot has been cut ... I have no idea whether a five by six
(which
is what your damaged-but-reinforced joist has now become over a short
length) is as strong as a seven by three but I suspect it is. Clearly, if
a
five by three joist was sufficient to carry the load, that's what would
have
been specified in the first place, not a seven by three, so I'd feel more
comfortable knowing the extra structure was there to help it!

Not quite true - friend of mine (who works in a materials engineering
department at a Uni) did a large project on his house. The roof work
because a large problem. Original plans for the roof were accepted and
passed by the building regulations. Then, during an inspection or something
the BCO then decided that the beams weren't strong enough. I think there
were 6x3" or something. In the end they ended up having to use 10x4" beams
I think. The funny thing was - the house was being extended out the back
and the rear pitched roof was going to be a copy of the existing front one.
The front one has stood for 100 years I think and the original design was
much stronger than that but for some reason they required a change to the
(previously approved) plans. Working out the loadings etc, he's worked out
he can park 2x Land Rover Discoveries on the roof, and it'll still stand the
weight! Talk about overengineering!

It was a large job though - 8.5mx60cm RSJ across the full width of the house
was just part of the work!

Just because a certain size joist may be sufficient - doesn't mean that they
used the minimum possible sizes.

D