On 1 Dec 2003 10:26:21 -0800, (Clive Long,UK)
wrote:

Bill

My concern is not a single hole in a wall, I'm sure the circular
profile helps distribute the load around the hole, the concern is when
the wall already has 4 x 150 mm core drilled holes within, say, 5
metres of each other

Clive

"Bill Gardener" wrote in message ...

I would be interested in hearing what the experts think of this as I have
just installed a Bosch cooker hood which required a 150mm hole through the
outside wall.

Does a 150mm hole really affect the walls structural integrity???


Thanks,

Bill
Domus produce a catalogue in .pdf form which you can download from
their website (sorry I have mislaid the URL) and which includes a
section on how you calculate what you require. I think the manual
that comes with a cooker hood tells you the flow rate required and how
the internal fan performs against various flow resistances.