In article , Mike
Mitchell wrote:
but I was wondering what a brand new house is like in
the loft. In a modern house, the walls are usually stud
type, i.e. not load-bearing. So how strong are the ceiling
joists in the loft in a modern house? How to they stay up
without load-bearing walls to support them?

The roof is usually constructed of trussed rafters - see
http://www.trussed-rafters.co.uk/ttypes.htm for typical shapes -
which bear on the external walls only: any support given by
internal partitions is purely incidental. They are perfectly
strong enough for the design loads but no stronger than required
- computer design minimises the sizes of the timber members and
connecting plates. Generally you would expect the ceiling ties to
be capable of taking a distributed load of about 0.75kN/m2 or
15lb/ft2

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser
http://www.sda.co.uk/qsedbuk.htm