Hi Knowledgeable Ones,
Can anyone point me at building reg's type span tables or similar for
steel purlins?

We're interested in a house that SWMBO wants to convert the loft in
(should we get it), and wooden purlin tables only go to about 4m spans, we'd
be looking at 6m (the current wooden 8x2" ones are braced to the tops of
interior walls at about 2m spacings, and right where the means of escape
windows would have to go, so there will need to be two purlins under each
face of the roof, one above and one below the windows...) It's a trad' cut
roof, so without the braces there's an usable space of about 25' (to the
eaves/wall plates) by 17' between end walls, enough for our New Big Bedroom
And En-suite, and a maximum floor joist span of 12'6", so within limits for
the span tables I've seen... there's even room for the staircase, we reckon
)

The house is brick + block, with a cast concrete floor, 2 storeys and
has probably used its permitted development rights when the previous owners
had the garage converted into a couple of habitable rooms and a further
bedroom with en-suite built above - the area above this extension is another
8'6 wide (nice short joist span, phew!) for another loft room, again 25' to
the wall plates but with an end wall suitable for a means of escape window,
so no issues with moving purlins for roof windows like the main area.

The Kitchen's too small for her too (and me, I like cooking!) so we'd
want to knock through the (load bearing) wall into the current dining room,
with an Irish Jay spanning about 12'. I presume we'll have to have a pair of
piers to support the ends - any idea on the sizing for these?

Thanks in advance,
Dave H.
(The engineer formerly known as Homeless)