In message , Jim
Walsh writes
Hello all.
My 1950s brick-built house has a light weight block wall, on the first
floor, separating the master bedroom from the bathroom. There is no
corresponding wall, on the ground floor, underneath.
A while back, when doing some work in the room below the bedroom and
bathroom, I made a hole in the ceiling to see how the wall above was
supported. I expected to find an RSJ or beam, but there was nothing. I
guessed that someone must have built the block wall directly onto the
floor boards; far from ideal, I would imagine, but it's been in place
for quite a few years without incident (though it is not original to
the house).
Recently, I had reason to remove the skirting board that runs along the
wall in question, in the bedroom. With the skirting removed, I can now
see the base of the wall and it appears that the blocks are not sitting
on the floor boards but are, in fact, fractionally aboove the floor
boards. Does anyone have any idea what's going on here? To all intents
and purposes, it appears that the wall is floating. The span is about
3m, so I would be surprised if it could all hold in place just from
being tied in to brick walls at either end. One notion that occurs to
me is whether there could be a supporting steel for the lowermost
course and that the blocks are shaped in some way that conceals it. Is
this plausible? Are such techniques well-known?
Suggestions appreciated. I'm reluctant to do too much exploratory
excavation for fear of disrupting what might be a fragile structure!

You can create a *hidden* beam by using strips of expanded metal in two
or more of the lower courses. Sounds unlikely here from what others have
said.

--
Tim Lamb