mark wrote:

How big are the cracks altogether? (At their widest)

The original cracks have long been filled - but would be around
20-25mm. The new cracks (about 2 years in the making) are about
1-2mm.


When was the porch built?

AFAIK at the same time as the house, ~1930.


Is the floor inside the cottage look like it has raised up very slightly?

The downstairs has two back rooms (the area of interest). One of
them has a wooden floor. The other has a concrete floor, which
had a big crack righ acoss it, like it had dropped about 30mm at
one end.


What could be happening is that the porch is 'rotating'; it's weight
could be pressing down on the earth outside the wall and heaving it up
inside the wall if you know what I mean. This would result in the
external wall's 'foot' moving off the vertical leading to an exaggerated
movement further up. Any bits of debris falling down vertically along
the edge of the partitions would keep wedging it out also. The porch
would tend to sink less where it is attached to the main wall because of
friction between it's (the porch) wall and the main house wall; this
shows as a lack of cracks between the porch and the main wall.
The roof will tend to hold back the top of the main wall so it 'bows' as
you have described.

You may be onto something here. The porch floor is decidedly
unlevel (slopes away from the house). But having said that, the
porch walls aren't enough off vertical to match the floor.


If the house is on a slope and the porch is on the down hill side then
this is very likely as most old houses on slopes had an element of 'cut
and fill'; back wall built on solid ground and the front wall built on
spoil excavated from the back.

Bingo - on a slope, with the porch on the downhill side.


I'm *not* an engineer so don't take this as 'proper' advice; Insurance
company's and mortgage company's tend to like ppl with bits of paper to
write it all on other bits of paper.

Noted - but if the problem is indeed as you diagnose, what
solution would you suggest? Underpin the back wall + porch?


May well be that the porch is still 'settling in'
Probably best to shell out a couple of hundred quid to any old chartered
struc eng with lots of PI

He'll be here on Tuesday :-). I'll let you know what he says.

Thanks for your thoughts.

--
Grunff