Cost of knocking some external wall out in cottage (super thick walls)

[Kitsmummy]

Hi, I'm moving into a very old cottage in the next six weeks or so (finger crossed). The kitchen has already had a big opening made in the outside wall which now goes into a conservatory/diner type thing.

the walls are super thick (around 2 foot) and I'd quite like to make the opening into the diner bit much bigger, probably making the opening about 4 foot wider than it currently is.

Obviously it will need a steel put in which I've had done in previous houses, but they all had regular thickenss walls, so I assume this is probably a lot more work?

Can anyone give me an idea of cost for doing this? Presumably the steel that's there now would need to be taken out and replaced with a much longer one?

You will also need advise from a structural engineer. He will work out the structural design for the steels, possibly two beams side by side with steel plates wielded on top. His cost should be under £300 including 1x visit.

if they are very thick walls, they might be made of stone rubble or cob or something, which might be very unstable when you make a hole in it. Apart from calculating the steelwork, find an experienced local builder who is familiar with how it is likely to have been built.

I was looking at some thick walls yesterday, which had flints in lime mortar as the outer skins, and inside filled with lime, lumps of chalk, odd pieces of stone. Probably when it was new they would have had lime render to look smooth and neat.