Creating 4m span opening in stone built house

[stuart45]

No Comment.

That's confused everyone.

 

[drpepe]

I can't see the back walls too clearly, but the stonework on the front looked like it's in courses which does make it a bit easier to prop.
However where I live many of the old houses were built by farmers etc so the stonework is well and truly random. However the walls can still be propped, it just means you might have to use a few more and take a bit more care.
You may find the inside is brickwork above floor level as it was easier to get the walls right for plastering with brickwork.

Hi Stuart - thanks for the response. I've just had a look behind a skirting board in the upstairs bathroom (rear wall) and it is definitely stone in there. The rear has much 'rougher' cut stone (and different type) than the front. I'll try to dig up a better pic.

I think I'm going to send an email to the SE to clarify that he knows how the house is constructed (the original quote I received was obtained by my architect tech).

 

[drpepe]

rear of the house above the to-be-replaced conservatory.
View media item 96425

 

[drpepe]

View media item 96910
Well the extension is well under way and the knock-through complete (all the props removed since this picture).

However, there was a lot of discussion regarding the steel and the foundations before everyone was happy (BR, SE, arch tech & builder), and the builder regards it as ridiculously over-spec at 52kg/metre for the 2 steels supporting the knock through.

In total we have:
2x 4.45m 203x203x52 UC (rear stone wall knock-though)
1x 4m 152x152x23 UC (extension vaulted roof)
1x 1.82m 203x102x23 (internal kitchen-diner knock through)

Thanks everyone for their comments.

 

[tony1851]

I wouldn't have thought the two 52s were undersized. If it's a stone wall (two skins plus core?) it is likely to be quite thick and perhaps the doubled-up 203 widths would be necessary.

Nice job btw.

 

[RonnyRaygun]

However, there was a lot of discussion regarding the steel and the foundations before everyone was happy (BR, SE, arch tech & builder), and the builder regards it as ridiculously over-spec at 52kg/metre for the 2 steels supporting the knock through.

Of course, most builders have no idea how to design steelwork...

I wouldn't have thought the two 52s were undersized. If it's a stone wall (two skins plus core?) it is likely to be quite thick and perhaps the doubled-up 203 widths would be necessary.

Tony, wouldn't you expect to see 203 UC 46s if they were sized simply for width?

 

[tony1851]

However, there was a lot of discussion regarding the steel and the foundations before everyone was happy (BR, SE, arch tech & builder), and the builder regards it as ridiculously over-spec at 52kg/metre for the 2 steels supporting the knock through.

Of course, most builders have no idea how to design steelwork...

I wouldn't have thought the two 52s were undersized. If it's a stone wall (two skins plus core?) it is likely to be quite thick and perhaps the doubled-up 203 widths would be necessary.

Tony, wouldn't you expect to see 203 UC 46s if they were sized simply for width?

Normally yes, I would agree. But FWIW two things made me think:

1. if the wall was brick, we could probably allow for the arching effect of the bond; as the wall is stone, it's likely that the inner 'skin' could be rough, random stones only casually mortared, so I personally would allow for all the area of masonry above the beam. Also, it's likely to be 150-200 thick, rather than the 100 we would expect for brick or block, so obviously a lot heavier.

2. there is the point load from the beams coming in from each side. Probably not particularly high I agree, but not worth taking a chance on IMO.

(PS, I speak from personal experience of this through a similar job on a stone-built house in Yorkshire some years ago.
Span was 4.5m and I specc'd two 8x8x52s, but the inner skin upstairs cracked badly through poor bonding. With hindsight should have used the 60kg beams (couldn't go deeper as headroom was an issue). Fortunately it was a complete re-furb and client (long-standing) was OK about it and we had it stitched. But it taught me not to take these old buildings for granted).

 

[cjard]

the builder regards it as ridiculously over-spec at 52kg/metre for the 2 steels supporting the knock through.

He'd have loved my 203x133x25 + 305x165x54 pairing for the same span..
View attachment 81670


Even better, look at these 203x203x46 puppies that hold my father in law's wardrobe up:
View media item 92602

 

[catlad]

Can anyone tell me what precautions are taken to stop moisture travelling down the masonry/stonework and into the house when these openings are made, I mean in a normal cavity wall you would install cavity trays to prevent this but in this type of wall?

 

[tony1851]

Can anyone tell me what precautions are taken to stop moisture travelling down the masonry/stonework and into the house when these openings are made, I mean in a normal cavity wall you would install cavity trays to prevent this but in this type of wall?

Probably very little; if it's got a rubble core, can't see how a cavity tray could be fitted.
Perhaps just make sure the outer skin is well pointed up?

 

[drpepe]

"code 4 lead abutment flashing with cavity tray and weep vents over"

...says the arch techs drawings.

 

[tony1851]

Obviously we don't know the build-up of your wall, but if it has a thick stone outer skin, and a rubble core(?) ask
the tech how he/she would propose to fit a cavity tray?

 

[drpepe]

Obviously we don't know the build-up of your wall, but if it has a thick stone outer skin, and a rubble core(?) ask
the tech how he/she would propose to fit a cavity tray?

Indeed! That was the reason for my roll-eyes smiley-thing. It certainly doesn't have a cavity... just a lot of (rather nice) stone that is currently sat on my driveway from the knock-through.

I assumed that the lead stops any water from getting into the house - or am i misunderstanding the question?