Digging into a concrete slab for a suspended concrete floor

[isitserendipity]

Hi, I have tried to upgrade an existing structure- a half walled conservatory into a room that is more habitable all year round.

I have now been told by BC that the flooring structure is insufficient and needs to be underpinned and the concrete slab dug into to allow for a suspended concrete floor with a 300mm void due to the proximity of a neigbour's tree.

The concrete slab appears to be about 0.75m thick.

Can anyone advise how easy it is to do this or should I just give up now.

Any advise would be very welcome.

 

[JohnD]

The slab thickness you state doesn't make sense for a conservatory.

Maybe it has strip foundation under the dwarf walls plus floor slab.

 

[pinenot]

Continue to call it a conservatory, that way there is no change and no need for building control!
Otherwise listen to the last poster, dig a trench/hole close to the external dwarf wall and see if it has strip foundations a bit thicker than 75mm. If not you probably have a diy/low cost job on your hands and need to heed building controls directive.
To underpin means to bolster up the foundation strip and provide a more substantial base for the walls to sit on. You can do this in segments, like this View media item 55996 of course it doesn't need to be as fancy as this (just an example of toothing in blocks of concrete under the existing foundation) just be sure that each alternate block is cured two days or three days (any shutters can be removed after 12 hours or so) before abutting the next one up against it

 

[JohnD]

about 0.75m thick.

0.75m is 750mm, or about two foot six.

 

[pinenot]

I assumed the poster had made a simple mistake, if building control is asking for an "upgrade" from 750 mm then there is something wrong here, could you isitserendipity poss explain?

 

[JohnD]

'mmm

The slab thickness you state doesn't make sense for a conservatory.