Building Homes or Extensions/Garage conversion floor


I work for a charity on a farm which is considering converting a garage to living quarters. I have just finished working on the buildings with 10 years experience in extensions and renovations/repairs.
The outside walls consist of poor quality stone work around 250-300mm thick. They consist of many random sized panels which are just cemented together. A few are a little wobbly. (like bits have been added over time.)
I have been told that they are going to build off the existing internal slab an inside skin, filled with bats then fill the oversite with damp sand compacted, dpm, Kingspan type insulation then lay wayrock t&g flooring direct to kingspan.
First of all, will this floor work and secondly will it pass building regs?
I am not involved with the build as they have a guy to do it but this is what he is saying they have to do.
Any advice or direction would be most appreciated.

Many Thanks


An internal wall would work, as long as the existing slab is strong enough to aact as a foundation. If it is not then new foundations will need to be dug out - from your description, this would probably cause the existing walls to collapse. To avoid this supports can be used, but they may not be 100% effective and could add significant costs.

The external wall will need to be "tied" to the new wall to make it stable. This is easily achieved, but the wall will also need to be insulated. Insulation can be installed between the walls, but then there may be issues with thermal bridging at the ties.

The floor could work if it is detailed properly. I cannot comment on the detailing of the floor without actually seeing the building and some drawings. Provided the right level of insulation is used and the structural problems are dealt with, then it should be approved by Building Control. Please feel free to ask on my forum if you need more detailed advice:

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Martin Owen


Anything relating to the design and construction of extensions and loft conversions.


I currently work as an Architectural Technologist for, where I design extensions and advise on legal implications.

Degree in Architectural Design and Technology

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