Subfloor

[Mark Hobbis]

hi looking for some guidance, to try and save money we are project managing our kitchen extension, we need to dig out footing 900mm deep x 600 and we have to have reinforced bar in the footings, The question is does the mesh have to be connected to the bar in the footings and what should the build up be for the subfloor, the building inspector has not stated we need any concrete for the subfloor just , hardcore dpm sand insulation mesh and screed? Any advice is appreciated

Thanks Mark

 

[r896neo]

Unless this is a specific engineered solution with some sort of complicated ring beam then the footings and floor are seperate animals.

You don't have to use mesh in the concrete subfloor, it would normally only be used if the ground was bad or was unsettled fill etc.

For standard strip footing and concrete floor the arrangement would be something like

100mm compacted hardcore

DPM

100mm concrete

insulation

Screed

The insulation can go below the concrete in some cases.

 

[noseall]

As said, foundation reinforcement and floor reinforcement are not usually connected unless a special design requires it. The two elements are built separately. We have been asked to put fabric in both the foundations and the sub floor and for similar but separate reasons. These were not connected though.

A typical foundation reinforcement would have two layers. The first layer on stilts a few inches off the floor and the second layer pushed in from the top a few inches down.

Similarly a floor slab can have the mesh pushed in or have it suspended on stilts and then surrounded by concrete.

 

[^woody^]

You should not be putting reinforcement into foundations in some random fashion. It should be designed, and if so designed to serve a purpose. Otherwise, you dont need any.

Floor slabs should be independant from the foundations and in most cases the structure. It would only be connected if it needed to be so as part of a design, again for a specific purpose, but not to the foundations.

What you have described is not a subfloor, but a floor. I'd be surprised if a building inspector said that you don't need any concrete for a floor - the concrete is the floor!