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Hard Flooring

Sub base for 4.8sgm concrete slab

Hi there,

I am just about to lay a concrete slab for the floor in our small extension (4.8sqm). Will be used as a utility room. So no heavy loads just people walking and basic utilities such as fridge/freezer etc.

As it is such a small area would i still need to lay 150mm of hardcore as a sub base or can I go shallower?

Someone has told me that for such a small area and with the ground being hard clay i would probably be ok pouring the concrete straight on top of it or just putting a layer of pea gravel and sharp sand with no need to whacker plate it down, is this incorrect?

Also is the size of the slab going to need re-inforcing or will it be ok without?

Any advice would be appreciated.


2 Answers from MyBuilder Flooring Fitters

Best Answer

It's always best to put the required level of hardcore in as you could end up spending more in the future if the ground moves and the concrete starts cracking.
It's not going to be a heavy traffic area so metal reinforment wouldn't be needed but for such a small area and the sake of £20 for the mesh I would just chuck one in anyway if i was doing it . Hope this helps .


Answered 4th Aug 2018

I would go with the 150mm crushed as your talking nothing in cost for that area, then you know it’s a sound job, don’t forget your layer of sand on top to stop any stones piercing your membrane.


Answered 16th Jul 2018

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