Concrete foundations/ floor levelling

[danielpoole]

Hi,

Help! I want to build a large garden room around 6m x 3m. I already have an old concrete base which is uneven. Can anyone tell me the best way to build on this? Should I level the floor or put in some piles? If I screed a concrete leveling compound on top of the existing concrete will it not crack? Alternatively I have thought about laying concrete blocks and build on these as supports (providing they are all level)

Any help would be greatly appreciated

Many thanks

Dan

 

[noseall]

With what will you be building the garden room - timber, masonry, plastic?

 

[danielpoole]

Hi Noseall,

I'll be using timber, possibly a SIPs system

Thanks

Dan

 

[noseall]

Personally, i use trench foundations whenever possible. That is not to say the base may not still be useful.

I would dig a trench foundation around the existing slab perimeter, lay concrete foundations then build blocks/bricks off the concrete up to dpc. If the existing slab is well below dpc then it could be used as a sub-floor or even hard core.

dpc should be set at 150mm above external soil level.

Use solid dense concrete blocks or class b engineering bricks below dpc.