Foundation for greenhouse ?

[KateMoss]

Hi, I am having a 1.8 x 2.4 m. wood frame greenhouse 2.2 m. tall with dwarf single skin brick wall about 0.7 m. high.
Would a raft foundation be OK and would reinforcing mesh be essential?
Any comments on minimum raft depth gratefully received.
...
If I were to have a trench footing instead could the concrete be poured to ground level (i.e. without frost heave protection) and what depth would be recommended.
(Re. Climate, I live near Heathrow)
Thanks,

 

[cAtLeYx]

Hi,

On the basis that this is a green house and you therefore have requirement for insulation or even damp proof membranes or damp proof courses -I would suggest the following options:-

Option A - Cheaper cost and would be sufficient for your use.
Raft foundation with thickened edges and mess reinforcement.
Excavate 100mm over the area 1.8 x 2.4 m, further excavate the perimeter say 300mm in from the edge at a depth of 200mm. Cast concrete slab.

Option B - Move expense but in my option of more substantial and lasting structure.
As above but reduce dig in both areas by a further 100mm and compact Type 1 stone base.

In either case make sure your brickwork does not site shy of your foundation edge or water will just sit there and cause issues in the short term.

Hope the helps.

 

[KateMoss]

Thanks for the response, after consultation I am leaning towards a strip/trench type footing as we want some bare ground inside. Any comments from anyone on whether it's permissible to pour concrete to just below ground level with no frost cover?
Cheers,