I’m not sure if this is the best sub-forum for this as it’s a building question. I plan to put down a 6” deep concrete footing followed by two courses of bricks to support a 10 by 6 foot greenhouse. Note, this goes round the edge, the soil inside will remain for planting. My neighbour did this, and it’s fine after 20 years. does anyone know if I could use 2” hardcore followed by 4” concrete for the footing instead? It would make mixing concrete easier.
Greenhouse footing
- Thread starter Leif
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Is hardcore this drainpack type rock? How deep is your frost line?
Hardcore is the stuff you mix with cement to make concrete i.e. stones, gravel and sand.
I have no idea how deep the frost line is here in southern England. It is usually above zero Celcius (freezing point) in winter, often a few days of zero, very rarely do air temperatures go down to -5 C or lower, and that is the early morning just before the sunrises. Last winter we had a couple of times when my car recorded -3 C when driving in low light in the local countryside at 9 am. I think I have recorded -5 C once in ten years in the morning.
I have no idea how deep the frost line is here in southern England. It is usually above zero Celcius (freezing point) in winter, often a few days of zero, very rarely do air temperatures go down to -5 C or lower, and that is the early morning just before the sunrises. Last winter we had a couple of times when my car recorded -3 C when driving in low light in the local countryside at 9 am. I think I have recorded -5 C once in ten years in the morning.
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It won't be too deep I imagine. The idea is to not allow ice to heave upward and break the footing from below.
The pack base need to be triangular so that it actually packs. Drainage seems equal to stability. I have a tamper tool that can dictate the width of my smallest footer. Depth depends on your heavy rainfall amounts and how well your soil percolates. Moist vs wet when freezing create different pressures. Footings float on soil and so get very wide and deep in the more unstable soil or climate violence prone areas. Its just energies really.
Then pour your cement footer up to the bottom of your frost line. We usually use a bit of metal rebar in a serious structure here but even that is environmentally less risky here as we rarely have earthquakes and when we do they are small. We make up for it with tornadoes that are capable of ripping structures out of the ground so uplift metal and deep wide footings are often used to tie the walls down into the subterreanian deep. I know your area is not that scary. I would think just the weight of one wall is not that much. But then I think how much earth in potsis going to be set upon the wall in time and how many tonnes will that be? Will it flex and crack the masonry or are the wall ties correct and supportive horizontally yet vertically flexible?