Foundations for porch

[Jake2021]

Hi,

I feel I should know the answer to this however I don’t do will ask someone more knowledgeable

I’ve dug my foundations out for a new porch - brick- which I’ve dug 1 metre down and 600 wide , we live in a very clay and high water tsble area

I was going to trench fill it with concrete and build up from there,

I’m just not sure how high I should fill the footings with concreted .

The current house and porch has three courses under ground but only sits on a slab may 6 inches .

I just don’t feel matching a 6 inch slab is the right call
Thanks
Jake

 

[Notch7]

I’m just not sure how high I should fill the footings with concreted .

for strength purposes you dont need to fill the trench -the depth of concrete is not the deciding factor on stability, that depends most on the ground beneath the foundation

You probably dont need much more than say 300mm but it depends how easy it is to lay blocks in the trench -typically builders trench fill to avoid laying blocks down in the mud.

You could finish your concrete say 2 blocks plus say 2 bricks below ground level -ie about 8 courses down equal to around 600mm down.

it depends on labour of laying blocks versus cost of concrete.

 

[Jake2021]

Thanks notch for your reply,

I’m mixing the foundation concrete by hand and have a couple of ton of ballast laying around so that’s the cheaper option .

I think my concern is because it’s clay and I always have water in the bottom which I constantly pump out it tends to be like mush in the trench … I will be pumping and scraping the bottom before pouring the concrete … it’s pretty awkward to lay blocks low down as I’ve got two soil pipes and a main power cable crossing the trench

Yea I know perfect footings!
Thanks
Jake

 

[23vc]

I’m just not sure how high I should fill the footings with concreted .

2 courses of block below house DPC

 

[noseall]

Hi,

I feel I should know the answer to this however I don’t do will ask someone more knowledgeable

I’ve dug my foundations out for a new porch - brick- which I’ve dug 1 metre down and 600 wide , we live in a very clay and high water tsble area

I was going to trench fill it with concrete and build up from there,

I’m just not sure how high I should fill the footings with concreted .

The current house and porch has three courses under ground but only sits on a slab may 6 inches .

I just don’t feel matching a 6 inch slab is the right call
Thanks
Jake

Top of concrete finish ideally is set at 7 courses of brick (525mm) down from DPC. Just right for accommodating a standard bottle gully with a wee bit of packing.