Hi, could anyone answer me a quick question wall foundations thanks

[Jake2021]

Hi
I’ve just started (literally taken the spade out of the shed) digging my foundations for my front garden wall.

it will 1 m high made on concrete blocks laid flat… I was thinking 30 cm trench deep but was unsure of the width as if it was single sling I’d probably make it at least 2x the width but with concrete blocks (breeze blocks) I’m really unsure of the width as if I do it 2x the width of a breeze block it would take up 1/2 the garden lol

the garden is around 6 inch lower than the path/pavement but will
Be increasing this height with type 1 and sand for artificial grass
Thanks again for the help and for all help , suggestions and advice
Jake

 

[John D v2.0]

Not sure why not replies on this so I'll have a go.
3⁰0cm doesn't sound very deep, if you imagine where the centre of gravity of the wall will be id say you need to go deeper, and you would need it to be half brick thick with one brick thick buttresses at intervals.
The width of the foundation is traditionally 30-40cm and 150mm thick. And make sure the concrete/trench is fairly square with flat bottom and sides.
The amount of leaning garden walls i see I'm sure you can make it as strong as you like if you really want. For an extension it would be nearly a metre deep and 600mm wide because the stakes are higher!

 

[Jake2021]

Hi John,

I really appreciate your reply and help.

for some reason I said 30 cm as I have it in my head foundations are approx 1/3 of the height deep but with all honesty I could of just made that up lol

I’m using concrete blocks laid flat so the wall will be 9 inch thick solid, again I could be making this up as I tend to make a lot up lol but I again thought if a wall is double skinned or 9 “ think I wouldn’t need piers … the wall is approx 1 metre high x4.5 metres long.

that’s a really good point about being flat at the bottom I never even thought about that but what I may do is when dug out use the whacked plate I’m hiring to flatten the bottom of the trench … do you think that would work?

im pretty sure you will be right on all points , I’m hoping someone else could also comment to back you up, not that I don’t believe you I just like checking , double checking and triple
Checking as I like my work to be right from the beginning to save me doing it twice
Thanks again
Jake

 

[23vc]

Don’t whacker in the trench. For the depth you need to be down to firm subsoil not the loose topsoil. The actual concrete thickness can be less, like 200mm. At a guess, in typical ground I reckon you’d want to be at least 500mm down. I’d go about 450mm wide as the wider you to will also help with stability

 

[Notch7]

for some reason I said 30 cm as I have it in my head foundations are approx 1/3 of the height deep but with all honesty I could of just made that up lol

foundation depth is determined mostly by ground condition. Your foundation wants to be on bedrock or solid clay….so dig down till you hit hard ground - if you are on soft clay, you will struggle to get a stable found.

You just need to remove the loose crumb when you get to bottom of trench - and make it roughly flat and level



On good ground 450mm wide x 150mm thick at least 150mm frost cover.

have a browse of paving expert

https://www.pavingexpert.com/featur03

 

[Jake2021]

Hi guys
Many thanks for everything

I’ll dig down 50cm and see what the soil is like.. it’s a bit deceiving as my garden was already 6 inches below the pavement

I’ll take the whacked plate out of the equation lol

the pic is the level of my garden with no digging lol I would like the end level at least somewhere near to the pavement level
Thanks again
Jake

 

[Notch7]

Hi guys
Many thanks for everything

I’ll dig down 50cm and see what the soil is like.. it’s a bit deceiving as my garden was already 6 inches below the pavement

I’ll take the whacked plate out of the equation lol

the pic is the level of my garden with no digging lol I would like the end level at least somewhere near to the pavement level
Thanks again
Jake

just dig down till you hit solid, hard ground - it should be clear the difference between top soil and load bearing ground

watch out for services - they could be at 500mm down

 

[cdbe]

If you have to go down a long way, you should concrete fill the trench as high as possible - when it comes to free standing walls their height is measured from the top of the foundation, not the ground level. If you had to excavate 700mm and build off a 200mm strip you'll effectively have a 1.5m high wall.

If you find decent ground around 5-600mm and your trench is 450mm wide you should find that 1m³ of ready mixed (generally the minimum volume that most barrow mix companies will supply) will fill it perfectly. And you won't need to be laying in the trench, which is hard work!

 

[Jake2021]

Cd ,

thanks for that, I was thinking about mixing it myself and trench filling it and even putting some shutter boards above ground to bring it just below the path height… the section of where it would be shuttered would be filled on the other side with type 1 and sand anyway… would that be ok to do that ?

I don’t suppose you know how many ton bags ballast and cement I would likely need?

On the pic
The blue
Line would be the shutter board and the grey where concrete foundation would come up to

thanks to everyone so far for the help

 

[noseall]

I don’t suppose you know how many ton bags ballast and cement I would likely need?

Untitled

• noseall
• 19 Jan 2015
• 1

Lols. Total length of the trench (in metres) x width of the trench x peg depth. For example a 6m long trench at 0.45m wide and say 0.3m deep concrete (pegs) would give you the volume at 0.81 cubic metres. This would equate to 1.5 tonne bags of ballast and about 11 x 25kg bags of cement.

 

[Jake2021]

Lol you got the same ball as me apart from mine doesn’t work lol

think I’ll knock the mixer on the head and get ready mix lol thanks

 

[cdbe]

I'm pretty tight and used to mix my own for my various jobs, automatically thinking it had to be cheaper - it probably was, by about a tenner if I didn't charge for my time.
However, mixing it myself had benefits in terms of much needed exercise, but the "downside" was that I then had to reward myself for the days hard work with expensive beers and takeaway - swings and roundabouts!

Now I use barrow mix, but I tell myself that the hard work is the tamping and floating so I still deserve the beer and takeaway!

 

[23vc]

I mixed pretty much exactly the amount predicted by mystic noseall recently and it took well under 2 hours, and I had to spread it around over steel mesh for a floor, which you won’t. As long as the bags are near the mixer just keep it going, feed it, tip it in the trench. Cut bags of cement in half and about 10 shovels of ballast.

 

[noseall]

I'm pretty tight and used to mix my own for my various jobs, automatically thinking it had to be cheaper - it probably was, by about a tenner if I didn't charge for my time.
However, mixing it myself had benefits in terms of much needed exercise, but the "downside" was that I then had to reward myself for the days hard work with expensive beers and takeaway - swings and roundabouts!

Now I use barrow mix, but I tell myself that the hard work is the tamping and floating so I still deserve the beer and takeaway!

We only ever use volumetric AND a pump. Our latest wee extension...

Lzy3

• noseall
• 10 Apr 2022

Lzy2

• noseall
• 10 Apr 2022

Lzy1

• noseall
• 10 Apr 2022

 

[Notch7]

We only ever use volumetric AND a pump. Our latest wee extension...

Lzy3

• noseall
• 10 Apr 2022

Lzy2

• noseall
• 10 Apr 2022

Lzy1

• noseall
• 10 Apr 2022

It makes a lot of business sense for a builder. With a pump, you only need one guy on site and it’s all done in under an hour. Otherwise it means 3 or 4 guys barrowing, then clean up. The frustration I would get is when the concrete delivery got delayed for hours - often meaning guys on a site with nothing else do - theres bugger all to get on with on a site with open trenches

I used to pay about £350+vat for the pump, although mixermate have a volumetric truck with pump built in - that’s the way forward, all one machine.