What type of stone to use to raise ground for steel workshop foundation?

LimerickThe061 · 08-11-2023 8:47am #1

Hi All,

Hope someone can help, I'm hoping to put in a new workshop/garage (40ft x 20ft) in the next few weeks but need to raise the ground to match the level of the current back garden area so need to raise it up 600m finish height, I'm going with 125mm (5") concrete slab so I'm wondering what stone I should use to raise the ground up the extra 475mm? I would have used 804 however I'm reading now that you shouldn't use 804 anymore so just wondering what to use now?

Also if I'm raising the ground, do I still need to excavate the ground or can I just compact into the soil ground? Ground is rock solid soil and after about 6" of digging is all rock

Also any idea of what this stone is costing? Extremely roughly

10-10-20 · 08-11-2023 9:43am

I was going to say 804... but what are the reasons that you shouldn't use it and is that from an Irish or UK source?

GreeBo · 08-11-2023 2:21pm

+1 on why not 804?

Are you planning on insulating under the slab?

If not, you should! :)

You could then do 250mm 804, 25mm blind with DPC and 200mm PIR and not have wet or freezing feet in your workshop.

Calahonda52 · 08-11-2023 3:11pm

Its longer called 804, new regs post pyrite/mica but I just had 20 ton delivered, I asked quarry for 804... 12 euro a ton plus vat at 13%

3 or more different classes of crushed stone now

The subfloor needs to be whacked in layers as well as restrained on the sides

You should dig out to the rock as the clay will settle under the dead load of slab and stone and crack the slab over time, even with A393 mesh, which is about 65 euro for 16 by 8 foot plus vat