Steel Frame Building Foundation and Pad Stone help please? :-)

[Greenmonster]

Hi all, looking for some advice please, build project in Scotland, I’m laying a slab for a 6.5m by 12m steel framed garage; The slab is fairly standard, with 150mm compacted Type 1, then a DPM layer (has to be a gas membrane as we’re in a low Radon area), then layer of A252 mesh sitting 50mm up in to 150mm of C28-35 4/20 concrete, however there is also to be 8 pad stones (concrete cubes) under the area of the vertical columns. So in my mind I’m planning to tackle the job as follows;

 

Part A – Form the Pad Stones (750mm concrete cubes)

1. Level the area off to laser level
2. Mark out the 8 pad stones holes, and excavate down to the depths required
3. Cut and fit a layer of A252 in to the base of each of the pad stones, and siting on 50mm riser cups as required (SER has no mesh noted, is this worth fitting anyway?)
4. Order batch/pour 1 of C35 Concrete mix and fill the 8 pad stones up to ground surface level
5. Use a vibrating poker and hand trowel to a reasonable level surface.

 

Part B – Form the Main Slab (6.5m by 12m)

1. Excavate 150-200mm down in between the pad stones fill with type 1 and compact to a level surface (so flush with the top of the pad stones)
2. Layout 150mm wood shuttering to the perimeter, laser level and secure with steel pins and posts & bracing
3. Install VisQueen DPM to full area, with minimum SER over lap of 150mm, and tape the seam
4. Install A252 Mesh, on 50mm risers, tied joints with minimum SER overlap of 440mm
5. Final level check and adjust shuttering if required
6. Order batch/pour 2 of C35 Concrete mix, level and power-float flat
7. The day after, cut the slab with a stihl-saw at the central crack promotion area

 

Questions;

1 Does all of the above sound okay, standard method, right order?

2 Do I need to shutter the pad stone tops, or okay just rough cast into the soil edges? (can vibrating roller the edge first)

3 Does DPM need to be folded up the edge of the shuttering, to ensure 100% coverage?

4 Do the pad stones need to be in a DPM envelope / kinda tanked in also?

5 Would this normally be done in the one pour, pads and slab, if so how is the DPM arranged arround or over the pad stones for a single pour?

 

Have all own kit, digger, dumper, vibrating roller, trench whacker and rammer, builders laser level (Stabila, with staff and laser detector) and some reasonable experience, though any help or advice in forming the above would be much appreciated, keen to get it all spot-on.

 

?

 

Cheers