Light-weight ground fill recommendations

[CharLou]

Once our underground garage is complete we need to reinstate the garden by burying it with the previously excavated soil. The SE has engineered the roof so it will carry up to 1 meter of soil over approx. 88M2 (11M x 8M). The soil coverage will be no more than 1M reducing down to 400mm.

Purely as a precaution I wanted lessen the weight by using a light-weight ground fill, I was thinking about EPS or possibly Jablite Fillmaster (just looking at Fillmaster now). I was a little concerned about the crush strength of EPS, but it should be within tolerance.

I don't need to do this at all, but it will help me sleep at night knowing I've reduced the load on the roof as much as possible.

Can anyone recommend something, ideally cheap, that can achieve our goals?

Thanks

[rab1]

think your causing yourself extra work and costs as any loading weight is by standered worked out at 5-1. just my thought

[rxbren]

These are questions for your structural engineer as that's what your paying him for.
Keep all work to what they have specified if you change anything without approval any defects from that wouldn't be covered under their indemnity insurance and you would have to put right at your own cost

[seanandruby]

When we did terminal 2 heathrow it was built over the tube line. The weight on the structure had to be constant for it to work. Monitors were installed to record the weight. We had red amber green . Green was good, amber was to regulate the weight and red was dlstop work and clear the site. Obviously it never went to red.as the ground was dug out we had to replace with structural slabs, 2x 100ml blinding and 1200 slab not to mention the thousands of tons of rebar. Without this the tube tunnel would of collapsed. Same as a lintel it must have about 300ml ( i think ) for it to work. Structural engineer time :;):

[lutonlagerlout]

as said go with the SE design
If you need cheap fill a local grab man is the man to ask ,they will normally tip sub grade for free as it saves their tipping costs
LLL

[CharLou]

The SE isn't concerned about using an alternative fill for the roof as long as we use something lighter than soil (which is precisely the point). He only mentioned we need to ensure whatever fill we use allows sufficient drainage so the lawn doesn't end up like a 'bog'.

As said this was just an idea and probably overkill.

Thanks for the comments.