How long to wait after drainage

Discussion in 'Renovation & Home Improvement' started by JSW, 19th Jun, 2022.

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  1. JSW

    JSW New Member

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    Hi all, I've recently bought a new PPOR with a need for partial restumping. Before that, our building inspector advised we install a drainage system. I had a civil engineer out a few days ago who is appropriately sizing the drainage and putting together some drawings. He advised waiting 2 seasonal cycles (i.e. 2 years) before restumping after the drainage install as it may take that long for the soil to fully settle.

    However, we've got some internal works we'd like to move a whole lot quicker on than that, but obviously don't want to do before finishing the restumping.

    My extensive research (Google) hasn't turned up any specific advice on drainage and soil settling. However surely this kind of delay doesn't occur for new builds for e.g.?

    Anyone have 2 cents to contribute here? Do I need to get a geotech out too?

    Thanks!
     
  2. Scott No Mates

    Scott No Mates Well-Known Member

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    The intent of subsoil drainage is to lower the moisture in the soil, this will cause the soil to shrink. This doesn't happen instantaneously unless you are in sand and may take years in clay.
     
  3. JSW

    JSW New Member

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    Thanks for the reply, it is clay where we are so maybe that's what we need to do. I wonder what that do for new builds in clay where drainage is required though? Not waiting 2 years to construct surely?
     
  4. Scott No Mates

    Scott No Mates Well-Known Member

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    Wait? You're talking gen Now, I want a new house and I want it now. :oops:

    (Footings are designed to the conditions hence use of waffle slabs, raft slabs to minimise differential settlement.)
     
  5. JSW

    JSW New Member

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    Thanks yeah it figures. Not sure if getting the restumpers to go deeper with the footings will help...but then I guess we'd need to restump the whole house.