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Checking foundations for second storey

  • 16-01-2022 3:34pm
    Registered Users Posts: 150 ✭✭ backwards_man

    Our house had a one storey extension at the back before we bought it 7 years ago. We need more space upstairs and we need to know if the foundations under the extension can support a second storey. Anecdotal evidence from friends tells me to get someone in to dig down would cost in the region of €1500, plus we have no side access for a digger to come through so it would have to be done by hand. Can anyone advise if I can do that myself, dig down until I reach foundations and then call in someone to assess it (? an architect? a structural engineer? ) or does the digging have to be done by a specialist?


  • Registered Users Posts: 286 ✭✭ Biker1

    Hard to see how any structural engineer could certify the extra loading on existing foundations. Even if you dig down all that will tell you is the depth of the concrete but no way of knowing the reinforcement in it.

  • Registered Users Posts: 150 ✭✭ backwards_man

    I was told by an architect friend that I phoned that this "digging down" to check the depth of the foundations was the first step. he proceeded to give me numbers of companies that did this and a few phone calls got me the ballpark of €1500. So I have assumed off the back of that conversation that this is how second storeys are done (when on top of an existing first storey). His reaction wasnt : hell no you cant do that.

    Anyone done this?

  • Registered Users Posts: 37,594 ✭✭✭✭ Mellor

    Structual engineer have to inspect and verify capacity of elements with unknown factors all the time. This is perhaps the simplest instance of that.

    Single story domestic foundations are nowhere near their max capacity with a single story dwelling on top. Digginf down is to confirm that they exist and inspect size and condition.

  • Moderators, Society & Culture Moderators Posts: 33,272 Mod ✭✭✭✭ Gumbo

    99.99% of the time, single storey extensions have the same size foundation as a 2 storey.

    You could contact a local engineer. Ask him where he wants the trial digs done. This may be every 1m along the perimeter of the extension.