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  • Building above garage that is attached to the house

    Posted by Charles Bell on January 12, 2025 at 5:51 pm

    We currently have an attached garage but are looking to potentially build above it. We don’t like the idea of underpinning due to the stigma attached to it.

    Roughly what would the difference in cost be to knock it down and starting again with a double storey extension vs underpinning and building over it?

    Rough measurements 3m x 6.5m (double storey).

    • This discussion was modified 3 months, 2 weeks ago by  Charles Bell.
    • This discussion was modified 3 months, 2 weeks ago by  Charles Bell.
    • This discussion was modified 3 months, 2 weeks ago by  Charles Bell.
    James Adams replied 3 months, 2 weeks ago 5 Members · 4 Replies
  • 4 Replies
  • Henry Smith

    Member
    January 12, 2025 at 5:57 pm

    First thing to do is do a test hole to see what the footings are like as the outer skin is not load bearing you can do it a couple of ways without knocking it down we’ve dug a trench and mass filled with concrete to take the inner skin we’ve also put Rsjs in to build off

  • Edward Jackson

    Member
    January 12, 2025 at 5:58 pm

    Knock it down and start again, it might be the same cost depending on the ground, but will be far quicker and easier.

  • Malc Nuneam

    Member
    January 12, 2025 at 6:01 pm

    Cost would be a 6 figure sum. You have to bear in mind the cost of demolition of the garage and clearing the existing foundations preparing groundworks for new foundations (deeper for two storey so more excavations, drainage etc) even before you have got to DPC level you would have spent £15-£20k at this point.

    • This reply was modified 3 months, 2 weeks ago by  Malc Nuneam.
  • James Adams

    Member
    January 12, 2025 at 6:04 pm

    Get a survey done and employ a structural engineer, otherwise, you are treading a minefield Builders will harp on about how to go about the work and they Havnt seen the job or done their site survey and then they will price it and Balls it up and still want paying

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