Advise Needed - Concerns on Building

Discussion in 'Builders' Talk' started by goldeneye78, Jul 4, 2018.

  1. goldeneye78

    goldeneye78 Member

    Hi community,

    Hope i can seek some valuable advise here. I am doing an extension back of my property and to complete this the builder

    1. Could anyone confirm what is the current regulations of external wall thickness, is it 300mm or 280mm? Our architect specified 280mm

    2. The trench foundation was defined as below:
    Provide 750mm x 600mm trench fill foundations, concrete mix to conform to BS EN 206-1 and BS 8500-2.

    When we measured, the base foundation fluctuated anywhere between 450mm-550mm. Would this cause a problem in future, when we are to build a second story extension? (Structurally)

  2. Dam0n

    Dam0n Active Member

    Your architect has specced the foundations at said size. Regardless if the 450mm will be suitable it's not in the drawings so shouldn't be used.

    Sounds like the builder is cutting corners.
  3. jonathanc

    jonathanc Active Member

    So what was the architect’s plans for. Planning or more detailed plans for building regs? What did the builder quote for? Sorry for the questions but both wall and foundation types could be ok. We need to know much more to help you
  4. stevie22

    stevie22 Active Member

    450 is normal foundation width, 600 on boundary where wall eccentric, so no need to worry per se but as DamOn suggests this ccould be a sign of future corner cutting.

    Wall construction is based on U value: you need to make sure builder does build what is detailed.
    Dam0n likes this.
  5. goldeneye78

    goldeneye78 Member

    Sorry for the late reply everyone, didnt have access for a while.

    Thanks for the advise above. DamOn, so what should I do, as now they have already laid the bricks to the DPM. and how would one quantify where should the DPM level be?

    The architect was for both, planning and detailed plan for building regs. The builder quoted to accomplish what is stated on the plans.

    I know my response sounds quite vague and if I could be pointed in what other information you require to assist me, please t me know,

  6. timpal

    timpal New Member

    If it says 600mm wide footings, that's what it should be. Might be worth checking Building Inspector has been out and checked, before footings were poured.
    DPC should be 150mm above external ground level.
    Do check the detail of the 280mm wall build up and specifically the type of block and insulation that goes in, is what is detailed on the architects drawings. Filling it with Rockwool will not cut it, with an 80mm cavity.
  7. jonathanc

    jonathanc Active Member

    Your quote was for 600 wide so 450 wide will be cheaper. If building control are happy then carry on but seek money off....

    280 wide is fine provide you hit the required u value
    Last edited: Jul 9, 2018
  8. Dam0n

    Dam0n Active Member

    Personally I'd be getting the BCO in to see what he thinks. If he's not happy as it's not to plan then it's down to the builders to put right at their own cost. The builder priced the work to the drawings and then didn't follow them to save time and cash (for him not for you I might add).

    Do the builders seem genuine?
  9. goldeneye78

    goldeneye78 Member

    what is BCO?

    long story with builder. i am not sure if he is genuine - we went with him through recommendations of friends and family. he is not listed on checkatrade or anything but have done fair amount of work for others who seemed to be satisfied with his work. one of the reasons we went with him is that, the previous people he did the extension for informed us, the DS was impressed with his footings and foundation, so to them, they felt he knew what he was doing.
  10. Dr Bodgit

    Dr Bodgit Well-Known Member

    BCO = Building Control Officer.
  11. KIAB

    KIAB Well-Known Member


    Did they give him a back hander!

    I would never go on the recommendations of friends,even family.

    'Others who seemed to be satisfied with his work', if they have no experience of building, then they are going on what they think is acceptable,looks good, looks right,& he could be the biggest cowboy around.
  12. goldeneye78

    goldeneye78 Member

    lessons learnt hard way but not with this builder as its almost like a trap we got into and cant get out of it. we changed our electrician and plumber (also through recommnedations) and the ones we found through checkatrade, we are quite happy with. its the builder - hard to say if he is cutting corners, using the right materials...i can provide some photos if it helps this forum to assess so far work being done.
  13. Dam0n

    Dam0n Active Member

    100% post as many photos as possible and we can all have a gander.
  14. goldeneye78

    goldeneye78 Member

  15. Dr Bodgit

    Dr Bodgit Well-Known Member

    Have Building Control seen/inspected the trenches and signed them off? Have you asked the Architect why he specified 750mm x 600mm dimensions and implications if one of those is only 450-550 (not sure which is depth and which is width)?

    None of the views expressed here mean anything at the end of the day, its the BCO who will ultimately sign off that everything is OK so you need to seek their view I'd say.
  16. goldeneye78

    goldeneye78 Member

    the BCO signed off the trenches - - the builder confirms that BCO said OK for trench and informed him that he just needs the photos after the concrete goes in. i am going to double check this.

    this is another question i have. is there a paper slip/document that BCO normally sign off for every stages?

    my Building Control Guidelines doesnt state there will be sign off but these are stages
    Foundation Excavation
    Foundation Concrete
    Oversite Preparation
    Oversite Concrete Laid
    Surface Water Drains Laid
    Foul Water Drains Laid
    Final Drains Rest
  17. sospan

    sospan Well-Known Member

    One of the deciding factors on depth of foundations is the condition of the ground, how solid it is and what it is made up of. The ground in the pictures looks quite sound which is why the builder probably stopped digging. There is also a fence line in one of the pictures which may have impacted on the width of the foundations.
  18. goldeneye78

    goldeneye78 Member

    im pretty happy with depth but concerned on the width, which what i am trying to understand is, would this be an issue when we eventually do our extension upstairs.
  19. Dr Bodgit

    Dr Bodgit Well-Known Member

    No idea. What do your plans cover with architect and BCO approval, single or double story?
  20. goldeneye78

    goldeneye78 Member

    the plan covers a side double storey extension and a back single extension for open planning. but we are not going ahead with double storey for now, though the foundation laid will cater for that at some point.

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