Loft conversion underpinning advice

Discussion in 'Engineers' Talk' started by Hornplayer, Aug 20, 2016.

  1. Hornplayer

    Hornplayer New Member

    Greetings all, some advice please would be greatly appreciated. We were considering a loft conversion. We have paid £3000 for drawings and £900 for structural engineer. Engineer came a few months after drawing were complete. Engineer has said we need the house underpinning. The structural engineer was recommended by designer. We don't know anything about procedure so asked designer to appoint structural engineer. We feel a bit miffed that we have paid for the drawings and only now we are told we need underpinning. Is this normal please? We are thinking, why didn't they advise us to have the foundations checked first? Especially as we won't go ahead if we need underpinning. Would you advise a second opinion from structural engineer? When he was here he seemed very positive and saying we had 13" exterior walls, he dug one trail hole. We are not sure how to proceed. Many thanks indeed.
     
  2. KIAB

    KIAB Super Member

    Would always prefer to use a independent SE,definitely not one recommended by a builder,designer.etc.
    I get very suspicious of personal recommendations, I alway think there is then a risk of extra work/unnecessary work just to line a mate's pocket.:rolleyes::oops:( always been a cynical bar-steward):eek:
    Also you should have had SE to visit first, even before thinking of drawings,seen identical to you, where drawings needed to redone after a SE visit,it added thousands to the bill.
     
  3. Hornplayer

    Hornplayer New Member

    thank you KIAB,I appreciate you taking the time, i think we will certainly get a second opinion, at least we have drawings from SE, he was saying also, all lintels above windows need plaster taking off inside the house to reveal lintels and size. Its a pity we learn after mistakes, if intact I've made one. I am wondering if we have any justification to ask for a partial refund, a solicitor friend has said there may be a case of negligence from designer??
     
  4. Hi Hornie.

    It's a toughie.

    You did what any normal homeowner would - employ a designer who, in turn, employs an SE. Sounds sensible enough.

    Except when it doesn't turn out as smoothly as you'd hope.

    (I have to say, £3k for drawings and a further £900 for SE calcs is pretty bludy expensive - unless your design is something quite awesome?)

    How to proceed? I dunno. Is your house a one-of design, or are there similar builds in the 'hood? How old is the property?

    Just how massive is this loft conversion - how much extra living space will it create. Can you explain roughly what the 'new' bits will be?

    I mean, a normal house has a roof. The roof is very heavy. To add living space to that roof means extra floor joists, partitions and other bits - these aren't all that heavy. So, if the average house is managing to hold up its roof ok, then it's extremely unlikely that adding a few extra rooms up there is going to suddenly make it begin to sink...

    So - is it a 'loft conversion' or are you, say, adding a whole new floor level?

    If the former, then I'd be astonished if underpinning was required.

    (From my own experience of having a loft conversion done, I know that architects are often in cahoots with builders, and some will even try and influence the design so as to cater more for a particular type of builder...)

    Anyhoo, if you could provide more details of the work, then it might suggest a direction to go.
     
  5. Oh, as for exposing the lintels - yes, if there's no other way of telling what kind they are, then that is very likely necessary.

    So, again, if your house is older or a one-of design, then they'd need to know.

    Mind you, I can't see why they couldn't chust add further lintels/beams/joists whatevs on the top of these walls to cope instead.
     
  6. Hornplayer

    Hornplayer New Member

    hi Devils Advocate, thank you so much for the detailed reply, its so appreciated. The house is from around 1870. 13" walls all around exterior. We wanted upstairs, one small bedroom. one small playroom and an on suite with shower. I didn't shop around for design quotes as I kept it local, my fault here re the price. At least now if I get a second SE i know that £900 will be on the high side and at least I have the drawings from original SE. I too was also wondering why a new joist, timber or steel couldn't just span over windows lintels if insufficient. Oh yes we were also looking to have 2 velux windows and 4 apex little windows, 3 back one front for ensuite to give head room.

    Thanks again
     
  7. KIAB

    KIAB Super Member

    3k for drawings & £900 for SE calcs seem excessive, but I'm out of touch with prices with regards to that.

    How old is this house?
     
  8. Hornplayer

    Hornplayer New Member

    hi KIAB again, thank you so much for the reply, its so appreciated. The house is from around 1870. 13" walls all around exterior. We wanted upstairs, one small bedroom. one small playroom and an on suite with shower. I didn't shop around for design quotes as I kept it local, my fault here re the price. At least now if I get a second SE i know that £900 will be on the high side and at least I have the drawings from original SE. I too was also wondering why a new joist, timber or steel couldn't just span over windows lintels if insufficient. Oh yes we were also looking to have 2 velux windows and 4 apex little windows, 3 back one front for ensuite to give head room.
    Thanks again
     
  9. KIAB

    KIAB Super Member

    Veil windows, I think you mean velux windows.:)

    The lintels over the windows, will most likely be timber,maybe orginal unless they have been replaced a later stage.
     
  10. Hornplayer

    Hornplayer New Member

    Thanks KIAB, indeed, predictive text really causes laughs sometimes. cheers
     
  11. Hi 'Player (I'm being less rude now...)

    How much alteration will there be to the upstairs roofline?

    What you propose - 2 small rooms and a loo - ain't going to add any significant extra weight to the building structure as far as I can see, so if this house has been standing without sinking for 150 years so far, I find it hard to believe it's suddenly going to need extra founds...

    When you say 'designer', do you mean architect? And what exactly is he designing - an incredibly complex layout? Or just modifying the upstairs roof space to take rooms?

    As a comparison - tho' this was 10 years ago - my archi cost me (I think) around £600 for a complete set of CAD drawings showing new joist layouts and flitch beams, completely new roofline, a re-profiled house face (taken up vertical with French doors and triangular windows rather than the old pitch), etc etc. The SE - working independently - came out, looked around the old loft and wrote up a couple of pages of calcs with suggestions of where to position the beams all for around £180, I think it was.

    £3k seems really high.

    Are there other houses of this age in your locality? Any been converted? If so, that's your first port of call. Failing that, contact another SE - ideally one familiar with this age and type of build - and ask them to come out for a chat.

    Explain - without going into too much detail - that you've been exploring the possibility of a loft conversion but that you'd been put off by another SE due to the cost of it needing strengthened founds/underpinning - ask for his opinion...
     
    BMC2000 and KIAB like this.
  12. BMC2000

    BMC2000 Screwfix Select

    It is the standard way of doing things in that the architect has the vision and then passes the proposal to the SE for his beam sizing etc and then the architect amends his design to suit the SE proposal.

    Underpinning for a loft conversion is not common, and as a fee has now been paid you need to go through this with your design team who have been paid for their services to ask is there anything that can be done by way of design amendment to avoid underpinning.

    You know where the term 'over engineering' comes from? SE' s protecting their bacon by designing OTT solutions to cover themselves.

    Question, question and question some more.

    Have the SE design reviewed afterwards if you are not satisfied.
     
  13. Astramax

    Astramax Super Member

    Have your footings been exposed for a visual inspection, external and internal of the property? That's what I had to do for building control to inspect that the depth of the footings were as on the original drawings and deep enough to take the extra weight. Two areas on opposing outside walls and two areas on the interior (load bearing) spine wall
     
  14. I would expect - unless the nature of the original build was fully known - that a test hole would be needed. But HP says the SE did a quick dig on his visit and seemed satisfied.

    I guess he's now covering himself?

    Our bungie didn't even require a test dig as the ground in this area is known to be very secure, second only to rock apparently. But I do recall it was 'mentioned' as one of the things to be considered - before being dismissed as "No issues there..."

    In retrospect, H-P should have had these issues confirmed first before proceeding. But, as always, how is a layman meant to know this? A good architect should have discussed all this during the initial meeting - things to consider. Likely costs, etc.

    Whether there's a case for negligence, tho', I kinda doubt it.

    £3k? Jeepers...

    If it's really a case of you won't be proceeding with the conversion if underpinning is required, H-P, then you are left with a £3,900 outlay for nothing. If that's the case, then I'd be tempted to try and obtain a discount from the Archi due to what you could consider less than professional service in not explaining these issues beforehand. Should he say "Tough", then you have recourse to leave honest reviews about his service "Very expensive - and ultimately pointless..." on as many review websites as you can find...

    Small consolation, tho'.

    The chances are, however, that test holes will be required (to satisfy BCO), but underpinning won't be.

    So, if it all goes ahead (fingers crossed), choose your tradespeeps with more care than you did your archi... :)
     
  15. Aneta

    Aneta New Member

    loft conversions in london is often problematic when everyone is working separately. They won't bother to give advice what you might have to consider before hiring architect, engineer or constructor. Outside of london people tend to be sincere but not always. Therefore best would be to consider someone who does all the job. From A to B. As it would be in his best interest to reduce the cost if there is a budget and could advice of all possible challenges.
     
  16. stevie22

    stevie22 Screwfix Select

    What sort of construction is your property?

    It's most unusual to need underpinning except perhaps for the central wall in a traditional build which may be load bearing in so far as it supports floors and roof loads but is not necessarily on a full depth foundation. If it is the central wall then it's perfectly possible to arrange steels to avoid that wall. I did one last year where the downstairs wall had been removed and the client didn't want to disturb downstairs to put in a bigger steel.

    May be worth a chat with any neighbours with similar properties that have been done or Building Control

    As an alternative look at Telebeams. They are primarily designed for trusses but can work well in traditional structures and the people are very helpful.

    I agree with opinions above that you have paid dearly!! If underpinning is not necessary then I think you have grounds for seeking some recompense.
     
    KIAB likes this.
  17. Almost certainly he won't need underpinning. And neither will his house (fnurrrrr...)

    But very likely the BCO will need to confirm this, usually by an understanding of the type of founds his type of house will have, coupled with the type of ground it's built on, and possibly reinforced by a test-dig (which, apparently, the SE has done)

    The chances of underpinning being required is tiny.

    Good point by Steve, tho'. I guess if the design of the upper floor is such that the bulk of its weight will now be taken by a few small pillars, for example, then perhaps these found areas will need boosting?

    I dunno.
     
  18. koolpc

    koolpc Super Member

    I think it is the SE that needs underpinning!! lol
     
    KIAB likes this.
  19. Rob_bv

    Rob_bv Active Member

    I've seen a few places over this way (NI) need underpinning for a loft extension - the old stone houses here just have packed stone foundations rather than concrete, so whilst they may very well be strong enough to hold the house up for umpteen-hundred-and-two years, designing for those type of foundations and additional loading may fall well outside the SE's factor of safety.
     

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