The builder has done this …. Need help.

Discussion in 'Engineers' Talk' started by Annoyedcustomer1, May 25, 2021.

  1. Annoyedcustomer1

    Annoyedcustomer1 New Member

    Hi all

    So I’m having 3 meter bifold doors installed in my new build. The whole needed widening from 2 meters to 3. I had the engineer do calculations and we had the steel fabricated. Because of a stock issue the steel had to be made slightly higher than it was originally because we had a deadline to meet and couldn’t wait for stock. The engineer signed this off and said the new height is sound.

    The builder has installed the steel BUT in the process, to allow for the I-beam joists to sit on the steel he has cut the corners off and moved the flange from the bottom onto the horizontal of the new cut. See pictures.

    The engineer has said this is a big no no and very dangerous. The manufacturer also stated this. I’m now left with a situation where I need to have these repaired or replaced. The builder will most certainly get the bill.

    I have asked the engineer about fixing in a timber through the inner leaf brickwork across the wall above the steel (it will overhang the steel a little) to hang the joists off but he advised this will create too much eccentricity. I don’t understand this because joists are hung from timber with hangers every day. All we would be doing is cutting the I-beam back to its original profile essentially shortening it, then hanging it.

    Does anyone have any idea how these can be repaired so that the load is transferred correctly? Any ideas ?


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  2. jonathanc

    jonathanc Screwfix Select

    what solution does the engineer suggest?.

    the only think i can think of is to drop the steel so the top is the correct height and then replace the I beams.
  3. Annoyedcustomer1

    Annoyedcustomer1 New Member

    The engineer suggested this.

    1. Create a support so that the full unaltered timber I beam can rest.

    2. Create a method so that the bearing force can safely transfer to the timber I beam. This could be some sort of fixity to the web of the I beam on to the new steel or block work.

    3. Could a new timber I beam be constructed to one side of the existing, in order to relieve loading from the compromised timber I beam?
  4. Annoyedcustomer1

    Annoyedcustomer1 New Member

    See engineers reply - changing the height of the steel is a no go as it’s sat at door height like the lintel that was taken out.
  5. Jord86

    Jord86 Screwfix Select

    Clueless * builder, unless I'm missing something and you stated similar in your first post I would fit a steel on the internal skin walls, bolt a timber into the web of the steel and use joist hangers on the I joists to hang them off that.
    Last edited by a moderator: May 25, 2021
  6. warcs

    warcs Member

    in answer to point 2. can you bolt short pieces or (one completely along) of steel angle into the web of the I beam which project out and under the bottom chord of the timber beams, will require the correct bearing from your timber truss manufacturer to get the correct size angle, also depends on if you can access the other side of the beam to get the bolts through if not you may have to weld them on.
  7. stevie22

    stevie22 Screwfix Select

    Timber I beams are great in theory but really quite fragile things if not used properly. Cutting like this is a complete no-no as others have said.

    Your opening is now 3m? This is is a pretty trivial beam. What size and section of steel was originally designed? What size and section was supplied ? You said fabricated so I assume you have a UB with a plate on th bottom flange to mimic a catnic CXL? There are plenty of sections other than the normal UB eg UC, SHS, RHS

    This situation graphically illustrates the problem of a disconnect between engineer and designer. If the engineer only has loads and no details of dimensional constraints he will naturally gravitate to a UB section as that will be lightest therefore cheapest to buy and easiest to install. It is a minutes work to say that this beam will do the same job as that beam. This something I often been asked for guidance on and I always ask if depth is an issue.

    I would insist on written confirmation from the joist manufacturer of any suggested remedials but I would want to have them replaced.

    Jord's assessment of builder spot on!!
  8. Annoyedcustomer1

    Annoyedcustomer1 New Member

    Here is the calcs.
    The engineer originally recommended a HDX catnic but I couldn’t get one for weeks so I had him do a calc for steel fabricated which I could get done in a few days. But then a stock issue ended up making the beam higher. This wasn’t advised by the engineer to be a problem with allowing the i beams to rest in them. I don’t know why.

    The building inspector has just been out and he gave a few possible ways to fix it with brackets bolted onto the steel possibly an doubts we would have to replace the ibeam.

    out of interest, how hard is it to replace i beams ? I live in a new build. I would need to replace 5.

    Attached Files:

  9. stevie22

    stevie22 Screwfix Select

    OK so Catnic originally. I assume CXL because I've never heard of HDX and nor has the catnic website. Basically a 203x133 UB with a 6mm flange. Alternatively he may have meant a more normal (cold formed) heavy duty catnic. These are typically harder to get hold of and are generally weaker than the CXL which is specifically for high load situations (often with point loads acting). They are not ideal for retro fitting.

    The beam on the calc is massively stronger than the CXL (why?) but it is the same depth (strictly 4mm deeper as plate is 10mm) so this shouldn't have caused the problem you are facing. Your engineer is either not properly briefed or not particulary good I'm afraid

    Replace I joists? Floor up, ceiling down, wires & pipes removed, replace joists, wires & pipes back, floor back, ceiling back.
  10. Bob Rathbone

    Bob Rathbone Screwfix Select

    You have employed an engineer to specify the job, varying from this spec is a very 'brave' thing to do. I would ask the engineer to visit the site and suggest a remedy, all at the builders expense.
  11. The Happy Builder

    The Happy Builder Screwfix Select

    The person who ordered the steel was clueless and possibly the engineer.

    How was the builder supposed to do it?

    I agree what you have ended up with is not acceptable, but it seems that the job was never designed correctly and the builder should have just not started or stopped when they realised what the issues are.

    The only option is to bolt a timber into the flange of the steel joist and use hangers or get the correct steel as to install as originally intended.
  12. The Happy Builder

    The Happy Builder Screwfix Select

    “Because of a stock issue the steel had to be made slightly higher than it was originally because we had a deadline to meet and couldn’t wait for stock.”.

    A problem of your own making, the builder just needs to learn to say no to customers.
  13. The Happy Builder

    The Happy Builder Screwfix Select

    Presumably that’s the inner leaf of a cavity wall to the upper storey above the I-beams and the block work needs making good above the new steel work, so either the ceiling needs to come down if they cannot get in from the exterior.

    What is happening to the face brickwork, is there a boot lintel to go in and soldiers?

    The job should never have been started and before anyone gets shirty with me I am a C&G qualified Construction Technician and used to design jobs like this getting a structural engineer to do the calculations for the steel work.

    What does the building inspector have to say about this? Presumably LABC will need to inspect the steel work before it is concealed.
  14. Annoyedcustomer1

    Annoyedcustomer1 New Member

    The building inspector said it could be fixed with some kind of support under the lower flange that is fitted to the steel. The engineer and builder have not communicated properly on this.

    However a specialist company has advised that only shear force is an issue at the bearing rather than bend and the i beam should still be thick enough to withstand this. I’ll have to have the engineer calculate this to see.

    Building inspector was happy with steel etc. It’s way over spec.

    The inner leaf blockwork has been made good onto the lintel.
  15. The Happy Builder

    The Happy Builder Screwfix Select

    I was looking at the drawing the wrong way around, the toe welded onto the steel was supposed to support the face brickwork and the I-beams sat on top of it.

    So the block work between the I-beams would never have been removed, but there wasn’t ever a way of installing the steel work if it’s to that design with a taller steel.

    With the ceiling down and the I-beams cut back and brickwork joist hangers on them the steel work could be installed then the block dork made good from the inside.

    But you aren’t going to get any Acrows and Strongboys in to support the internal block work without taking parts of the floor above up then taking the skirting off in the room above to insert them into the wall, then you need a second set of Acrows and timbers to hold the I-beams up, because the inner block work will no longer be supported by the I-beams.
  16. The Happy Builder

    The Happy Builder Screwfix Select

    I am seeing you as the Project Manager and as someone who is in too much of a rush to get things done, so don’t think it is fully justified blaming the builder, the builder does need to learn to say no.
  17. The Happy Builder

    The Happy Builder Screwfix Select

    Looking at the pictures on the other forum the beam is in and the block work made good, leaving the bottom of the I-beams unsupported.

    There’s no many options left now other than chocking a bit of wood under them supported off the web of the steel.

    Over forty years ago a structural engineer told me “Always check availability of stock when selecting a section of steel, because there’s no point in specifying a certain size if the steel stockholders don’t have it”.
  18. Annoyedcustomer1

    Annoyedcustomer1 New Member

    That’s good advice.

    Thanks for the input.

    This was our first major build work and it’s certainly been an eye opener.
  19. The Happy Builder

    The Happy Builder Screwfix Select

    Over on the other forum someone said you may be able to strengthen the timber floor I-beams by gluing and screwing plywood fillets into the I-beam flanges, but you cannot do that now because the blockwork has been filled back in. It would have been worth finding out if the was a practical way out, it sounds sensible to me.

    I hope you have installed a cavity tray and plenty of insulation or else you may have further issues with damp penetration and cold bridging.
    Annoyedcustomer1 likes this.
  20. Annoyedcustomer1

    Annoyedcustomer1 New Member

    the engineer advised the same with the plywood glued onto the web. We are going to have some of the internal blockwork taken out to do this and then made good. Wil use a different builder this time.

    I asked the builder if we needed DPC and he advised no due to the steel having a true full weld and nothing would penetrate from the outside ?

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