My builder disagrees with my structural engineer who is right?

Discussion in 'Carpenters' Talk' started by SeanDean, Jan 18, 2020.


Who is right, the builder or the structural engineer?

  1. Builder

    0 vote(s)
  2. Structural engineer

  3. Both

    0 vote(s)
  1. SeanDean

    SeanDean New Member

    So I have some roofers creating a balcony roof for me and midway through the build, my architect/structural engineer who is working on another project on my house took a look and had some concerns.

    He said the constructed frame in the photos below was not sufficient in his opinion for a roof and even more so one that would be used as a balcony with foot traffic.


    His main concern was the direction of the joist and that the endplate over the doors to the right only consisted of one 200x50 board. This is the end the water will run off into a gutter.

    He also pointed out the board running along the garden retaining wall had a gap behind it as highlighted with the arrow below.


    He advised me that the load-bearing plates should be attached to the wall of the house and the garden retaining wall with the joist running between them in the opposite direction to what they are running in the photos above. Illustrated in his drawing below.


    He said the board above the door should be made up of at least two boards fastened together with coach bolts and they should also be attached within the plates like his drawing above shows and not on the ends, he also said the boards should not rest on the aluminium frame of the doors at all and there should be a gap.

    My builder has made the changes but is saying that the advice given is wrong and there was nothing wrong with the original frame, he also states that the way the structural engineer says it should be done is much weaker than his original frame

    Here is an image of the updated frame that will be lifted slightly and fixed to the retaining wall and the house where the photo is taken from, note the double boards above the doors have been attached to the end of the frame not within it as per the drawing above.


    What do other people think about the above situation, I'm not a builder so I dont know who is right and I feel really awkward in the middle of it all, I just want a GRP balcony roof that's going to be strong and last the 25-year guarantee that is being placed on it.

    I thank you in advance for any input helping me understand who is right.
  2. jonathanc

    jonathanc Guest

    I’d agreed with the engineer.
  3. Abrickie

    Abrickie Screwfix Select

    Has your builder changed you extra for the alterations ?
  4. Mancone

    Mancone Member

    What qualifications do builders have?
  5. SeanDean

    SeanDean New Member

    No, but he is hinting at it, to be honest, I dont think he will it's just he is saying my structural engineer has given bad advice and its not going to be as strong.
  6. SeanDean

    SeanDean New Member

    I am not sure what qualifications he has to be honest.
    Mancone likes this.
  7. jimoz

    jimoz Screwfix Select

    builder is wrong 100% who there is a reason we put lintels above door frames and that is because they're not designed to hold up weight/structure.
    Hes dropped a ******* again with that end rafter you will have to see if there is some kind of connector/hanger that will suit that arrangement
  8. Mancone

    Mancone Member

    To be honest I just thinking out loud. Perhaps get another engineer to give a second opinion ;)
  9. Mr Rusty

    Mr Rusty Screwfix Select

    I'm not surprised your SE had concerns. With a french door/window on one side all those joist ends would be loading into that single 200x50 which is majorly supported by the windows and door frames. I agree, the individual joists should feed their loads into wall plates directing the loads down through brick walls.
  10. jimoz

    jimoz Screwfix Select

    Has he put any dpc between that plate and brickwork
  11. SeanDean

    SeanDean New Member

    I did not want to go back to the builder about the endplate and cause more issues, my SE said not to worry as he would dig out some sort of brackets (cant remember the name) and come strengthen it up for me from underneath afterwards. Not ideal but saves the awkwardness and I really dont want the builder walking off the job and leaving me without a roof.
    Mancone likes this.
  12. SeanDean

    SeanDean New Member

    No, it's just the board there at the moment but maybe he is going to do that when he comes to raising the frame and fixing it to the wall. I will question it.
  13. jimoz

    jimoz Screwfix Select

    See the dpc in my pic id say it's more important in your case as looks to be retaining wall

    Attached Files:

  14. Abrickie

    Abrickie Screwfix Select

    It pains me to say it but your builder is wrong and knows it or he won’t have altered anything without agreeing a price for the alterations
  15. SeanDean

    SeanDean New Member

    Thank you for sharing this.
    Maybe I should just go buy some dcp just incase and then hand it to him when he returns on Monday. is there any particular stuff i should be looking to buy, the boards are 200x50?
  16. Magjul

    Magjul Member

    I'd go with the engineer - he will surely have liability insurance of some sort where-as your 'builder' may not.
    If it's built as the engineer has designed and it fails, it's down to him: if the 'builder' does what he thinks is best and it fails, what's the chances of him coming back to put it right - at his cost??
    Mancone likes this.
  17. Mancone

    Mancone Member

    Yeah but m8 they have that insurance printed on the side of their van (sarcasm).
  18. SeanDean

    SeanDean New Member

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