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Feasibility of extension?

Discussion in 'Building' started by voicey, 26 Jul 2012.

  1. voicey

    voicey

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    Hi - I'm hoping to get some advice on just how feasible my plan for a small extension actually is. I should state up front that, subject to no major concerns being raised here, I will be engaging professionals to prepare drawings/calculations and to perform the work. I have also confirmed with the planning office that the proposal falls under permitted development.

    The back of our (mid terrace) house is stepped - I would like to square off the ground floor and install a single window/door across the back of the house. I attach a couple of pictures - one crude plan and an actual photo of the rear of the house.

    The first floor has a brick walled balcony above the part of the ground floor that sticks out. I am guessing that I will need three steels put in - one between point A & C, one between D & F and a small one bridging B & E. I assume I already have a lintel/steel between points A & B in both the ground floor and first floor ceilings.

    I have seen that prior to inserting steels, walls are propped up with smaller steels inserted above and perpendicular the proposed location of the new steel. My concern is that this cannot happen across the whole wall as the balcony is in the way. However, I'm hoping that as there is a large window in front of the balcony that there isn't much propping up needed in this area.

    I realise that this project is going to cost quite a bit for a small amount of extra floor area but the lack of light in the house will make it worth it.

    Is this feasible or am I crazy?!

    Also, is there anything else I need to consider before paying out for drawings? Cheers!


     
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  3. ^woody^

    ^woody^

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    That can be propped no problem. Your quotes will just reflect the amount of messing about for the builder
     
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  4. voicey

    voicey

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    Thanks Woody - you have put my mind at ease.

    What sort of proffesional do I need to engage to prepare the drawings? I know I'll need the correct size steels calculated but I'll also want drawings to submit to planning for the certificate of lawfulness and I expect building control will want to see some kind of plan.

    Any help is gratefully received!
     
  5. freddiemercurystwin

    freddiemercurystwin

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    An architectural technician would be a good choice, some surveyors and structural engineers will submit to Planning/Building Control too though they can be pricey (SE's). Whoever you choose pick a one man band as they will generally be a lot cheaper than the bigger firms. Unless suitably qualified a technician/surveyor will need to employ a structural engineer separately but they should be happy to handle the lot ie choose and liaise with the engineer. You could do a lot worse than looking on your local authority planning online website to see who the popular technicians are.
     
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  6. voicey

    voicey

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    Thanks for the heads up re an architectural technician - I have a couple of leads.

    A further complication has reared its head. I knocked off a bit of coving to see if an ugly brick pillar in the room was holding up the floor joists only to discover that there's an existing steel between points B & G in my revised plan(below). The floor joists run perpendicular to the steel and are notched into it (if that makes sense).

    How feasible is it to put a steel between points A & C and join it to the existing one between B & G? I fear that my plan of a "simple" extension is out of the window!




     
  7. freddiemercurystwin

    freddiemercurystwin

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    Your ideas that it would not require a steel or 2 were always way off. If you want to do as per your proposed plan then you have 2 walls to support so you'll either need a pillar here or there and some beefy lintels or a couple of steels. Depends on how much you want to spend.
     
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  9. voicey

    voicey

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    Thnaks for the response. I've never thought I'd not need steels - I know I'm going to need three in an H pattern for the extension. What I'm unsure of is can the existing steel be joined to the new ones at the same level?

    The other option would be to put the new steels under the existing one but that would mean the ceiling height of the new part of the room would be lower (which I'd like to avoid).
     
  10. freddiemercurystwin

    freddiemercurystwin

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    As you would be increasing the spans of that existing steel the idea of joining a bit on the end to make 1 longer one is probably a non starter. Unless it was oversized in the first place. Consideration would also needs to be given to the end bearing walls and whether they can take the loads.

    Unless you can get a good builder to do a good assessment of how the structure works at present you'll either need to do some better measurements ie spans and sizes of steels etc for the forum to comment on or you'll have to employ someone (as per my previous post) for some feasibility.

    Really though anything can be done just depends how much cash you want to throw at it.
     
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  11. voicey

    voicey

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    Thank you for the reply. I have made some measurements (in cm on the drawing) and done some more digging about and have determined the following:

    - Between points D&E (above the patio doors) I have a lintel.
    - There is no structural support between points A&B
    - There is a steel beam that runs between points G&B which is supported by a brick pillar.

    I was hoping the brick pillar could be removed to open the kitchen up but I think it'll have to stay.

    I am hoping that a steel can be inserted between points A&C - I realise that this will have to sit underneath the existing steel which will means the ceiling will be lower at that end of the room. Is it acceptable to have a steel resting on another steel?

    I am hoping that a steel can be inserted between points D&F - is it acceptable to have the steel underneath the existing lintel?

    The only thing that needs supporting now is the balcony wall between points B&E - I'm hoping a small steel can be used that fixes onto the other two steels.

    I would be grateful if my thoughts could be confirmed or otherwise. If this plan is acceptable I will go ahead and get the drawings prepared. I just don't want to throw money at drawings if it turns out that they can't even be executed.

    Thank you to you both for your help - I really do appreciate it and apologies for my amateurism.

     
  12. freddiemercurystwin

    freddiemercurystwin

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    Sounds OK in theory but as mentioned there may be posts required or masonry nibs at the ends of the new steels. Your SE will determine all that.

    What does the steel between G&B actually support?

    It may be possible to get the steel between A-C to sit level with the steel on G-B, just needs propping and connecting on site.

    Just outline your optimum set-up to whoever you employ.
     
  13. maltaron

    maltaron

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    I am wondering what the steel from b to g supports. I would suggest that it is to support chimney breasts upstairs. If so it may be possible(but by no means certain) that the upstairs breasts and chimney stacks could be removed thus negating the steel. Or, if the room is as open plan as it looks the steel would be replacing the spine wall and thus cannot be lost.
     
  14. voicey

    voicey

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    Thank you both. The steel between B&G supports the floor joints for the first floor. There are no chimney breasts (property was built in 1985). The joists run perpendicular to the steel and are notched into it - I guess it replaces a spine wall. I am of the opinion that it cannot be removed.

    Alsdo, thank you for confirming that the B-G steel could be connected to the A-C steel. This would be my optimum solution and I will talk to the SE to see if it is possible.
     
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