Small fireplace lintel bearing

Discussion in 'Builders' Talk' started by Kriskringle26, Mar 21, 2016.

  1. Kriskringle26

    Kriskringle26 New Member

    Hi,

    I'm looking to widen a small fireplace and wondered if 70mm is enough bearing / overhang for either end of a concrete lintel spanning across a 460mm gap?

    Thanks in advance!
     
  2. Kriskringle26

    Kriskringle26 New Member

    Hi all, any help here would be very much appreciated.

    Thanks
     
  3. Phil the Paver

    Phil the Paver Screwfix Select

    A pic of said fireplace would help.

    It not ideal only having 70mm, but i doubt it would move much.
     
  4. Kriskringle26

    Kriskringle26 New Member

    Thanks Phil. I've just uploaded a pic. At the moment most of the brickwork is plastered over though so its probably not much help.

    As you can see it's a pretty small hole. I'm planning to take out a brick width on either side. At the moment the gap is only supported by 2 steel bars, which seeing as I can flex them with my finger, I don't think are doing much..
     

    Attached Files:

  5. Phil the Paver

    Phil the Paver Screwfix Select


    Is it stud work either side of the existing fireplace? If not why can't you carry more Baring on the lintel by cutting into the brickwork more.
     
    CGN likes this.
  6. Hi Kris.

    The holes that can be seen drilled - is that the shape of the opening you are after?

    Any reason why you cannot go the full 150mm bearing - or even a compromise at 100mm+? It's hardly any more difficult to do.

    As Phil says, tho' the chances of any issues arising are minimal - provided the brickwork on either side is solid with sound mortar. How are you planning to remove the bricks - cut the verticals with an angle grinder (very messy - but neat & strong) or drill/chisel (less messy but will risk loosening/cracking bricks, and won't be perfectly straight - so your actual bearing bricks could be effectively less than even 70mm)?

    If the latter, then make sure you don't loosen or crack any of the bricks you'll be relying on to support your lintel :).

    But, why not at least a ~120mm bearing?

    Anyhoo - your call. It wouldn't 'conform', but if done neatly I can't see why it should fail (unless another chancer comes along after you are wants to widen the opening a couple of inches more and thinks "Hey, it's bound to already have 150mm bearings, so losing 50mm off that won't hurt...)
     
  7. Kriskringle26

    Kriskringle26 New Member

    Cheers Phil - There's no stud work so shouldn't be any problem there. I've already bought a 600w concrete lintel so I was working to that. By the time I take out a brick width either side, that only leaves me with the 70mm bearing either side. Have been struggling to find any info on lintel requirements for such a small gap.
     
  8. Kriskringle26

    Kriskringle26 New Member

    Hey Devils - Thanks for your reply (sorry I didnt see your response before my previous)! The holes you can see were there previously, but they're probably a good representation of how far I would like to go.

    I've already bought a 600w lintel in a hurry so was trying to work to that, however it sounds like it might be a good idea to go wider to be sure.

    I was planning to drill and chisel, but I hear what your saying about disturbing the remaining brickwork. Will an angle grinder give me enough depth to take out all the mortar across the full depth of the brick?
     
  9. Concrete lintels are cheap. You know you'll feel better doing it right :)

    You'd need a 9" angle grinder, and this will go almost the full depth of the bricks - it'll chust leave a little bit of tidying up of the remaining edge afterwards.

    BUT, grinding is VERY dusty. I would only suggest it if your were daft enough to continue with the small lintel ;).

    A builder made an opening in my sis-in-law's wall recently and used a drill and SDS chisel (as well as manual bolster and 'ammer). It was my job to make it good afterwards - and there were plenty of cracked and loose blocks there... The finished vertical edge was all over the place, and varied by a couple of inches. And he even left out a part block that must have fallen out a couple of rows below the lintel, so if you traced down 8" below the lintel's bearing, it was effectively only sitting on around 4" of block.

    So quite a bit of tidying up before the BCO came visiting...

    For such a small opening, tho', you'll be fine SDS drilling a series of holes along the vertical required cut lines (and along the mortar lines for the bricks to be removed for the lintel), and then replacing the drill bit with a chisel. Slow and steady - let the drill do the work.

    The chimney breast won't fall down in the process. Or at least it shouldn't...

    The proper way is to remove chust the 'lintel' bricks first, clean up the slot, dampen, apply a bed of mortar where it'll be 'bearing', and slip in the concrete lintel. Pack in mortar tightly all around.

    Allow to set before then cutting and removing the space below.
     

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