Advice needed to support chimney stack

Discussion in 'Builders' Talk' started by streetrep, Feb 12, 2010.

  1. streetrep

    streetrep New Member

    Hi Builders/ Engineers,
    I am proposing to support the chimney stack at the Loft.

    I will be using RSJ steel beam to support the chimney stack 6mtr length 8"inch height and 4" wide RSJ.

    The problem i have is 1st floor bedroom it has the fitted bedroom, so i will have to DO everything from the loft.

    What is the best way to support the chimney stack while i take enough bricks out, so i can install the RSJ.

    The chimney stack is about brick and half. Is there Short acro or do i use strong boy.Rsj will be fitted between the ceiling and new loft floor.

    What about the corbelled brick do they need to be supported or can i run at a 90 degrees steel or wood and supoorted on the party wall.

    Spoke to Neighbour and he said it is ok to to use his side of wall, as long there is no damagage outside his chimney.

    The brick built chimney is corbelled meaning half brick is bedded on the party wall.
     
  2. streetrep

    streetrep New Member

  3. manassa

    manassa New Member

    How are you going to get the 6m steel into the loft?
    A chimney of that width which is tied in well will stay up while you cut out bricks for the steel.
     
  4. fitero

    fitero New Member

    Build a tower up to eaves level,take out tiles to make an opening at wall plate level and slide your steel in.Cut out three course of brick under the stack and slide the steel into place and onto the next wall and make good the brickwork.You may have to cut the steel at about 45 degrees at the wall plate end,I know the hard way,just done one and it took two of us a full day.Good luck[never even put a boot through the ceiling!!!]
     
  5. mightyapu

    mightyapu New Member

    Speak to an engineer and get him to design a set of gallows brackets.
     
  6. streetrep

    streetrep New Member

    Thank you all for your replies.

    I do not know if this is good idea, but the joiner advise me over the weekend to get a 2mtr steel rsj and weld a plate on the end and have 4 holes.

    He said place across the chimney on the centre wall only and at 90 degrees place the other x 2 wood joist 8x2 joist into the wall using masonary hangers and then other end jiffy hangers attached to the joist.Then bolt the RSJ to the joist which is going across.

    Do you think is this good idea.

    I may be able to get a steel beam, as there is large enough opening where i could carry the rsj front of the house into the small bedroom, which is the annexe and then slide through where the new staircase will go into.I still need to check, as i have opening of 2 mtr by 1mtr on the loft.

    http://s1015.photobucket.com/albums/af271/deltaman/?action=view&current=untitled.jpg

    Please confirm your thooughts, as when he explained to me i wasn't so sure, as it is like a sea/saw effect, this is why he said you have to attach the joist 90 degrees to tie it in
     
  7. D.S Builders

    D.S Builders New Member

    You need some gallow brackets designed. Then you need to bolt the to the wall with sheild bolts.Span the brackets (3 of) with prestressed lintels. A average size bracket will be approx 375 x 490 x 10mm with 12mm holes.

    D.S
     
  8. streetrep

    streetrep New Member

    Hi D.S Builders,

    Thank you for your reply.

    So i need to make 3 gallow brackets 375mm Depth, 490mm will be the lenght/height and i need to fix it with shield bolt and place a prestressed Lintel going across.

    Is the prestressed Lintel will this be in stone or Steel.
     
  9. D.S Builders

    D.S Builders New Member

    The lintels will be concrete 65x102 by the with of the chimney.I would sugest that you get a engineer to do a quick calc for how much load will be on them as this will be down to the witdh of the steel ie 50mm - 100mm. How much chimney is sticking out the roof ? SF sell them but there only small. Where bout are you ?

    D.S
     
  10. streetrep

    streetrep New Member

    Hi D.S Buliders
    Thank you for your reply.

    I am in Bolton, near Manchester.

    Above the roof it is only 3-4 courses sticking out, as the neigoubour reduce the height of the chimney 5-6 years ago.Chimney stack above the roof is stone work not normal bricks.

    So Screwfix sells them or i will ask to metal fabricator to make one, if screwfix is not suitable.
     
  11. D.S Builders

    D.S Builders New Member

    If you mesure how deep the chimney is this is the size of the top of bracket. I would use 75mm x 10mm steel and 450-500 drop (depending on the depth) and the same steel for the diagnal. Paint with red oxide bolt to wall and pack with slate job done.

    D.S
     
  12. streetrep

    streetrep New Member

    Hi D.S Buliders
    Thank you for your reply.

    Chimney is about 14"inch (35cm) deep. So i will make the bracket depth 40cm and follow the rest of the measurment as you mentioned below 75mm x 10mm x 500 and diagonl steel.

    While i do the job attaching the gallow bracket, do i still need to use strong boy acro, to support other part of the above chimney stack , while i am taking out enough bricks to place the gallow bracket.

    The other chap said the chimney is well tied in and it will not fall while you place the steel, i just wanted to be sure.
     
  13. D.S Builders

    D.S Builders New Member

    Always use acros and strongboys its not worth the risk.It may look well tied in on the outside but beware the flus are normally stack bonded and they can and do drop out.

    D.S
     
  14. streetrep

    streetrep New Member

    Thanks D.S.

    Will use the acro and strongboy.

    The back part of the chimney stack is tied in the wall with the neighbours party wall and the front needs to be held up by acro, while i take the bricks out to make room for gallow bracket.

    Thankyou for you all replies.
     

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