repairing a rotten beam, in situ.

Discussion in 'Carpenters' Talk' started by rich6757, Jun 7, 2022.

  1. rich6757

    rich6757 Member

    I'm in Dorset.
    House is 1901.
    Today I pulled the laths off and knocked out the pebbledash plaster from inside the loft, on the other dormer, just to see what the cladding looks like from the back. I also pulled off some from the sides of the dormers to see if the rot has moved down the sides.

    The other dormer has rot, bad at the bottom of the cladding. The are also one or two spots where the rot has come through at the joints at the very bottom of the cladding on the sides of the dormer. Looks like I will only have to replace the lower part of the cladding on the sides. I can now spray the back of the cladding from inside the loft.

    Here you can the other dormer frontage, with the lath& plaster removed. The back of the cladding is covered in rot at the bottom and it's just started to creep through half way up the board
    20220612_121348 (Medium).jpg


    close up:
    20220612_121326 (Medium).jpg


    Here's the side of the dormer:
    20220612_115124 (Medium).jpg
    Mostly ok, but rot is just begining to creep in at the joints, from the bottom.
    20220612_115025 (Medium).jpg
     
  2. rich6757

    rich6757 Member

    Before:
    20220620_131419 (Medium).jpg

    20220628_162143 (Medium).jpg



    Slowly progessing... Working on the corner now.

    20220704_173313 (Medium).jpg
     
    Rosso likes this.
  3. rich6757

    rich6757 Member

    Well it's now October and one dormer is done! Onto the second one. This time I am cracking throught it about 5 times quicker, now I know what I'm doing!

    The method I used before to clear off the front of the beams worked but it is S-L-O-W... (routing it off in 5 inch wide strips, in 30 inch sections)

    Just thinking again about other ways to slice off an inch of timer from the front of the beams. I can access the top and bottom of one of the beams, which is 125mm thick, so it may be possible to run a circular saw along the top and then along the bottom as my saw cuts to 70mm depth. Tricky holding it upside down though.

    The lower beam is tapered so its 175mm thich in the middle and 100mm at the ends. No access to underneath though as its resting on joists.

    Wondering if a reciprocating saw would cut straight enough, if it was following the groove cut by the circular saw first?

    The router method is good as it allows me to go deeper where the rot has penetrated more, but on the second dormer the rot seems more uniform and is nearly all no more than an inch deep.
     
  4. Resmond

    Resmond Active Member

    My experience with recips is they turn to butter as soon as they heat up, so good for demo but mot for straight cuts. That said see lots of videos from across the pond of them being used for all sorts..
    What about circ saw from above followed by hand saw
     
  5. rich6757

    rich6757 Member

    Yeah could try that, would be a long cut though! 3 metres! The beam that's sat on joists will still be a challenge too.
     
  6. qwas123

    qwas123 Screwfix Select

    OP, you didn't see fit to recognise my June post so i'll only say that after 4 months of work, & more
    to come in winter weather you've only "done" (whatever that means) one dormer, and now you suggest another weird method using saws!

    Not best practice but chiseling the rot out would have been simpler & quicker.

    If you leave any dry rot pockets still in any of the timbers, and damp gets to it you will again have a full scale outbreak of fungal damage.

    You seem to believe that removing "beams" will require the whole roof to be removed.
    Thats not so. No need to remove the dormer roofs, they can easily be supported when removing the full pediment frontage "beams" and all.
     
  7. rich6757

    rich6757 Member

    Trying hammer and chisel approach on this side. The rot is shallower and of more consistent depth (about 1/2"), so taking an inch off the front, the spraying and fitting new timber. Made a guide for the circular saw to make vertical cuts easier.

    Oh and here's the 'done' side!

    20221009_172605 (Medium).jpg 20221009_174724 (Medium).jpg 20221009_175020 (Medium).jpg 20221008_115517 (Medium).jpg
     
  8. Mr Rusty

    Mr Rusty Screwfix Select

  9. Abbadon2001

    Abbadon2001 Screwfix Select

    Although I admire the work and effort, I cant help in thinking that is a bit of an odd arrangement? Maybe its just the angle, and looks better from further way :D would be good to see the overall building from a slightly further away aspect!
     
  10. rich6757

    rich6757 Member

    What you mean the construction? Yes it is unusual. The carved joist ends were covered up before, so I decide to leave them exposed an I'll strip and repaint them. The other dormer has some worse rot in these joist ends, so i looks like I will have to make new ones.

    Still not sure about replacing the mock tudor bits that were on the front. They seemed to be a breeding ground for rot.

    What it looke like 12 years ago.
    P1030003 (2) (Medium).JPG P1030004 (Medium).JPG
     
  11. Mr Rusty

    Mr Rusty Screwfix Select

    Unless it's listed, I do think I'd have taken the opportunity to consider reverting to a more functional arrangement. Are those constructions really just ornamental with no useful space inside?
     
  12. rich6757

    rich6757 Member

    Not listed. You mean just rebuild the roof without an dormers? Could do, but our place is a bit of a landmark in the area and it might not go down well with the locals!

    There's nothing inside the dormers, just loft space, but if we ever converted the loft, these might be good to make into windows...

    By the way, Rusty, I might want to pick your brains some more on sash window construction!
     
  13. Mr Rusty

    Mr Rusty Screwfix Select

    I'm here fairly frequently......
     
  14. Rosso

    Rosso Screwfix Select

    Nice gaff. The dormers are unusual, with those sidewalls they are quite tall.
    Personally I think the mock tudor trim is an essential design element, but its your house-you don't have to do what you don't want to.
     
    rich6757 likes this.
  15. rich6757

    rich6757 Member

    Thanks!
    The mock tudor is not as nice as the original frontage I found behind it. It had a row of 4 quartrefoils with pebbledash inset between the woodwork.

    Very similar to this pic.

    I might go for an opening in the cladding using a quartrefoil design.

    The main issue I have with added on mock tudor is that it appeared to be a perfect breeding ground for the rot!
     

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    Rosso likes this.

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