Causes/Remedies for Crumbling Sandstone?

Discussion in 'Builders' Talk' started by glob@l, Sep 11, 2019.

  1. glob@l

    glob@l Active Member

    If this was happening outside I would suspect the damage was caused by water penetration and the weather generally. This is happening inside a 150 year old stone built semi detached cottage on the adjoining (attic) gable. There is a dissused joint chimney stack vented from the top and the adjoining roof tiles are bridged (cement bedded) with ridge tiles. I'm not aware of any evidence of water penetration elsewhere in the house. Looking at it you would think it was okay, but poke it with a finger and it crumbles?
     
    Last edited: Sep 11, 2019
  2. KIAB

    KIAB Well-Known Member

    Sandstone is porous,it will soak up any moisture,water.
     
  3. glob@l

    glob@l Active Member

    The attic is insulated between the ceiling joists, so the roof space will be cold in the winter and warm in the summer. Is that wall likely to attract any airborne moisture as condensation when it's cold.
    Apart from identifying the cause, how do you remedy crumbling sandstone?
     
  4. glob@l

    glob@l Active Member

    Can anyone offer a remedy for crumbling sanstone? Would the above post suggest the moisture is caused by leakage or perhaps airborne moisture? There are a few members who seem to have a good knowledge in this area.
     
  5. Joe the Plumber

    Joe the Plumber Well-Known Member

    You could try asking the conservation specialists at any large church or cathedral. Unfortunately though, from what I've seen, they tend to repair it by replacement rather than by applying some magic potion.
     
  6. glob@l

    glob@l Active Member

    If the sandstone is being damaged by airborne moisture, presumably improved ventilation in the attic would address the cause?
     
  7. Richard_

    Richard_ Active Member

    Cement mortar can be a problem within sandstone because cement sucks in water so the stone never dries out. It's often much better to use lime mortar because it breathes.

    I've seen horrific before and after pics of cement pointing to replace lime. Although they're usually external, but seats of it happening internally.
     
  8. Mr Rusty

    Mr Rusty Well-Known Member

    It is quite likely that if there was a heavily used chimney the sandstone has been contaminated by salts which are the result of the compounds in the sandstone reacting with combustion gases. These salts are hygrosocopic and will draw moisture in to the stone. I presume its a bare stone wall.
     
  9. ajohn

    ajohn Well-Known Member

    There are some companies about that do stonework cleaning and renovation. I suspect it would be best to get some people like that to have a look. If they do the lot they will have some stonemasons about. They fix all sorts so are likely to aware of what causes what.

    Our house a had a lot done under an insurance claim. I'm pretty sure the company name was Relco or something very similar. Another that could have done the job is this outfit

    https://www.fearandsons.com/projects

    This was a fair old time ago though so not sure if the same people are involved. Must be over 20 years ago now.

    It's a very specialised business so take care on who you pick if you go in this direction. In any area where there are properties about that use stone there is likely to be some around. Masons should be aware of fixes as well not just able to shape stone.

    John
    -
     
  10. glob@l

    glob@l Active Member

    Thanks for the feedback.
    The overall width of the adjoining stone walls will be approximately two feet thick, where the chimney void passes through the wall the thickness will be reduced to about 6 inches I imagine. Since the problem area is in the attic (not seen) would the job of repairing the crumbling sandstone be better if replaced with brick? More cost effective, easier to do and wouldn't need to revisited with the same issues at a later date.
     
  11. glob@l

    glob@l Active Member

    THe sandstone seems to have a white coating on it, a lime wash perhaps?

    I've had a good look at the gables now and the damaged sandstone is confined to the top two thirds of the wall horizontally and coinsides vertically with the line of the chimney stacks.

    The chimney is vented from above so I may also vent it from below to provide additional ventilation.

    Please also see my previous post.

    Can the sandstone be removed and replaced/repaired with brick without running the risk of the chimney stack falling over?
     
  12. glob@l

    glob@l Active Member

    A local stone mason has said the likely cause of the sandstone crumbling is heat in the attic and since the area is not seen would advise removal of the effected stone and brick it up.
     

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