Weatherproofing stone?

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    Weatherproofing stone?

    Does anyone have a view, or even better, first hand experience, of any successful method of protecting exterior stone walls against rain? Like most of the houses in this part of the Yorkshire Dales, the walls are constructed of a double skin of stone with a rubble-filled cavity. The chimneys go right through and are particularly prone to let the damp through, but the stone can be pretty porous as well. The pointing is fine - it's coming through the stones, not the pointing.

    Opinion seems to be divided between

    1. Render the lot
    2. Silicone
    3. Something called Surfapore whjich is like Gortex for stone

    Views welcome.
    'Pause you who read this, and think for a moment of the long chain of iron or gold, of thorns or flowers, that would never have bound you, but for the formation fo the first link on one memorable day'. Charles Dickens, Great Expectations

    #2
    You say the pointing is fine. However I'm wondering if your lime mortar has been repointed at some stage with cement pointing which indeed does look fine.

    However stone(and old porous brick) buidings were built and designed to 'breathe' in moisture in rainy periods, and then 'breathe out' the moisture via the porous lime mortar. Repointing with cement blocks this ability to 'breathe'.

    Limewashing would be the traditional method of exterior protection for stone when not left bare.

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      #3
      2 coats of Thompson's Waterstop seems to have solved this on my London Stock 1906 porous bricks in an open SW facing situation.

      Rendering would be sacrilege IMO



      Freedom at the point of zero............

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        #4
        There are many sources that would argue waterstop etc is the wrong thing to apply, and could lead to deterioration of the building.

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          #5
          Originally posted by Interlaken View Post

          Rendering would be sacrilege IMO
          There is render and render....Lime render has been traditionally used in the Dales for centuries and still allows the stonework to show.
          'Pause you who read this, and think for a moment of the long chain of iron or gold, of thorns or flowers, that would never have bound you, but for the formation fo the first link on one memorable day'. Charles Dickens, Great Expectations

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            #6
            Visqueen VX90 Waterstop would be helpful in this regard. Google it and look for customer reviews first.

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              #7
              Stephen Boniface who answered this is former heads of RICS.

              SUBJECT: Should I seal my repaired brick worth with Thompson Water Seal?
              FROM: Stephen Ledger (Sheffield)
              I have an Edwardian property that is in need of re-pointing in many areas. Some of the bricks show frost damage. As well as re-pointing and replacing frost damaged bricks, the builder has recommended applying Thompson Water Seal. There is no internal damp penetration.

              Stephen Ledger
              The pointing should be the sacrificial element of the elevation rather than the brickwork. The mix used for re-pointing should therefore be relatively soft. It should not be a hard dense cement mortar but rather a softer lime gauged mortar. This will help relieve some of the damage to the brickwork.

              Regarding your second point about the application of a sealant, I do not recommend this. This building has survived probably 90 years or so with only some (not all) brickwork beginning to show frost damage etc. By applying a sealer you could increase the rate of deterioration. Whilst the sealant will help prevent some water penetration it also prevents moisture within the brickwork (or from within the building) from escaping. Further, I have often found that these sealants are impossible to apply uniformly and there will inevitably be areas where water will be able to get through due to poorly applied sealant or a gap in the sealant that is invisible to the naked eye. Once the water is behind the sealant it will cause damage and because it is trapped within the brickwork it will cause more rapid and more extensive deterioration. I therefore suggest that you ensure that careful re-pointing and repair is undertaken but no more than this.

              Period Property UK would like to thank Stephen Boniface, Tony Redman and other partners at the The Whitworth Co-Partnership with Boniface Associates for responding to this question

              Comment


                #8
                I am very reluctant to apply anything which in waterproofing the wall on the outside inevitably traps water in, since that water/damp will inevitably make its way through the internal walls and wreck my very expensive decorating.

                I much prefer the idea of working in sympathy with the stone and repointing using lime mortar. That's my summer sorted out, then...
                'Pause you who read this, and think for a moment of the long chain of iron or gold, of thorns or flowers, that would never have bound you, but for the formation fo the first link on one memorable day'. Charles Dickens, Great Expectations

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                  #9
                  Has it been pointed over with cement, if so that'll be fun to remove......

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                    #10
                    Oh, we have some very effective power tools for that kind of thing. Plus, it's actually only a SW facing area of about 12 sq. m which has ever been a problem, so we'll start with that and see how we get on. If we really enjoy it, we might even do the whole lot.
                    'Pause you who read this, and think for a moment of the long chain of iron or gold, of thorns or flowers, that would never have bound you, but for the formation fo the first link on one memorable day'. Charles Dickens, Great Expectations

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                      #11
                      Be wary of attacking it with the power tools if your stone is soft. Cement pointing is pretty hard stuff and you could easily start trashing your stonework. If it's only 12m2 then a hammer and chisel will possibly be a better option. I gave up on mine as I was ruining the edges of the bricks. I'll be interested to know if it actually has any effect on the damp once you're done. Please uodate the thread once you've completely finished.

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                        #12
                        I think it will probably end up being a combination of power tool and hammer & chisel, but the stone is pretty hard. It's not sandstone, but random limestone (mix of mainly slate and limestone). There's more danger of it breaking the power tool than vice versa.

                        Will certainly update, however, like Scott of the Antarctic, I may be gone some time.
                        'Pause you who read this, and think for a moment of the long chain of iron or gold, of thorns or flowers, that would never have bound you, but for the formation fo the first link on one memorable day'. Charles Dickens, Great Expectations

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                          #13
                          Your original post said that the chimneys are particularly prone to letting damp through.

                          Whereabouts do you see the damp emerging on the chimneys? Externally, or on the internal chimney breasts, or on the chimney visible above the roof?

                          Are all these chimneys still intact and still in use? (no extenal cement mortar, no capping over or removal of external chimneys, chimney pots still there, no boarding up or removal of fireplaces)

                          Unless there have been alterations, you shouldn't be seeing a particular problem with the chimneys. And they should be ventilating the whole building.

                          Comment


                            #14
                            Originally posted by Sad S View Post
                            Your original post said that the chimneys are particularly prone to letting damp through.

                            Whereabouts do you see the damp emerging on the chimneys? Externally, or on the internal chimney breasts, or on the chimney visible above the roof?
                            All three, although I think we have it under control now, thank you.

                            Are all these chimneys still intact and still in use? (no extenal cement mortar, no capping over or removal of external chimneys, chimney pots still there, no boarding up or removal of fireplaces)
                            Yes, no, no, yes, no.

                            Unless there have been alterations, you shouldn't be seeing a particular problem with the chimneys. And they should be ventilating the whole building.
                            The house is over 200 years old. There are bound to have been alterations...and if there is enough water pounding at the stones of the walls, some of it is bound to come through to the inside via the solid chimneys.
                            'Pause you who read this, and think for a moment of the long chain of iron or gold, of thorns or flowers, that would never have bound you, but for the formation fo the first link on one memorable day'. Charles Dickens, Great Expectations

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