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Stonemasonry
How do you check for porous bricks? and how do you remedy?
Anonymous user 24 August 2016 - 10.30 AM
Hello, I have had an on going problem with penetrating damp for over 6 months now and have been through all the usual ways of trying to fix this. So far I have had the following work done: :- New Felt and Eaves trays installed with all broken tiles removed and replaced with new ones on the bay window roof. :- Patch pointing work on the bay window wall including the removal of the virgin media box with this filled in with mortar. :- Windows re-sealed and ensured there are no gaps for water to enter the wall/windows. I am wanting to check if the bricks have become porous as I am stuck for any other ideas but I am unable to find ways of testing this. The house was built in approximately 1905. If it is porous I would be looking into treating this with something like Stormdry Masonry Protection Cream but I have a painted house so I have read this needs removing first. It is a back to back house with only one external wall and I was wondering if there is a rough cost for removing the paint and applying this. Alternatively if there is a way to do this without removing the paint that would be even better. Any help with either of these points would be greatly appreciated. Thanks, Andrew.
2 answers from MyBuilder tradespeople
1) Have you looked to see if the house has a damp course fitted some of this age might not ? (I think you are not at ground level though so we can rule this out) 2) Is the house of cavity construction if so get a camera survey 3) Most bricks of this age will have some porosity by now even if in good condition older bricks can't match up to modern standards unfortunately 4) Cold bridging is a problem in this situation the paint will hold moisture behind and not let it evaporate, the more heat you have in the house the damper it will be as the moisture will be attracted to the heat, your problem is that if you have modern plaster work inside the damp condensates behind the plaster finish and you will have a damp wall 5) Condensation from your windows and walls can produce lots and lots of water several pints a day in some cases ventilation is key 6) Paint removal is best achieved without chemicals / pressure washer with a glass bead feeder will work best, I know we've done it before and this is the way to go for sure Hope some of my ramblings will help
Answered
2 January 2019
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As the product you are using cannot be applied to a wet/damp surface the job would have to be done in two stages. In order to remove the paint, the quickest way would be to use a pressure washer with a water/brick acid mix, then a wash down with just water to rinse any acid off. You would then need to leave it to dry and return 24 hrs later to apply the damp seal cream. As for testing to see if the bricks are porous or not, I can only suggest soaking the exterior wall with water, then checking to see if you notice any areas inside that are damp or damper than normal.....or wait for the next lot of rain and check then! Hope that helps.
Answered
27 January 2017
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