Hi everyone. I have a rental house that has recently been letting in some penetrating damp through a narrow subsidence crack. The render is about 15 years old and has never been painted and as a result some areas like the drip on the bottom the cement is washed out and although sound you can brush the top surface away its sound underneath. the rest of the wall is sound and flat and in good condition. I suspect that the wall is rat trap brick construction not cavity as the house is before 1900s. I havent had damp problems before as its a terrace house and this is the wall down next doors side path that is protected by their house. I have sealed the crack using a good quality acrylic sealant and I need to paint the wall to complete the weatherproofing. I was thinking originally of phiolite but I now indertand that would not be a good idea as that would keep the moisture that is already trapped in the wall inside, I need to use breathable. I think that means I am back to Weathershield or Santex which is a good price in screwfix. the question is do I use stabilising solution on the washed out areas or over the complete old render? I can see screwfix sell santex stabilising but not weathershield stabiliser. can I use santex stabiliser with weathershield? There is the option of watering down the 1st coat but I dont know if that would be good enough and to be honest a few extra pounds on primer is not the issue for me. I just want it done properly, looking nice and the right job as this wall is next door I have to ask for access everytime so the reality is it isnt something I will check regularly. Your advice is appreciated. John
Another excellent stabilishing fulid is Everbuild 406,have used litres of it, only treat the affected areas, make sure render is free of loose flaky bits & not blown in places. Our Astramax might suggest otherwise, but I wouldn't water the paint down, also he would recommend Dulux Weathershield Trade Smooth, which is a favourite with him. http://www.everbuild.co.uk/index.php?route=product/product&product_id=148
Do not water down the stabilising sealer as it is a solvent base, water and solvent will not mix together, use straight from the container. Unless the area to be painted is powdery and friable it is not needed if the sound also it will not be needed, small areas can be painted with an oil based primer sealer or even Zinsser 123 which is a high adhesion primer. Over use of stabilising sealer can cause problems with paint adhering as it can leave a glazed surface once dry causing the masonry paint to prematurely fail..
Ok thanks. I am assuming the washed out cement bell drip would be classed as friable as you can rub off the surface. I would be happy to just use on the bell area and paint the rest. I am a big zinsser fan and have 123 in the van so will use if needed. I think Ill use Dulux weathershield trade after as it is a good price in screwfix at the moment and the local depot has stock. Thanks for yor advice . It is much appreciated. John
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