Window Replacement

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I am having 3 windows replaced on the weather side of a granite cottage. These were previously poorly sized and fitted. There has been a history of damp in this wall mainly below the windows. The exterior is pointed with a ‘hard’ concrete, the internal wall is rendered with 1-2” of sand/cement render. I believe repointing and re rendering with lime is the best solution but due to time and money am going to get new windows installed well first.

I am going to fit vertical dpc and lead trays. What is the best product to finish the reveals inside and bed the windows in/fillet externally?

Could I try to waterproof with a tanking layer of prompt natural cement or use Cornerstone Insulating Render to insulate and possibly absorb any moisture?

marcusconrad Asked question June 23, 2020

Thank you for your enquiry via our website.

As window reveals are generally an area susceptible to moisture we usually advise using Cornerstone tanking render (2x 10mm layers) to provide protection  from water ingress and then Insulating Render on top to allow any excess moisture chance to escape.  You can find the products in the Cornerstone section on our website.  If you would like further guidance or to talk to us about application etc please call us on 01208 79779 and we’ll be able to assist.


marcusconrad Posted new comment June 29, 2020

Many thanks for your response.

Before replacing the windows, do you have any advice on pointing the existing gaps between the granite in the reveal as on the photo? Some of these bridge to the external masonry. Is it too small an amount to use lime and attempt to ‘absorb’ moisture?

If using lime, what product would you recommend for this and an external 1-2” external fillet around the window?

Thank you for your enquiry. An appropriate lime mortar can fill the gaps between the stonework, but if you are looking to fill the fillets between the stone and window our burnt sand mastic would be the most suitable product. Here’s a link to the product:

I have moved some loose ‘pointing’ stones on the reveal with rubble/earth behind. Should I remove loose material or go back further. Can I apply any depth of lime or should I do build this up in stages?

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