Damp caused by cement render on walls

This is a brilliant example of a Grade 2 listed Georgian house, covered with cement render, with a problem.

Most surveyors only carry with them a damp meter.  Useless.

We use thermal imaging cameras all the time.  We look for subtle changes in temperature that might indicate a problem.  Why don't most surveyors carry them?  Well - for a start, they are expensive - our latest one cost over £7,000.  But - we get to see things that nobody else does, and that means we do better surveys, find more problems, and sort them out.  Which is good for everyone.

Now then, back to the house.. 

I looked at it from the outside, and although there were cracks, didn't think they were out of the ordinary. Now then - it's solid brick, built with soft lime mortar.  It moves with the seasons.  It flexes, it shrugs, it settles - it's an old house.  It likes to be that way, and its why it is still standing after 200 years.  Cement is rigid, inflexible, horrible stuff, and it cracks when the house moves.  So then it lets water into the crack, and traps it there.

When I was looking at the inside of the house, I absent mindedly pointed the thermal camera at the bedrom walls, not expecting to see anything. But I did.  Under the window, a large cold patch emerged.  On closer examination, and something I would have missed if the imaging camera had not alerted me, was a very skilful paint job.  The owner had recently patched the paintwork on the wall to cover up something.  What, we wonder? Water.... tracking into the bedroom through the wall - from the crack we saw in the external render. 

SNEAKY VENDOR ALERT!!!!!!

So now we know the seller is covering stuff up.  So we have to look doubly carefully at everything.  In this case, we didn't find anything else - the house was superb - and I'm sure this was a case of covering something she thought was just a bit of a stain from something..