If you are going to get ripped off by builders, the three prime areas where you will get screwed are Roofs, Damp Courses and Tarmac (see above).
If you buy an old building, there is a strong possibility that it does not have a proper damp course - a layer of lead, slate or felt that runs across the brickwork a few inches from the ground. This stops the damp slowly moving up the wall.
You will see endless adverts for various miracle cures for rising damp and that should give you a clue - this is an area where margins are big - as in enormous. One of the systems promising to solve the problem is chemical injection.
What happens is that a couple of guys turn up in with an impressive looking machine and a couple of big drills. They then strip off the plaster up to about three feet and drill six holes into the bricks or stone a few inches off the ground. They then insert six nozzles into these holes and inject silicone derived chemicals into the holes which then totally permeate the bricks and mortar making it impossible for the damp to rise.
They then re-plaster the wall with waterproof plaster and leave - giving you a 20 year guarantee
So does this solve the problem? No, it does not, it is a total and complete rip off. Here is why.
One of the six bricks or stones they drill may well be fractured (or fractures as a result of drilling or they drill right through it - trust me, this will happen) so when they connect the pump, expensive chemicals squirt everywhere but it is not obvious where the fracture is. So, they hastily disconnect and move on.
Many bricks are impervious - I connected one of these machines to a hole in an engineering brick (a standard foundation brick) and after twenty minutes there was zero penetration.
They only inject the bricks inside the building usually - what about the outside? And in older buildings the wall may be a couple of feet thick with rubble in the middle so that is where the problem is but this method does not address that problem
The problem is not in the brick anyway, the problem is that the mortar is easily penetrated with water and provides a route upwards so injecting the bricks (even if it worked, which it doesn't) is irrelevant.
Maybe some of the other "patented" methods work? Who knows? They all appear to work for a while because the waterproof plaster keeps out the damp for a couple of years - long enough to enable the company and its 20 year guarantees to quietly disappear and move on ...
You employ a guy who relentlessly works his way along the wall removing all the bricks for a couple of feet and inserting a wide sheet of lead from a big roll. Don't worry, the wall will not fall down or fracture. You can easily check every inch of progress and from direct experience this is 100% effective. It is also cheaper than any of the patented methods. The guy should be able to do about a metre per hour and if you pay him generously it will be half the cost and far superior to other methods.
Once I start writing, even I am amazed at how much I know ... no wonder I am so rich.
Bob Cory
Modified on 20/09/2019 at 07:33:22 by ℗ Bob Cory