A client had a very damp gable wall, water was running down and the damp patch was growing ever larger. Outside the gable was complicated by a chimney breast that was once inside, but since the house has been knocked down, the inside chimney breast was now an outside protuberance. The problem was, of course, that it was cement rendered and that the cement had cracked, there was a nice crop of ferns stating to get established.
When we removed the cement, starting at the top, we had a bit of a surprise: the building stones were rather small, the size of paperback books, and the mortar was mud, and still was mud, very wet and all the stones moved as you tried to get off the cement.
I decided to remove only half the render before roughly flush pointing the wall to protect the masonry joints – this work has been done through February, so it’s been a bit wet a times.
As we removed more cement we revealed more delights; voids filled with buckets of cement for instance. When we got to the bottom section and started to remove the cement on the left and right edges we found that the cement was covering about 100mm 0f dry earth and ash mortar sort of bulked out with roofing tiles face bedded. As we removed this useless stuff we soon came upon the inner brick skin of the house: the gable to the right of the chimney breast is 9 inch brick, to the left thick stone masonry. The brick seemed to have been butted up against the now gone front elevation of the house, we just couldn’t work out the sequence of building events, but it seemed that the elevation had been roughly removed and, like a rotten tooth, the root had been left embedded in the brickwork. The root, as i say consisted of rubbish on one side, whereas on the left side there was more definite masonry and even a trace of plaster or render. I cant understand why, for the sake of the day or so we took to remove the rubbish and to replace it with bricks, the original ‘builders’ had just smeared a load of cement over the top.
Anyway, with some care, some frustration at the weather, a good bit of worry, especially when our earlier higher up first coat of dubbing out/pointing/render, it was all those really, cracked along a definite line above our new work ( I eventually put it down to a bit of settlement and a bit of shrinkage as the edifice began to dry, goodness knows it must have expanded with all that water content!) we got it all secured and the first coat of render on.
Throughout the project I was considering sheeting it up at night because of the rain but reconsidering because of the wind, likewise I was sometimes wishing the scaffold had a roof and then, because of the gales, glad it hadn’t.
Lime is remarkable for its ability to withstand rainfall within just a couple of hours of being applied, it doesn’t withstand running water, but copes very well with rain, as there was no frost I had worries in that direction. Because of time limits and slow drying we were forced to apply the second and third coats whilst the first was still soft but as each coat was applied as thin as possible I believe that the render will be alright especially as its finished with a roughcast surface which gives maximum chance for evaporation and drying.