Professional Render Cleaning in Blackburn

Damp air off the moors, and what it does to a wall

Blackburn takes a little over a metre of rain a year and sits between the West Pennine Moors and Pendle country, which keeps the air damp and the winter sun low and brief.

A rendered elevation facing north or east here will barely dry out between October and March. Render is porous, so it holds that moisture in its surface, and algae colonises it. Four years from new is a realistic point for a north wall to start showing green.

Darwen and the higher ground above it are harsher again, being both more exposed and colder for longer.

Silicone, monocouche, pebbledash and paint

The newer housing at Shadsworth, Roman Road and the developments out towards Feniscowles is largely modern thin-coat render, silicone or acrylic. Thin, through-coloured and impossible to patch invisibly if it gets damaged.

Much of the interwar and post-war stock across Blackburn is pebbledash, which traps growth in every gap between the stones and needs a long dwell time rather than more force.

Then there is painted sand-cement render, where the question is often whether the paint is sound. If it is already flaking, a clean will take more of it off, and we will tell you that before we start rather than after.

The soft wash method

Wet the elevation, apply the biocide, let it dwell so it penetrates the surface, rinse at low pressure. That is the whole method, and the biocide is the part that does the work.

Because it kills the organism at root level and keeps working in the surface for months, a soft washed wall in Blackburn stays clean for years. A pressure washed one looks better for a summer and is green again by the following winter.

The wall keeps improving for several weeks after we leave as the dead growth weathers off.

Why we will not put a pressure washer on your render

On thin-coat silicone the coat comes off and the colour goes with it, because it runs through the material. The only repair is re-rendering the elevation.

On pebbledash the stones come off and leave grey patches. On monocouche you get permanent lance striping. On painted render the paint comes off in sheets.

And on any render it drives water into and behind the substrate, which is the opposite of what you want on a wall you are trying to protect.

Check the gutters and the sealant first

A good share of the marked render we are called to look at in Blackburn is gutter overflow staining rather than organic growth. A blocked gutter runs down the same stretch of wall every time it rains, and after two winters it looks like the render has failed.

Cleaning that without fixing the cause means doing it again next year. We check the guttering as part of the survey. See gutter cleaning in Blackburn.

We also check cracks, blown sections and window sealant, because any of those let water behind the render and need sorting before a clean is worth doing.

Darwen, Mellor and the exposed properties

Higher ground takes more driven rain and more wind-borne spores. Properties around Darwen, Tockholes, Mellor and Ramsgreave show growth sooner and on more elevations than equivalent houses in the town.

Three years between cleans is sensible up there. In the more sheltered parts of town four or five is usually fine once the render has been properly treated.

Price and doing it alongside other work

Area of render, number of storeys, severity and access. We work from the ground with poles wherever possible, so scaffolding rarely comes into it on domestic work.

Fixed price in writing before anything starts. If the roof or the driveway want doing too, combining them into one visit is cheaper than three separate call-outs.