Any recommendations for coating/sealing cellar walls? I'd like to tidy up the appearance, and avoid the mess that builds up.
The cellar has high humidity (always 70%+), and water will form if anything is left up against the floor/walls, but is basically dry. What looks to be masonry paint has stuck where the other side of the wall is open to air, but where there's soil the other side it's crumbled away. The main cellar walls are made of what look like stone rubble held in place with coarse mortar.
This doesn't answer your question, but our cellar was very similar to what you describe. When we replaced the central heating, the new boiler was put in the cellar along with the hot water cylinder and that was transformative. The space is much more usable.
As Clive and Davey say, heat and ventilation are your friends. The danger with sealing is that it will trap water behind and only a substantial treatment will hold it back (e.g. tanking, I know of one basement that was sorted with about a quarter of an inch of pitch, applied molten, then covered with a sand-cement render).
I don't have a cellar, but I have a rubble-stone cottage built straight on the limestone bedrock, with a hill reaching 120 metres within a few hundred metres on one side. Although the road and pavements are drained effectively, in wet weather the water table is at ground level.
So, at one end of the house I had a *very* wet wall. The previous owners' solution had been to batten it, cover with polythene sheeting and then plasterboard and plaster, so that it all looked OK.
The building society discovered damp and required all this to come out, put in an electric DPC and render with impermeable render. I had to replace the bottom half of the staircase, a window frame, and a few joists for the ceiling which dry rot had reached thanks to the previous "solution". Within a few years the impermeable render was blown from water behind, and I figured it was not worth fighting over the "guarantee". My solution was to have all the rendering off, expose the stonework as a feature and repair and repoint with lime mortar, while adding a ventilated wainscotting (mounted on treated timber) to the lower part on the end and one side wall. The exposed stonework above keeps the wall dried out (there are a few salts to brush off every couple of years). (Oh, as an aside, this is not penetrating damp, the outside has been very carefully fixed). Anyone who claims there is no such thing as rising damp, I could show you photos of it reaching 6 feet from the floor.
Thanks, and to the other posters. The ventilation isn't that bad - 2 12" square vents in a 4m x 4m room. But I'm loathed to heat a space with that level of ventilation, and cutting off the ventilation and heating doesn't bear thinking about. And however unlikely it might seem, nothing rusts down there, and even cardboard's OKish for very long periods.
The problems to be solved are appearance, and the constant crumble mess - just cleared half a bucket of the stuff yesterday - which prompted the post. Repair/repoint with lime mortar would seem to be the way forward from posts here. Still wondering if a permeable coating, like a lime wash might do what I'm after.
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