Cleaning Windows on a Sandstone Tenement: What Actually Matters
If you own a flat in one of Glasgow’s sandstone tenements, you’ve probably noticed something the guys who clean windows for a living notice too: the stone stains in a way that brick and render just don’t. A window cleaner who’s only ever worked on modern houses can do real damage here without meaning to — and most people don’t find out until the sill’s gone a funny colour or the pointing’s started crumbling.
Why sandstone behaves differently
Sandstone is porous. That’s the whole story in one sentence, really. Brick and modern render mostly shed water off the surface, but sandstone soaks a bit of it in, along with whatever’s dissolved in it — cleaning chemicals included. Use something harsh on the glass and let it run down onto the stone, and you’re not just cleaning the window, you’re feeding whatever’s in that bottle straight into the sill and the surrounding stonework. Over months and years that shows up as staining, and in bad cases it can speed up erosion of the stone itself.
High-pressure washing is the other one we see causing damage, usually from people trying to blast algae or grime off a sill quickly. Sandstone isn’t as tough as it looks. A jet washer set too strong can strip the surface layer clean off, which looks fine for about a year and then starts flaking.
What we actually do differently
Pure water, and nothing added to it. No detergents running down onto the stone, no chemical residue soaking in. We use hand tools and a squeegee on the glass itself, and we’re careful around the sill rather than letting water pool and sit there. It’s not complicated, but it does mean the job takes a bit more attention than just spraying and wiping.
The other thing worth mentioning is the sash frames. A lot of West End and Southside tenements still have their original timber sash windows, some of them over a hundred years old. The putty holding the glass in can be original too, and it gets brittle with age. We don’t lean on it, and we don’t force a sash that’s stuck — if something’s not moving the way it should, we’d rather tell you than push it and end up cracking old putty that’s been fine for decades.
The close windows are a different question entirely
Worth saying clearly: the stairwell windows in a tenement close usually aren’t any one flat’s to arrange. They belong to the building. If you’re keen to get them done, the honest answer is you’ll need to go through your factor, or if you self-manage, get the other owners on board first. We deal with this fairly often and are happy to speak to a factor directly rather than leaving it to you to chase everyone up — see our tenement and factor-arranged cleaning page for how that usually works.
A few things worth checking before you book anyone
If you’re comparing quotes, it’s fair to just ask: what do you use on the stonework, and how do you handle the sills? A cleaner who’s used to tenements will have an answer ready. One who mostly does modern semis might not have thought about it much, which isn’t a knock on them — it’s just a different job.
It’s also worth asking about reach. A lot of tenements are three or four storeys, and ladders on a back court or a narrow street aren’t always practical, sometimes not even safe. We use a water-fed pole system that gets us to the top floor from ground level, which also means nobody’s balancing on a windowsill above your neighbour’s garden.
If you’re not sure what your building needs, get in touch and tell us the address — we can usually tell you straight away whether it’s a straightforward flat clean or something that needs the factor involved. See our domestic window cleaning page for pricing, or head back to the homepage for the full picture of what we cover.
