Once the builders have gone, the windows are often the worst of what is left behind: plaster specks, roller mist and the odd drip of gloss. Most of it comes off with patience and the right method, but the wrong one can scratch glass for good. Here is how to do it properly in a Manchester home.
Not every splash comes off the same way, and treating them all alike is how windows get scratched. After a typical extension, loft conversion or replaster in a Manchester terrace or semi, you will usually find a mix of these on the glass and frames.
The last one matters most. Cement and render are alkaline and can etch glass permanently if left, and Manchester's regular rain makes it worse by washing fresh run-off down from new brickwork onto the panes below. If you see grey streaks outside, deal with them within days, not months.
Dry plaster is abrasive. Rubbing it with a dry cloth or scouring pad drags grit across the glass and leaves fine scratches you only notice when the sun comes out. Wet it instead. Spray or sponge the splashes with warm water and a drop of washing-up liquid, leave it for 10 to 15 minutes, and re-wet if it starts to dry.
Once the plaster has gone soft, lift it with a plastic scraper or an old bank card, then wash the whole pane and finish with a squeegee. Manchester's tap water is soft, so it rinses clean without much limescale spotting. Thick lumps may need two or three soaks. Do not chip at them dry.
Fresh emulsion mist usually comes away with warm soapy water and a microfibre cloth. Older drips need a glass scraper with a new blade. Keep the glass wet, hold the blade at around 30 to 45 degrees, push in one direction only and lift it off on the return stroke. Change the blade as soon as it catches or feels gritty.
For gloss or oil-based paint, dab a little white spirit onto a cloth and work on the spot itself, keeping it away from rubber seals and uPVC. Test a corner first. Toughened glass, which is standard in patio doors, bifolds and low-level panes in newer homes and flats across areas like Ancoats and Salford Quays, can carry tiny surface particles that a blade drags into scratches. If a test patch sounds gritty, stop.
Frames are easier to damage than glass. On white uPVC, use a plastic scraper and a cream uPVC cleaner, and avoid acetone, cellulose thinners and nail varnish remover, which melt the surface and leave a dull patch. On powder-coated aluminium, including the anthracite grey frames common on new extensions, use only warm soapy water and a soft cloth. On the painted timber sashes found in Victorian and Edwardian houses in Chorlton, Didsbury and Levenshulme, soften splashes with water and lift them gently so you do not pull the paint beneath.
Clear the plaster dust out of tracks, hinges and drainage slots with a vacuum and a dry brush before you wet anything. Wet plaster dust sets like paste in the mechanism.
A few splashes on a couple of windows is a sensible DIY job for an afternoon. It is worth getting a professional in if there is cement or render on the glass, if the panes are toughened or have a self-cleaning coating, if the windows are above ground floor, or if the whole house is covered.
As a rough guide, a post-building window clean for a three-bed semi in Greater Manchester tends to fall somewhere between £80 and £200, depending on the number of panes, how heavy the contamination is and whether access needs poles or a ladder. Compare that with replacing a scratched double-glazed unit, which commonly runs from about £100 to £300 or more per pane depending on size and glass type. Before anyone starts, photograph any existing scratches so there is no argument about who caused them, and raise them with your builder while they are still on site.
Yes on ordinary float glass, provided the glass is wet, the blade is new and you push in one direction only. Be cautious on toughened glass and never use a blade on self-cleaning or coated glass.
Brief contact wiped off straight away is unlikely to cause harm, but it can dull the surface and perish rubber seals if left. Keep it on the glass and use a cream uPVC cleaner on the frames instead.
It depends on your contract. Many Manchester builders leave a site broom clean only, so check whether a final builders' clean is included before you pay the last invoice.
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