A pre-war shophouse window in the George Town heritage core is timber-framed, single-glazed, and often older than Merdeka. Cleaned the way we clean a Gurney Drive condo — plenty of water, a scraper on the glass, a rinse down the facade — it does not get clean, it gets damaged. Heritage glass work is a drier, slower, hand-first version of the job, and this is what changes and why.
What makes shophouse windows different
The frames are old hardwood sashes, louvres and shutters, holding single panes that are bedded in glazing putty rather than rubber gaskets. The timber has moved with a century of weather, the putty lines are original in places, and the paint is often the only thing keeping water out of a hairline joint. None of that is a reason to leave the windows dirty — it is a reason to control exactly where water goes.
Why water is the enemy of old timber
Flooding a modern aluminium frame is harmless; the water runs out of the drainage slots. Flood a heritage sash and the water finds the end grain and the tired putty line, soaks in, and stays — swelling the timber, lifting the paint from underneath, and starting the slow rot at the joints that costs real money to repair. So we work damp, not wet: wrung-out cloths, purified water in small amounts, and the putty line detailed dry the moment the pane is finished.
No pressure anywhere near the render
The walls around those windows are lime plaster, and lime is soft, breathable and irreplaceable in kind — it is what lets a shophouse wall dry out through its face. A pressure washer erodes the render and drives water deep into it; the wall then sheds its face in flakes over the following months. Our pressure equipment stays off heritage facades entirely, streetside or courtyard, and that is consistent with what George Town's conservation guidance asks of anyone working on these buildings.
Glass older than the paint
Plenty of panes in the core are early drawn glass — slightly wavy, thinner than modern float, and impossible to replace like for like. We treat it accordingly: no scrapers as a habit, only flat and sparing where paint spots demand it, and any hard water treatment tested on a corner before it touches the middle of a pane. If a pane is cracked, we say so before we start, because a crack found afterwards becomes an argument nobody enjoys.
What a heritage clean looks like from us
More time per window and more of it by hand. Frames and louvres are dusted and damp-wiped rather than rinsed, glass is cleaned with minimal liquid and detailed to the edges, sills are cleared of the grit that holds moisture against timber, and nothing is allowed to run down the facade. Zaidi's island crew handles the heritage streets, and the same 48-hour guarantee applies as on any other job.
If you run a cafe or guesthouse in the core
Your street glass is your shopfront, and on Lebuh Armenian foot traffic reads it up close all day. Little and often beats one heavy annual clean: a light monthly clean keeps traffic film from bonding, costs less per visit, and never puts the frames through a restoration-scale wetting. We schedule before opening hours so the ladder is gone by the time your first table sits down.
Heritage jobs are quoted individually, because access, frame condition and glass age genuinely change the work. Send us photos of the frontage over WhatsApp and we will price it properly, and tell you honestly if any of it needs a conservator rather than a cleaner.
Want it done properly instead?
Window cleaning in Penang starts from RM100, with purified water on every job and both guarantees included.