The problem with deciding to renovate an old sash window is knowing when to stop. The Mitre 10 do-up team would just slap on yet another coat of paint. But, in our case that would produce mixed results at best.
Having removed the window from the frame, we were able to commence sanding. However, we soon noticed some pretty mulash* glazing work done in years gone by that was now causing water to seep through. Furthermore, some of the glass was cracked, and even the panes that were still in tact were sealed in with very brittle putty.
Ultimately, the windows were no longer water tight, causing part of the frame to rot.
The glass had to come out.
Glass removal, and prep-work
Even if the glass is broken, it is still advisable to try and remove it in one piece rather than smash it (no matter how tempting), as it will shatter, and removing the shard fragments in the frame is a hazardous and time-consuming affair.
- Using a chisel, gently nudge out the old putty.
- Underneath the putty, the glass pane will be held in place with small metal staples, known as glazing points, or tingles depending from which generation you ramble. These can also be wedged out with a chisel.
- Once the putty has been chipped away, and glazing points removed, the glass should lift out with a bit of gentle encouragement. However, if the pane is otherwise in tact and remains firmly rooted in place, it may be advisable to just let it be and re-putty rather than risk breakage.
- After taking out the glass, the inside frame will need to sanded smooth with as much of the old putty removed as possible.
- Paint the sanded fame with oil-based primer. (The helpful man at Resene recommends using oil-based rather than water-based, as the original paints were likely oil-based and would have seeped into the wood somewhat). Oil-based primers can be top-coated with a water-based enamel. The downside to using an oil-based primer is that it only lasts 50 years, but I told the nice Resene man we would be able to live with that. (A more immediate downside with oil-based paints, is that it is difficult to cleanse the brushes afterwards, and they need to be rinsed with turpentine. However, it’s useful to keep some of the turpentine rinse, as it will come in handy when doing the glazing).
- Once paint is dry, lightly sand with 150 grit sand paper.
A pane of glass for a sash window costs around $40, and places such as Auckland Glass will even provide free delivery.
A professional glazer charges around $45 per hour, and glazing a non-complicated window takes about an hour. So, if there are multiple windows to glaze it’s worthwhile to consider a DIY approach.
However, if undertaking self-glazing, one should be prepared to break a couple of glass panes along the way. Even so it’s probably still worthwhile.
How to: Glaze a Sash Window
- Prepared frames
- Glass cut to measure. Allow around 1 – 2mm spare room between the wooden frame and the glass.
- Glazing points, available from Bunnings Warehouse
- Small scraper
- Have a practice fitting session, and gently place the glass pane into the frame. It should sit loosely. Any tight spots will put pressure on the glass and likely break it. Use 60 grit sandpaper, and an old chisel to even out any tight spots in the frame.
- Molest handful of putty until smooth and squishy.
- Squeeze a small amount of putty evenly into window frame, enough for the glass to sit on.
- Gently place glass on top, position such that it is not touching the sides of the frame anywhere.
- Gently press glass down with cloth and fit in place.
- Apply glazing points around 30 – 40 cm apart. These should be eased in with a scraper, horizontally directly over top of the glass. (Not vertically, that will cause breakage).
- Apply a generous amount of putty over top.
- Lubricate putty knife or scraper with turpentine, and use to produce an angled finish.
Putty takes several weeks to harden, and should be painted with final top-coat (water-based enamel) between 1 – 2 weeks after application.
mulash: verb, known as doing a half-assed job. ‘To mulash’, mulashed, or mulashing.