Glazing
Double glazing in Watermael-Boitsfort
When the window frame is still sound, replacing just the glass may be enough. But the frame also has to be able to take glazing that is thicker and heavier than the original. That is where most of the nasty surprises hide.
In Le Logis and Floréal
The heritage management plan for the two garden cities allows two thin types of glazing, known as type A and type B. They make it possible to keep the original joinery.
The rules for the two garden citiesWhat people forget
The glass is only part of the job
Old single glazing is a few millimetres thick. Standard double glazing is twenty or more. That change in thickness affects everything around the glass.
The original glazing beads, the strips that hold the pane in place, are cut for single glazing: they often have to be remade. The rebate in the frame (the recess the glass sits in) must be deep enough to take the new glass. And the opening sash becomes much heavier, to the point where the original hinges and hardware cannot always cope.
On this kind of job, the labour regularly costs more than the glazing itself. A quote that only mentions the glass is not telling you everything.
Before you decide
Four checks on your windows
- Is the wood or the profile sound? A rotten or warped frame is not worth new glazing.
- Is the rebate deep enough? If not, the frame has to be reworked or thinner glazing chosen.
- Will the hinges take the weight? A sash that sags ends up rubbing and not closing properly.
- Are the seals in good condition? Excellent glazing in a frame that lets air through does not achieve much.
Weighing it up
Replace the glass or the whole window?
If the frame is sound, the rebate allows it and the hardware can cope, keeping the window and replacing the glazing is a reasonable solution. That is often the case with fine wooden windows that have been well maintained.
If two or three of these conditions are missing, you end up paying for heavy renovation work for a middling result. A new window then becomes the most sensible choice, and the longest-lasting.
On site
You judge it by looking at the window
No photo can tell you whether a rebate is deep enough or whether a hinge is worn. Coming to check the state of your windows costs you nothing. If we then repair or adapt them, the call-out appears as a separate line on the quote.
See the repairs pageFrequently asked questions
Glazing: what people ask us
Can double glazing be fitted in an old wooden window?
Often, provided the rebate is deep enough and the hinges can bear the extra weight. If not, the frame has to be reworked, or you turn to thinner glazing.
Why does replacing glazing sometimes cost more than expected?
Because the glass is only part of the job. The original glazing beads are cut for single glazing a few millimetres thick, so they often have to be remade, the rebate adapted and the hardware checked. The labour then regularly costs more than the glazing.
Is there any funding for high-performance glazing?
The Ecoreno loan, a Brussels renovation loan, counts super-insulating glazing among the work it finances. Renolution, the Brussels Region’s renovation grant scheme, is suspended at present.
What glazing for a house in Le Logis or Floréal?
The heritage management plan allows two thin types of glazing, known as type A and type B. Their specifications are set out on our page about the two garden cities.
Keep your windows, replace the glass?
Send us a close-up photo of one window, with the sash open if possible. We will tell you whether the idea holds up before we come out.
Did a rule change at the commune, or do you see a mistake on this page? Let us know and we will fix it.