Heritage sash window reglazing in Hobart.
Hobart has more intact colonial and Victorian housing than any other Australian capital, and reglazing those windows is a different trade to putting a pane in a project home. Different glass, different putty, different pace. This is how it is actually done, and where the honest limits are.
Matching a century of wavy glass.
Stand in front of an original sash in Battery Point and look at the reflection of the street. It moves. That ripple is not damage, it is how glass was made before the float process, and it is a large part of why a heritage window looks like a heritage window. Put a flat modern pane next to it and the eye catches the difference from the footpath.
Often, yes, it can be matched. The ripple in an original Hobart sash is old cylinder or early float glass, and the way to match it is restoration glass, which is made to reproduce that period distortion. It costs considerably more than plain float and comes in different grades of waviness, so we match a sample to your existing panes before ordering. Where only one pane in a sash has broken, we sometimes shuffle the original glass into the most visible opening and put the new pane where it reads least, which is a trick as old as the houses themselves.
That shuffle is worth asking any glazier about. On a six-over-six sash where one small pane has gone, moving the survivors around so the new glass sits in a lower or less visible light costs nothing but care, and it is the difference between a repair you notice and one you do not. It is also the sort of thing a glazier who works Sandy Bay and West Hobart weekly will suggest without being asked, and a glazier who does not, will not.
Why putty, still.
Linseed oil putty is used instead of modern beads because it is what the sash was designed around and it is what a heritage assessment expects to see. It gives the correct external profile, that angled bevel line that reads as a period window from the street, and it lets the timber move and breathe. Modern silicone and timber beads look wrong on a Georgian or Victorian sash and can trap moisture against the rebate, which rots the very timber you are trying to preserve. Putty needs painting once it has skinned over, usually after a couple of weeks.
The work behind that is slow and there is no way around it. The old putty has to be hacked out without bruising the rebate, the sprigs pulled, the timber cleaned back to sound material and primed, then the pane bedded, sprigged and the putty faced off to a clean consistent line. On a hundred-and-thirty-year-old sash in South Hobart, that is an hour of careful work for one small pane. It is why heritage reglazing prices toward the top of the ordinary band rather than the bottom.
Double glazing a heritage sash: the rebate decides.
This is the question every heritage owner in Hobart asks, because the cold is real and the windows are the weak point. The answer is: sometimes, and it depends entirely on the rebate depth. A slim double-glazed unit needs somewhere around 10 to 14mm of rebate to sit in, and plenty of Hobart sashes were cut for 3mm or 4mm glass and simply do not have it. Where there is depth, or where the rebate can be carefully deepened without weakening the sash, a slim unit goes in and the window looks the same from the street. Where there is not, discreet secondary glazing on the inside is the better answer and it leaves the original sash completely untouched.
We check the rebate at the measure and tell you which of those two you have got. Nobody can answer it from a photo, and anyone who quotes a slim-unit retrofit on a heritage sash over the phone has not checked the one thing that determines whether it is possible. The single vs double glazing guide covers why the thermal case is so strong in this city, and the timing guide covers when to book it.
Approvals, briefly.
Heritage status changes the approval path, not the safety standard. If the opening is a door, a side panel beside a door, or a window with glass within 500mm of the floor, the replacement must be Grade A safety glass even in a listed building. The usual answer on heritage work is laminated rather than toughened, because laminated holds a closer resemblance to original glass, does not carry the faint distortion that heat treatment leaves, and can even be made with a restoration-glass outer leaf.
Separately from AS 1288, if the property sits on the Tasmanian Heritage Register or inside a heritage precinct under the local provisions of the planning scheme, works to the fabric can need approval from Heritage Tasmania or the council first. Straight like-for-like reglazing is ordinarily maintenance and does not, but changing the glass type visibly, or altering the sash, can. The compliance guide goes through that properly, and the short version is: ask before you start, not after.
Worked example: a broken sash in North Hobart.
A four-over-four double-hung sash in a 1890s North Hobart cottage, inside a City of Hobart heritage precinct, one upper pane broken by a branch in a westerly. Rebate is shallow, cut for 3mm glass, so a slim unit is out. The surviving glass is clearly cylinder glass with strong ripple. What we do: template the opening, order restoration glass in a grade matched to the neighbouring panes, hack out the old putty, prime the rebate, bed and sprig the new pane, face the putty off to match the other lights, and leave it to skin before the owner paints. It lands at about 420 dollars on 2026 rates, near the top of the 180 to 450 dollar band because of the restoration glass and the hour of careful hand work. Because it is a like-for-like reglaze in an unchanged opening, it is maintenance, so the City of Hobart never needs to be involved.
The honest costs across this work: a single pane reglazed in a heritage timber sash with plain float and traditional putty typically sits in the 180 to 450 dollar band, toward the upper end because hacking out century-old putty and cleaning the rebate back is slow work. Restoration glass to match original waviness adds meaningfully to the glass cost. A slim double-glazed unit retrofitted into an existing sash runs around 1,100 dollars per window. Where the sash itself has rot in the bottom rail, that timber repair is a separate cost and has to be done before any glass goes back in. The pricing page has the full set of bands.
Frequently asked questions.
Can the old wavy glass in a heritage Hobart window be matched?
Often, yes. The ripple in an original Hobart sash is old cylinder or early float glass, and the way to match it is restoration glass, which is made to reproduce that period distortion. It costs considerably more than plain float and comes in different grades of waviness, so we match a sample to your existing panes before ordering. Where only one pane in a sash has broken, we sometimes shuffle the original glass into the most visible opening and put the new pane where it reads least, which is a trick as old as the houses themselves.
Why is putty used instead of modern beads on heritage sashes?
Because linseed oil putty is what the sash was designed around and it is what a heritage assessment expects to see. It gives the correct external profile, that angled bevel line that reads as a period window from the street, and it lets the timber move and breathe. Modern silicone and timber beads look wrong on a Georgian or Victorian sash and can trap moisture against the rebate, which rots the very timber you are trying to preserve. Putty needs painting once it has skinned over, usually after a couple of weeks.
Can a heritage sash be double glazed without changing its appearance?
Sometimes, and it depends entirely on the rebate depth. A slim double-glazed unit needs somewhere around 10 to 14mm of rebate to sit in, and plenty of Hobart sashes were cut for 3mm or 4mm glass and simply do not have it. Where there is depth, or where the rebate can be carefully deepened without weakening the sash, a slim unit goes in and the window looks the same from the street. Where there is not, discreet secondary glazing on the inside is the better answer and it leaves the original sash completely untouched.
Does a heritage window still have to meet AS 1288 safety glass rules?
Yes. Heritage status changes the approval path, not the safety standard. If the opening is a door, a side panel beside a door, or a window with glass within 500mm of the floor, the replacement must be Grade A safety glass even in a listed building. The usual answer on heritage work is laminated rather than toughened, because laminated holds a closer resemblance to original glass, does not carry the faint distortion that heat treatment leaves, and can even be made with a restoration-glass outer leaf.
What does heritage sash reglazing cost in Hobart?
A single pane reglazed in a heritage timber sash with plain float and traditional putty typically sits in the 180 to 450 dollar band, toward the upper end because hacking out century-old putty and cleaning the rebate back is slow work. Restoration glass to match original waviness adds meaningfully to the glass cost. A slim double-glazed unit retrofitted into an existing sash runs around 1,100 dollars per window. Where the sash itself has rot in the bottom rail, that timber repair is a separate cost and has to be done before any glass goes back in.
Keep reading.
More plain guides for Hobart homeowners:
Got an original sash that needs glass?
Send the quote form with a photo of the window and a close-up of the rebate if you can. We will tell you what can be matched and whether a slim unit will physically fit.