New windows or just new glass? How to tell which you need

26 September 2026 · The Home Upgrade Co.

It is one of the most asked window questions on Irish forums. One boards.ie poster's neighbour paid around €9,000 for new windows and frames, while a man on Facebook said he would just change the glass. On r/DIYIreland the same question, window replacement or just the pane, drew more than thirty replies.

Both answers can be right. It depends on the frames, not the glass. Here is how to tell which one your house needs, from a company that only sells the more expensive of the two options and will tell you when you do not need it.

What does replacing just the glass mean?

Taking out the sealed glass unit and fitting a new one into the frame you already have. The frame, hinges, handles and seals around the frame all stay.

A double glazed window is really two parts: the frame, and a sealed unit of two panes held apart by a spacer bar around the edge, with gas in the gap. When people say just the glass, they mean swapping that sealed unit. It is a glazier's job, usually done in an hour or two per window, with no disruption to the walls or sills.

When new glass is enough

• Fog or water between the panes. The seal on the unit has failed and the insulating gas has leaked out. The unit will not recover, but the frame may be perfectly fine.
• A cracked or broken pane in an otherwise good window.
• The frames are sound. No rot, no warping, no draughts around the edge, and the windows open, close and lock properly.
• You are happy with how they look and how they open.

If that is you, a new sealed unit is the sensible, cheaper fix. You do not need us, you need a good local glazier.

When new glass will not fix it

• Rotten timber. Soft sills or frames that a key pushes into. New glass in a rotting frame is money wasted.
• Warped or discoloured uPVC, or frames that no longer sit square, so the window binds or will not seal.
• Draughts around the frame, not through the glass. That is the frame and its seals failing, and glass will not touch it.
• Worn hinges and locks across most of the house. These can be replaced individually, but past a point you are rebuilding the window piece by piece.
• You want triple glazing. A triple glazed unit is thicker and heavier. A frame designed for a double glazed unit may not take one at all, and its hinges may not carry the weight.

Check what you have now: count the spacer bars

Look at the edge of the glass, where it meets the frame. Every gap between panes has a spacer bar, usually a thin metal or black strip. One spacer bar means double glazed. Two means triple glazed.

Do not go by how many reflections you can see. Reflections between panes can make a double glazed unit look like it has three layers. Count the bars, or check the manufacturer's printing on the spacer, which often names the unit.

What about the SEAI grant?

The SEAI windows grant sets a standard for the new windows, including a U-value of 1.4 W/m²K or lower, confirmed on a declaration signed by the contractor. If you are hoping to use the grant, read its rules before you choose glass only, and ask SEAI whether your plan qualifies. Our grant guide sets out the rules as published in September 2026.

What we do, and what we do not

We supply and fit complete windows in uPVC, aluminium and timber, in double or triple glazing, across Dublin, Meath, Kildare and Wicklow. We do not replace glass units on their own.

Every opening is measured on a free visit and priced separately, and every window carries our 10 year warranty, written on the quote. The minimum order is 5 windows or doors in any mix, because on one or two the freight alone costs more than the window. If your frames are sound and only a couple of units have fogged, a glazier is the right call, and we will tell you that on the visit.

Frequently asked questions

Can you replace just the glass in a double glazed window?

Yes. A glazier can take out the sealed glass unit and fit a new one into your existing frame. It makes sense when the frame is sound and only the unit has failed or cracked.

Is replacing the glass cheaper than new windows?

Yes, because the frame, hinges and handles all stay and there is no work to the walls or sills. It only saves money if the frame is in good condition, though. New glass in a rotten or draughty frame is money wasted.

Why is there fog between the panes of my window?

The seal around the sealed unit has failed, letting moist air in and the insulating gas out. It will not clear on its own. The unit needs replacing, but the frame may still be fine.

Can I put triple glazing into my existing frames?

Often not. A triple glazed unit is thicker and heavier than a double glazed one, so a frame designed for double glazing may not take it, and its hinges may not carry the weight.

How do I know if my windows are double or triple glazed?

Count the spacer bars at the edge of the glass. One spacer bar means double glazed, two means triple. Do not count reflections, which can make a double glazed unit look like three layers.

Do you replace glass only?

No. We supply and fit complete windows, with a minimum order of 5 windows or doors. If your frames are sound and only a unit or two has failed, a local glazier is the right call.