Windows & Glazing
Windows take the blame for cold, draughts and condensation, but the cause is often elsewhere. Knowing whether you truly need new glazing saves spending on the wrong fix.
Do I need new windows, or is it something else?
New windows are one of the most-sold home improvements, and often the first thing blamed for cold, draughty or condensation-prone rooms. But the windows are frequently not the main cause — walls, air leakage elsewhere, ventilation and cold surfaces can all produce the same symptoms. Knowing whether you genuinely need new windows, before spending thousands, is what a measured diagnosis provides.
Read the guideWhy are my windows cold and draughty?
Cold, draughty windows have two distinct parts: the glazing itself running cold, and air leaking around the unit, frame and reveal. Single or older glazing has a cold inner surface you feel as radiant chill, while worn seals and gaps let air through. Telling the radiant cold from the air leakage is the key to fixing the right thing.
Read the guideWill new windows stop condensation and mould?
New windows are often bought to cure condensation and mould, and they can reduce condensation on the glass by giving it a warmer surface. But they do not remove the moisture from the home — and by sealing up draughts they can push condensation onto the next-coldest surface, sometimes making wall mould worse. Whether new windows help depends entirely on whether ventilation is addressed too.
Read the guideWhy do my window frames get damp and mouldy?
Damp and mould around window frames, reveals and sills are usually condensation, not a leak. The reveal and frame run cold, humid room air condenses on them, and mould grows in that persistently damp band. Because it looks like water ingress, it is often misdiagnosed — but the cure is warmer surfaces and better ventilation, not sealant.
Read the guideIs triple glazing worth it?
Triple glazing genuinely improves comfort and reduces heat loss at the window, with warmer internal glass that feels more comfortable to sit beside and less prone to condensation. But whether it is worth it depends on the whole building: in a home still losing most of its heat through uninsulated walls and air leakage, triple glazing is rarely the most cost-effective next step. Its real value emerges as part of a well-sequenced, fabric-first approach.
Read the guideWhy are my windows misted up between the panes?
Misting between the two panes of a double-glazed window is the unmistakable sign of a blown (failed) sealed unit — the airtight seal around the edge has broken down, the dry gas or air inside has been lost, and moisture is now condensing inside the cavity where you cannot wipe it away. Unlike condensation on the room-side surface, this is not a ventilation problem; it is a failed component, and the only real fix is to replace the glass unit, though usually not the whole window.
Read the guideWhy is there condensation on the outside of my windows?
Condensation on the outside of your windows — dew or misting on the external pane, usually on clear, still mornings — is almost always a sign that your glazing is working well, not a fault. Because efficient, well-insulated windows let very little heat escape outwards, the outer pane stays cold enough to drop below the dew point of the night air, and dew forms on it just as it does on a car roof or the lawn. It clears as the sun warms the glass, and it generally means the opposite of a problem.
Read the guideIs secondary glazing worth it?
Secondary glazing — a discreet, independent pane fitted on the room side of your existing window — is often very good value, and in some homes it is the better choice than replacement double glazing. It can markedly cut heat loss and draughts and is outstanding for noise, while keeping original windows intact, which makes it ideal for period and listed properties. Whether it is worth it depends on what you are trying to solve and on the condition and significance of your existing windows.
Read the guideWhy are my sash windows so draughty?
Traditional sliding sash windows are draughty largely by design: they work by two sashes sliding past each other in channels, and those moving joints, together with the original counterweight boxes, leave gaps that let air leak in and out. Decades of paint, shrinkage and wear usually make it worse. The good news is that a well-made sash window can almost always be draught-proofed and kept — you rarely need to replace it to stop the draughts.
Read the guideShould I repair or replace my old windows?
Whether to repair or replace old windows is one of the most common — and most over-simplified — decisions homeowners face. The replacement industry presents new windows as the obvious answer to cold, draughts and condensation, but a sound timber window that is draughty and cold can often be repaired, draught-proofed and upgraded for far less, keeping its character and lasting longer than a modern unit. Equally, a window that is rotten, beyond repair or performing very poorly may genuinely warrant replacement. The right call depends on the condition of the existing windows, what is actually making them uncomfortable, and what you want to achieve — which is worth establishing before committing to an expensive replacement.
Read the guideWill new windows make my house warmer?
New windows will usually make a home feel a little warmer — modern glazing has a colder-resistant inner surface and is less draughty — but they are rarely the biggest source of heat loss, so they often deliver less than homeowners expect for the cost. Most homes lose far more heat through their walls, roof and air leakage than through their windows, which are a relatively small area of the total envelope. Replacing the windows while leaving the dominant losses untouched changes little, and can disappoint. Whether new windows are worth it for warmth depends on how much heat your windows actually lose compared with everything else — which is worth measuring before committing to an expensive replacement.
Read the guideHow do I choose the right windows for my house?
Choosing the right windows is not just about picking the lowest U-value or the cheapest quote — it depends on your home's heat loss, the orientation of each window, the home's character and the way the windows are fitted and sealed. The best glazing badly installed, or chosen without regard to solar gain and overheating, can disappoint; while a thoughtful choice matched to each elevation delivers warmth, comfort and light without unwanted summer heat. The right approach is to understand how your windows actually perform in your home before specifying, so the considerable spend matches the building rather than a generic recommendation.
Read the guideWhy do my new windows have condensation?
Condensation on new windows is one of the most common surprises after a window replacement, and where it forms tells you what is happening. Condensation on the inside of the glass usually means the room's humidity is high and ventilation is now too low — because new, well-sealed windows removed the draughts that used to let moisture escape. Condensation on the outside of the glass, by contrast, is a sign the glazing is performing well. Condensation between the panes means a sealed unit has failed. So new-window condensation is rarely a fault with the glass; it is usually a ventilation message, and sometimes good news.
Read the guide