A window that lets a steady draught through the hinge side or the frame perimeter adds pounds to your energy bill.
Fixing that one gap is usually what it takes to keep your home warm again.
Work through the fix in order rather than jumping straight to secondary glazing or a new hinge.
Each step targets a different point where cold air gets in, and skipping ahead usually means paying for a fix the window never needed.
What You’ll Need Before You Start – By Glasgow’s double glazing experts
Self-adhesive foam strips or rubber weatherstripping for the sash, a cartridge of flexible exterior-grade caulk and a caulking gun for the frame perimeter, a clean cloth, and a screwdriver for the hinges and locking points cover most jobs.
Add a secondary glazing kit or shrink-fit window film with double-sided tape if you’re dealing with an older single-glazed window rather than uPVC double glazing.
None of it needs specialist tools, and the whole list costs a fraction of what a professional call-out would charge to stop window draughts for good.
Step 1: Confirm Where the Draught Is Coming From
Close and lock the window properly, then run the back of your hand slowly around the window to find the source of the draught.
Check the frame, the hinge side, the lock side, and both rails.
A steady chill in one exact spot points to a specific fix rather than a window that needs replacing outright.
A perished seal, a dropped sash and a gap at the frame’s perimeter are the common causes worth checking for in that order, since a fix aimed at the wrong one won’t touch the draught at all.
Check around the opening sash on a casement window separately from the fixed frame.
The two often fail for different reasons, and don’t skip the perimeter where the frame meets the wall.
Gaps there get blamed on the window when the render around it is the actual problem.
Step 2: Fit Foam Strip or New Weatherstripping
Clean the track where the sash meets the frame, then press self-adhesive foam strip or rubber weatherstripping firmly along the hinge side and lock side.
Close the window slowly afterwards to check it compresses evenly rather than catching.
A perished seal is the single most common cause of a window draught.
A fresh foam strip is often all it takes to reduce draughts within minutes, though it wears out and needs replacing every couple of years.
Sliding sash windows need a brush-pile strip rather than compression foam, since the sash slides rather than presses shut.
But the principle stays the same: a continuous seal along every point of contact.
Step 3: Seal the Frame Perimeter with Caulk
Run a strip of masking tape either side of the joint where the frame meets the wall.
Then apply a bead of flexible exterior-grade caulk along the gap and tool it smooth with a wet finger before it skins over.
Skip anything rigid for this step.
uPVC frames expand and contract slightly with outside temperatures, and a stiff sealant will crack within a season, undoing the whole job.
Seal both the outside and the inside of the frame if you can reach both, since a gap that’s only closed on one face still lets air move through the cavity behind the plaster or render.
Step 4: Add Secondary Glazing or Window Film for Single Glazing
Fit a secondary glazing panel, or stretch a shrink-fit plastic film across the frame and hold it with double-sided tape, then shrink it tight with a hairdryer.
The trapped layer of still air helps insulate the window and cuts both draughts and heat loss.
It won’t match a proper double-glazed unit for performance, and it’s not invisible.
But it buys real comfort over a winter on an older single-glazed window while you weigh up whether replacement is worth the outlay.
That’s exactly why we offer 0% finance with no deposit required on every window we fit, so weighing up replacement doesn’t have to mean finding a lump sum upfront.
Spreading the cost puts the decision on the window itself, not the bill.
Step 5: Check the Hinges and Locking Points
A stiff handle or a hinge that’s dropped slightly lets cold air in even with the window closed and locked.
It’s easy to miss because nothing looks obviously wrong.
Tighten the screws on the hinges and locking points, then test whether the sash can close properly and pull back square against the seal.
A seized mechanism is worth leaving to a professional rather than forcing, since a stripped screw or a snapped keep turns a ten-minute job into a call-out.
Step 6: Don’t Block the Ventilation While You’re At It
A home needs some background ventilation even after every draught is dealt with. Blocking it up completely traps moisture indoors instead of letting it escape.
Trickle vents, the small slotted openings along the top of many uPVC window frames, provide controlled ventilation once you’ve draught-proofed everything else, so leave them clear rather than taping over them.
Moisture from cooking, showers and simply breathing needs somewhere to go, and without enough airflow it settles on the coldest surface in the room, usually the window.
A well-sealed home with nowhere for that moisture to escape ends up with mould around the frame and poorer air quality inside your home instead of a draught.
Condensation between the panes, rather than misting on the inside surface, is a different window problem. The sealed glass unit has failed, and no amount of ventilation or caulk will fix it.
When to Stop DIYing and Call a Professional
Foam strip, caulk and a tightened hinge fix some draughty windows.
But old windows that need resealing every year, or a frame warped enough that the sash won’t sit square no matter how you adjust it, have gone past what DIY can solve.
Scotland’s building regulations set a U-value target for any replacement windows, and meeting it is where the real energy saving comes from, not another round of caulk.
If you’re weighing up new windows against more repairs, a qualified installer can tell you within a home visit which one pays off.
Draughty Window FAQs
What tools do I need to fix a draughty window myself?
Foam strip or rubber weatherstripping, a cartridge of flexible exterior-grade caulk with a caulking gun, a clean cloth, and a screwdriver cover most jobs. A secondary glazing kit or window film only comes into it on older single-glazed windows.
Why did my draught strip fall off after a week?
Usually because the track wasn’t clean and dry before it went on. Grease, dust or old adhesive stops the new strip bonding properly. Wipe the channel down with a damp cloth, dry it fully, and press the strip on firmly so it can stop draughts rather than just sit in the gap.
Do you need caulk on both the inside and the outside of the frame?
Ideally yes. A gap sealed only on the outside can still let air move through the cavity behind the plaster on the inside face, so caulking both sides closes the path properly rather than half of it.
What’s a good temporary fix if I can’t sort the draught properly straight away?
A rolled towel or a shop-bought draught excluder along the sill buys time without committing to anything, and painter’s tape run along the worst gap holds until you’ve got an hour free to stop the draught properly.
How long does draught-proofing a window take?
Foam strip and caulk together take under half an hour per window once you’ve cleaned the surfaces. Secondary glazing or window film adds another twenty minutes, and letting the caulk cure properly is the only part you can’t rush.
Fixed the Draught but Still Feel the Cold?
A window that’s still cold to stand near after you’ve fitted foam strip, sealed the perimeter and checked the hinges usually has a glazing problem rather than a draught, since none of those fixes touch the glass itself.
We’ve fitted uPVC windows and doors across Scotland since 1988.
A free home survey will tell you honestly whether what you’re feeling is a fixable draught or a window that’s reached the end of its working life.
Every window we fit carries up to a 15-year guarantee and 0% finance if you’d rather spread the cost, backed by a 9.6 out of 10 Trustpilot rating from over 500 customers.
Call 0800 050 2502 or book your free survey online, and find out for certain rather than guessing through another cold winter.
