The £5 DIY draught fix around windows that rivals pro installations, according to heating engineers

The first time I realised my living room was basically outdoors with cushions was when a January wind threaded itself straight through the gap by the window and down the back of my neck. The radiators were on, the thermostat was sensibly set, and yet there I was, huddled under a blanket, watching the gas meter spin and wondering what on earth I was paying for.

Like most people, I blamed the usual suspects: “old house”, “terrible insulation”, “we really should get new windows one day”. Then I saw the quote for replacement double glazing and closed the tab fast enough to sprain a finger. New windows are not a casual purchase. They’re “we’ve planned this for a year” money, not “it’s Tuesday and I’m cold” money.

A few weeks later, a heating engineer came to service the boiler. He barely glanced at the controls before walking over to the window, running his hand along the frame and saying, “Here’s half your problem.” He tore a tissue in two, held a strip up to the edge of the sash, and it wafted sideways in the invisible draught. Then he said the thing that properly annoyed me: “You can fix most of this with a fiver’s worth of tape.”

That’s how I ended up in the draught-proofing aisle, holding a roll of self-adhesive foam strip that looked more like craft supplies than house armour. It cost less than a takeaway coffee and claimed to seal gaps “like a pro installation”. I didn’t believe it, but I also couldn’t feel my toes, so I gave it fifteen minutes and a Saturday afternoon.

The difference was…quiet. No big reveal, no fanfare. Just that the next time the wind picked up, the room didn’t. The usual cold river of air by the window vanished. The radiator clicked off sooner. For the first time that winter, the living room felt snug without nudging the thermostat up “just for tonight”.

It turns out the most effective “upgrade” in that room wasn’t smart controls or a flash new boiler. It was a £5 strip of squishy foam, stuck neatly around the window frame.

The tiny gaps that are cooling your whole room

Here’s the bit heating engineers tend to say with a kind of weary fondness: our homes leak warm air in the least dramatic ways. It’s not always huge cracks or smashed panes. It’s millimetre-wide gaps where the sash meets the frame, corners that don’t quite close, old seals that have flattened and given up.

We notice the cold as a vague “this room just never feels warm”, and we blame the boiler or the age of the building. But from a heating engineer’s point of view, draughts are just uncontrolled ventilation. You’re paying to warm air that escapes through those gaps, while fresh cold air slips in to replace it, over and over again.

Think about how it actually feels:

• That one armchair by the window that nobody wants in winter.
• Curtains that twitch on a windy night, even with everything “shut”.
• The mysteriously colder patch of floor by the skirting board.

Those are all soft clues that warm air is leaving – and that your heating system is working harder than it needs to. Engineers know this, which is why many of them now say the same thing: before you spend thousands on new kit, seal the obvious leaks. It’s boring. It’s not Instagrammable. And it works.

The £5 fix: self-adhesive draught strip

The star of this story goes by a few names: foam draught excluder, self-adhesive weather strip, rubber window seal. It usually comes as a roll of squishy material with peel-off backing, designed to sit in the tiny gap where two hard surfaces meet.

On windows, that’s typically:

• Where the opening sash meets the fixed frame
• Along the bottom edge where you feel the worst draught
• On older wooden frames, around slightly warped corners

When the window is closed, the strip compresses, filling the gap and creating a soft, continuous seal. Instead of cold wind snaking through, you’ve got a cushion of still air, which is exactly what you want for warmth.

There are a few common types:

• Foam strip – cheapest, easiest to cut, great for slightly uneven, older frames.
• Rubber or silicone strip – a bit tougher and longer-lasting, good for uPVC or well-fitted timber.
• Brush strip – better for doors, but can help on very large, rough gaps.

Heating engineers like this stuff because it copies what good window manufacturers do at the factory – just in a simpler, stick-on form. Done neatly, it can feel surprisingly close to a pro-level seal.

How to spot where you need it (the two-minute test)

You don’t need fancy tools to find where the cold is getting in. Try one of these:

• Hand test – on a windy day, run the back of your hand slowly around the window frame, especially corners and the bottom edge. The back of your hand is more sensitive to temperature changes; you’ll feel little “rivers” of cold air.
• Tissue test – tear a thin strip of tissue, hold it gently near the edges with the window closed. If it flutters or pulls, you’ve found a leak.
• Candle/incense test – if you’re careful with flames, place a lit candle or incense stick on the sill and watch the smoke. Strong sideways movement means draughts. Never leave it unattended, and keep it away from curtains.

Mark the worst spots lightly with a bit of masking tape or a pencil. Those are the first places your £5 strip should go.

How to fit draught strip in under 20 minutes

You don’t need to be “good at DIY” for this. You just need to go slowly the first time.

What you’ll need

• 1 roll of self-adhesive foam or rubber draught strip (usually £3–£6)
• Scissors or a sharp knife
• A cloth
• A bit of washing-up liquid and warm water (for cleaning first)
• Optional: a tape measure and a pencil

Step-by-step

1. Clean the frame
   Wipe the areas where the strip will go with warm, soapy water. Let it dry fully. Dust and grease are the enemies of sticky backing.

2. Measure (or just offer up)
   Either measure each section with a tape, or simply hold the roll up to the frame and mark where to cut. Cut pieces slightly longer than needed; you can trim at the end.

3. Choose the right face
   The strip should sit on the part of the frame that meets the window when closed, not on the moving part itself if you can avoid it. You want it to compress, not get scraped off.

4. Peel and stick slowly
   Peel off a short length of backing, press the strip into place, then peel a bit more. Work along the frame in one continuous line where possible rather than lots of tiny pieces. Press firmly with your fingers to help the adhesive grab.

5. Check the close
   Gently close the window. It should shut fully without needing a shove, and you should feel mild resistance as the foam compresses. If it won’t close, the strip is too thick; swap for a slimmer profile.

6. Test again
   Repeat your hand or tissue test. If you’ve sealed the line well, that cold river should be more of a quiet pond now.

You don’t have to do every window in the house in one go. Start with the one that annoys you most – the draughty sofa corner, the bedroom that never warms up – and see how it feels over a couple of days.

Why heating engineers rate this as “almost pro-level”

From an engineer’s perspective, good heating isn’t just about making heat. It’s about keeping it where you want it.

Properly installed new windows have built-in seals all the way round the opening parts. Over time those seals can flatten, crack or pull away, especially on older timber or cheaper uPVC units. That’s when you start to feel the chill again.

A well-fitted draught strip:

• Restores the continuous seal that the window had when it was new (or should have had).
• Reduces cold spots and convection currents – less of that rolling “chill” across the room.
• Helps your boiler cycle less often, because the room loses heat more slowly.
• Makes thermostats more accurate, especially if they’re on chilly external walls.

Is it as perfect as fully replacing the frame and glazing? No. But for a few pounds and a short afternoon, it gets you surprisingly close to the comfort of a more expensive upgrade in the rooms you actually use. That is why people who work with heating systems all day quietly recommend it before anything fancy.

Make it snug, not suffocating

There is one important caveat every decent engineer will add: you still need fresh air.

Draught-proofing is about stopping unwanted cold air whistling through cracks, not about sealing the room like a Tupperware box. To keep things healthy:

• Don’t block trickle vents – those small slots at the top of many modern windows are there for controlled ventilation. Leave them open unless your installer has advised otherwise.
• Keep bathroom and kitchen ventilation working – use extract fans or open a window briefly when cooking or showering.
• Check for condensation – if you suddenly get steamy windows and damp corners after draught-proofing, ease back a bit or open windows regularly for short bursts.

The goal is comfort you can actually live with: less shivering on the sofa, fewer guilt-fuelled thermostat nudges, and a home that feels looked-after rather than hermetically sealed.

Where this £5 fix helps most

Where	What to use	Why it helps
Old timber sash windows	Foam or rubber strip on meeting rails and sides	Fills small warps and gaps without needing joinery work
Slightly leaky uPVC windows	Slim rubber strip where original seal has flattened	Restores the “squish” of a fresh factory seal
Around window frames & skirting	Foam strip or decorators’ caulk (for fixed gaps)	Stops cold air coming in from behind plaster and boards

None of this stops you upgrading windows or insulation in future. It just means, in the meantime, you’re not pouring heat (and money) out through gaps you can fix in an evening.

Turning it into a tiny, manageable ritual

The quickest way to avoid doing any of this is to decide you’re going to “draught-proof the whole house this weekend”. You won’t. Life will get in the way, and the tape will end up sulking in a drawer.

A better approach is to treat it like seasonal maintenance:

• One chilly evening, do just the living-room window.
• Next weekend, tackle the coldest bedroom.
• On a windy day, do a quick hand test around the rest and note what to do when you have another spare hour.

You don’t have to become the sort of person who lovingly catalogues every air gap. You just need a few small, repeatable fixes you can actually see yourself doing.

FAQ:

• Will draught strip damage my windows?
  For most modern uPVC and painted timber frames, no. The adhesive sits on the surface and can usually be peeled off later with a bit of patience. On very old or flaky paint, test a small area first in case it lifts loose paint when removed.
• How much can this really save on bills?
  It depends on how leaky your windows are to begin with and how much of the house you treat. Engineers are cautious about exact numbers, but cutting down strong draughts can noticeably reduce how often your heating runs and make lower thermostat settings feel comfortable.
• Does it work on rented homes?
  Often yes, especially if you use removable foam strip and avoid anything that stains. Many landlords are happy for tenants to draught-proof as it doesn’t alter the structure. If in doubt, ask first and keep the packaging to show it’s non-permanent.
• How long does the strip last?
  Foam strip typically lasts a couple of winters before it compresses too much or the adhesive gives up, especially on very frequently used windows. Rubber and silicone types can last longer. The good news is they’re cheap and simple to replace.
• What if my gaps are larger than the strip can handle?
  If you can see outside through the gap, or if the window doesn’t close properly even without strip, you’re beyond the £5 fix. In that case, you may need basic repairs (planing, refitting, or new hardware) before draught-proofing can do its best work.