Buying Guide
Why Is My House So Cold Even With the Heating On?
Updated June 2026
You're spending hundreds on gas but your home still feels cold. The radiators are on, the thermostat says 21°C, yet you're sitting in a jumper under a blanket. The problem isn't your boiler — it's where the heat is going. UK homes lose heat through gaps, cold surfaces and poor insulation that most people don't even notice. Here are the 7 most common causes and the cheapest products to fix each one.
Quick answer
Our top pick: The three biggest heat thieves in UK homes
Total fix under £50 on Amazon
Draughty doors and windows (fix with silicone weather stripping, £8), uninsulated behind radiators (fix with Radflek panels, £22), and single-glazed windows (fix with Duck Brand insulation film, £12). Total: under £50 to make your home noticeably warmer.
Check Price on Amazon →The 7 fixes for a cold house
Self-Adhesive Silicone Weather Stripping
Gaps around doors and windows let cold air pour straight into the room you're trying to heat. The candle test is the easiest way to find them: hold a lit candle near the frame on a windy day and watch the flame move. Even gaps of 1–2mm lose huge amounts of heat over 24 hours because they never close. Most UK homes have a dozen of these gaps the owners have never noticed. Silicone is the upgrade from cheap foam tape — it doesn't compress, crack or lose shape over years of use. Waterproof and soundproof, this strip seals gaps around doors and windows permanently. Self-adhesive backing sticks to wood, PVC and metal frames. One 5m roll seals a typical door and 2 windows for under £10 — the fastest, cheapest warmth upgrade you can buy.
Pros
- Silicone doesn't compress or crack over time
- Waterproof and soundproof
- Sticks to wood, PVC and metal frames
- Peel-and-stick — no tools
- Renter friendly, removable
Cons
- Adhesive can mark old paintwork
- Won't fix very large gaps
- Needs a clean, dry surface to bond
Who it's for: Sealing gaps around door frames and window sashes you can feel cold air coming through
Check Price on Amazon UK →Stormguard Under-Door Draught Excluder Cover
The gap under your front door is one of the biggest single draughts in any UK home — put your hand on the floor next to it on a cold day and you'll feel the wind. A clip-on brush strip from Stormguard, one of the UK's most recognised draught-proofing brands, fits onto the bottom of the door without adhesive — slides on and off. The brush bristles seal the gap while still allowing the door to open and close smoothly over carpet or hard floors. Fitting takes under 10 minutes with a screwdriver. Also worth fitting on the door of any unheated room (spare bedroom, hallway) so cold air doesn't migrate into your warm rooms.
Pros
- Stops floor-level chill instantly
- Clip-on fitting — no adhesive needed
- Trimmable to fit any door width
- Works on uneven floors
- Brush bristles flex over carpet
Cons
- Needs basic DIY to fit
- Doesn't suit very thick rugs
- Brush type wears with heavy use
Who it's for: The gap under a front door or interior door where you can feel cold air with your hand
Check Price on Amazon UK →Duck Brand Max Strength Window Insulation Film Kit
Windows are the biggest cold surface in most UK rooms. Single glazing and old double glazing lose 25–30% of your home's heat — you can feel it as a 'cold radiance' when you sit near a window in winter. The most recognised name in window insulation film worldwide, Duck Brand Max Strength uses the classic shrink-fit approach — apply double-sided tape around the frame, stretch the film over it, then use a hairdryer to shrink it taut. Creates an invisible insulating air layer that reduces heat loss by up to 25% on single-glazed windows. Max Strength film is 40% thicker than standard Duck film. One kit covers 3–4 standard windows for under £15. The temperature next to the window typically rises by 3–5°C.
Pros
- Cuts window heat loss by up to 25%
- Max Strength film is 40% thicker than standard
- Invisible once shrunk tight
- Renter-friendly, removes cleanly
- One kit covers 3–4 windows
Cons
- Window can't be opened until removed
- Needs a hair dryer to fit
- Replace each winter
Who it's for: Single-glazed windows or old draughty double glazing in bedrooms and living rooms
Check Price on Amazon UK →Radflek Radiator Reflector Panels (3-Pack)
If your radiator is on an external wall — especially in an older property — up to 40% of its heat goes straight into the brickwork behind it and out of your home. The only radiator reflector tested by the Building Research Establishment (BRE), Radflek is proven to reflect heat back into the room instead of letting it escape through the wall behind your radiator. Each sheet cuts to fit any radiator size. 3 sheets cover 3 radiators — start with the rooms that feel coldest. If your radiator is on an external wall, up to 40% of its heat is going straight into the brickwork. Radflek stops that. They're cheap, invisible once fitted, and the only fix on this list that actually makes your existing heating more efficient instead of just stopping heat loss. Best fitted in autumn before the heating goes on for winter.
Pros
- BRE-tested to reflect heat back into the room
- Hidden behind the radiator
- Each sheet cuts to fit any radiator size
- Cuts heat loss into external walls
- Pays for itself in 1–2 winters
Cons
- Only worth it on external walls
- Awkward fit on tight bracket gaps
- Marginal on already-insulated walls
Who it's for: Radiators mounted on external walls of pre-1990 UK homes
Check Price on Amazon UK →Ultimate Dual-Sized Radiator Bleed Key
A radiator cold at the top but warm at the bottom is full of trapped air, not water — and air doesn't carry heat. Gurgling, ticking or rattling sounds are the same problem. Dual-sized to fit both standard metric AND older imperial radiators, this key is essential for UK homes where you might have a mix of old and new radiators. Bleeding takes 2 minutes per radiator: turn the heating off, insert the key, turn anti-clockwise, let the air hiss out until water appears, close. If you have a combi boiler, check the pressure gauge afterwards and top up to 1–1.5 bar if it's dropped. This single 2-minute job often makes a freezing room warm again — and costs nothing.
Pros
- Dual-sized for metric and imperial radiators
- Fixes cold-at-top radiators in 2 minutes
- Restores full heat output
- Solid metal build
- Essential for UK homes with mixed radiators
Cons
- Just a key — not a fix on its own
- Use a cloth to catch drips
- Repressurise combi after bleeding
Who it's for: Any radiator that gurgles, ticks, or is cold at the top but warm at the bottom
Check Price on Amazon UK →UAP MailPlate Telescopic Letterbox Cover
A standard UK letterbox is essentially a hand-sized hole punched through your front door, straight to the outside. In winter it acts like a mini wind tunnel, pouring cold air into your hallway every time the wind blows. A full internal letterbox cover plate that blocks 100% of draughts — not just a brush that reduces them. Telescopic design adjusts to fit any door thickness from 40-80mm. Screws on from the inside over your existing letterbox. Over 3,430 reviews on Amazon. Unlike brush-style excluders that still let wind through, this creates a complete seal. Fitting takes 5 minutes with a screwdriver and you'll feel the difference in the hall the same day.
Pros
- Blocks 100% of draughts — not just reduces them
- Telescopic design fits doors 40–80mm thick
- Screws on from the inside in 5 minutes
- Over 3,430 reviews on Amazon
- Creates a complete seal unlike brush types
Cons
- Some letterboxes need cover sizing
- More expensive than basic brush strips
- Doesn't fix gaps around the door itself
Who it's for: Any UK front door with a standard letterbox slot
Check Price on Amazon UK →BLACK+DECKER TLD100 Thermal Leak Detector
Without measuring, you're guessing. Point the BLACK+DECKER TLD100 at any wall, ceiling or window and it tells you exactly where heat is escaping. The infrared sensor shines blue when it detects a cold spot (heat leak) and red when it detects a warm spot. One UK reviewer found a 5-degree cold spot in their bedroom ceiling, fixed it with one roll of insulation, and saved buying five rolls. Instead of guessing where to insulate, this shows you exactly where the problems are. Pair it with an energy monitor on your worst-running appliance and you have a complete picture of where money and warmth are leaving your home. The data turns guesswork into a fix list.
Pros
- Shows exact heat leaks with infrared sensor
- Blue for cold spots, red for warm spots
- Point-and-shoot — no setup needed
- Finds insulation gaps you'd never guess
- Battery-powered, handheld
Cons
- Doesn't see through walls
- Less detailed than a professional thermal camera
- Reads surface, not air, temperature
Who it's for: Diagnosing exactly which walls, ceilings or windows are losing heat
Check Price on Amazon UK →Buying advice
When to call a professional
Safety first — gas, carbon monoxide and damp
Frequently asked questions
Bundle
The complete Cold Room Fix Kit — Under £80
- Self-Adhesive Silicone Weather Stripping£8Amazon →
- Stormguard Under-Door Draught Excluder£10Amazon →
- Duck Brand Max Strength Window Insulation Film£12Amazon →
- Radflek Radiator Reflector Panels (3-Pack)£22Amazon →
- Ultimate Dual-Sized Radiator Bleed Key£4Amazon →
- UAP MailPlate Telescopic Letterbox Cover£18Amazon →