Your Home Climate
Heating · The problem library

Why do parts of my house feel cold even when the heating is on?

Recently reviewed·Reviewed June 2026, next review December 2026

A house that fails to warm up evenly is usually losing heat faster than the boiler or heat pump can deliver it. The losses come from three places: surfaces that conduct heat outward, air that leaks through gaps, and rooms that the heating circuit was never balanced to serve properly. Upgrading the heating before addressing those losses tends to deliver a smaller improvement than people expect.

Editorial confidence
High confidence. Multiple regulator, government or academic sources agree.
Evidence status
Recently reviewed · reviewed June 2026 · next review December 2026
Monitoring
Every six months, plus whenever Approved Document L or the EST loft-insulation guidance is updated.
Evidence drawn fromGovernment guidance: ECO4, GBISBuilding standards: ADLProfessional bodies: EST, Loughborough DEFACTO

Loft insulation depth (current standard)

270 mm mineral wool

Source: Energy Saving Trust · The Energy Saving Trust treats 270 mm of mineral-wool loft insulation as the practical target for a typical UK home; many older lofts still sit between 100 and 150 mm.

Cavity-wall insulation U-value (refurbishment)

≤0.55 W/m²K

Source: Building Regulations; Approved Document L · Approved Document L sets the refurbishment U-value for filled cavity walls; uninsulated cavities typically sit two to three times higher.

Who this advice is for

Applies to

  • Houses and flats heated by gas, oil, LPG or heat pump
  • Properties built before the year 2000 with original or partial insulation
  • Homes where one or two rooms run colder than the rest of the house
  • Wet central heating systems with radiators or underfloor circuits

Not intended for

  • Properties with confirmed boiler or heat-pump faults
  • Listed buildings where the recommended fabric work is restricted
  • Damp or mould diagnosis rather than temperature
  • Single-room electric heating with no wider distribution

What it usually looks like

These are the symptoms readers describe most often. None of them alone is diagnostic, but together they build a picture.

  • Some radiators struggle to warm certain rooms
  • Cold draughts at floor level
  • Big temperature swings through the day
  • The thermostat reads higher than the room feels

Most common in: Victorian terrace · Interwar semi (1920s–1930s) · Postwar semi (1945–1980)

Before you buy anything

Watch the house respond as you scroll.

These checks are listed in the order we would work through them. The illustration on the left changes with each one, so you can see what each check is actually addressing before deciding whether it is worth doing.

The radiator is on and the room never quite warms. Heat is leaving faster than the system can replace it.

01

Walk the house with a thermal camera or an infrared thermometer

Cold patches around windows, behind radiators on external walls and along skirting tell you exactly where heat is leaving. Insulation directed at the worst spots gives the largest return.

02

Check the loft insulation depth

Anything below 270mm is below current standards and is doing less than half the job it could be doing. Topping up costs little and pays back quickly.

03

Have the radiators properly balanced

An unbalanced system sends most of the hot water to the rooms nearest the boiler. A plumber can re-balance the circuit in an afternoon and it often transforms how the upstairs feels.

04

Inspect window seals and floor edges

Failed seals around old double glazing and gaps where floors meet external walls can move surprising volumes of warm air outdoors. Sealing these is some of the cheapest work available.

05

Look at how the heating is being controlled

A single thermostat in a hallway often allows the rest of the house to overshoot or undershoot. Smart zoning or thermostatic radiator valves can quietly recover several degrees of comfort.

Before you spend money

The cheapest answer is usually the one nobody sold you.

  1. 01

    Put a £15 thermometer in the coldest room for a week

    You will know whether the room actually runs cold or just feels it, and by how much. Every later decision depends on that gap.

    £15
  2. 02

    Bleed every radiator and check the system pressure

    Trapped air leaves the top of a radiator cold even when the boiler is firing. Fifteen minutes with a radiator key often restores a room with no further work.

    Free
  3. 03

    Close internal doors for an evening and see what changes

    If the cold room warms once cut off from the rest of the house, the heating is being short-circuited by a hot return rather than being undersized.

    Free
  4. 04

    Walk the room with a candle on a windy day and find the draughts

    Plugging gaps around skirting, floorboards and service penetrations costs almost nothing and often closes most of the gap before any kit is bought.

    Free

What we recommend, and why

Every recommendation explains why it comes first, the evidence behind it, how confident we are, and when it would not apply.

01

Top up the loft insulation before anything else

Why this comes first

Roughly a quarter of a typical uninsulated home's heat loss escapes through the roof, and the work is one of the cheapest and least disruptive interventions available. Topping a loft from 100 mm to 270 mm has been the EST's standard recommendation for two decades, and it usually delivers a more obvious comfort gain than any controls change.

Evidence

Energy Saving Trust guidance and the ECO4 and Great British Insulation Scheme delivery data all treat loft top-ups as the highest-return measure on a typical pre-2000 home.

EST · ECO4 · GBIS

Confidence

High confidence. Multiple independent sources agree on the direction and the order.

Exceptions
  • Lofts already at 270 mm or more
  • Room-in-roof conversions where the loft floor is not the heat-loss surface
Next step
Open the insulation hub
02

Have the radiator circuit properly balanced

Why this comes first

An unbalanced wet system sends the bulk of its hot water to the rooms nearest the boiler, so distant rooms never reach setpoint even when the boiler is working hard. Balancing is a half-day job for a competent heating engineer and frequently fixes a cold upstairs without any new kit.

Evidence

CIBSE design guidance and EST consumer advice both list balancing as a standard step in fault-finding before recommending replacement plant.

CIBSE · EST

Confidence

High confidence.

Exceptions
  • Homes already commissioned and balanced within the last year
  • All-electric heating with no shared circulation loop
Next step
See the boiler decisions hub
03

Seal the obvious draughts before new heating kit

Why this comes first

Air leakage is one of the largest single heat losses in older UK homes, yet it is usually the cheapest to fix. Sealing the loft hatch, the floor perimeter and the chimney can recover several degrees of perceived comfort without changing how the heating runs at all.

Evidence

EST measured energy and comfort gains from draught-proofing in typical UK homes; the Loughborough DEFACTO programme found uncontrolled air leakage to be a dominant cause of uneven indoor temperatures.

EST · Loughborough DEFACTO

Confidence

Reasonable confidence.

Exceptions
  • Tightly built new homes where over-sealing risks ventilation problems
  • Properties with active condensation or mould issues that need ventilation strategy first
Next step
Plan it on the Home Planner

The trade-offs

Every choice gives you something and asks for something back.

  • Rebalance and bleed the existing system

    You get

    A measurable improvement at almost zero cost, and a clearer picture of what is left to fix.

    You give up

    An afternoon with a screwdriver and bleed key, and the chance the rebalancing alone is not enough.

  • Add or upsize a radiator in the cold room

    You get

    Targeted output where the room actually loses heat, with no change to the rest of the system.

    You give up

    A morning's plumbing, possible redecoration, and a system that may now need rebalancing again afterwards.

  • Lower flow temperature and run the heating for longer

    You get

    Quieter, more even warmth and a system already set up for a future heat pump.

    You give up

    A longer warm-up in the morning and the discipline to leave the controls alone for a fortnight while it settles.

Real homes that faced this

Publicly documented UK projects that ran into the same problem and reported what happened.

We did not run these projects. Each links back to the original publisher so you can read the figures in context and judge for yourself what carries over to your home.

How we'd approach this

Fix the cheapest cause first; size kit against the room you actually have.

If we had a single cold room ourselves, we would not order a radiator on day one. We would bleed every radiator in the house, check the pressure, and run the heating for an hour to see which rooms reach temperature and which never do. Half the cold-room cases we see resolve in that hour without spending anything.

If the room is still cold after that, we would treat the fabric before the kit. A draughty sash window or an uninsulated external corner will defeat any radiator you put under it, and the radiator will then be wrong the day the fabric is fixed. Plug the gaps, then size the heat.

And we would be honest about whether the heating system can carry the house at all. A boiler running flat-out for one cold room is usually a clue the whole system is undersized or unbalanced, not that this room needs more output. The proportionate answer there is a system review, not another radiator.

Evidence behind this page

Every recommendation on this page is traceable to its source. Click a publication to read the original.

Products that may help

Only consider these once the checks above have been ruled out. A product fitted into the wrong cause is rarely satisfying.

House Summary

The cheapest answer to cold rooms in winter is usually the one that addresses the cause rather than the symptom. The list above is in the order we would work through it, because the checks at the top tend to rule out the most expensive mistakes further down.

Related decisions
Next Best Step

Heat Pumps; the honest case

Take the next step