Start with the symptom. Understand the cause.
Cold rooms, condensation, mould, draughts, high bills — they all have measurable causes. This is a building-physics guide to what is really happening in your home, and how we diagnose it before a penny is spent on fixes.
- Certified Passive House Designer
- Building physics-led, not product-led
- Investigation before any remedial work
- Thermal imaging, blower door, moisture & ventilation diagnostics
Describe your problem, or filter to find it
Do not fix symptoms before you understand the cause
Most home comfort problems — a cold room, a wet window, recurring mould — are symptoms of how the building loses heat and manages moisture. Treating the symptom (a bigger boiler, anti-mould paint, a dehumidifier) rarely solves it, because the underlying physics has not changed.
Each guide here explains what the symptom usually means, the common causes, what most people check first, and — crucially — what most people miss. Then it shows how we diagnose the real cause with thermal imaging, blower door testing, moisture and dew-point readings and a ventilation review, so any money you spend goes on the right fix.
Explore the problem hubs
Connected problems, grouped by the building physics behind them — and the diagnosis that solves the whole cluster, not one symptom.
Damp, Condensation & Mould Hub
Damp, condensation and mould are the symptoms most homeowners search for — and the ones most often mis-treated. They are usually one connected problem: humid air meeting cold surfaces that are too poorly ventilated to dry.
53 guidesCold Homes & Energy Hub
A home that is cold whatever the heating does, or expensive to run, is almost always losing heat faster than it is made — through the fabric, draughts and cold surfaces, not the boiler.
73 guidesSurveys & Diagnostics Hub
Before paying for a treatment — or buying a home — it pays to measure what is actually happening. An independent, product-neutral diagnosis finds the real cause and the cheapest correct fix.
15 guidesRetrofit, Windows & Extensions Hub
Insulation, new windows and extensions can leave a home damper, hotter or no warmer when done without diagnosis. These guides explain why common upgrades fail and how to get them right.
39 guidesNew Build & Snagging Hub
New builds can be cold, draughty or damp when the airtightness, insulation or ventilation was not built as designed — and developers often blame 'lifestyle'. Measured evidence reframes it as a defect.
8 guidesBrowse by problem
Cold Homes
When a home feels cold whatever the heating does, the cause is usually the building — heat loss and cold surfaces — not the boiler.
14 guidesHeat Loss & High Energy Bills
High bills and warmth that won't last are signs of excessive heat loss. The fix starts with measuring where the heat — and the money — escapes.
12 guidesCondensation & Moisture
Condensation is humid air meeting cold surfaces below the dew point. It's a fixable balance of moisture, ventilation and surface temperature.
12 guidesMould Problems
Mould is a building-physics problem, not a cleaning one. It grows where surfaces stay cold and humid — so the cure is warmer surfaces and better ventilation.
13 guidesDamp Problems
Damp can be condensation, penetrating or rising — and each needs a different fix. Diagnosis before treatment saves money and solves the problem.
15 guidesDraughts & Air Leakage
Draughts mean uncontrolled air leakage carrying heat out. A blower door test measures and locates it so sealing is targeted, not guessed.
11 guidesNoise & Soundproofing Problems
Unwanted noise is airborne or impact, and travels by direct and flanking paths. The right fix depends on diagnosing how the sound actually reaches you.
12 guidesVentilation & Indoor Air Quality
Poor air quality and stuffiness signal inadequate ventilation. Measuring CO₂, humidity and airflow shows whether the home is genuinely ventilated.
13 guidesHeating & Warmth
A home that's slow to warm, never cosy or expensive to heat is usually losing heat faster than the system can replace it — a fabric problem, not just a boiler one.
15 guidesLoft & Roof
Heat rises, so the loft and roof lose a disproportionate share of a home's warmth — and trap moisture too. Thin insulation, air leakage and poor ventilation are usually the cause.
14 guidesWindows & 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.
13 guidesRetrofit Mistakes
Insulation, sealing or new windows can leave a home damper or no warmer when done without diagnosis. These guides explain why common fixes fail and how to get them right.
10 guidesFloors & Ground Floor
Cold and draughty floors come from uninsulated ground floors and air leaking up from the void below. Damp under the boards is a ventilation problem worth catching early.
7 guidesOverheating & Summer Heat
Homes overheat when more solar gain enters by day than can be purged at night. Shading, roof improvements and night ventilation usually cool a home without air conditioning.
8 guidesExtensions & Conservatories
Extensions and conservatories expose a lot of glazing and surface, so they swing cold and hot. Better fabric, junctions and ventilation make them comfortable year-round.
8 guidesNew Build & Snagging
New builds can be cold, draughty or damp when the airtightness, insulation or ventilation was not built as designed. Testing proves the defects for a snagging claim.
8 guidesSurveys & Diagnostics
Before paying for a fix — or a home — it pays to measure what is actually happening. These guides explain the surveys and diagnostics that find the real cause, independently.
15 guidesMost-searched problems
Why is my house always cold?
If your home feels cold however long the heating runs, the problem is rarely the boiler — it is the building losing heat faster than you can replace it. The way to fix that affordably is to measure where the heat is going, not to guess.
Read the guide Homeowner questionWhy are my energy bills so high?
If your heating bills feel disproportionate to the comfort you get, the building is almost certainly losing heat faster than it should. The cheapest unit of energy is the one you never have to buy — so the fix starts with measuring where it escapes.
Read the guide Homeowner questionWhat's the most cost-effective way to reduce heat loss?
The most cost-effective way to reduce heat loss is not a single measure but a method: measure where your home actually loses heat, then fix the biggest losses with the lowest cost first, in a sensible sequence. For most homes that usually means cheap, high-impact basics — loft insulation and draught-sealing — before bigger investments like wall or floor insulation and glazing. The key is that the right order depends on your specific home, so a measured assessment is what tells you where to start for the best return.
Read the guide Homeowner questionIs it worth getting cavity wall insulation?
Cavity wall insulation can be one of the most cost-effective ways to cut heat loss and bills — but only in a wall that is genuinely suitable, properly assessed and correctly installed. In the right house it works well and pays back quickly; in the wrong one, or done badly, it can bridge the cavity and let damp cross to the inside, causing problems that are expensive to put right. Whether it is worth it for your home therefore depends on the wall construction, the exposure to wind-driven rain, and the condition of the cavity — none of which can be assumed from the fact that you have cavity walls. The sensible step is to establish suitability before installing, not after.
Read the guide Homeowner questionShould I get external or internal wall insulation?
For a solid-wall home — one with no cavity to fill — the way to cut the large heat loss through the walls is either external wall insulation (a layer added to the outside) or internal wall insulation (a layer added to the inside), and the two suit different houses. External insulation generally performs better and avoids the moisture risks of internal, but changes the appearance and is more expensive; internal is cheaper and keeps the outside unchanged, but reduces room size and, done without care, can cause condensation within the wall. Choosing well depends on the building, the appearance constraints, the budget and — crucially — getting the moisture detailing right. It is a decision best made on the building physics, not on cost alone.
Read the guide Homeowner questionIs it worth insulating my solid walls?
Insulating solid walls is one of the most effective ways to warm a solid-walled home and cut its bills — solid walls lose far more heat than insulated cavity walls — but it is also a major, costly intervention that only pays off when it is done correctly. Whether it is worth it for you depends on how much the walls actually lose relative to the rest of the home, whether internal or external insulation suits the property, and crucially whether the work is detailed to avoid the condensation, damp and thermal-bridging problems that poorly designed solid-wall insulation can cause. The decision should rest on a heat-loss assessment and a moisture-risk appraisal, not on a generic sales pitch.
Read the guide Homeowner questionWhy do I have condensation on my windows?
Condensation on windows is the visible result of two things meeting: humid indoor air and a cold glass surface below its dew point. It is a building-physics problem with a clear cause — and a clear, lasting fix.
Read the guide Homeowner questionHow do I stop condensation in my home?
Stopping condensation for good means tackling the two things that cause it together: too much moisture in the air and surfaces cold enough for that moisture to condense on. Wiping windows, running a dehumidifier or opening a window now and then treats the symptom briefly. The lasting fix is to lower indoor humidity with controlled ventilation and to warm the cold surfaces, so the air no longer reaches its dew point indoors.
Read the guide Homeowner questionWhy does mould keep coming back?
Mould keeps coming back because cleaning and painting over it treats the symptom, not the cause. Mould grows wherever a surface stays cool and humid for long enough — so until those conditions change, it returns.
Read the guide Homeowner questionIs black mould in my home dangerous to health?
Black mould can affect health — it can trigger or worsen respiratory problems, allergies and irritation, and the risk is greater for babies, the elderly, and anyone with asthma or a weakened immune system — so it should not be ignored. But cleaning it off treats only the symptom: mould grows because a surface is repeatedly damp, so the lasting protection for your health is to remove the moisture that feeds it. Understanding both the health risk and the real cause is what lets you deal with mould properly rather than fighting it forever.
Read the guide Homeowner questionIs mould in my rented home the landlord's responsibility?
Mould in a rented home is, in most cases where it stems from the condition of the building, the landlord's responsibility — but the question turns on what is actually causing it, and that is where tenants and landlords often disagree. If the mould results from a building defect or from inadequate provision the landlord is responsible for — cold, uninsulated walls causing condensation, a leak, or ventilation that does not work — then it is generally the landlord's to remedy. Landlords frequently attribute it instead to 'lifestyle'. The way to resolve that is independent, measured evidence of the cause: showing whether the building, not the occupant's normal use, is producing the conditions in which mould grows.
Read the guide Homeowner questionHow do I get rid of mould permanently?
Getting rid of mould permanently means removing the conditions it needs to grow, not just cleaning what you can see. Mould needs a surface that is cold and humid enough for moisture to settle on it; cleaning or painting over it treats the symptom, so it returns within weeks or months because the cold, damp surface is still there. The permanent cure is to warm the surface (so it stays above the dew point) and lower the indoor humidity (so moisture isn't deposited) — usually a combination of insulation, heating and ventilation. Clean the mould, yes, but only as the last step after you have removed the cause.
Read the guide Homeowner questionWhat is the difference between condensation, rising and penetrating damp?
Damp is not one problem — it is three. Condensation, penetrating damp and rising damp produce similar-looking stains, smells and mould, but each is driven by entirely different building physics, and each needs a completely different fix. Getting the diagnosis right is the single most important decision you will make, because the cure for one type does nothing for the others.
Read the guide Homeowner questionIs rising damp real, and do I need a damp-proof course?
Rising damp is real — ground moisture can rise through masonry by capillary action where there is no working damp-proof course — but it is far less common than the volume of 'rising damp' diagnoses and injected damp-proof courses suggests. A great many homes treated for rising damp actually had penetrating damp, a bridged DPC, high ground levels, a leak or condensation, none of which an injected course addresses. So the honest answer is: rising damp exists, but you should only treat it once it has genuinely been confirmed.
Read the guide Homeowner questionShould I be worried about damp when buying a house?
Damp in a house you are buying is worth understanding rather than panicking over — what matters is what is causing it and what it will cost to fix, not the word 'damp' itself. Much of the damp found in homes is condensation, which is manageable and relatively inexpensive to resolve; some is penetrating or rising damp from a defect, which ranges from a simple repair to a significant job; and occasionally it signals a more serious underlying problem. A mortgage valuation and a standard homebuyer survey often flag damp without diagnosing it, which can either scare buyers off a sound house or hide a costlier issue. Getting the cause properly assessed before you commit lets you decide, negotiate or budget with confidence.
Read the guide Homeowner questionDo I need a damp-proof membrane?
A damp-proof membrane — a sheet or coating that blocks moisture — is the right answer in some situations and exactly the wrong one in others, so the question is really about diagnosis. Membranes make sense where you must manage water you cannot stop, such as a cellar or a below-ground wall, where a cavity-drain membrane controls and channels it. But applied to an ordinary solid wall suffering condensation or misdiagnosed 'rising damp', a membrane or tanking simply traps moisture in the wall, hides the symptom temporarily, and often pushes the damp elsewhere. Whether you need a membrane depends entirely on what the moisture is and where it comes from — which means measuring before sealing.
Read the guide Homeowner questionWhy is my house so draughty?
A draughty house feels cold even when the heating is on, because uncontrolled air is moving through the building, carrying warmth out and pulling cold air in. Draughts are not just an irritation at the doors and windows — they are the visible end of a whole-house air leakage problem, and most of the leakage is in places you cannot feel or see. Understanding how and why air moves through a home is the key to stopping it.
Read the guide Homeowner questionWhy can I hear my neighbours through the wall?
Hearing your neighbours through a wall means sound energy is finding a path from their home into yours — and that path is not always the wall itself. Whether it is voices, a television or music, the noise is travelling either directly through the dividing structure or indirectly through the surrounding floors, ceilings and junctions. Understanding which path dominates is the key to reducing it, because soundproofing the wrong element wastes money.
Read the guide Homeowner questionHow do I soundproof a party wall in a terraced house?
Soundproofing a party wall in a terraced house can work very well, but only if it is done in response to how the sound is actually reaching you. The instinct is to line the shared wall, yet in many terraces the neighbour's noise is not coming straight through the masonry — it flanks around it through the floor joists, the chimney breast, the ceiling void and the junctions. Lining the wall alone then makes a disappointingly small difference. The reliable approach is to diagnose the dominant transmission path first, decide whether the problem is airborne (voices, television) or impact (footsteps, doors), and then build the right amount of mass, separation and damping where it counts.
Read the guide Homeowner questionWhy is my house so stuffy?
A stuffy home is one where the air is not being changed often enough. Carbon dioxide from breathing builds up, moisture and smells linger, and the air feels heavy and stale — all signs that fresh air is not arriving and used air is not leaving at the rate the household needs. Stuffiness is rarely about temperature; it is about ventilation, and it is very fixable once you understand why the air is not moving.
Read the guide Homeowner questionDo I need mechanical ventilation in my home?
Whether your home needs mechanical ventilation depends on how much moisture it produces, how airtight it is, and how well it can ventilate naturally. As homes are sealed up to save energy, the accidental draughts that used to carry away moisture and stale air disappear — so a tighter home increasingly needs deliberate, mechanical ventilation to stay healthy. The right answer ranges from improved extract fans, to a positive-input ventilation (PIV) unit, to whole-house mechanical ventilation with heat recovery (MVHR), and depends on measuring the home's actual conditions rather than guessing. The aim is controlled, adequate ventilation that removes moisture and pollutants without throwing away heat.
Read the guide Homeowner questionWhy is my house cold even with the heating on?
When the heating is on but the house still feels cold, it is tempting to blame the boiler. Far more often, the building is losing heat through its fabric — walls, windows, roof and air leakage — as fast as the heating can supply it. The system is working; it is simply pouring warmth into a building that cannot hold it. Understanding that balance is the key to a home that finally feels warm.
Read the guide Homeowner questionIs my house ready for a heat pump?
A heat pump can heat almost any home, but it works efficiently and affordably only in one that loses heat slowly and can be warmed with low-temperature water. So the real question is not whether a heat pump will fit, but whether your house is ready to run on the gentle, steady, low flow temperatures heat pumps prefer. That depends on your fabric — insulation and airtightness — and on your radiators and system being sized for low-temperature heat. Getting this right first is what makes a heat pump cheap to run rather than disappointing.
Read the guide Homeowner questionDo I need a heat loss survey before getting a heat pump?
Before installing a heat pump, a proper heat loss survey is not an optional extra — it is the step that determines whether the system will work well, run cheaply and keep you warm. A heat pump delivers heat at a lower temperature than a gas boiler and is most efficient when the home loses heat slowly enough to be heated by large, low-temperature emitters. If the heat pump is sized from a rule of thumb or the old boiler's output, rather than from a measured, room-by-room heat loss calculation, it is likely to be wrong-sized, run inefficiently and disappoint. The survey establishes the home's actual heat loss, whether the fabric is ready, and exactly what each room needs — which is what makes a heat pump a success rather than a costly mistake.
Read the guide Homeowner questionWhy is my heat pump not keeping my house warm?
A heat pump that cannot keep a home warm is almost never a faulty heat pump — it is usually a mismatch between the system and the building. Heat pumps deliver heat at a lower flow temperature than a gas boiler, so they rely on the home losing heat slowly, on emitters sized to give out enough heat at that lower temperature, and on a correct heat-loss design behind the installation. When a home is colder than expected after a heat pump goes in, the cause is normally one of three things: the heat loss was higher than the system was sized for, the radiators or underfloor circuits are too small to emit enough heat at low flow temperatures, or the system has been set up or controlled badly. Each is diagnosable, and each points to a different fix.
Read the guide Homeowner questionWhy are my heating bills so high with a heat pump?
A heat pump that produces high bills is usually running inefficiently, and that almost always comes down to one of three things: it is running at too high a flow temperature, it is badly controlled, or the home loses heat faster than it should. A heat pump's efficiency — how much heat it delivers per unit of electricity — depends heavily on running at the lowest flow temperature that still keeps the home warm, on running steadily rather than blasting on and off, and on the building not bleeding heat through poor insulation and air leakage. When bills are high, the heat pump is rarely the fault; the set-up or the fabric is dragging its efficiency down, and both are measurable and fixable.
Read the guide Homeowner questionWhy is my loft or roof losing heat?
Because warm air rises, the loft and roof are among the biggest routes for heat to leave a home — and they are also where insulation is most often thin, gapped, compressed or bypassed by air leakage. A loft that feels warm in winter is a loft letting your heat escape. Finding out exactly how and where it is lost is the key to a warmer, cheaper home.
Read the guide Homeowner questionIs spray foam insulation in my loft a problem?
Spray foam insulation applied to a loft or the underside of a roof can be a problem — and it is increasingly flagged by surveyors and lenders — but whether it is actually causing harm in a particular roof depends on the type of foam, how it was applied, and what it is doing to the roof's ventilation and timbers. The concerns are real: spray foam can trap moisture against the rafters, encourage condensation and rot, hide defects from inspection, and make some lenders unwilling to lend. Equally, not every installation is failing. The sensible approach is not to panic or to rip it out blindly, but to have the roof properly assessed so you know whether it is sound, at risk, or in need of removal.
Read the guide Homeowner questionDo 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 guide Homeowner questionShould 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 guide Homeowner questionWill 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 guide Homeowner questionHow 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 guide Homeowner questionWhy did my retrofit make things worse?
It is a dispiriting and surprisingly common story: money is spent on insulation, new windows or draught-proofing, and the home ends up damper, stuffier or no warmer than before. The work was not necessarily done badly — but it was almost always done without first measuring how the building actually behaves. A retrofit that ignores moisture, airflow and the order of operations does not just underperform; it can move problems around and create new ones.
Read the guide Homeowner questionWhy is my cavity wall insulation causing damp?
Damp appearing after cavity wall insulation usually means the fill is doing the one thing the cavity was designed to prevent: bridging the gap so water can cross from the wet outer leaf to the dry inner one. This happens when the wall was not suitable for filling in the first place — too exposed to driving rain, a narrow or debris-filled cavity, or an outer leaf already letting water in — or when the insulation was installed badly, leaving slumped or bridged material. The result is damp patches and mould on internal walls that were dry before. It is a building-physics failure, and the fix is to diagnose what is bridging the water and, often, to extract the insulation and put the wall right.
Read the guide Homeowner questionWhy are my floors cold?
Cold floors are one of the most-felt comfort problems, and they have two clear causes: the ground floor is poorly insulated so heat is conducted away into the cold ground or ventilated void below, and air leaks up through gaps in the floor carrying cold draughts. Because you are in direct contact with the floor, even a slightly cold surface feels uncomfortable — and the fix depends on which mechanism dominates.
Read the guide Homeowner questionWhy does my house overheat in summer?
A house overheats in summer when more solar heat enters during the day than can be removed at night. Sun through unshaded glazing and a hot roof pours energy in; if the home is then unable to purge that heat overnight — because windows stay shut, ventilation is limited or the structure holds onto warmth — temperatures climb day after day. Overheating is a building-physics balance of solar gain in versus heat out, and it is increasingly common in modern, well-insulated and glazed homes.
Read the guide Homeowner questionWhy is my extension cold and hard to heat?
Extensions are often colder and harder to heat than the original house because they expose more surface to the outside per square metre, usually contain a lot of glazing and roof area, and frequently have thermal bridges where the new structure meets the old. Add heating that was sized for the original home rather than the extension, and the room struggles to stay warm. The causes are specific and measurable — and fixable once identified.
Read the guide Homeowner questionShould I replace my conservatory roof with a solid roof?
Replacing a conservatory's glass or polycarbonate roof with a solid, insulated roof is often the single most effective way to turn an unusable, baking-then-freezing conservatory into a comfortable year-round room — because the roof is usually where most of the heat is lost in winter and gained in summer. But it only delivers if the rest of the structure can keep up: the glazed walls, the floor and any dwarf walls also need to perform, and the existing base and frames must be able to carry and suit a heavier roof. So it is usually worth it, provided it is done as part of the whole picture.
Read the guide Homeowner questionWhy is my new build cold or draughty?
A new build that feels cold or draughty is almost always a sign that the airtightness or insulation was not built as it was designed. On paper the home should perform well; in reality, gaps in the air barrier, missing or compressed insulation and thermal bridges at junctions are common defects that let heat out and cold air in. Because these are buildability and quality issues, they can usually be proven by testing — and that evidence is what supports a snagging claim.
Read the guide Homeowner questionShould I get an air test or survey on my new build?
If your new build is cold, draughty, or prone to condensation, an independent air test and performance survey is well worth it, because it provides objective evidence of whether the home was actually built to the airtightness, insulation and ventilation it was designed and sold with. New builds are tested at handover, but that single result does not always reflect how the finished home performs, and an independent survey can measure it, locate the defects, and give you the documented proof needed for a snagging or warranty claim.
Read the guide Homeowner questionWhy is my new-build warranty not covering damp?
Many homeowners find their new-build warranty rejects a damp or mould claim on the grounds that it is 'condensation' or caused by their 'lifestyle' rather than a building defect — a frequent and frustrating outcome. Warranties typically exclude condensation and routine maintenance, so developers and warranty providers lean on that exclusion, attributing damp to how the home is used. But condensation in a new build is very often the symptom of a genuine defect — inadequate ventilation that was never properly installed or commissioned, missing or bridged insulation creating cold spots, or airtightness and thermal-bridging failures. Independent evidence is what reframes the problem from blamed lifestyle to provable defect, which is the basis of a successful claim.
Read the guide Homeowner questionHow do I prove my new build is underperforming?
Proving that a new build is underperforming — cold, draughty, damp or expensive to run despite its modern specification — means measuring how the home actually behaves and comparing it with how it was designed and certified to perform. Subjective complaints ('it feels cold', 'the bills are high') are easy for a developer to dismiss; measured evidence is not. The tests that build a credible evidence pack are an airtightness (blower door) test against the design figure, thermal imaging against the insulation specification, ventilation flow measurement against the design rates, and humidity and temperature logging. Together they show whether the home was built as designed, which is the basis for a snagging or warranty claim.
Read the guide Homeowner questionDo I need a thermal imaging survey?
A thermal imaging survey is worth it when you need to see what is happening inside your walls, roof and floors without opening them up — missing or slipped insulation, thermal bridges, air leakage paths and sometimes damp. It turns invisible performance problems into a clear, located picture, which is exactly what you need before insulating, after a retrofit, when snagging a new build, or when diagnosing cold spots, draughts and damp. It is a diagnostic tool, not a fix, and its value is in directing the right action.
Read the guide Homeowner questionHow much does a thermal imaging survey cost, and is it worth it?
The cost of a thermal imaging survey varies with the size and complexity of the property, what you need it to answer, and — most importantly — whether it is carried out properly under the right conditions and interpreted by someone who understands building physics. A cheap survey done in the wrong weather, with no temperature difference across the walls and no analysis, can be worthless; a well-conducted, properly interpreted survey can save many times its cost by directing money to the defects that actually matter and away from work that would not have helped. Rather than asking only what it costs, the better question is what makes a thermal survey worth commissioning, and when it pays for itself.
Read the guide Homeowner questionDo I need a building survey before buying an older house?
Before buying an older house, a survey is almost always worthwhile — but it matters which survey you commission. A standard homebuyer report or mortgage valuation tells you about visible condition and broad value; it rarely tells you how the building actually performs — how much heat it loses, how airtight and well-ventilated it is, where it is at risk of condensation and damp, and what it will realistically cost to make warm, healthy and efficient. For a period or solid-wall property, those performance questions are exactly the ones that determine your running costs and the size of any retrofit bill. A building performance survey answers them with measurement, so you buy with your eyes open and can negotiate or budget accordingly.
Read the guide Homeowner questionWhat does a damp and mould survey involve?
A damp and mould survey should do one thing above all: establish why the home is damp, so the right treatment follows. Done well, that means more than running a damp meter over a wall and naming a problem — it involves measuring the moisture, temperature and ventilation, distinguishing condensation from penetrating and rising damp, and identifying the cold surfaces and moisture sources that actually drive the mould. A survey that skips this diagnosis and recommends a single proprietary treatment can lead to money spent on the wrong fix. Knowing what a thorough survey involves helps you commission one that finds the cause rather than just confirming there is damp.
Read the guide Homeowner questionHow do I evidence damp and mould for a housing disrepair claim?
If you are pursuing a housing disrepair claim over damp and mould, photographs of the mould are rarely enough on their own. A claim is strengthened by independent, measured evidence that establishes the cause of the damp, links it to a disrepair the landlord is responsible for, and distinguishes it from anything that could be blamed on how the home is used. That is a building-physics question — whether the damp is condensation driven by a building defect or inadequate ventilation, penetrating damp from a fabric failure, or rising damp — answered with monitoring, thermal imaging and inspection, and set out in an expert report. Understanding what such evidence involves helps you commission a report that actually supports the claim.
Read the guide Homeowner questionDo I need an airtightness test for my extension?
A new extension may well need an airtightness test to satisfy Building Regulations, and even where it is not strictly required it is worth carrying out, because airtightness is one of the biggest factors in whether the new room is warm and comfortable or cold and draughty. Building Control increasingly expects new work to demonstrate its airtightness, and the energy calculations that justify the design often assume a level of airtightness that has to be proven on site. Beyond compliance, a test carried out as the extension is built locates leakage while it can still be sealed cheaply — turning an air test from a box-ticking exercise into the thing that ensures the extension actually performs.
Read the guide Homeowner questionDo I need a survey before buying a leasehold flat?
Before buying a leasehold flat, a survey is worth considering — but the questions that most affect your daily comfort and running costs are ones a standard valuation or homebuyer survey rarely answers. A flat's warmth, damp risk, ventilation and, crucially, how much noise you will hear from neighbours are determined by its construction and its position in the building, and these performance issues are common in flats yet largely invisible to a visual inspection. A building performance survey measures how the flat actually behaves — heat loss, airtightness, condensation risk and acoustic transmission — so you know what living there will really be like, and can negotiate or budget, before you commit to a lease you cannot easily change.
Read the guide Homeowner questionHow do I choose an independent surveyor?
Choosing a surveyor matters because not every 'survey' is impartial. A great deal of damp, condensation and insulation advice in the UK comes from firms that also sell the treatment — a 'free survey' that ends in a quote for chemical injection, render or coatings. That is a sales inspection, not an independent diagnosis, and it has a built-in incentive to find the problem the firm happens to treat. A genuinely independent surveyor earns their fee from the diagnosis alone, has no product to sell and no stake in the remedy, and is therefore free to tell you the cheapest correct answer — including that you need no treatment at all. Knowing how to spot the difference is what protects you from spending thousands on the wrong fix.
Read the guide Homeowner questionWhat is the difference between a HomeBuyers Report and a building survey?
When you buy a home you will be offered different 'levels' of survey, and the names cause real confusion. A HomeBuyers Report (often called a Level 2 survey) is a moderate, mostly visual overview that flags obvious defects and gives a condition rating; a building survey (Level 3, sometimes called a full structural survey) is a deeper, more detailed inspection suited to older, larger, altered or unusual properties. Choosing between them depends on the age, type and condition of the house and how much risk you are willing to carry. But there is a third issue both share: a standard survey is about defects and condition, not how the building actually performs — so neither tells you whether the home will be cold, draughty, damp or expensive to run.
Read the guide Homeowner questionDo I need a survey before buying a period home?
A period home almost always warrants a deeper survey than a modern one, and ideally a performance-aware one too, because old houses are built and behave differently. Solid walls with no cavity, lime-based breathable construction, suspended timber floors, original windows and decades of alterations all create risks — and opportunities to misdiagnose — that a light, modern-house survey will skim over. The two big questions a period-home buyer needs answered are whether the structure and fabric are sound, and how the house will perform: whether it will be cold, draughty and damp-prone, and what it would cost to make comfortable. A standard HomeBuyers Report rarely answers either properly for a period property.
Read the guide Homeowner questionHow much does a blower door test cost, and is it worth it?
A blower door test — also called an airtightness or air-pressure test — measures how much uncontrolled air leaks into and out of your home, and locates where. The cost depends on the size and complexity of the property, whether it is a simple compliance test or a full diagnostic with smoke and thermal imaging to find every leak, and where you are in the country. For most homeowners the question behind the price is whether it is worth it, and the answer turns on what the leakage is costing you: in a draughty home, air leakage can be one of the largest heat losses, so a test that finds and prioritises the leaks usually pays for itself many times over in targeted, effective sealing.
Read the guide Homeowner questionDo I need a survey if my house is cold and damp?
If your home is both cold and damp, a survey is usually worth it — because the two problems almost always share a cause, and guessing at fixes is the expensive way to solve it. Cold surfaces, heat loss, air leakage and poor moisture control tend to feed each other: cold walls and windows lose heat and also drop below the dew point so moisture condenses on them, and a home that is hard to heat is also one where surfaces stay cold enough to grow mould. A survey that measures where the heat goes and how moisture behaves identifies the real cause, so a single coordinated fix addresses both — rather than spending separately, and often wrongly, on heating, damp treatment and mould paint.
Read the guideNot sure which problem you have?
A building performance diagnostic measures what is really happening in your home — heat loss, air leakage, moisture and ventilation — so you can fix the cause once, rather than the symptom repeatedly.
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