Loft & 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.
Why 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 guideWhy is there condensation in my loft?
Condensation in a loft happens when warm, moist air from the house below leaks up into the cold loft space and condenses on the cold roof structure — often made worse by inadequate loft ventilation. Left unchecked it dampens timbers and insulation and can grow mould. The cure is to stop the moist air getting up there and to keep the loft properly ventilated.
Read the guideIs my loft insulation good enough?
Loft insulation can look complete from the hatch and still under-perform badly. Depth is only part of the story: gaps at the joists, compression under boarding, insulation pulled away from the eaves and air leakage through the ceiling all leave it working far below its potential. Judging whether yours is good enough means looking past the surface to coverage, continuity and air-sealing.
Read the guideWhy is my loft room too hot in summer?
Loft and top-floor rooms often overheat in summer because the roof absorbs intense solar heat, thin or gappy insulation lets it through, and the room has little ability to lose that heat or keep it out. Overheating is the summer counterpart of winter heat loss — and the same fabric weaknesses usually cause both. Controlling it is about insulation, shading, ventilation and thermal mass.
Read the guideWhy is my flat roof getting condensation?
Condensation in a flat roof is usually interstitial condensation: warm, moist air from inside the home rises, reaches the cold underside of the roof deck, and condenses there — soaking the insulation and timber from within, often before any sign shows on the ceiling. It is rarely a leak from above; it is moisture from inside meeting a cold surface within the construction. The cure depends on the roof type, but it always comes down to keeping warm moist air away from the cold deck and getting the build-up right.
Read the guideWhy is my loft conversion cold in winter and hot in summer?
A loft conversion that is cold in winter and hot in summer is suffering from the same root cause in both seasons: the roof is the thinnest, most exposed surface in the house, and a room built into it sits right behind that fabric. If the roof slopes, dwarf walls and flat ceiling are not well insulated, airtight and free of thermal bridges, the room loses heat fast in winter and gains it fast in summer — and poor ventilation makes the summer heat worse. The fix is to treat the roof as a high-performance element, not an afterthought.
Read the guideWhy is my loft damp or musty?
A damp, musty loft is usually a condensation and ventilation problem, not a leaking roof: moist air from the house below rises through gaps in the ceiling into the cold loft, condenses on the cold underside of the roof and on the timbers, and — if the loft is poorly ventilated — that moisture lingers, dampening the insulation and timber and producing the characteristic musty smell. The cure is to stop the moist air getting up there and to keep the loft well ventilated, rather than assuming the roof has failed.
Read the guideShould I board my loft for storage, and will it cause problems?
Boarding a loft for storage is fine and worthwhile, but only if it is done correctly — and the common mistake of laying boards straight onto the joists causes real problems. Modern loft insulation is usually deeper than the joists, so boarding directly onto them squashes the insulation, drastically reducing its performance, and can trap moisture and cause condensation. The right way is 'raised boarding', which lifts the boards above full-depth insulation on spacers, giving you storage without sacrificing warmth or risking damp.
Read the guideIs 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 guideShould I insulate between or above the rafters?
When you are insulating a sloping roof — for a loft conversion or a room-in-roof — the choice between insulating between the rafters, above them, below them, or a combination is not just about cost and headroom; it determines how warm and how condensation-safe the roof will be. Each option has consequences for the depth of insulation you can achieve, the ceiling height you lose, the continuity of the insulation, and crucially how the roof manages moisture. Getting it wrong can leave cold bridges through the rafters or trap moisture against the timber. The right choice depends on the roof construction, the headroom available and the moisture strategy — which is best decided from the building physics, not a single rule.
Read the guideShould I repair or replace my flat roof?
Deciding whether to repair or replace a flat roof is not just about the leak in front of you — it depends on the condition and age of the covering, how the roof is insulated, and whether it is a 'cold deck' or 'warm deck' construction, because those determine both how long a repair will last and whether the roof is at risk of hidden condensation. A patch repair can be sensible for an isolated fault in an otherwise sound roof, but where the covering is near the end of its life, or the build-up is a cold deck prone to condensation and rot, replacement that also corrects the insulation and ventilation is usually the better value. The right call comes from assessing the whole construction, not just the visible defect.
Read the guideShould I get room-in-roof insulation?
Room-in-roof insulation — insulating the sloping ceilings, dwarf walls and flat ceiling of a converted loft or attic room — is usually worth it if the room is cold, hot in summer or expensive to heat, because these rooms have a lot of roof area exposed on all sides and are often poorly insulated. But it only delivers if it is detailed continuously: the insulation must be unbroken across the slopes, the dwarf walls, the little 'eaves' cupboards and the floor of the space behind them, with no gaps where heat can bypass it. Patchy room-in-roof insulation is one of the most common reasons a loft room stays cold despite 'being insulated'.
Read the guideWhy is my loft insulation not working?
If your loft is insulated but the house still loses heat upwards, the insulation is usually being undermined rather than absent — it is gapped, compressed, too thin, or bypassed by air leakage. Loft insulation only works when it is an unbroken, full-depth layer and when air cannot flow around or through it; in practice, missed areas, boards laid straight onto it, gaps around the hatch, downlighters and service penetrations, and air leaking up from the house below all let heat escape. The result is a loft that feels insulated but performs poorly. The fix is to find the weaknesses and restore a continuous, airtight insulated layer.
Read the guideWhy are the ceilings upstairs cold?
A cold upstairs ceiling is a direct sign that heat is escaping through it into the loft or roof above — usually because the loft insulation over that ceiling is missing, thin, gapped or bypassed by air leakage. Because heat rises, the ceilings below a loft are a major route for heat to leave the house, and any weakness in the insulation above shows up as a cold ceiling, sometimes with condensation or a 'ghosting' pattern of marks along the cold joists. The fix lies above the ceiling, in the loft: restoring continuous, full-depth insulation and sealing the air paths so the ceiling stays warm.
Read the guide