Condensation typically appears on cold surfaces like windows and external walls, especially in bathrooms and kitchens during winter — it’s caused by moisture in the air hitting a cold surface. Rising damp usually shows as a tide mark on a ground-floor wall up to around one metre high, often with white salt deposits. Penetrating damp follows rainfall patterns and tends to appear in patches on walls or ceilings directly linked to an external defect like a broken gutter, cracked render, or failed pointing.

Current UK guidance recommends a minimum of 270mm of mineral wool insulation in your loft — 100mm between the joists and 170mm laid across them at right angles. Many older homes still have just 100mm or less, which falls well short of modern standards and is costing you on every heating bill. Topping up existing insulation is a quick win and costs very little if you do it yourself.

Yes, and it’s well worth doing — an open chimney is essentially a direct hole to the outside and can account for a significant heat loss in a room. A chimney balloon or draught excluder fitted inside the flue just above the fireplace opening is an easy DIY fix costing around £20–£30. Just make sure it’s clearly labelled so nobody lights a fire with it in place, and remove it if you ever use the chimney again.

In most UK homes with a condensation problem, better ventilation makes the biggest difference — extractor fans in the kitchen and bathroom that actually vent to outside (not just recirculate) remove moisture at source before it can cause problems. Insulation helps by keeping wall surfaces warmer so condensation is less likely to form, but ventilation tackles the root cause. For persistent issues, trickle vents in window frames and positive input ventilation (PIV) units are worth considering.

A standard cold loft is the easy case — a warm roof or room-in-roof is significantly more complex and usually requires rigid insulation boards or spray foam installed by someone who knows what they’re doing. Getting it wrong can cause condensation within the roof structure, leading to timber decay that’s expensive to fix. Get a proper assessment before attempting any insulation work in these situations, as the approach is entirely different to a standard loft.