Heat is money, and in an uninsulated home a quarter of it escapes straight through the roof. Insulation is unglamorous, invisible and — pound for pound — the best investment most homeowners can make. This home insulation guide explains the main types, what they typically cost, and the order in which to tackle them so each upgrade pays back as fast as possible.
Loft Insulation: Start at the Top
The loft is the first place to insulate because it is cheap, easy and makes the biggest difference. The recommended depth for mineral wool blanket insulation is around 270mm; many older homes have half that or less, and topping up is a job a confident DIYer can do in a weekend (wear a mask and gloves, and lay boards if you use the loft for storage). Typical costs run from a few hundred pounds for materials done yourself to around a thousand or more fitted, and the saving on heating bills is usually measured in hundreds per year — a payback of just a few winters.
Wall Insulation: Cavity vs Solid
Homes built from the 1920s onwards usually have cavity walls — two layers with a gap that can be filled with insulation by a specialist installer drilling small holes from outside. It is one of the best-value upgrades there is, typically costing in the low four figures for a typical house and cutting heat loss through walls substantially. Older solid-wall homes need internal or external wall insulation instead — a bigger, more disruptive job that costs significantly more, but which also transforms how the house feels. If you are already renovating a room, internal insulation added then is far cheaper than doing it standalone; see our breakdown of home renovation costs for how to plan it into a budget.
Floor Insulation and Draught-Proofing
Suspended timber floors leak heat and draughts. Insulation fitted between the joists from below — or rigid boards laid under a new floor finish — makes ground-floor rooms noticeably warmer underfoot. But before spending on floors, do the cheapest job in this entire guide: draught-proofing. Foam tape around window frames, a brush strip on the front door, covers on keyholes and letterboxes, and sealant on skirting gaps can cost under £50 in total and stop the cold air that makes even a heated room feel chilly.
Pipes, Tanks and Radiators
Small jobs, real returns: foam lagging on hot water pipes, a jacket on the hot water cylinder, and reflective panels behind radiators on external walls (which bounce heat back into the room instead of into the wall). Each costs very little, takes under an hour, and belongs on the same weekend list as the other quick wins in our energy saving tips.
Windows: The Honest Options
Single-glazed windows are a major source of heat loss, but full replacement is expensive. Heavy, lined curtains closed at dusk, secondary glazing panels, and even well-fitted window film all reduce heat loss and condensation at a fraction of the cost. When you do replace windows, modern double or triple glazing with a good energy rating pays back in comfort long before it pays back in cash — treat it as a comfort and renovation decision, not purely a savings one.
What Order Should You Do It In?
For most homes: loft first, draught-proofing second, cavity walls third, then pipes and tanks, floors, and windows last. That order follows a simple rule — cheapest and most effective first. Check whether grants or local schemes can help with costs before you book anything, as support for insulation appears regularly and can cover a large share of the bill for eligible households.
The Bottom Line
Good home insulation is not one big project; it is a series of small, sensible ones. Start at the top of the house, seal the draughts, and work down the list as budget allows. Your home will feel warmer this winter — and every winter after. Find more practical guides in our home improvement ideas.
