Do I Already Have Insulation?
The fact you’re reading this site suggests your house may be cold and therefore unlikely to be well-insulated. However, unless you installed it yourself it’s often difficult to determine the extent and type of any existing insulation.
If you bought the property within the last 10 years it’s likely it was sold with an EPC (Energy Performance Certificate) which graded it with an Energy Efficiency Rating from A (the best) to G (the worst). If you didn’t pay attention at the time, check if the property is still listed online – if so, the EPC may be shown. However, EPCs don’t tell the full story. The assessment process is a simple checklist and assessors often don’t even visit the property. There is also evidence that actual energy use varies dramatically from that predicted by the EPC system. EPCs can be a useful starting point, but we’d be wary of putting too much faith in them.
EPC ratings give you a “current” and “potential” score, indicating the potential improvements you could make with insulation and other energy-saving measures.
UK housing can be characterised quite reliably based on the age of the property. Unless you know any better, the wall construction is likely to follow the bands below. You can also distinguish solid from cavity walls by checking the brick pattern. Bear in mind that any extensions may have a different form of construction to the original house.
Pre-1920 - solid brick wall 225mm thick (no insulation)
1900-1995 - unfilled cavity 270-300mm thick (usually constructed without insulation, but may already have been upgraded)
1995-present - filled cavity 300mm+ thick (insulated)
Checking for loft insulation is usually simple. If you have an accessible attic just pop your head up and have a look. Loft insulation normally takes the form of “wool” type insulation rolls laid on the attic floor, leaving the loft space unheated. Loft insulation is also sometimes attached to the underside of the roof, meaning the loft space is heated.
Floor insulation is less common and it's usually fair to assume older houses don't have any unless you know otherwise. If you have an accessible basement or under-floor void you may be able to look beneath a suspended floor to check for insulation but otherwise you may need to raise a floorboard which can be a disruptive job if you have carpet or other finishes on top. Failing that, you may be able to sense whether your floor is insulated by how it feels to the touch in cold weather. If the floor is cold while the heating is on it could probably benefit from some insulation.
The final element of your home to check is the openings – windows and external doors. Historically windows featured single-glazing. These windows generally underperform from an insulation perspective and are often poorly sealed around the edges, allowing cold air into the room. The Victorians counteracted these problems by covering windows with thick full-length curtains. These provided an effective layer of insulation, but most modern houses have removed these curtains to avoid obstructing radiators which are often positioned beneath windows.