Assuming you're in a house with brick external walls: If the bricks are all lying length wise (so no short sides showing) this is a clear sign of cavity walls. Houses that are built from solid brick (double layers of brick) will have walls showing a few long sides of the bricks, then a short side, then a few long sides, etc. See this page for examples:
www.thinksulation.co.uk
Checking whether the cavities have been filled is harder. If you have windows replaced you will be able to view into the cavity to see for yourself. The filling is usually a yellowy material that will be noticeably different from the solid brick or concrete either side. You can also try to peer down the cavity from your loft, this may involve crawling out over ceiling joists and trying to angle a mirror and torch so that you can see under the eaves and down the cavity. If you ever need to drill through the walls, a small amount of material may spill out or appear as residue on the drill bit. Building work that knocks through outside walls may also let you see one way or another.
But the easiest thing to do is usually to get a survey done (no obligation) by a reputable insulation company. The professionals drill a small hole into the outside wall, and use something called a boroscope to peek into the wall. The boroscope is like a tiny periscope with a bright light on it. You can look through the boroscope for yourself and verify whether there is any insulation in there.
www.thinksulation.co.uk
Checking whether the cavities have been filled is harder. If you have windows replaced you will be able to view into the cavity to see for yourself. The filling is usually a yellowy material that will be noticeably different from the solid brick or concrete either side. You can also try to peer down the cavity from your loft, this may involve crawling out over ceiling joists and trying to angle a mirror and torch so that you can see under the eaves and down the cavity. If you ever need to drill through the walls, a small amount of material may spill out or appear as residue on the drill bit. Building work that knocks through outside walls may also let you see one way or another.
But the easiest thing to do is usually to get a survey done (no obligation) by a reputable insulation company. The professionals drill a small hole into the outside wall, and use something called a boroscope to peek into the wall. The boroscope is like a tiny periscope with a bright light on it. You can look through the boroscope for yourself and verify whether there is any insulation in there.
