If your house was built after the 1920’s it is likely to have cavity walls. Older houses are more likely to have solid walls
If you can see the brickwork on the outside of the house, look at the pattern of the bricks. If your home has cavity walls, the bricks will usually have a regular pattern.
If your home has solid walls, the bricks will have an alternating pattern
If the brickwork has been covered, you can also tell by measuring the width of the wall. Go to a window or door on one of your external walls. If a brick wall is more than 260mm thick then it probably has a cavity; a narrower wall is probably solid. Stone walls can be thicker still but are usually solid.
If your house was built in the last ten years or so, its walls are probably insulated already. To find out whether they are:
Ask a us to come out and do a boroscope inspection (free of charge). We will drill a small hole in your external wall to see if your walls are hollow or filled.