First thing, mark a horizontal line around the room at the desired dado height. Use a spirit level to get the line perfectly level. Decide on a size and profile that you want to use—there are various sizes and patterns available. Starting at a suitable point, mark off the dado to be cut while noting at which direction the miter needs to be cut. Use a 10-inch saw and miter block to cut. Smooth down any rough edges with glass paper and now you can try the dado for size.
Now position another piece of dado to cut the external 90 degree angle. Again, mark the position of the miter cut while noting the direction. Cut to size as you did before using the 10-inch saw. Now try the two pieces of dado together checking the accuracy of the miter. As with the bath panel, it’s a good idea to at least start the pins or nails in the dado. We’re actually fixing the dado up with wallboard adhesive. Once this is dry, the pins can be removed.
Line up the dado with the pencil line and knock the pins into the wall. The second piece can be fitted in exactly the same way. Unlike external miters, internal angles are tackled somewhat differently. One of the lengths is cut straight into the corner and now you can cut a miter into another length of timber and using a coping saw, cut around the profile of the miter. After that, measure the length that the dado needs to be cut to and cut it.
This can be now knocked into place and fixed. The internal angle is now complete! The reason the internal angle is cut and fixed this way is because it allows for any movement, that’s to say any shrinkage or expansion in the timber.
Work your way around the room until the entire dado is done. If you’re interested in skirting board, it’s fixed in exactly the same way as the dado except that it is advisable to drill, plug, and screw the walls.