If you want to install a door or window in a wall made of breeze blocks, you will need to cut a hole through the wall first. Cutting a hole through a breeze block wall is a messy and time consuming project, and it requires safety equipment such as ear plugs, a respirator and eye protection. You should allow at least a weekend for this project.
Obtain a building permit from your local building authority. If you do not obtain the necessary permit, a building inspector may impose fines or force you to suspend work. When applying for a permit, it is a good idea to have an inspector verify that you are not cutting through a load-bearing wall.
Draw the outline of your opening with a straight edge and a piece of chalk. Use a carpenter's level to make sure all lines are level. Repeat this process on the other side of the wall, making sure the outline lines up on both sides. You can ensure that they line up by measuring from a fixed point, such as the floor or a corner.
Put on safety goggles, gloves and a respirator mask, and put in earplugs. Drill a hole at each corner of the opening outline with a 5/8-inch masonry bit. Repeat the process on the other side of the wall.
Choose which side you will start with, and punch a hole in the other side with a sledgehammer, which will help draw concrete dust away from you as you cut through the wall.
Insert the masonry saw blade in one of the holes, and cut along the line. Cut through the remaining lines until you have created the opening. Move to the other side and cut along the lines.
You may need to brace the opening with an angle iron before framing a door or window. Bracing can help prevent the wall from cracking. Do not attempt this task unless you have significant building knowledge and experience. This is a difficult project that should not be attempted by beginners. Improper placement of the opening can weaken a breeze block wall and cause the structure to collapse.