When planning on adding a doorway or window to a brick wall, you need to make sure that the wall does not lose its strength. Window and door frames are not designed to carry heavy loads so you should always support the opening with a lintel. Even in a non load-bearing wall, unsupported bricks above the opening can cause major problems. In load-bearing walls, the problems could be disastrous.
Choosing a Lintel
The type of lintel you need will depend on the amount of weight that will be pressing down on it. The lintel will need to be able to resist the combined weight of bricks, upper floors, etc without bending or shearing. You can find more information about the different types of lintel in our Lintel Guide. But is it also a good idea to speak to a structural engineer or experienced builder for wide spans. The amount of weight the lintel will need to support varies greatly depending on where the opening will be, and working out the exact amount is not an easy or lightly undertaken task. Again, if in the slightest doubt, always check with a professional!
When you need to support a wall
As we said before, it is always a good idea to support the brick wall above any new opening, but for openings less than 1m in a well bonded, non load-bearing wall, you can actually do without any supporting lintel. In such a narrow opening, the self-corbelling effect of the brickwork means that only a few bricks are actually being supported on the door or window frame. As the width of the opening increases, so does the pressure being exerted. Check the condition of the wall to see if it is bonded well and in good condition.
If you are planning to create an opening in a load-bearing wall such as an external wall, you will need to erect temporary supports before you start to remove bricks. You can hire adjustable steel props from hire shops on a daily or weekly rate. You will also need a length of at least 150mm x 100mm wood (called a Needle in this situation) and a couple of scaffolding boards to spread the weight of the bottom of the props.
Mark out your doorway or window opening and then move up 2 course of bricks to above where the lintel will be. Knock out one brick and slide the needle through the hole. Support either end of the needle with the adjustable props (remembering to place the scaffolding boards underneath them). Openings wider than about 1m will require 2 Needles and 4 props, spaced out evenly.