Making an opening in a load bearing wall is perfect if you want to adapt the living space in your home. The wall you wall you want to demolish however, may be load bearing and supporting masonry above. This may be a brick load or even the floor joists so a few precautions ought to be adhered to. In a typical layout of a dwelling with two reception rooms, rear and front, the rear room joists usually run from the external walls, rest on the intermediate wall dividing dining room and living room, and then another set of timbers would run from the intermediate dividing wall to the front elevation external wall.
Should you find that the wall you want to remove is in fact load bearing then it will need to be supported before any structural adjustments can be undertaken. This will usually be done (domestically) by using acrow props and strong timber needles. Alterations can be made in a similar fashion on larger commercial projects, however, stronger supports may be required by using super props. For this article though, we will assume that any structural alteration is to a domestic dwelling.
Some loads may not be from masonry by the way, they could be from timber partitions above the wall you want to take out. In the same fashion the load must be supported both before and after any alteration is taken out. You ought to make every check to establish what load the wall is carrying.
So OK, you’ve made the opening and the structure has been temporarily supported. This is great at the moment but nobody wants to leave ugly looking steel props in the middle of the room forever so it will be necessary to provide a more permanent support method. This structure will need to be supported by using a concrete or steel lintel which may be of either concrete or steel construction depending on the engineers specifications for the job. A structural engineer will be able to help you choose the right support for the job. Never guess and think you know if you are not entirely sure! Structural engineers are paid to calculate loads and will save you a hell of a lot of money if you get it wrong and calculate incorrectly.
Your local building control officer will want to be informed of any alterations you intend to carry out to ensure all work conforms to current building regulations. You should also be issued with a ‘completion certificate’ when the work has been satisfactorily completed.
Before taking any brickwork away, mark out the opening in the wall that is required. Use a hammer and bolster to remove any plaster on the wall. This way you will know exactly what you are taking away and also ensuring there are no hidden pipe or cables that may cause an obstruction. You will want the new RSJ or concrete or steel lintel to rest on a minimum of 150mm bearings so make provisions for this when marking out. After the structure is propped and secure you can start the opening by using an angle grinder at the openings boundary or by using hammer and bolster.
With most of the work out of the way now, it is time to fit the new RSJ or lintel in place. The RSJ will be fitted onto 150mm minimum bearings with a stiff 3:1 sand and cement mix. Ensure the bearings are sound that the RSJ will sit on and that you have adequate help to lift the new steel RSJ in place. Use trestles with scaffold boards going across as a safe working platform to carry out the operation. Pack up the concrete or steel lintel with slate afterwards to ensure it is tight to the brickwork above.
Leave your support props in until the next day to let the mortar set. Only after this can the props be taken away and in doing so, fill in any holes you made for the props with bricks and point up and slate if required. All you need to do now is make good the plaster work afterwards. Make sure the building control officer has seen all works etc, before re-plastering.