Before making a door opening in an internal wall, check to see whether the wall to be removed is load-bearing or not. If it terminates at ceiling level, the wall can be removed without installing a steel beam or RSJ (rolled steel joist).
As this sort of alteration is structural, detailed drawings will have to be submitted to the local authority for approval. This entails drawing a metric plan to a 1:10 scale, with a section through the wall that has been removed, showing the beam — and its fire protection — in position. The Local Authority will tell you of any particular details it requires.
If the wall is load-bearing, proceed as follows:
1 Determine the beam design and size by consulting a specialist; there are many factors to consider in determining the stress loading. If possible, keep the thickness of the beam the same as that of the wall above the beam. A brick pier may have to be provided at the ends of the beam, to spread the Load.
2 Mark the size of the opening required on the wall above the future position of the new beam, making this large enough to take 4 in. by 4 in. (or 10 by 10 cm) pieces of timber, called “needles”. These holes have to be at about 2 ft (or 60 cm) centres.
3 Position timbers through the holes and place into position the metal or timber props. To cut down on the props required, another piece of timber, not smaller than 10 cm by 10 cm, could be used to support the load from the pieces of wood passing through the.wall; thus the props could be positioned at 4 ft (or 1 .2 m) centres.
4 If the props are to rest directly on the floorboards, either spread the load by placing a piece of wood under the prop or remove the floorboards and rest the props on to the ground surface. This is only possible if you are working on a ground floor or in a basement. If the ceiling joists above the room in which the wall is being removed are built into the wall, it is sometimes easier to support the ceiling some 2 ft (or 60 cm) on either side of the wall. This gives more space in which to work and eliminates the need for knocking holes through the wall. The beam may then be positioned at a higher level, directly under the ceiling joist.
5 After the props have been placed in position and thoroughly checked, knock out the slot in the wall.
6 Place the beam in position, a job for which you need the help of strong friends. Make sure it is centralised all round.
7 Fill in the space over the beam with brick or slate slips (flat pieces of brick) with a 1:3 mix to ensure that the brickwork above the beam has a solid base to rest on.
8 The wall beneath can then be knocked out. If prior inspection when cutting the slot for the RSJ shows a crumbly brick composition, it may be necessary to form a 1:2:4 concrete pad 6 in. (or 15 cm) thick on the pier ends.
9 After the mortar has set, perhaps after two days, the props can be removed and any holes filled up with pieces of brick bedded in a 1:3 mix.
10 Make good the jambs of the new opening and any holes left in the floor. Finally, finish off with plaster.
Anti-fire. All steel beams that are supporting any part of the structure in a habitable dwelling have to be protected against fire. One way to achieve this is by boxing in with -a in. (or 10 mm) plasterboard or asbestos insulation board screw-fixed to asbestos battens. This will normally give the statutory fire resistance required by the Local Authority.
Arching. A pleasing effect can be achieved by forming an even archway framework in timber, the faces of which can be covered in plasterboard and the underside in in. (or 6 mm) plywood.
The method employed in strengthening a brick wall is to build piers on to the walls. The piers should be bonded into the wall. The type of bonding can take various forms.
Here is the simplest method:
1 Cut out the mortar joint, using a bolster at every third or fourth brick course and simply pushing in half of a galvanized wire brick tie.
2 Mix up a very stiff 1:3 mortar.
3 Dampen the joint with water, using a brush, and then force in the mortar with a small trowel.
4 Repeat this process all the way up the wall to the full height of the pier. Hack out all the joints first so that you do not dislodge any newly inserted brick ties.
5 Once the mortar has dried, you can build the pier. This is fairly simple, as the bricks will be in line with the existing ones. “Block” bond. Another method is to use a “block- bond. Knock out the bottom three courses of bricks the thickness of the pier. Then knock out a further block at the seventh, eighth and ninth courses. Repeat this ratio to the full height of the wall. The method enables the pier to be physically built into the thickness of the existing wall, giving a much stronger support.
“Toothing”. This method involves knocking out alternate bricks the width of the pier instead of three courses at a time.