The techniques for removing a wall between two rooms to turn them into one large, through-room are essentially the same as those needed to make a new doorway or a pass-through but on a larger scale.
However, if the wall is load-bearing much more of the structure of the house will be at risk from collapse, so you must take particular care to ensure that you provide temporary support for any loads carried by the wall before you start to remove it and, just as importantly, that there is adequate permanent support when finished. This means finding out if the floor joists of the room above rest upon it and also if the same wall continues upwards to form a dividing wall on the floor above, for example. This is where you may find it necessary to check first with a professional contractor.
If there is no continuation wall above and the floor joists simply rest on top of the wall, you can remove it completely, using stout wood planks and adjustable props to bear the weight of the joists from below while the supporting beam is set in place. However, if there is a continuation of the wall, you must leave a margin at ceiling level to allow for the insertion of wooden needles at 3ft intervals.
Ceiling joists at right-angles to the wall must be supported by props under planks, spaced at 3ft intervals.
As already mentioned, it is normal for wide spans c: this sort to be supported by a steel beam but the beams can be very heavy and you might find it easier to use a steel angle instead. This will be lighter and only good for shorter spans depending on the size.
You could also use a reinforced concrete beam or a pre-stressed concrete beam (the lighter of the two). But both will only cope with spans of 10ft so they are only really suitable for narrow rooms.
In any event you may have to gain approval from your local Building Inspector for the way you intend to tackle the job, and this includes your choice beam. If you are not sure of the best type to us always take professional advice or check with your local Building Code.
Whatever type of beam you choose, it will still be heavy and you will need helpers to lift it into position. You will also need enough extra adjustable props to support it at 3ft intervals while you mortar it in place.
The ends of the beam must rest on bearings that are 6 to 9in wide, and because of the heavy loads carried it is usual to support the beam on concrete “padstones” (concrete blocks are ideal). This helps to spread the load evenly across the bearings.
As an alternative to a concrete padstone, you could use a heavy steel plate, or one or two courses of a strong brick; normal facing bricks would crumble under the weight.
The bearings must have substantial support below them to cope with the loads imposed on them from above and the way you arrange this support can take several forms. It is something that the Building Inspector will pay particular attention to.
A common method of supplying support for the bearings is to build brick columns or piers at each end of the span, toothing every second course into the brickwork of the adjoining walls.
Such piers must have substantial foundations of their own and this usually means digging down into the ground below, putting in a layer of well compacted gravel and pouring a thick layer of concrete on top. The exact requirements will be specified by your local Code which should be checked at the beginning.
Once the foundation has hardened. you can begin building the footings of the piers, remembering to set flashing in one of the mortar joints level with the flashing of the existing walls. This should be just below the level of the floor. If the floor is solid concrete, it should have a damp-proof membrane and you must take steps to see that your new flashing and the membrane are sealed together.
In some cases you may be allowed to use a set of engineering bricks as a flashing.
When the pier has been built, it is topped with mortar and the padstone set in place and leveled.
If the wall you are breaking through is a solid Sth thick wall, you may be able to leave short stubs of the wall projecting into the room to act as piers for the ends of the beam. However, you will need to check with your local Building Code to be satisfied that the original wall has substantial enough foundation. Remember, the weight carried by the wall, which was spread evenly along the length of its foundations on removal of the wall, be concentrated on two much smaller patches.
The mortar of the old wall should be in good condition, too. If it is loose or crumbly. rake out all the joints and repoint them with fresh mortar.