Hi I want to increase the width of a doorway. The wall is internal, concrete block partly supporting a loft floor above. The problem is at present the existing concrete lintel needs to be either replaced or the load 600-800mm of blockwork above plus some weight of the floor supported by in effect extending the length of the lintel by 300-400mm. I thought that maybe a mild steel flat 15mm or more thick could be inserted into the wall extending below the end of the existing lintel to partly occupy the pad area.
You're going to have to put in a new lintel to the correct length so it bears 150mm on each side. May be able to remove a full block and cut the rest in half, if the joints are plumb.
Another RSJ post Depending on the age of your house you may find that the loft floor could be part of your roof structure and be holding quite a weight I would post some pictures
Hi CGN Thanks the doorway is tight to another wall. The drawing below shows that the floor joists approx 55x 170 are joined above the wall. So I would bolt together those joists affected which at presetn are nailed. There is another wall about a metre away that is also supporting the floor. The runner/binder has struts that are joined to the purlin