We are having an existing outbuilding rebuilt as the old one was falling down. There are 3 window openings and a sliding door opening. The window openings are 610mm, 1210mm and 1610mm wide, with the door opening at 2810mm.
The builder has brought the catnic lintels (for 100m cavity walls) to site and they are 900mm, 1400mm, 1800mm and 3000mm wide. He's installed the 1400 one above the 1210mm opening, and has partially installed the 3m one above the main door. My concerns are:
These lintels (except for the 900mm) do not give a bearing size of 150 either side. I thought openings below 1200 could be 100mm but not above 1200. Also catnic specify 150mm bearing widths? I'm especially worried about the one for 2.8m wide doors where the opening width should be 2810mm. He's only made the width 1790mm and when quizzed he said he would open it up when the rest of the build was done before installing the door. The lintel seems to have a bearing width of 105mm on one side and 100mm on the other - and it is this side he plans to cut out 20mm to increase the opening width to 2810mm.
The walls are block work with 100mm cavity. I noticed today that on Thursday he had built three courses of blocks above the lintel on inside wall only, and despite having props on site has not bothered to support the lintel. On the outside wall there are no blocks above the lintel over the bearing pads which has caused the lintel to lift clean off the pads on the outer wall side. I could slide a slate through the gap. Also the blockwork on the inside wall above the lintel has cracked along the pointing and the lintel is 8mm lower to the floor in the centre than at the edges.
What should we say to the builder when we see him next?