I'm building an extension onto an old house with a 600mm thick rubble stone wall. Two RSJs are being let into the wall and spanning a 3800mm opening to the new outside wall. The steels will support a standard cavity wall above, ~1.8m high and with a roof above that resting onto the wall (ie the ridge is parallel to the wall).
On my plans the RSJs are shown as 4000mm long and the structural engineer also saw the plans and calculated for 4m beams - so this is what I bought. I have excavated into the rubble stone wall removing face stones and some of the harting stone behind to create a cavity ~250mm into the wall & ~400mm wide. I have filled this with concrete ~100mm deep, pushed deeply into any spaces between the harting stone and with 2 pieces of reinforcing steel embedded.
So far so good. However, when I offered up the beam I realised that it is only long enough for a 100mm bearing at each end. This seems OK at the end bearing onto a 300mm piece of lintel as a padstone onto a thermalite wall but I am concerned that it is not enough into a rubble stone wall - or will the concrete pad adequately transfer the load into the whole wall?
Unfortunately my structural engineer is away for the whole month and his drawings do not specify a bearing distance. My building inspector is also away for a week.
Can anyone offer some advice and/or solutions if an adjustment is required.
On my plans the RSJs are shown as 4000mm long and the structural engineer also saw the plans and calculated for 4m beams - so this is what I bought. I have excavated into the rubble stone wall removing face stones and some of the harting stone behind to create a cavity ~250mm into the wall & ~400mm wide. I have filled this with concrete ~100mm deep, pushed deeply into any spaces between the harting stone and with 2 pieces of reinforcing steel embedded.
So far so good. However, when I offered up the beam I realised that it is only long enough for a 100mm bearing at each end. This seems OK at the end bearing onto a 300mm piece of lintel as a padstone onto a thermalite wall but I am concerned that it is not enough into a rubble stone wall - or will the concrete pad adequately transfer the load into the whole wall?
Unfortunately my structural engineer is away for the whole month and his drawings do not specify a bearing distance. My building inspector is also away for a week.
Can anyone offer some advice and/or solutions if an adjustment is required.
