I have had my steels sized for my extension and had something raised by the SE as to weather or not i want to proceed with a larger deflection or stiffen up with an additional column. The calcs work both ways and i imagine they will prefer another column as it means belt and braces for them but the scenario to our preferred (no additional column ruining our open plan vibe) method is as below;
Steel in question will be holding the upper level or pebbledashed solid wall masonry, 1st floor roof structure etc With the assumed loads the calcs have spat out an expected deflection of 13mm over a 9m span. The SE has warned that such deflection may well result in cracks to the wall above almost straight away as the load settles after which movement should be minimal from live loads. He has identified a window in the centre of the upper floor where he anticipates cracks from the lower corners down as it settles following the steel install. He has also stated that this is the risk and not a forgone conclusion. There may be no cracking at all.
Has anyone worked with similar deflections / scenario. I guess the risk is a lot down to the quality of the install and level of packing etc? Is the worst case scenario after the settlement that the pebbledash upstairs has to be removed and then re plastered with reinforcement mesh or fibrous render to repair and prevent the cracks resurfacing at a later date.
For the record i am not having anything to do with the install it will all be done by professionals.
Steel in question will be holding the upper level or pebbledashed solid wall masonry, 1st floor roof structure etc With the assumed loads the calcs have spat out an expected deflection of 13mm over a 9m span. The SE has warned that such deflection may well result in cracks to the wall above almost straight away as the load settles after which movement should be minimal from live loads. He has identified a window in the centre of the upper floor where he anticipates cracks from the lower corners down as it settles following the steel install. He has also stated that this is the risk and not a forgone conclusion. There may be no cracking at all.
Has anyone worked with similar deflections / scenario. I guess the risk is a lot down to the quality of the install and level of packing etc? Is the worst case scenario after the settlement that the pebbledash upstairs has to be removed and then re plastered with reinforcement mesh or fibrous render to repair and prevent the cracks resurfacing at a later date.
For the record i am not having anything to do with the install it will all be done by professionals.