I'm having two doorway sized gaps knocked in a stone and breezeblock wall between two houses. The builder I got in to quote said that building standards would specify the size lintel they want. Building standards want me to put the lintel spec in the warrant application. (To quote: " load calculations and a span table for the lintels should be sufficient.") Who should I get to calculate the load for me? Get a builder that knows what he's talking about? A structural engineer? An architect? Someone else? Is this something that can be done without a site visit? I've looked at SE's locally and they all seem to do only big industrial stuff. (I'm in NE Scotland) I've looked at how the calcs work and it's not something I fancy trying to do myself. thanks in advance.
If it's just a standard doorway then a basic lintel will do (PROVIDED THERE ARE NO ODD LOADS) In this case a decent builders merchant would guide you as would a decent builder so I'd be a bit dubious about the one you have. Go for option 1