The message
from "Mara" contains these words:

what reinforcing method should be used to bridge a 5.5 ft wide 4.5 ft high
opening through a ground floor, concrete block, load-bearing wall in a 2
storey building which has a concrete ceiling/floor between the two levels?
Our current builder has installed a reinforced concrete lintel turned
on its
side with approximately 6 inches of lintel beyond the opening on either
side, but another builder has just told us that this is not sufficient
support and should be replaced as it is potentially dangerous. Who do we
believe?? and if this is wrong, what is best to use for the job??

If it is a proprietary lintel it should be up to the job if used
properly but turning it on its side suggests it hasn't been used
properly.

No doubt these days there are guidelines that I am not familiar with but
I wouldn't have thought that a 6 inch long seat was any cause for alarm.

Is your builder working from plans already agreed with the local BCO or
is he working under a building notice? Either way the BCO has the final
say.

--
Roger Chapman