I have just stumbled accross the ELECSA stance on wind loading.
Elecsa - Adding Loadings to a Roof
It basically says "Approved Document A stipulates requirements for roof loadings with respect to weight of loads imposed and wind loading". I would say they should be carried out on every install.
In full it says (my bold font):
'Approved Document A stipulates requirements for roof loadings with respect to weight of loads imposed and wind loading.
Both of these issues will need to be considered by contractors installing solar photovoltaic panels. In many cases this may involve structural checks and/or calculations being undertaken. Decisions involving these issues will form part of Microgeneration Certification Scheme (MCS) assessment so must be documented. '
Now, while I agree that it is no small matter, ELECSA (who we are currently using) do not say that you must undertake calculations; only that you have to justify your decision. I have asked ELECSA to clarify this in relation to MIS 3002, issue 2.1, which says in section 4.4.4 (again my bold text):
'The contractor shall ensure that the roof structure is capable of withstanding the
loads (static and wind loads) that will be imposed by the PV modules and their
mounting arrangements.
If there is any doubt, a structural engineer must be
consulted. Guidance on the mechanical installation and wind loads are given in
BRE Digests 495 and 489 or BS 6399.'
So, if I read things correctly, currently, I could say that I have considered the roof's integrity and decided that my mounting system and modules are acceptable and that would be enough to satisfy the MCS inspector (at least for ELECSA) as long as it's documented. This seems vague and should be clarified. Surely, it should be that we either do need to have calcs done or not and the smart money, as Bryan would no doubt agree, would be on having them done.
We too were told to use common sense on our 2399 course and inform domestic customers if we thought a survey should be done, taking care not to offer any advice on structural matters which we are unqualified to do. The additional £250.00 for a structural survey cuts into margins but if we all have to do it, there isn't an unfair price advantage for those who do not have them done every time.
Scottish Borders Council Building Control, for example, require a survey with all PV installations.
It does feel though, that more and more burdens are being placed on installers all the time. EPCs, FiT chaos, Green Deal etc........
