Wind loading as per BRE489

sambotc · Jun 28, 2012

I know this has been covered before but is anyone here still doing this themselves?

F=qs x Cp net X Ca x A ref

2 x 980 x 1650 panels = 3.3m2

Qs = 1243 (take from key zone chart in bre495)

Pp net = -0.7 & 1.0

Ca = 1.0 (as per recommendations)

A ref = 3.3m2

uplift = -2871.33N

downwards = 4,101.9N

So my 2 panels are on 2 rails with 3 hooks per rail or 6 hooks in total.

Do I divide the above by 6 and then find a suitable rook hook? Where does the panel details come into all of this?

Thanks in advance

Gavin A · Jun 28, 2012

We've never done it.

I took one look at those calcs, compared it to the schuco mounting guide and just decided it was simplest to just assume that each job would be the worst case scenario of wind and snow loading given in the guide and install on that basis, given that this also means the weight is better spread across all the rafters anyway vs using the maximum possible distance between brackets.

That way we can never have a situation where we've misjudged the wind / snow loading situation and mounted it using the wrong kit / with too wide spacings etc.

I will sometimes adjust this if there's a good reason for needing to reconsider on a particular job, but I just do this based on the Schuco mounting guide, as they've obviously already done the calculations to produce those figures, and we're then also following the manufacturers instructions, which is another requirement really.

eta - basically, why make life hard for yourself if someone's already done the hard work and you'd just be doubling up the effort.

sambotc · Jun 28, 2012

Didn't even know such a guide existed so will look for that now. Presumably it is only applicable to their products, do you always use the schuco kit or do the other manufacturers have similar guides for their products.

Thank for that i'll take a look now.