Structural Engineers Reports?!

[chrissolar]

Hi all,

Just wondering what you do regarding Structural engineers reports, seems a bit of a grey area and id be interested to see if you guys get reports and if so are they remote or onsite visits? We only install on domestics and none are very old ie old cottages or farms, to be honest the majority are 1960s plus

Thanks Chris

 

[chrissolar]

Hi still no replies on this ? Can anyone help ?

 

[Gavin A]

We do structural surveys ourselves, then email them for a desktop assessment (calcs) to a structural engineer - not sure if you can get pm's, but I can send you our SEs details.

Napit wanted us to get reports for every job, but tbh we won't do it where we've already done several with the same roof structure dimensions - eg trussed roofs with 70x38mm rafters our SE always makes us double up the rafters we mount to, so we may as well just do that on those installations rather than paying each time for someone to tell us the exact same thing.

If in any doubt get a report done, if you'#re not very experience then get them done on every job until you are - better that than risking it.

 

[jason121]

Is the extra rafters to strengthen the roof or for the fixings ?

 

[chrissolar]

thanks Gavin A appreciate your reply , on trussed roofs what timber do you use to double up the rafters as I know there are different grades? If you could send me a pm that would be great .
Just seems another loop to jump however i do understand why it is important especially as we could potentially have another harsh winter!
Thanks Again

 

[Gavin A]

Is the extra rafters to strengthen the roof or for the fixings ?

bit of both, mainly the roof due to concerns about the point loading on such thin rafters - not from the panels themselves, but because it transfers all the wind and snow loading through those points rather than it being spread evenly across the rafters. These roofs tend to be very close to the loading limits apparently, which you can often actually feel in the roof as it flexes below you when mounting, so we'd always done something to strengthen those roofs even before getting an SE involved.

It allows us also to only mount to every other rafter using rails that can cope with the 1200mm span, so doesn't really add much time or cost to the install vs the alternative of mounting to every rafter in order to spread the loading... or the other alternative of risking a monster insurance claim and negligence law suit for just chancing it.

I have had another SE say it should be ok without, so it's probably a borderline decision, but better safe than sorry eh

 

[Gavin A]

thanks Gavin A appreciate your reply , on trussed roofs what timber do you use to double up the rafters as I know there are different grades? If you could send me a pm that would be great .
Just seems another loop to jump however i do understand why it is important especially as we could potentially have another harsh winter!
Thanks Again

just bog standard C16 35/38 x 70mm, can even be cut in the middle as long as it is as long as the span between each support (diagonal cut, bolted back together).

tbh smaller than that would probably be ok as you're not doubling the loading, but it's probably only a couple of quid difference and less likely to split than something thinner.

 

[chrissolar]

Thanks Gavin A that helps can i just ask a question ive been looking tonight at building regs are we covered under part a as we are using a CPS under MCS ?

 

[Worcester]

See reply under your other thread...

 

[chrissolar]

Gavin/ Worcester,

When strengthening the roof have you ever had to submit a buildings reg application prior to install ??
Chris

 

[Gavin A]

Gavin/ Worcester,

When strengthening the roof have you ever had to submit a buildings reg application prior to install ??
Chris

not unless you're in scotland where the system is different, and building warrants are needed in advance for some work.

You need to speak to your CPS / MCS provider, but your MCS certification and CPS scheme accreditation combined should cover you, as long as you can demonstrate that you either are competent in this field, or have obtained advice from someone who is - ie a structural engineer.

I have had a building control officer apparently being a bit put out that we'd not sought their go ahead for a commercial installation once, but nothing came of it, and as far as I know we're covered for it.... would be interested in Worcesters take on that though as he does a lot more commercial than us.

 

[chrissolar]

Thanks for your reply Gavin, it seems to be a very grey area . What annoys me the most is that you are trying your ultimate best to keep to the regs yet a lot dont even do the calcs on any installs!
Thank again guys for all your help its been much appreciated!!

 

[Worcester]

We always have fully documented third party structural surveys and engineers reports on commercial installs (they usually run to between 24 and 30 pages) , whether it's a farmers barn or a retail store. The potential professional liability is far too great for us (me) to carry on those.

Ironically we find building control far less concerned on commercial properties than domestic - perhaps because in most cases they are not as well qualified as those people designing / specifying and building them when new - just like the electrical instillation side where they have little jurisdiction, that comes under the far more onerous Electricity At Work Act. We still send Building Control post install notification though re the panels through our certifying body.

 

[chrissolar]

So worcester if you needed to strengthen the roof and you did it in accordance with the structural engineers report you dont pre notify building control as you can do it after the install under the CPS ?

 

[Worcester]

In short, yes - if you are competent, and that has nothing to do with your CPS.

In practice it depends upon how much strengthening, and effectively what proportion of the cost of the project it is. A new roof needs full building control, a loft conversion with structural alterations, needs full building control, they key is in the CPS wording: "Any building works which is necessary" however even under a CPS you need to prove to your certifying body that you are competent to carry out the type of works that you are doing, and will need the appropriate insurances to cover it. Bear in mind that your work can also be post install inspected by the BC.

If you look at what is covered under a CPS / exempt from BC, you find that almost all structural alterations need BC approval. So if we were strengthening because fundamentally the roof was weak, then I would involve building control in advance. If we aren't competent to carry out the works required by the Structural Engineer, then I'd involve BC in advance, and appoint a specialist subcontractor. The project isn't going to kick off tomorrow in that instance any way so there is no problem with timescales.

It's down to your competence if that makes sense