Structural assessment of roofs for PV - Building control approval

[TMGL]

Thanks again. So far one potential installer has said I don't need a building warrant, another says I do and it will be £350 based on total cost, and a third says it will be less because it is just the part that supports the panels that it should be costed on. It is totally confusing to the consumer and BC.

FitstartIt was the case up until about 2 weeks ago that certain councils (Scottish borders for example) insisted on a building warrant. However the building standards director for Scotland has confirmed that a building warrant is not required for solar pv unless i) strengthening work is to be carried out to the roof or ii) the building is above a certain height (can't remember exact height but normal 2 storey building will be fine).Most pv installations in Scotland will therefore not need a building warrant but your installer should confirm that i) and ii) above do not apply in your case.Hope this helps.

 

[BruceB]

<br><br>Bruce<br> out of interest was the self certification you refer to for the electrical installation? Im assuming it is. Some of them really are confused! Asking for fees when they are not entitled and forgetting to advise when they should be. E.G Part A. <br>Regards,<br>

I started out as electrical with NAPIT, but for a year have been MCS registered with Napit, so the self certification was for everything. Napit have just changed the 'rules' of their scheme which now make it clear in words of few syllables that MCS registered members can self certify under building regulations.
Regards
Bruce

 

[Fitstart]

FitstartIt was the case up until about 2 weeks ago that certain councils (Scottish borders for example) insisted on a building warrant. However the building standards director for Scotland has confirmed that a building warrant is not required for solar pv unless i) strengthening work is to be carried out to the roof or ii) the building is above a certain height (can't remember exact height but normal 2 storey building will be fine).Most pv installations in Scotland will therefore not need a building warrant but your installer should confirm that i) and ii) above do not apply in your case.Hope this helps.

Excellent News! - I shall of course get a structural survey done. Hopefully this information has filtered through to Fife.

 

[mapl_co_uk]

We are structural engineers undertaking these assessments - about 50% of domestic roofs need some form of strengthening to resist not only the weight but the uplift forces generated as wind passes over the panels.

Building Control in England & Wales have recently confirmed that assessments are needed and have guided building control departments accordingly. The MCS accreditation bodies are also starting to ask for evidence of competent structural advice when assessing or annually auditing installers, so that their schemes can be considered CPS and allow self-certification. But if you self certify without site specific checks, you are potentially creating a huge future liability! Put a check from us on file, so you are covered by our insurances if there is a structural problem!

 

[SRE]

Where are you based? We've done structural surveys for every install since we started and have had a failure rate of approx 10% not 50%. Ours have been mainly in 50's - 70's builds, newer and older seem to be coming through ok.

 

[mapl_co_uk]

Assessments have been across southern England and covered a vast range of property ages and forms of construction. Even trusses can have issues, although urban myth suggests a trussed roof is automatically OK!

Most fails are due to uplift when applying the BRE489 loads to the roof.

 

[SRE]

Must be different build quality in the North, best not to make sweeping generalisations about failures I find

 

[Fitstart]

FitstartIt was the case up until about 2 weeks ago that certain councils (Scottish borders for example) insisted on a building warrant. However the building standards director for Scotland has confirmed that a building warrant is not required for solar pv unless i) strengthening work is to be carried out to the roof or ii) the building is above a certain height (can't remember exact height but normal 2 storey building will be fine).Most pv installations in Scotland will therefore not need a building warrant but your installer should confirm that i) and ii) above do not apply in your case.Hope this helps.

If you do have the source of that statement from the BS Director could you possibly give me a link just in case I need to quote it to Fife Council - thanks.

 

[TedM]

I still think the basic issue here is the difference between what the legislation says - which is quite categorical that a member of a (named) CPS can self certify their main work and any associated building work - and the interpretation of that by LABC.

I don't see that the two tie up.

Whether MCS is or isn't a CPS is not material (and seems to have been included as a red-herring) as it is not one of the named CPS's in the legislation in any case.

 

[TedM]

Installers claim victory in solar planning battle - 26 Jul 2011 - News from BusinessGreen

 

[BruceB]

I find it surprising that 50% of roofs need reinforcement from the ones I have seen.

I also would be interested to know from the structural engineers here whether BRE489 is overestimating the wind uplift? The reason I think it may well be is that the assumption to come to Cp.net of -1.3, the wind uplift coefficient for panels <300mm from the roof surface on page 5, is that the panels are touching and so effectively impermeable and working like a single large aerofoil. In fact with the schuco mounting system I have been using there is a space of about 22mm around the edge of each panel which would impair the build up of any pressure differential and would destroy the lift generated by the array acting as an aerofoil.

Regards
Bruce

 

[rt1200]

We are structural engineers undertaking these assessments - about 50% of domestic roofs need some form of strengthening to resist not only the weight but the uplift forces generated as wind passes over the panels.

Building Control in England & Wales have recently confirmed that assessments are needed and have guided building control departments accordingly. The MCS accreditation bodies are also starting to ask for evidence of competent structural advice when assessing or annually auditing installers, so that their schemes can be considered CPS and allow self-certification. But if you self certify without site specific checks, you are potentially creating a huge future liability! Put a check from us on file, so you are covered by our insurances if there is a structural problem!

I know you are in Southern england but where abouts? You can send a confidential email via the forum if you wish?
Regards,

 

[rt1200]

Installers claim victory in solar planning battle - 26 Jul 2011 - News from BusinessGreen

Thanks TedM.

This link underlines one of the points I was initially making. That is MSC is not CPS in relation to structural integrity. I have copied and pasted a paragraph from the link here for others -
"The government's revised documents make it crystal clear that customers using companies ... which are members of the Competent Person Scheme and MCS approved can allow us to self-certify all aspects of installation including roof structure,"
If anyone is willing to, I would be grateful to learn what indemity insurance PV installers have, specifically for structural assessment of roofs, who is the scheme underwriter and how much it costs. Also, what CPS scheme they operate under and does this require any formal training or qualifications? I have heard of a City and Guilds qualification which may be accepted by some CPS schemes.

 

[rt1200]

FitstartIt was the case up until about 2 weeks ago that certain councils (Scottish borders for example) insisted on a building warrant. However the building standards director for Scotland has confirmed that a building warrant is not required for solar pv unless i) strengthening work is to be carried out to the roof or ii) the building is above a certain height (can't remember exact height but normal 2 storey building will be fine).Most pv installations in Scotland will therefore not need a building warrant but your installer should confirm that i) and ii) above do not apply in your case.Hope this helps.

Thanks for this. Its interesting to know how things differ in Scotland, particularly for companies operating near the border I guess!! Sounds sensible - if your going to load a roof, undertake a competent assessment and if no strengthening is required thats it - no fees for checking it, particularly when no works are required.

One thing Im not sure about is if the "competent person" is competent enough to undertake structural calculations in the first place - surely they would be as equally competent to design, oversee and check the solution? Thats what I would expect from a competent person and therefore why the need for Scottish building Regs to apply at all? A fair point?

 

[ScottishKev]

View attachment Minor domestic work guidance v2.pdfI have dealt with Fife Council in the last week. Fife Council insist on a building warrant when installing PV Solar panels. Fife Council insist on a structural survey when fitting more than one row of PV panels on a fram above the roof, i.e. adding to the weight - see attached document 'Minor domestic work guidance v2.pdf'. I guess that Fife Council have had sight of the study by BRE that recommends a structural survey when installing more than one row of panels - see attached file 'BRE_Study.pdf'.View attachment BRE_Study.pdf I would say that having a structural survey is good practise and every install should have one.