Rafter screw sizes

[ROSSMAC]

Been lurking for a while!

Doing my 1st install for my own roof for my assessment before the cutoff! For what its worth!

Managed to get a complete kit with panels, fixings etc.

The kit comes with M8x80mm s/steel wood screws.

Reading through other threads there could be a problem with these as my rafters are only 35mm wide, as I understand the screws should be 4mm max.

Is this correct? What should I do to make the install comply?

 

[powervan]

get to b and q find what your looking for!!! whateva u use PRE DRILL first!

 

[alexpau]

Under british building regulations and Euro codes the diameter of the hole drilled or screw used should be no more than 4 x the distance from the centre of the timber so i otherwords 35mm timber the screw max size is just over 4mm however this diameter screw would be to small to use on a pv install so the only option available would be to install timber noggins either side of the 35mm roof timber and you then can use 8mm screws re drilled.

 

[moggy1968]

thats intersting because the screws krannich supply are considerably larger than this. Also the holes in their brackets are offset so you aren't going into the centre of the joist, your going into the edge.

 

[alexpau]

Many Screw suppliers or manufacturers of pv mounting systems dont know or understand Gb building regulations or will not mention it unless you ask, the reality is there exist and should be complied with beacuse an install will fail if the wron screws are used in the wrong timber. We do have 6mm screws which are approved in PV installs but again dont comply wiht building regs or Eurocodes in 35mm-38mm rof timbers so as mentioned before timber noggins are really the only way forward

 

[ROSSMAC]

Alex - When you say put in noggins, do you screw them either side of the rafter or do you secure the noggins between adjacent rafters?

 

[powervan]

im always amazed that clic fit is mcs approved and just sits on batterns but fixing with screws/bolts have so many rules! being in the building game for 25yrs i NO when a FIXING is a GOOD one EVERYTIME but it may not comply with Gb building regs?

 

[alexpau]

Hi i have heard that some building control officers refuce to allow clic -fit beacuse of compliance issues as well, with regards to noggins screw either side of the battens or rafter it is all about makig the roof timber wide enough to comply with building regs

 

[alexpau]

Also just beacuse something is MCS approved it does not make it building regs approved

 

[powervan]

thats y i dont use it!!!! like i say IF IVE FIXED IT!! IT AINT GOING NO WHERE!! wel if it comes off it will be WITH the ROOF)))