Fixing hanger bolts.

[woko]

Hi, I need A little info in how you fix hanger bolts to a steel fabricated roof. The roof is tapezoidal sheets sandwiching insulation.I was told by the Hilti rep to use Hanger bolts straight through the roof into the steel purlin. Do you then put timber along the purlin to hold the bolts?

I was told I can't use tapezoidal fixings as the top sheet isn't strong enough for the wind loading.
Any help with this would be appreciated.

 

[SolarCity]

You need to pre-drill the purlin and then screw the hanger bolt straight through.

I wouldn't give up on the trapezoidal fixings just yet though - what thickness is it?

 

[woko]

Thanks Solarcity.

I'm not sure of the thickness of the sheets but I was told I couldnt use the trapezoidal fixing because the sheets may lift in strong winds. Have you used them?

The hanger bolt threah looks to me like it need to be screwed into timber. Can this thread be used on steel purlins?

I have done many domestic roofs but never one of these types of roof. I appreciate the info as once I've done on I can then confidently do others.

Cheers

 

[SolarCity]

You can get hanger-bolts specifically for the purlins and you can even get ones for thicker steel-work.

If you speak to SunFixings they will be able to advise you on what you can use.

 

[pvman]

I've never been convinced about the predrilling and then screwing the hanger bolt through method, all the hanger bolts i've see don't look like self tappers. We use bolts with a nut on the underside. Takes a long time but I'm sure it is more secure than the roof sheets.

 

[Worcester]

You'll need special hanger bolts for the steel purlins (not the usual ones for wood purlins) plus you'll need to make sure they are the right length (only have a 25mm fixing range) you drill a pilot hole through the roofing material into the purlin, then drill a clearance hole in the roofing, then insert the hanger bolt. It self cuts a thread rather than being a 'self tapper'- try Krannich they usually have them in stock - (p.s. hope you've got deep pockets, these bolts (s/s) for steel purlins aren't cheap)



There are occasions when you can't actually get to the underside of the purlin, so a threaded rod and nuts approach won't work in those circustances.

If you can avoid these there are better methods of fixings - though on one site we did have to stitch down the whole of the top skin to the purlins ..... 10 pages of engineering calculations, 5000 s/s bi metal tech screws later ..... and we could then fix to the top layer !

 

[moggy1968]

That makes me feel quite inadequate!!!

Aren't some jobs just too much aggro?[SUP]

I've used the K2 ones for wood from Krannich and they were pretty good[/SUP]

 

[SpitfireW'sale]

Woko if you still need these items we have both the steel fixings that Worcester has posted and also fixings that fix directly onto the trapezoidal sheet from Renusol. These are suitable for anything 0.4mm or thicker, so you should be OK to use them?

 

[Worcester]

Hi Spitfire, it's good to know others have them available as well, at one time the only way we could get them was bring them in direct from Germany ourselves!

We have found that these guys are also helpful Stainless Steel Solar Fixings

 

[woko]

Some great replies. Really helpfull thanks. We are getting up on the roof next week to give it a good coat of looking at. I'd like to use the trapezoidal fixings but I may have to go for the hanger bolts.
Thanks again.

 

[woko]

Right!!! Had a look at this roof. The top sheet is fixed down to Z bars which are then fixed to the purlins below. I want to use the K2 speed rail system and fix to the top sheet. Has anybody else used this system in this type of roof?

 

[Worcester]

Speedrail or Flatrail both are excellent systems, on larger systems we find the Flatrail slightly quicker and easier to install (less fiddly), If you are mounting the panels in landscape you could always use the Metasole system (see Spitfire above)

You'll need to ensure that there are enough fixings both from the top sheet to the "Z bars" and also from the "Z bars" to the purlins.

Make sure you get the correct type of tech screw, bimetal will go though both Aluminium and steel, s/s Ok on aluminium, they struggle to go through steel.

 

[woko]

Worcester, thanks for the reply. There is one fixing between each tapezoid into the Z bars and the same from the bottom sheet into the purlins. I'm going to get my structural engineer to look at this but as a rule how many fixings needed before you can fix to the top sheet?
The hanger bolt method is a better anchor but in landscape there are only 6 fixing points (purlins) and the span between each in 1.4m. I think speed rail is the best way.

 

[SolarCity]

Woko if you still need these items we have both the steel fixings that Worcester has posted and also fixings that fix directly onto the trapezoidal sheet from Renusol. These are suitable for anything 0.4mm or thicker, so you should be OK to use them?

Have Renusol fixings been tested to 0.4mm? I wasn't aware of that.

 

[SpitfireW'sale]

Have Renusol fixings been tested to 0.4mm? I wasn't aware of that.

Hi SolarCity - Yes, which should make them suitable for the vast majority of sheet available in the UK. They shoud be installed in landscape orientation only to meet their warranty conditions however. I have copied and pasted from their installation manual the below:
"MetaSole is very well suitable for the installation on all pitched roofs with a roof pitch of 5 – 45° and a trapezoidal sheet thickness of at least 0.40 mm (steel quality higher or equal S280GD) for snow load zone 3 and wind load zone 4 (according to DIN 1055)".