mounting systems for welsh slate roof

[GPack]

How would you mount a pv system to welsh slate. The slate is so thin and they are nailed in so they can't be slid up. Probably a silly question but any help is appreciated. A link or a picture would be great if possible.

 

[Markc]

Hi GPack

I think you may have some issues which might not be overcome. Slat is naturally brittle add into this years on the roof and every slate nailed I would say there's little chance in getting them off in one piece. There are some so called slate mounting brackets out there but form what I have seen in demonstration they still look to be quite thick so lifting the slate up.
Not having worked on a slate roof (Not to many round my way thankfully) myself I certainly not looking forward to doing so. I would suggest having a chat (Or visit) with Wind and Sun in Leominster. They can be found online from a Goggle search. They supply and install and have a eco education centre with a slate roof with PV on it. Worth a try.

 

[GPack]

Thanks for your advice Markc. Much Appreciated.

 

[Markc]

Sorry I couldn't give better information. If you do find something then it would be good to let us all know.

Cheers

 

[GPack]

No problem. Will do.

 

[solgen]

Hi,

Did you find a solution to the slate problem? I'm now faced with a similar situation and wondered if you could provide any tips. The cottage is about 100 years old and so is the roof slate. Any ideas/tips would be welcome.

 

[JulianC]

Have a word with Dulas Solar Roof Fixings - Dulas

We recently installed a couple of systems on slate roofs, using their Unirac post mount systems. Our roofers liked this system and found it quick and easy to install. They removed any nails in the slates with a ripper, removed the slate where the post was to be fixed to the rafter and replaced it with a specific sheet of alu flashing which has a rubber sealed hole in the centre to fit over and seal against the post. Then it's a simple case of fixing brackets to the top of the posts and bolting the rails to the brackets.

 

[Martin Dawes]

Is it not possible to use standard brackets? And then to make good with lead? A messy solution, perhaps, but it will be largely hidden by the array anyway.

 

[Noshocks]

I was working with a full time PV roofer who says thier company uses the post type mounts on nearly all roof types now, including slates, drill a hole through slate or pantile with masonary sds, drilll a pilot into rafter with auger bit then screw post in putting some roofing mastic around rubber seal for extra measure. It sounded a lot easier than I am sure it is in practice, would need precise measuring for a start to hit rafter each time.

 

[JulianC]

Hmmm, drilling through a tile and mounting a post through it sounds like a bit of a cheap and nasty bodge to me.

 

[Noshocks]

It does sound a bit bodgy i agree.

 

[Mark.W]

Guys

I have worked on many slate rooves and the best way I have found is to use what's called a hanger bolt. I start by drilling a small pilot hole from the inside through the joist and through the slate (that way you are sure not to miss the joist from the outside). I then get up on the roof and drill the hanger bolt into the joist. The hanger bolt has a small rubber gland which fits nicely into the hole you have made making it water tight.

Cheers
Mark

 

[Martin Dawes]

I really don't like the idea of rubber seals. Sounds to me like a recipe for leaks in the future.

 

[edexlab]

I really don't like the idea of rubber seals. Sounds to me like a recipe for leaks in the future.

we've used same hanger bolt system on several slate roofs it is an approved method and the washers are epdm rubber same as these rubber roof coverings which have long lifespans
one of our competitors has mentioned to several prospective customers that drilling the slates and fixing thru is bad practice but we've looked into it in depth and its an acceptable method and on some older uneven slate roofs its the only realistic option
as it happens the above company when asked by several customers could not provide them with an example of not just a slate roof but any install done on a genuine customers roof only on their own installs they did for MCS yet they're going about slagging off other local installers incidently we have now installed all of the jobs mentioned above !

 

[Mark.W]

As above post has mentioned it is not just a standard rubber.

Tell me this does not look good! One of my installs!

 

[Martin Dawes]

That looks pretty good. I suppose one of my big fears with getting involved in PV installs was maintaining the integrity of the roof and drilling through a tile defintely bothers me (probably unjustly).

Would you mind me asking who manufactures that system?

 

[Markc]

As above post has mentioned it is not just a standard rubber.

Tell me this does not look good! One of my installs!

View attachment 2865

How do you sell this to your clients? I bet you get some concerned customers about drilling a hole straight through their roof. We haven't worked on slate roofs (Yet) but I would be concerned if it were my roof.

How does this comply with building regulations also? You should not drill a hole more than 10% of the rafter width. I assume this bolt is a M8 or M10?

Not knocking your install and I can't think of a practical solution either, its just a question!

Some pictures of the finished article may be good as well.

Thanks

 

[Martin Dawes]

One other thing, have you found that over-tightening of the bolt cracks the tile?

 

[JulianC]

One other thing, have you found that over-tightening of the bolt cracks the tile?

Was going to ask the same thing! Is this part of a proprietary PV mounting system? It looks a little flimsy to me and I'd be concerned about wind loading amongst other things. It just doesn't look strong enough to me.

Incidentally, I mentioned drilling through slates to mount rails to the roofing contractor we use on our installs. He screwed his face up. I can't tell you what he said since I believe this forum has a pretty good swear filter. Suffice to say, he didn't think much to it.

 

[Mark.W]

How do you sell this to your clients? I bet you get some concerned customers about drilling a hole straight through their roof. We haven't worked on slate roofs (Yet) but I would be concerned if it were my roof.

How does this comply with building regulations also? You should not drill a hole more than 10% of the rafter width. I assume this bolt is a M8 or M10?

Not knocking your install and I can't think of a practical solution either, its just a question!

Some pictures of the finished article may be good as well.

Thanks

Let's get this sorted quickly....!

This is an approved method of installation and the hanger bolts get bought from segen for this use. I always show the customer what is involved and they are more than happy to have their tiles drilled as long as it is water tight, which it is!! Try it for yourself before you slate this method, excuse the pun!
I did not say that I drilled an M8 or M10 size hole throught the joist, I drill a pilot hole with a 2mm drill bit and from the outside drill the hanger bolt into the joist! It would be ludricrous to drill an 8 or 10mm hole!