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!

 

[Mark.W]

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.

I have around 50 install under my belt, and I have used various types of mounting systems, and to be honest the hanger bolts sit tighter than your normal roof anchors.

 

[Mark.W]

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

You can adjust the nut on the bottom so you can drill literally the entire hanger bolt into the joist and then tighten up afterwards. You don't want to tighten too tight and you will know when you do because the rubber seal squashes.

 

[solgen]

Hi, I'm glad I re-opened this subject because as we all know it's a tricky one to deal with!

Mark W, you mentioned hanger bolts are an approved method - but are they approved for slate roofs and who says they are approved?

Thanks

 

[Mark.W]

Hi, I'm glad I re-opened this subject because as we all know it's a tricky one to deal with!

Mark W, you mentioned hanger bolts are an approved method - but are they approved for slate roofs and who says they are approved?

Thanks

Who do you want to approve it, the manufacturers of course! Of course they are approved for slate rooves that's what these specific hanger bolts are designed for. With any other roof you'd use a standard bracket!

Mark

 

[solgen]

Can you submit a link to the documention where you say the manufacturers recommended this type of fixing for slate roofs please as I have only seen them recommended profiled sheeting or corrugated sheeting.

 

[Mark.W]

I didn't say anywhere that it is the recommended method, there are a number of methods of fixing to a slate roof. This is the method I have found most effective.

Speak to your supplier. I've had enough!

Best of Luck!

 

[solgen]

Mark C,

I find your attitude to the people on this forum rather aggressive and abrupt! You seem to take peoples questions as some form of personal critism which in my opinion isn't the case. I believe we are just trying to learn from one another the best possible approach to challenging problems whilst keeping within MCS rules and manufacturers specifications. You have stated in a previous reply to MarkC ...

"This is an approved method of installation and the hanger bolts get bought from segen for this us"

I have looked on the Segen website and cannot find any documentation which states they are approved for slate roof mounting so I was rather hoping that you could direct me to where this is mentioned. I was incorrect in my previous e-mail using the word "recommended" I meant to use your word "approved" so my apologies for that.

All I and others are trying to do is exchange ideas and it seems that slate roofs are problematic and there isn't an ideal solution. Perhaps the method you describe is the best offering.

If anyone else has some considered opinions on this subject great!

 

[Markc]

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!

View attachment 2881View attachment 2883View attachment 2882

Charm down Mark, Just asking the question! As I said I'm NOT slating the work. It looks like a good installation method (As I said in my post).

I accept this is an approved method and was asking how you over come the customers concerns over drilling through their roof. I know some of my client would rather we didn't remove and replace tiles let alone drill them.

And where did I say you are drilling 8 or 10mm holes? I asked how you over come the building regs using this method? I assumed from the picture the bolt is a M8 or M10. Not that the bolt is like a coach screw? Not having used these I don't know.

 

[Markc]

Mark C,

I find your attitude to the people on this forum rather aggressive and abrupt! You seem to take peoples questions as some form of personal critism which in my opinion isn't the case. I believe we are just trying to learn from one another the best possible approach to challenging problems whilst keeping within MCS rules and manufacturers specifications. You have stated in a previous reply to MarkC ...

"This is an approved method of installation and the hanger bolts get bought from segen for this us"

I have looked on the Segen website and cannot find any documentation which states they are approved for slate roof mounting so I was rather hoping that you could direct me to where this is mentioned. I was incorrect in my previous e-mail using the word "recommended" I meant to use your word "approved" so my apologies for that.

All I and others are trying to do is exchange ideas and it seems that slate roofs are problematic and there isn't an ideal solution. Perhaps the method you describe is the best offering.

If anyone else has some considered opinions on this subject great!

Solgen.

Have I upset you? I certainly didn't mean to. I was only asking how Mark W over comes issues I know I would be asked about. I certainly didn't mean my post to be aggressive or abrupt and I have re read my post and can't see what I have said to upset.

I sincerely apologise if I have offended.

Mark C

 

[GPack]

Hey Mark. Chin up mate. This is probably the most useful thread I have followed on the forum. The information you have shared is really valuable and if I get a slate roof I will be using this method. As electricians I appreciate how nervous we all are about roofing. I think if the manufacturers instructions are followed, what's the problem. I think another way is to use a lead/aluminium slate but this is only from pictures I have seen over the past couple of weeks. I haven't had an install yet but I know this is a problem I will have to deal with in the future. I like the idea the the rubber seal starts to squash and so you are able to gauge the tightness. It wouldn't suprise me if the was a measurement in newtons in the manufactures instructions as well to get the correct torque setting. A phone call to them could establish that and if you're as interested as I am you will probably look into it further. Experience is king in this game and I think it would be foolish to ignore the advice of someone that has done over 50 installs.
Thanks for the photos you posted and sharing the knowledge

 

[solgen]

Apologies to MarkC, my last posting was to Mark D.

 

[solgen]

I'm losing the plot now - Apologies to Mark C again I meant Mark W

 

[Markc]

I'm losing the plot now - Apologies to Mark C again I meant Mark W

No problem Solgen. These things happen to us all.

Thanks

 

[solgen]

Well said GPack.

I think you have summarised and hopefully diffused some of the tension around this subject. If anyone does have any reference to manufacturers instructions for the use of Hanger bolts I would appreciate if they could post it on this forum.

Solgen.

 

[Markc]

The only thing I can find is this.

 

[edexlab]

We used this system on our Mcs assessment and discussed it at length with the assessor he was more than happy with our install and took a lot of pics of it . We know a consultant for BRE and he recommended it, this same person has Pv installs numbering in the hundreds having installed Pv for 9 years .Its a system which is also used on solar thermal a lot ,but its horses for courses you have to decide whether its the right mount for the roof ,we looked at other mounts first but on some jobs the spacing between battens was too tight to use a hook or fixed mount ,also the rafter size needs checking as these bolts are quite thick and should only be used on rafters of suitable size

 

[Mark.W]

Mark C,

I find your attitude to the people on this forum rather aggressive and abrupt! You seem to take peoples questions as some form of personal critism which in my opinion isn't the case. I believe we are just trying to learn from one another the best possible approach to challenging problems whilst keeping within MCS rules and manufacturers specifications. You have stated in a previous reply to MarkC ...

"This is an approved method of installation and the hanger bolts get bought from segen for this us"

I have looked on the Segen website and cannot find any documentation which states they are approved for slate roof mounting so I was rather hoping that you could direct me to where this is mentioned. I was incorrect in my previous e-mail using the word "recommended" I meant to use your word "approved" so my apologies for that.

All I and others are trying to do is exchange ideas and it seems that slate roofs are problematic and there isn't an ideal solution. Perhaps the method you describe is the best offering.

If anyone else has some considered opinions on this subject great!

Solgen

I apologise if I come accross abrupt, it's my personality!

I accept that we are here to discuss ideas, but I don't actually see anyone coming forward with any......! I mentioned that I have done many slate roof installs and this is the best method I have found.

All anyone can say is they don't like the idea of rubber seals or they don't like drilling through roof tiles, wind loading and stability, when they haven't seen it or felt it. No reason as to why they don't like the rubber seals or drilling through tiles.

I just wish I had a forum like this to ask for advice before I started installing. I had to find out the hard way, many hours spent on the phone to suppliers discussing various methods, and yes it does feel like my installs are being criticized.

Trust me I would not go drilling through customers rooves without doing my homework first.

Anyway best of luck to all you installers,

Cheers
Mark

 

[Martin Dawes]

No one is criticising your installations. Don't take things personally!

We were just discussing methods and showing an interest in yours. I do have concerns about the rubber seals, although as I've already stated, probably without justification.

For what it's worth, I think I'm going to try your method when we get a slate tile roof job

 

[Markc]

Hi All

Funny how things happen. Saw our PV Supplier today and in the boot of his car he had one of these! Hasn't now as I have it!!

Hopefully will make this post make a little more helpful now we can see the entire hanger.

 

[GPack]

What did he think of them. I take it sells a fair amount of them?

 

[Markc]

He said he sell's lots of them and has known them to be used on a multitude of different roof structures. I mentioned the "big debate" on here and he wasn't surprised. It's in powering trust into the rubber washer which he said is the issue. Obviously from their construction they are designed to be water proof and be drilled through the finish roof structure. Can be used on slate, metal roofs, flat roofs and others. He recommended use on a fixed material rather than a movable one like pan tile. He also said other installers use the same method as described in earlier posts, so it seems its a case of having some faith in the product. An idea he put to me to sell it to a concerned client is to fix one though the bottom of a lunch box or Tupperware box as a sample and then fill the box with water. Seems a fairly easy thing to demonstrate..........unless it leaks!!!

I also questioned the issue on build regs on the size of the bolt. He did agree the 10% rule but hasn't come up against issues regarding that point so far. We discussed the possibility of applying additional timber to side brace the rafter and fix into that rather than the rafter itself. I will be seeing a build inspector next week on a different job so may ask the question to him and see what his take is.

My opinion now see it is, it looks like it will do the job. Still not looking forward to our first slate roof job but fortunately not to many of them are around this way.

 

[GPack]

Thanks Mark. Some fair points. I Like the idea of fixing a length of timber to the rafter to avoid issues with building regs. It'll be really interesting to see what the building inspector thinks about it. I think after that meeting you will have gone a long way to exhausting all aspects of this type of fixing and should be in a good position to advise future customers. Would love to know what he thinks.

 

[Martin Dawes]

Thanks for the pictures, Mark. I think it'll definitely be the method I use on our slate tile PV installs.

Regarding the 10% rule, it is possible to use bigger fixings but you must supply engineer calculations to prove that it won't affect the roof structure too much. We had to take this route on an unusual loft conversion where we had no choice but to drill holes for cable runs.

 

[JulianC]

Been looking into slate roof mounting methods again briefly today and found these hooks:
Solar PV roof fixing slate - £9.99 : Solar PV Systems, The Best Online Store
The benefit from my point of view is that we can standardise on the K2 mounting rails that we use for concrete tile roofs as they are part of the same range.

I am still unsure on the hanger bolts. Neat as they undoubtedly are, I can't ignore our roofer's opinion. Also just read that the flex inherent in the bolts (quite normal) can, over time, stress or crack the slates. Not seen any proof of this though. Oh, I dunno!....

 

[GPack]

Hey, I got my first call today to install a system. Went around to have a chat and take a look at its suitablity and came across asbestos slates. Like welsh slates but asbestos!
Any ideas if these are okay to work on? The building is an old cobb cottage. Chap says it may have had a thatch before these tiles were put on. I'm going to talk to a local roofer in a few days and will ask him what he thinks. Any one here had any experience with them. I can't believe having worked out how to deal with welsh slate I get interest from someone with asbestos slate! Unbelievable!

 

[JulianC]

Funnily enough, our first slate roof job was initially suspected to be asbestos tiles (householder thought they were). Our roofers went up and had a look and confirmed they weren't. However, had they been asbestos our guys would have had to have gone up 'suited and booted' and taken extra care of any waste (double bagging and taping etc) and all manner of other asbestos related H&S requirements. The slates themselves don't present any problems unless they're damaged, or get damaged during the course of the work. The upshot was the job would have taken longer and cost a lot more!

 

[GPack]

Hey MarkC. Would you mind telling me who your supplier is? I hope to get a few quotes from MCS accredited suppliers for a PV system. I was thinking about just sending out a quote request to all the suppliers and seeing what comes back. How did you go about finding your supplier? Also apparently the roof that I thought might be asbestos tile is cement siding. I think this is still a product that can be used legally but I'm pretty sure it does contain asbestos.

 

[Markc]

When it comes to the possible presences of Asbestos there is no other way in knowing than getting it tested. NO ONE can visually confirm the lack or presence of Asbestos and that statement came direct form a very good family friend who works with asbestos every day.

The cost of sample testing is so negotiable it isn't worth not testing. Better to know for certain than have a doubt over what some one said. If you are working on an Asbestos material you will have a duty of care over ALL the other occupants and trades working or being around that area so if its is discovered you were negligent in having a material tested you could find yourself in trouble. It is also the duty of the property owner to inform you of the presence of Asbestos if they know its there. As for removal of it, it must be done by a licensed contractor. Not a job I would perform myself. Not worth the risk.

As for my suppliers we use lots. Look about on line and call them, not just email, they all want the business and I found the call got more response than the emails. finding a good supplier is something you will have to put the leg work into as its as much about forming a working relationship as anything else.

 

[JulianC]

When it comes to the possible presences of Asbestos there is no other way in knowing than getting it tested. NO ONE can visually confirm the lack or presence of Asbestos and that statement came direct form a very good family friend who works with asbestos every day.

Depends on the circumstances. ie. from ground level impossible to tell, up a ladder - definitely slate. That's the extent of the testing our blokes did and it was enough.

 

[GPack]

Thanks for the help. I'll let you know how I get on.