Fixing to new slate roof

[BruceB]

I quoted and got a job to put solar pv and thermal on a (demolish and) new build with straightforward interlocking concrete tiles. However I have had an email mentioning in passing that they have changed to Marley Duo Edgemere interlocking slates! I have used Schuco anchors to date on other installations. Anyone know the best one to use for this? Schuco make a slate anchor and a plain tile anchor, but I cannot get my mind around how they work. It appears the slate one actually lies on top of the slate, which seems wrong making a slate loadbearing. Or have I misunderstood? Do we do our roofs different from the Germans, because it looks to me like standard concrete tile anchor would work.
Regards
Bruce

 

[funboy57]

Why would it be load bearing. Use the Shucco fixing with the neopene gasket, pilot hole the slates with a dill bit not on hammer slightly over sized than the screw your using. Apply mastic to hole, screw the slate anchor down but just pinch up at first, then manually use screwdriver to bite down a bit more, your are fixing to rafter, noggin or what ever, do not over tighten or you will crack the slate, job done. I done a few like this, they have lasted through last years snow etc. no problem.

 

[Solus Direct]

Hi Bruce,

We are a Solar PV wholesaler of Schuco and other makes of brackets. The slate bracket is a little awkward and the best way is to cut out the slate over the rafter, fit the bracket and lead flash over it.

Funboy57 is right, the best way to do it is with an hanger bolt and drill through the slates into the rafter. The majority of our customers do it that way and have had very few problems.

Let me know if you need any help on this

Mark
Solus Direct

 

[BruceB]

Well you may be right that is the best method - I know a few on here have recommended it. It just seems a pity to be drilling holes in brand new slates if there is another way. What I was actually asking about was the Schuco slate anchor SCH-256313. I have tried to attach a picture.
Regards
Bruce

 

[SRE]

We do loads of slate and NEVER drill through it regardless of how old it is. Fix the anchor to the spar, take a notch out of the slate so it fits snuggly back on top and flash it in with lead. We always use experienced roofers they and our customers would be horrified at drilling through slate and using sealant to bung the hole up. I'm sure it's in the MCS info that this isn't regarded as good practice. Of course others will disagree

 

[funboy57]

Well each to there own I suppose, the mastic is not used to bung up the hole its there to provide expansion and contraction around the fixing screw/bolt. The bracket shown by BruceB has a neoprene gasket underneath it,THAT provides the water seal not the mastic.

 

[BruceB]

I had no idea the Schuco anchor I had shown had a neoprene gasket! Where do you know that from? Are there some installation instructions that mention it?
Regards
Bruce

 

[funboy57]

If that is the slate anchor it has a gasket underneath the flat side that fixes to the roof, the gasket is full length of the anchor which helps not only to seal around the fixing holes but provides some cushioning. How do I know? I`ve used them.

 

[MCS Renewables]

We use them as well.
They look like this.
Solar thermal installers have been using them for years with no problems.
You just need to be careful with drilling to ensure you dont miss the timber !
No sealant required for waterproofing but good for peace of mind.

 

[Worcester]

Would you do that on a £1m house?

And accept the potential liability?

 

[MCS Renewables]

Would you do that on a £1m house?

Yes and we have done. These approved fixings will not leak as opposed to cutting slates and bits of lead. They are designed for this purpose and are superb.

MCS registered since 1st April 2010, over 112 jobs on houses worth up to 5.4 million, no leaks yet !

probably get one tomorrow now ..... thanks !

 

[SRE]

The point is the leaks will come 4/5 years down the line not now. The constant wearing of the wind loosens the washers eventually and that's when the leaks happen. Our roofers have patched up quite a few of the solar thermals that were installed 6 years ago under a project that I used to run.

Last time I looked lead flashing was what most UK housing used to keep waterproof ....

 

[Worcester]

@SRE,

That's precisely my concern, I know lead isn't cheap, and I know baxi use a similar system.

Can someone show me the TUV or Building Research Labs test certificates, most building materials need that and more (Agreement Board), instead of colloquial, 'it works mate'. Show me the proper, tested, (freeze/thaw, hot/cold , wind/slack) results that simulate 25 years and I'll change my mind, untill then I reckon you're building up a massive potential liability, that no warranty clause will exclude you from.

I attended a recent MCS Inspection for a friend of mine, and the Inspector specifically asked to see the test certification for the mounting systems they used....

Good old Mississippi "Show Me" state..

This is your opportunity to convince me..

 

[Ecodan]

Hi,

I am new on here as well as to PV instalations. I am currently finalising my MCS instalation. I have the Schueco hanger bolts as recomended by some for my own slate roof. However the more I think about it the lead flashing seems the better option. Does anyone know which code lead to use or if anyone sells a preformed flashing?

thanks in advance

Dan

 

[DomB]

We've got our first slate job next week.

Our roofer said he'd prefer to cut out slots for for the anchors to fit into and then lead flash over them. The anchor distributor has said to use Code 3, 150mm lead, to have some lead sealent to hand and to cover the lead with patination oil to finish.

 

[Worcester]

@DomB

That sounds good advice to me.

 

[funboy57]

Not sure where this is going. BruceB picture is the anchor I was referring to, MCS renewable anchor I thought was more for corrugated roofing , like on a warehouse/garage. I would be very disappointed if shucco did not have a certificate for that anchor BruceB put up, but then can a roofer put up a cert for his opinion, why trust the roofer just because he is a roofer, colloquial, 'it works mate'. Good debate though

 

[SRE]

Not sure where this is going. BruceB picture is the anchor I was referring to, MCS renewable anchor I thought was more for corrugated roofing , like on a warehouse/garage. I would be very disappointed if shucco did not have a certificate for that anchor BruceB put up, but then can a roofer put up a cert for his opinion, why trust the roofer just because he is a roofer, colloquial, 'it works mate'. Good debate though

Roofer with 20 years experience working on slate roofs every week, excellent references and member of FMB with experience putting right problems with solar fixed this way to slate 5/6 years ago v 12 months experience installing solar panels mostly on tiled roofs ...... I know who's advice I would take

 

[solarsavings]

So much damage do expect to happen from the ingress of water (if any) around a hanger bolt? mountains and molehills spring to mind.

 

[Ecodan]

DomB
Sounds like the lead option is more work but l would rather leave a job confident it will last. I really don't want to be refiting panels in years to come. All the best for the slate job next week.

 

[Worcester]

So much damage do expect to happen from the ingress of water (if any) around a hanger bolt? mountains and molehills spring to mind.

It's doesn't take a lot of water to cause a couple of grands worth of damage to some of the properties that we work on.

For example for all work inside we put down dust sheets from the entrance to all the work areas, and when wet also put down disposable poly ones on top. The last thing we want is a claim for a few grand because of a messed up carpet or wooden floor.

Same with the roof, seems false economy on a dwelling to me.

Having said all that, we do intend to use them on a garage install, there is nothing in the garage that would be harmed by water damage.

 

[SolarCity]

It's doesn't take a lot of water to cause a couple of grands worth of damage to some of the properties that we work on.

For example for all work inside we put down dust sheets from the entrance to all the work areas, and when wet also put down disposable poly ones on top. The last thing we want is a claim for a few grand because of a messed up carpet or wooden floor.

Same with the roof, seems false economy on a dwelling to me.

Having said all that, we do intend to use them on a garage install, there is nothing in the garage that would be harmed by water damage.

Likewise. We lay dust sheets wherever we tread - things like this get noticed by the customer more than anything....

Having spoke to various roofers, we definitely won't be using hanger bolts and slate tile roofs. They may be ok.... I don't know. The truth is that none of us really know. I'm just a lot happier with using roof anchors with lead flashing.

 

[funboy57]

Ive never used anchor bolts on slate roofs only the slate anchor the BruceB has shown on the first page of this thread. I think this is a good debate. There will always be a difference of opinion which is fair enough. I just wondered what are the objections that roofers have against the Shucco slate anchor? Im definately not a person who wants to cut corners on a job, however I feel that if a anchor that has been designed fit for purpose by a company that manufactures mounting systems it should be ok. Another point is, if it did go belly up 5/6 years down and the customer tries to sue you they have to prove negligence, if you have used the appropriate anchor fixed according to manufacturers instructions and it fails, will that make you negligent ?
The problem BruceB has got the slates on his roof are interlocking, nightmare to work with, ever tried replacing a damaged one? As soon as BruceB gets on the roof the company that has installed the new roof will void their warranty. To me on a brand new roof would it not look a better job if it was integrated, perhaps it cant be for some reason. Interesting one this.

 

[BruceB]

The problem BruceB has got the slates on his roof are interlocking, nightmare to work with, ever tried replacing a damaged one? As soon as BruceB gets on the roof the company that has installed the new roof will void their warranty. To me on a brand new roof would it not look a better job if it was integrated, perhaps it cant be for some reason. Interesting one this.

I am grateful for the replies to date. Funboy57 is right that the slates I cited are modern interlocking slates and are in many ways more like tiles than slates because they are laid with a single lap rather than the double lap of traditional slates. I am concious of the point he makes above and intend for the anchors to be put on as the roof is covered rather than ripping it apart as soon as it is finished. I did offer integrated, but it was more expensive and budget for this client is tight. If it were not for the council insisting on a Code 3 sustainable home and a certain percentage of renewables in order to grant the planning permission, then he would not be doing as much as he is on this front.
Regards
Bruce

 

[Worcester]

Would you do that on a £1m house?

Yes and we have done. These approved fixings will not leak as opposed to cutting slates and bits of lead. They are designed for this purpose and are superb.

MCS registered since 1st April 2010, over 112 jobs on houses worth up to 5.4 million, no leaks yet !

probably get one tomorrow now ..... thanks !

@MCS Renewables, Do you have a copy of the appropriate BBA, CE Certificate etc, plus a detailed installation process? I'd like to see that before I used it..

 

[solarsavings]

It's doesn't take a lot of water to cause a couple of grands worth of damage to some of the properties that we work on.

For example for all work inside we put down dust sheets from the entrance to all the work areas, and when wet also put down disposable poly ones on top. The last thing we want is a claim for a few grand because of a messed up carpet or wooden floor.

Same with the roof, seems false economy on a dwelling to me.

Having said all that, we do intend to use them on a garage install, there is nothing in the garage that would be harmed by water damage.

I fail to see the connection between dust sheets and hanger bolts And for what it's worth I've been putting dust sheets down for 30 odd years with out a claim. I've been using hanger bolts to install solar thermal collectors (and more recently pv) where needed since 2005. We also have them on a training roof where the underside of the tiles is exposed and it shows no signs of water ingress. There is a fixing system I wouldn't use and it doesn't rely on hanger bolts.

 

[funboy57]

I agree about the dust sheets.It would be great if we could just debate this rather than shouting peeps down, surely the point of the forum is to learn from other people experiences and not some sort of professional oneupmanship. if a roofer says he dont like the anchor/bolt it would be better to explain why he dont like the anchor/bolt, if it fails after 5/6 years why did it fail, if we were not looking for guidance or help in areas we are not quite sure about then we wouldn`t be here, or am I being too simplistic.

 

[SRE]

I don't think it was one upmanship, if you have a look at the contributions that Biggs and Worcester make on the forum you'll see they aren't like that, they always make a valuable contribution - I've been helped with their advice no end. I think it was just a point about cutting corners and some people think that drilling and using hanger bolts cuts corners. I'm not saying they're right, but everyone's entitles to their view.

 

[funboy57]

@SRE I agree with what your saying about Biggs & Worcester I am grateful for their contribution,yours and everyone elses, and everyone is entitled to their opinion, however for the purpose debate an explanation as to why someone has opinion would be helpful. I dont want to cut corners but I ( and probably others) would like to know if I have been mis sold something that was alleged to be fit for purpose and would like to draw on other peoples experiences as to why these fixings fail. As in fact not heresy.

 

[Worcester]

As per another post a long discussion with the Hilti rep and they do an identical anchor bolt and won't authorise them for use on slate, (Hilti have neen making pv mounting systems for ages on the continent)

As I say, show me the CE, TUV or BBA certificate for them and the detailed instructions for them and I'll change my mind, until then I won't use them on a house on slate. Wind load, Dead Load, Snow load, something has to flex.

Which distributors are promoting them / saying it's OK ?

And I'll happily discuss it with them *(without mentioning names!)

 

[solarsavings]

The only roof fixing that I've used and had trouble with just happens to be Hilti's plain tile roof anchor flexing under wind loading and causing the lap tile to break. Never had that happen with an hanger bolt and doubt I ever will. We use Schletter hanger bolts I'd be surprised it they weren't approved.
[h=1][/h]

 

[solarsavings]

From Schletter's website

Special roof hooks Slate/ Prefa
VA-quality, without plate
In case of slate roofs the optimum form of mounting is mainly
determined by the roof covering! In certain circumstances, a
mounting on hanger bolts can be advantageous.

Seems they are TUV certificated too.

 

[JD6400]

As per another post a long discussion with the Hilti rep and they do an identical anchor bolt and won't authorise them for use on slate, (Hilti have neen making pv mounting systems for ages on the continent)

As I say, show me the CE, TUV or BBA certificate for them and the detailed instructions for them and I'll change my mind, until then I won't use them on a house on slate. Wind load, Dead Load, Snow load, something has to flex.

Which distributors are promoting them / saying it's OK ?

And I'll happily discuss it with them *(without mentioning names!)

Not wanting to fan the flames but i have been told by a very good source this is because the hilti fixings were splitting the rafters due to the fact we use a lower grade timber in our roofs than Germany .
Flashing IMO would give me more peace of mind personally .
Seem to remember a post a couple of months ago where they had been pulled on a inspection for fixing through the tile ?

 

[Worcester]

@dp, yes that what he said, the wider offset of the german fixings (which are almost identical to the schletter ones) when used with 8mm coach screws and our narrower rafters caused the rafter wood to split. So the UK spec ones use 3 x 6mm instead of 2 x 8mm and are more in line.

 

[DomB]

Heya, I'm made it back from that first slate job! It went well, I've attached a couple of pics of how we mounted the anchors (which were basically just 90' angles like Schuco's are).

We removed the top slate, attached the anchor by coach screwing through the slates underneath into the rafter, flashed over the anchor and put on some patenation oil. We then cut a strip out of the top slate and replaced it. We used 'lead clips' to put the slates we'd had to rip out back in place (I think you can see the bottom of the lead clip holding the slate above).

For info, the slates were 20"x10". For 24 anchors we got through 9m of Code 3 150mm lead and less than 1/2 a litre of patenation oil.





Cheers

 

[Worcester]

Looks good, well done, and looks like the weather did its usual thing!

 

[MikeXl426]

Hi DomB

Thanks for that. Useful info and I'd much rather do that than use the anchor bolts!!!!!!
As you say you screwed through the slate underneath, I take it the bracket is resting on that slate and so the slate is taking the weight. Is that right? I'm just trying to get my head round this one as you've got the thickness of the battens so it seem the coach-bolts don't actually screw right to the rafter?

Thanks

Mike

 

[DomB]

That's right MikeXl426; the anchor sat on the underneath slates with the main weight bearing point being the batton underneath. The anchor was put in line with the rafter so the coachscrews basically just held the anchor in position.

We were trying to suss out how to get the anchor to sit on the rafter itself but that would have involved taking a long strip out of the two slates underneath (they were double lapped) and that would have left us with an unflashable area right at the bottom of the anchor. The other method we considered was padding the back of the slates but again that would have been alot of slate removals and lead-clippings. The way we chose was the lesser of several evils!

 

[MikeXl426]

No problems with the slates cracking then?....they can be sooooo brittle!

 

[DomB]

We did have a few cracks, aye. But mostly from tearing and walking, not from the anchor tightening. Must admit, much as yourself I suspect, I'd have preferred the weight to not be on the slates at all. I figured if people are bolting the anchors straight to the top (our dist'y said that was an option!) then having them bolted to the underlayers & flashing for water ingress was OK.

Meantime I'll defo keep my eyes out for ways of getting the anchors to sit direct on the rafters