First post here - i cam accross this thread as im still not comfortuble with slate, ive done a slate roof and my way of doing it was drilling through and coach bolting an aluminium bracket with lead flashing over. I watch another companys website as they post photos each week of there jobs and on the last one it was slate and it looks like they use a pantile bracket bolted to the rafter and flashed over, they must cut the slate to fit.
Welsh slate & yorkshire stone. The best way is inroof strip it and fit it but thats because i like the roofing aspect and that when i walk away from the install i know there will be no leaks in years to come and dont mention sealants on roofs as they dont work. If you need to use sealant you have not installed the gromit properly and it will leak in the future but if the anchor bolt is installed properly square of the slate and tightened down properly it will be ok. Thin brittle slate - you are better using the in roof kit but that could make you less competitive so back to plain tile brackets, lead flashed in and slate cut to suit.can give you pictures to see what you think just drop a line
I think this is a great idea for locating the position of the bolt. But one thing is confusing me....Do you drill squarely through the entire depth of the joist (4 inches, say) and then through the slate, or in through the side of the joist at an angle? It seems that you'd need a very long drill bit to drill squarely up through the joist and 2mm is a bit thin. Anyone got any ideas?
If your going to use hanger bolts, this method satetment looks probably like the best you'll get. (Slate starts on page 12)
Now, why don't all the PV mounting system providers, panel makers, etc provide information as comprehensive as this?
The edpm rubber glands should come with the hanger bolts, - check with your supplier.
I don't want to restart this debate but when using hangerbolts on a slate roof with no loft access, ie loft conversion, no visible rafters or nails at the facias, how does one find the rafters to fix to? You would need to be pretty accurate surely. Is there a scanning tool to locate them from above?
Not wishing to be piccy but really you need to know the size, spacing and condition of the rafters, to determine the anchor spacing at the time of survey. Can be a leap in the dark otherwise !!
You can strip a section to have a look , better safe than sorry
Mark
Are people really using hanger bolts for slate roofs????????? Unfortunately 70% of our roofs are slate and we'd never use hanger bolts, our roofer and customers would be horrified. MEP - there's a knack for walking on tiles, roofers have learnt through bitter experience others haven't. Employ the appropriate trade and you'll have a few cracked slates ( we did a Spanish slate roof yesterday - known to be the most brittle. 4kwp install 10 broken tiles replaced) do it yourself and you'll have loads more even if you're 8 stone wet through
unirac sounds good but if all else fails you cant fall of with lead slates dressed over the brackets, like martin says not pretty but totaly hidden by the array and in my opinion weather proof is better than pretty, theres a training company in york who run a good panel instalation course covering all scenareo's
These bolts are NOT good!. As a roofing contractor for many years with about twenty installs under my wing i would not recommend the use of these bolts. Drilling holes in slates without the correct knowledge of how to make the penetration water tight doesnt make good sense to me. When the EPDM washer and roof bolt fall dead in between two slates, there is no way that the washer can make the penetration in the slates water tight. If you have to use these bolts then i suggest that you get either a roofer or plumber to make a lead slate similar to a siol pipe flashing and use the EPDM washer to seal the top of the pipe upstand, the other way is to use a roof hook and cut the slates around the hook and flash with a piece of lead, then cut slates around the top of the hook to create a neat and tidy finish.
Hi guys, I was reading this thread with interest, and my contribution was going to be to post that Baxi article, as it does seem to be the most comprehensive set of instructions out there.
Nice to see I've been beaten to it !
There is no need for lead on a slate roof if you do it properly, position the right brackets correctly and you'll be able to cut them perfectly to make a weathertight seal that is almost invisible. When I get a chance I'll photograph the process. It's a bit like one of those ornamental puzzles but when you get it then it's easy!
Hanger bolts excerpt pressure down on the slate to make the seal. slates are very weak in that plane and will crack, if not immediately then at some point down the line. Hanger bolts are for tin roofs! I wouldn't want to be one of those installers who's put loads of systems up with hanger bolts, time to close the company and re-open with a different MCS or you'll catch the warranty claims further down the line.
There is no need for lead on a slate roof if you do it properly, position the right brackets correctly and you'll be able to cut them perfectly to make a weathertight seal that is almost invisible. When I get a chance I'll photograph the process. It's a bit like one of those ornamental puzzles but when you get it then it's easy!
I'm definitely interested in seeing what method (and brackets) you use.
Slate is tricky stuff to work with, so anyone who has any neat tricks please pass them on.
I like the Baxi method, purely because it's a neat and simple solution, and as Baxi are hardly a tinpot fly-by-night concern, then their I'd think that their method is certain to meet with approval from any certification body.
I use a thick aluminium roof anchor, fix the anchor flat to the top of the slate over a rafter carefully drilling through the slate with a masonry bit with the hammer drill-action turned off (like you would a ceramic tile). Sandwich a flash-band pad between the slate and the anchor and use lots of roofing sealant (from the roofing supplier) Use your favourite coach bolts and don’t over tighten. It helps to make your cable entry first then you can measure off from the inside and find the rafters from the outside. You’ll defiantly need a slate ripper, to replace Brocken tiles and you’ll need at least two good roofing ladders which you may have to modify with extra padding to protect the sates.
I have pictures if you're really interested, I live on the Dartmoor national park all the local installs are on slate roofs. It's a really unpleasant task but it works a lot better than you would imagine. We’ve never had trouble with leaks on slate installations because they’re so much easier to seal up.... You can still give me a tiled bungalow any day !!
We're in a national park too, on slate roofs - agree with you about the tiled bungalows, urban installers don't know they're born ;-). Our roofer just takes the slate out fixes the hook and flashes it all back in with lead. None of it a problem just more time consuming and a bit of extra cost for lead and replacement slates. The only problem we've had was with cambrian slate which gave us problems with the hooks and flashing it back in. I wouldn't expect you to be having problems with leaking after such a short period, it's after a few years of the slate moving with the wind that the leaks wil appear and need to be resolved. None of our customers would let us near their homes if we were drilling through the slate.
You don't find many properties in urban locations where the builder has used pine trees as rafters which seems to be very common here specially in houses built just after the war As a family we've been installing solar products on our houses we have built since the 90s, no problems yet. Thankfully.
I've been trying to !
Well, I've been trying to post some images, and a link to a Unirac solution, but my posts are awaiting approval from a Moderator.
I assume it's because I'm a Newbie.
I don't really want to 'cheat' the system, I've PM'd Admin and hopefully my posts will arrive in due course.
In the meantime, if you go to Google Images and search for Unirac Two Piece Standoff and Flashing then you should see plenty of lovely pictures.
Jason has sorted out my posts.
If you go back to page 8 the images are there, and a couple of posts below that is a link to a pdf document concerning installation of the things.
Hi there, we have more than 1 MW of PV system installed (domestic, commercial) all over Europe and couple domestic in UK. Maybe it is not case in UK (temperature is not going below zero often), but when applying constant pressure on tile roof (even minimal), thermal expansions over time does the job. After several years slate tiles with hanger-bolts tends to not leak, but to crack. Also hanger-bolts tend to bend a little under panel weight (as I said, no snow in UK, maybe not the case), but even little is enough to create pressure. We had serious problems in mountain areas 2 years ago, had to remove panels and change mounting system and tiles. Hilti or K2 has got bracket mounting system for slate tile roof, check their pdf manuals, they have also mounting instructions there. Hanger bolts we use only for metal / aluminium roofs.
We've looked at many roofs lately with damaged, broken or completely missing slates or tiles. The residents had not even noticed so certainly no major leaks... Just wondering if the roofers are protecting their own interests somewhat...
Not new regs, it's revised / expanded guidelines for the LABC, and is about to hit a series of right royal challenges (some justified, some not) that will see speedy retraction / rewrite.
What you you may be thinking of is the guidlines for screwing into rafters. Ironically there is a BS (5658 if I remember correctly) plus Eurocode that cover this.
The problem is that nearly all (except 2 that I know of) the roof hooks have come out of germany where the use of timber in the roofs is very different from ours, net effect if you use any of the 100+ roof hooks out there, you are not complying with the BS and Eurocodes, so are in breach of the Building Regs. Rather than give a solution, they have given an interpretation which says:
Distance from screw to edge of timber must be at least 4 x screw diameters
So that means that their is no way you can screw an 8 mm hanger bolt into a rafter unless it is at least 72mm wide!
Can i point you to building regulations BS5268-2 and you will find that hanger bolts will not probably meet the BS requirements + also i dont think any manufacturer will warranty 10 years using this product in slate + would you want to garrantee the EPDM rubber washer/mastic will last 10 years in welsh weather conditions?
Hey Worcester. As a side point whilst were on Building Regs, do you mind me asking which brackets and screws you would use for a trussed roof with concrete tiles with 35mm rafters?
Also does the local building control officer get involved in your installs or is it enough to be part of a cometent persons scheme?
G PACK You need 6mm screws to comply with BRE regulations on a 35mm rafter which HILTI sell and are approved under Eurocodes along with item - MSP-RHC-B HILTI ITEM - 435504
Thanks! Didn't realise that much of the roof needs to be stripped back! Did see something else I want to ask, the panels were butted up to each other, don't they need an expansion gap to all edges?
Thanks for the picture, Gordon. This is a similar method to ours. Our brackets are somewhat different to yours so we can't install the bracket under the timber like the way you do it. Looks neat and tidy, thanks for posting it.
Hilti have customers who have sent over ways of installing on slate roofs with a great finish that will not allow water ingress or damage to the tile, if you send me over your email address i will forward the photos
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