SuperlecDirect - ElectriciansForums.net Electrical Suppliers
This official sponsor may provide discounts for members

Discuss Roof anchors fixed directly to large tiles (stone?) in the Solar PV Forum | Solar Panels Forum area at ElectriciansForums.net

I

IronLiver

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:  American Electrical Advice Forum

Hi All

I went to inspect an installation yesterday at a customer's request as the company has now ceased trading. The installation was quite neat in general, though I'm not quite sure what to say about the method used to mount the brackets.

I have attached a picture below showing what I found.

Roof-anchors.jpg

The installer has drilled the tiles and used a fixing with a rubber seal as well as applying mastic or similar sealant to the underside of the anchor and presumably into the holes to maintain water tightness. I am not overly convinced by this method of acheiving an effective seal (consequently we have never used hanger bolt style fixings on slate roofs) and I am also wondering what damage may occur over time to the tiles.

That said and to be quite honest given the size of the tiles I am not sure what we would have done in this instance either. I think we would at least have flashed over the top of the bracket and tried to devise some way of fixing directly to the rafter, but just how you would go about doing this is a bit of a mystery. If you remove the tile completely to accomodate the bracket and then flash this could leave unsightly gaps. Cutting the tiles would risk damaging them but might be the best option. The tile does look like it could withstand a fair amount of abuse. Has anyone got any comments regarding the fixing method employed or indeed any suggestions for a better way of doing it?

I don't want to include this in my report without being able to offer some kind of solution. The wording of the MCS standard is pretty clear on this subject and I am not sure that the grommets used are "durable solutions", though I know this is debatable; according to MIS 3002:-

4.4.2 All roof penetrations (e.g. for PV modules, cables or bracketry) must be durably
sealed using purpose-made products capable of accommodating the movement
and temperatures to which they may be subjected.


Note: In all circumstances the building's weather tightness must be maintained. Holes drilled
through roofing felt and/or roof tiles/slates sealed with mastic or silicone sealant are not
considered durable. Purpose-made roof tiles and flashings for the routing of cables from a PV
module are examples of durable solutions.


Any help you can offer would be appreciated.

Cheers

Monty
 
Electrical2Go - Online Electrical Supplier
This official sponsor may provide discounts for members

Gavin A

-
Arms
were they bolted through the stone to the rafter below, or simply bolted to the stone?

We've actually done a couple early on like that on slate roofs, but in scotland where there is sarking board below the slates, so effectively the force is just compressing through the slate and sarking board onto the rafter, and slate should be fine with compression forces, as long as you make the drill holes around the screws wide enough to prevent any vibration issues. Obviously it needs to be bolted through to the rafter though, which is what presents the real challenge.

I must say I wasn't entirely happy with this solution, but this is what the supplier recommended at the time, and we were new to it.

One of these installs was on my Aunties house on a hill on the black isle in north east scotland and I've been back a number of times since and seen no visible signs of any broken slates yet, 2 years down the line, so fingers crossed.

Obviously if it's just bolted to the yorkshire stone, then it's a take it off the roof and redo it job, as the stone will definitely split, but those bolts look like the outdoor decking bolts that can come in 200mm lengths, so I can well imagine that they might be bolted through to the rafters.

If it's bolted to the rafters, and there's no sign of water penetration of broken stones, I'd think it'd be a case of makeing a note of it on the report, but not being something that would go down as a dangerous situation / must be sorted out immediately.


fwiw we use hanger bolts on yorkshire stone, with holes pre-drilled from the inside to ensure the bolt is centred on the rafter, and then enlarged on the stones to stop vibrations from cracking the stones, and the compression gasket for the main seal, with flashing around any that are close to the edge of the stones. It's the only sensible method of mounting to them IMO without hugely disturbing the stones by cutting them to fit a full bracket through to the beam then flashing (assuming you can find a bracket that has a 3-5inch rise on it), or ending up putting pressure directly on the stones as in this case.
 
M

moggy1968

  • Thread Starter Thread Starter
  • #4
what size are the tiles? What size is the overlap?
I reckon Krannichs wide profile plain tile brackets would fit a treat
 

Gavin A

-
Arms
what size are the tiles? What size is the overlap?
I reckon Krannichs wide profile plain tile brackets would fit a treat
I doubt it, they look like yorkshire stone, which means each stone is about an 35-40mm thick, and they're triple layered like slates, so the total thickness is around 900-120mm + a lat below, so around 1100-1400mm to the actual rafter, and each stone's upto 7-900mm long with only 300mm showing, and 400-500mm or so below the stone above, and can be the same in width or more.

We like our roofs solid up here.
 
Last edited:

Worcester

-
Mentor
Arms
So would the Red-Tip large tile bracket.

There are lots of possible solutions, wether it is the best or not was not the OP's question, it was 'is this OK', that depends upon
(a) length, size (dia) and material of the bolts?
(b) what are the bolts screwed to?
(c) how the bolt is sealed - what material is used for the sealing washer?
(d) what material is used under the bracket? - If it's CT1 or EDPM, these are approved construction materials for sealing joints, and are used widely throughout the construction industry. Silicon and Mastic aren't suitable materials as has been specifically mentioned.

If all the materials have been correctly specified, (sealants, bolt sizes etc) clearance holes drilled in the stone tiles, fixed correctly to a rafter or noggin, then it is probably OK.

Possibly not the way we would have done it, however that is another thread.
 
M

moggy1968

  • Thread Starter Thread Starter
  • #8
it looks to me like the hangers are bolted through the steel bracket plate so the seal should be good. Providing the holes in the tiles have been drilled carefully to avoid cracking I think this would be ok. With a hanger bolt the tile shouldn't be load bearing, the hanger just passes through it to the rafter.
 
I

IronLiver

  • Thread Starter Thread Starter
  • #9
Thank you for your responses. I can't say for sure whether the bolts are actually screwed through into the rafters, though I had assumed that they were given the look of the fixings (one of you mentioned that they looked decking type coach screws that come in various lengths and that was the impression I got as well).

I was primarily there to check the supply cabling to the inverter as the other system I had visited, which had been installed by the same company had an SB 3800 fed in 2.5mm T&E over a distance of around 16m, which I replaced with 6mm. Despite also being fed in 2.5, the system was smaller and the distance negligible. However, the more I think about it the less I like the mounting method, but like I said I have never had to fit brackets to a roof with tiles this substantial.

Unfortunately the installation is 185 mile round trip from me so it's not a case of nipping up the road with one of our lads to remove a few panels to get at the anchors to check the fixing. I'm not sure I would ever be able to tell what type of sealant was used in any case.
It seems like the only choice I have in this instance is to highlight the potential weakness of this method in terms of weatherproofing in the long term and to say that as it was a visual inspection of the anchors from above, it was not possible to establish how securely they were fixed (if at all) to the rafters. From the look of the rest of the installation I would be very surprised if the installer hadn't fixed to the rafters but you never know!

Monty
 
M

moggy1968

  • Thread Starter Thread Starter
  • #10
yesd, I think your right. advise the cutomer to check periodically for damp penetration and tile integrity and ring you if any problems. At the minute it's not really your problem.
2.5mm will be fine over a very short distance. we woudn't do it but it should be ok. evidently the intaller doesn't understand the importance of wiring size for distance (volt drop) rather than current carrying capacity. I would bet all their installs are done in 2.5mm!
 

Reply to Roof anchors fixed directly to large tiles (stone?) in the Solar PV Forum | Solar Panels Forum area at ElectriciansForums.net

Instyle LED Lighting Specialists UK
This official sponsor may provide discounts for members

Select the ways in which you gain online business

  • MyBuilder.com

  • Federation of Master Builders

  • CheckaTrade.com

  • RatedPeople.com

  • TrustaTrader.com

  • Which? (TrustedTraders.Which.co.uk)

  • MyJobQuote.co.uk

  • Yell.com

  • Google Paid Advertising

  • Own Website with Natural Ranking (SEO'd website)

  • Social Media (Facebook Twitter Instagram etc)

  • Word of Mouth Only for me


Results are only viewable after voting.
Bulk Workwear - Clothing Suppliers for the Whole Forum Network
This official sponsor may provide discounts for members
Top Bottom