Slate fixings

[powervan]

Ok got first slate job in a week! new slates ! just been reading on net that the screw through the slate type is non compliant with mcs! the neighbours hse to this job has used them so when i remove a tile and replace with lead client bound to say Y havnt u used same type as u dont have to damage the slate!! i think for 25yrs the lead is best but whats the GENERAL opion PLEASE!
bracket ref number would help !

 

[JulianC]

Always use the Unirac post and flashing system for slate - available from Dulas.

 

[The Solar King]

Remove tiles over joist, make lead flashing. Use Schuco hanger bolt SCH-259583 fixed through flashing into joist, sealed with sealing washer on bolt plus leadmate. Re-tile around. Frame attached using right-angled brackets SCH-259665 (called hanger bolt adaptor). You will need to cut the bolt down in length once fitted to prevent fouling and interference with panels, plus to allow access to fixing screw to rail. Picture is on a Scottish Roof which is close boarded and does not use battens to support tiles. Detail would be same on an English roof.

 

[GaryM]

An eylet crimp for the bonding conductor would make a much more reliable connection.

 

[SolarCity]

Ouch! I don't like the idea of the hanger bolts at all.

 

[Worcester]

@JulianC, If you are going to do it that is the right way, look very neat. - What size are the unirac bolts and what size was the rafter?

@The Solar King, are you prepared to state that that won't give problems over th enext 25 years? as Biggs says 'Ouch'

 

[jerriais]

I've seen a draft of a new version of the DTi guide and it specifically states that hanger bolts are not recommended apart from on metal roofs or when the slates are large and very thick older stone slates. I think we will all be flashing soon (in a manner of speaking). That's fine for us as that has been our policy from day one, I just think it lessens the risk of expensive call outs later so it makes business sense now even if it takes a bit longer to install. Also quality work builds reputation and when the FITs are reduced, reputation will be one of the key issues that determines who sinks and who swims.

 

[powervan]

Julian (very neat) the house next door just have hanger bolts drilled straight through tiles and silicone then rubber cap tight to slate!! bound to crack slate! what length hanger bolts are they? schuco M10x110? thanks lads for info!!

 

[powervan]

julian can u point me in right direction for flashing item ie cat number?

 

[JulianC]

Afternoon all. For the UniRac system, Dulas' part number for the flashing is SSFSM990103 (Unirac's number 990103) - the sheet is 18" x 18" but for the job above we were able to fold the excess under to make it look a bit neater. The stand-off that pokes up through the flashing is part no. SSFSM004400C. The bolts that hold the L-bracket to the top of the stand off are supplied with the kit and are 3/8 UNC x 3/4" (it's a US system!)

The stand-offs have a flanged base with two mounting bolt holes - we use 8 x 80mm Spax screws. Rafters on this particular job were 3x2 and we added some strengthening noggins between rafters on the recommendation of our structural survey.

 

[powervan]

this is got to be the answer?

 

[powervan]

found it all (its the dogs doooo darrrrs i will sleep easy tonite!!! thanks

 

[JulianC]

Looks like one of the other Unirac stand-offs from their range. Same system - screw the post to the rafter and fit the flashing tile over the top. Works a treat.

 

[Worcester]

@JulianC, you can pm me if you like. What is the typical cost of one of those mounting posts, when you take a basic roof hook, add in the lead, and the time of a good lead capable roofer they aren't cheap, so they could be cost effective.

 

[powervan]

respected member price is £174.74 for unirac 2 piece standoff pack 24
£103.40 pack of 12 flashing
bit costly but if it works then i have no prob (FIT AND FORGET)

 

[Worcester]

@powervan, thanks.

In materials that works out at £16 a mount, if the roof will take 1200mm between supports, that is a similar price to the mounts I use at 600 mm centres (including the lead).

as they say in the ad "Peace of Mind - Priceless"

 

[The Solar King]

Been away a few days so not able to reply until now.

@Gary M. You are right, an eyelet crimp would have been tidier. However the photo was taken for MCS inspection. I raised this point with my assessor and he was happy with this.

@Biggs Solar. Do you have a better way? We are happy with this because it overcomes the issue of drilling through slates. If you use a J Shaped bracket you still have to make that weather proof or mount it on top of a flashing in the same way. you would end up with a much bigger flashing. The spacing is every 800mm also exceeds wind loading according to Schuco data. (the info is all in German but Google translator does a great job). Remember Scottish roof with no battens.

@ Worcester. Yes I am happy this will last. The rest of the lead on the roof is now 22 years old and is in perfect condition. I should know, I built the house and still own it!

@ jerrials. I would go back and re-read the 3rd edition draft. This is what is actually says:

"Tiles or slates removed for fixing a mounting bracket should be re-attached to include a means of mechanical fixing.

Mounting systems on slate or tile roofs that rely on a fixing bolt through the tiles/slates are not recommended. This is due to the potential for damage to the slates/ tiles and the difficulty for ensuring a lasting weather tight seal.

Bolt through fixings systems that incorporate a rubber sealing washer (originally designed for metal roofs) are sometimes suggested as a way of ensuring a lasting weathertight seal on slate or clay tile roofs. However, due to the potential for cracking slates and subsequent worries over long term durability, this method is not considered appropriate in most cases. Only installations on large stone slate roofs, where the slat es are very large, thick and robust – are considered suitable for this method."

They are talking here about fixing through slates. What We have done is to remove the slate and install the flashing to overcome this very problem. It is re-slated around the fixing which is directly into the roof joist. (in this case also through the close boarding).

 

[SolarCity]

Sorry for criticising your install, SK. I just hate the idea of drilled holes and hanger bolts. I've not worked on a roof with no battens so I can see it is a difficult one.

 

[The Solar King]

None taken

It is actually very important to have the views of others. How else do we learn or improve?

The Install would look tidier without the Leadmate. The bolts are designed to seal using just the neoprine washer. The roofers who are experienced in leadwork suggested the sealant, so we went along with this. We all screw into roof joists as a matter of course. The difference here is the size of fixing. The roof joists are 150mm x 50mm, so are big enough to take the bolts. On an engineered 38mm truss I would be using noggins. The install is a single row of 15 Sanyos. Due to altitude and latitude, this meant 30 fixing points (15 per rail) to meet wind loading. You can be certain there will be no issues over pull out! Using the other system being discussed here may not be as cost effective. Unirac would be £480.00 plus rails and mountings . What we did cost £180.00 plus rails and mountings. This includes a roll of code 4 lead at a shade under £100.00. Both require the removal and refitting of slates, so labour should be equal.

If we get pressure on margins due to reductions in FIT, we all have to have cost effective solutions that still do the best job for the customer. If someone can come up with a cost effective system that also minimises the labour input involved, I'll be first in the queue.

 

[Worcester]

Cost effective: but would never condone it, in fact if I was building control I'd probably condemn this:

[video=youtube;jxdQnsFlGlg]http://www.youtube.com/watch?v=jxdQnsFlGlg[/video]