Slate roof gable extension - is this work acceptable (solved).

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I have a contractor installing external wall insulation at the back of my house. As part of the job, the roof of the gable end wall needed to be extended by 125 mm (half a slate width). I offered to source and buy the slates. After meeting with the contractors I suggested "There are 19 courses in total. Along the edge there are full width and half width slates so it seems logical to extend the roof-line by 125 mm. Marley make 500 mm x 500 mm slates for cutting so the probable solution could be pulling out all the tiles at the edge and cutting wide tiles to 375 mm for the 250 mm wide ones removed. This should allow them to be fixed on the existing battens which go virtually to the exterior edge of the brick. It would make sense to me to buy all the 250 mm wide slates as well as I can use the originals left over for other roof repairs".

They agreed to the slates and the subcontractor fitted them. The first picture shows the result - new slates are obvious.

GableEnd.JPG


The instructions for the slates say copper rivets must be fitted on all slates, here many are missing and it isn't possible to fit some of them because double width slates in the body of the roof - see detail:

GableDetail.JPG


He extended the battens even though I hadn't expected this. At the edge of the roof hit put some thin flexible board on the underside then tried to fill the space with mortar. I thought it was hardboard but he showed me a small bit and it is called Superflex:

GableEdge.JPG


The main contractor tells me it is undercloak and a "requirement". I haven't worked on roofs for decades but I would never put mortar onto a flexible board and expect it to stay.

The contractor has offered to do some remedial work. Screws with watertight grommets to hold down the tiles and a better mortar for the gap.

Advice please. Should I reject the work or am I being unnecessarily critical? Can it be made good without major work? Can I cut back the undercloak and battens to wall level and render up to slates?
 
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No it is not acceptable. All of the slates should be riveted, which is possible with doubles.
Whoever did the work did not have a clue.
The cement fibre undercloak is ok but the muckwork is crap and so is the ridging.
 
Hi Palecray. Thanks for response. Is the mortar supposed to stick to the undercloak and keep it in place from above?

Is there any way of fitting the rivet for the single sitting above the double as now in place and no slot to slide it under.
 
Anyone who can find mortar that successfully sticks (over four seasons) to Eternit slates ought to contact NASA (555-6707-323)
 
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as above all should have cdrs, even the half . saying that the doubles generally are used at the verge cut to 1 1/2 and valleys or abutments. not in stead of two whole slates side by side.
They have bonds so leaking isnt an issue , no cdrs is.
its rubbish
 
And what's wrong with the render? Looks like it's been put on with a roller to a few microns thickness.
 
Thank you all for your advice and support. The roofer came back and re-did the job under strict supervision from the project manager. I had to give them some tips on how to do tiling but the end result looks much better:

GableFixed.JPG


Now I have a better roof and know NASA's telephone number. :)
 
good you are happy with it.. maybe buy the guy a new trowel for xmas.
there are still a few rivets missing but nothing serious.
 

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