Poor velux fitting

[an203888]

Hi all. I am writing this on behalf of my inlaws. They are having an extension built. Windows, electrics, floor and insulation are in but the Velux windows seem to be leaking.
Builder has had a look but quite honestly we don't trust him. He will never admit any error, can never get hold of him and really don't want any long term issues with this extension.

So there are 4 of veluxs largest roof windows installed into a 15degree pitch roof. The tiles being used are Sandtoft double pantiles which go down to 15 degrees if the smooth is used. All 4 seem to be leaking a bit top and bottom. There is also the usual condensation droplets on the underside of the aluminium but this doesn't appear to be that.

I have had a look today and all seems to be done fairly neatly and appears the right flashing has been used. There is not the extra skirt flashing installed.

However, I don't think he has put his windows/tiles in the right position. The tiles do not overlap the window/flashing at the top enough - they are about 155mm away from edge of external window fitting and the tiles don't sit on top of the little angled bit of ally. Same seems to be true for the bottom of the window - the flashing only overlaps the tiles by about 50mm so that bottom tile hasn't been fixed close enough to the window.

I hate telling builders they have done somthing wrong because they never admit it so some opinions from others would be good - please see pics.

Thanks

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• an203888
• 24 Jan 2021

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• an203888
• 24 Jan 2021

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• an203888
• 24 Jan 2021

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• an203888
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• an203888
• 24 Jan 2021

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• an203888
• 24 Jan 2021

 

[Barthy]

The angled bit of ally is used to provide kick to tiles above and moves accordingly
If the front apron only covers 50mm then the tiles aren't covering 100mm judging by your pictures as it's just shy
Course looks stretched above the windows I think there's sufficient cover on the back gutter from what I can see
Is there any plastering work being carried out?

 

[datarebal]

all of the above, what is important.. post the length of the exposed tile not the length from frame to bottom of the flashing.

mostly tidy

 

[catlad]

On a couple of the windows the tabs haven't been folded down on the back gutters so its possible they are not sealed fully. The tiles behind the skylight should be between 60 -100 if I remember correctly.

 

[an203888]

The angled bit of ally is used to provide kick to tiles above and moves accordingly
If the front apron only covers 50mm then the tiles aren't covering 100mm judging by your pictures as it's just shy
Course looks stretched above the windows I think there's sufficient cover on the back gutter from what I can see
Is there any plastering work being carried out?

Not sure what you mean that the tiles aren't covering 100mm?
Umm, yes, I haven't checked to see if tiles above are stretched.
No plastering has been done yet.

all of the above, what is important.. post the length of the exposed tile not the length from frame to bottom of the flashing.

mostly tidy

I measured under the flashing to top of tile which was 50mm. In the fitting instructions it should be 130mm from wooden window frame to top of tile - this seems way out.

On a couple of the windows the tabs haven't been folded down on the back gutters so its possible they are not sealed fully. The tiles behind the skylight should be between 60 -100 if I remember correctly.

The measurement is 60 - 150mm and this is 155 so right on the edge.

What would you say to the builder? Just ask him to fix the leaks!!

 

[Barthy]

Tiles should have 100mm cover/headlap if you say the front apron only covers 50mm then the tiles appear to only have around 65mm which is sufficient for a roof of suitable pitch, not 15 degrees.
As data mentioned measure the tile exposure to show gauge.

 

[an203888]

I measured the headlap - it's 100mm but the apron still only covers 50mm of the tile.
I am not able to remeasure just popped over today to have a look for them.

 

[Barthy]

I'm going off assumptions, judging by the tiles they shouldn't of required a cut course under the window.
The front apron is 15/20mm max above the corresponding tile if you say it covers 50mm, and you've lost 20mm maximum...where's the other 30mm gone.

 

[datarebal]

what is the measurement of the exposed tile. not your interpretation .
no point measuring the front apron , its always going to be the same

 

[an203888]

what is the measurement of the exposed tile. not your interpretation .
no point measuring the front apron , its always going to be the same

The exposed tile will be 370mm.

 

[datarebal]

will be or is..doubtful

 

[an203888]

I'm going off assumptions, judging by the tiles they shouldn't of required a cut course under the window.
The front apron is 15/20mm max above the corresponding tile if you say it covers 50mm, and you've lost 20mm maximum...where's the other 30mm gone.

Excellent point. I must admit, I didn't measure every tile to see how much they overlapped each other, just two hich were about 110mm.

So what people seem to be saying is that above the window looks OK? Even though its on the limit. However the bottom apron needs to overlap more than it does?

I will see if I can go back to take some better measurements. It does look like quite a neat job to be fair.

 

[Barthy]

From my memory interlocking tiles are around the 420mm mark meaning you definitely don't have 100mm headlap

 

[an203888]

From my memory interlocking tiles are around the 420mm mark meaning you definitely don't have 100mm headlap

Spot on - tiles are 420 long and as you say it looks as if some do not have 100mm headlap. I know that some do though. What would you ask the builder to do if this was the case?

 

[datarebal]

There is also the usual condensation droplets on the underside of the aluminium but this doesn't appear to be that.

why not?