HELP - Aluminum/Zinc Roof Leak??

[hyeung]

Hi,

We have had a long on going issue with our dormer roof leaking (started since Feb this year).
To cut a long story short, our housing factors contractors carried out a major repair (a full dormer roof rebuild with a steeper pitch).
However, since this work a new leak was introduced around where the barrelled section meets the new dormer roof section (see highlighted red lines in AFTER image).

BEFORE


AFTER



Since the inital repair, it has taken the contractors 3 further visits to locate the issues. Each time refusing to believe that the issue is related to their work. Since then they have agreed that cracks have been introduced when bending the metal (where the old meets the new).

During their recent visit, they identified some cracks and have attempted to seal these up. Its been a good number of weeks of which we've had a fair bit of rain and no further leaks have been noted. So i have reason to believe the cracks have been the cause of the problems to date.

With regards to the sealing of the cracks; I cannot comment on what was used other than some form of roof bonding agent.

Since the repair I have spoken to the housing factors and argued that damage was caused due to the inital repair works, and that i am now concerned with the longiveity of such repair i.e sealed cracks?
The factors have spoken with their contractors and offered an alternative detailing to the repair. At the moment i'm not sure what the exact details are of this?

Can i get some advice with regards to the recent repair works i.e. sealing cracks on an Aluiminum roof?
What is the longiveity of such a repair, Based on what was done, is this appropriate?

My knowledge is limited of such roofs and my dilemma is whenever to accept what was recently done (sealing cracks) or should i challenge this and request to get it repaired in a certain way???


Cracks

 

[htgeng]

I don't think you have to be an expert in roofing to realise that design will always have a inclination to leak where those two roofs meet. btw, what are 'housing factors contractors'?

I'd like to hear what 'hardmetalking' has to comment since he is a Zinc roof installer, but this is my view; When it rains hard, water will shoot down down both pitches towards that valley area and then just sit in the troughs until it spills over and is able to drain away. When the rain stops, the only way for water to go away is by evaporation or by capillary action through the seams and into the space below.

Whoever designed the original roof was correct in their layout. What was the leak on that part of the roof? The people who who made the modification to raise the flat section haven't taken into consideration the rainfall issue and to be honest, I think it will have to be removed. There will always be leaking at that valley point. It may be possible to bodge it for a few months by squirting something down the joints, but water will always find the tiniest leak point and then the whole lot is compromised.

 

[hyeung]

The roof has been fine for just over 5 years as we've been there from the beginning. The original leak was near the gutter, on the middle section of the dormer roof. We were told there was an insufficent slope on the dormer roof in the orignal design. This was the cause of ponding and water managed to seap in via capillary action.
So they suggested that it would be best to perform a full dormer rebuild. The area was stripped back and additional plywood was applied to construct a steeper pitch. New sheets were laid and integrated into the existing roof (light grey in colour).

Thereafter, the original leaks were fixed but a new leak was introduced around the area where the old panel meet the new around the barrelled section in the images (red line highlighted). They suspect that when bending the metal back during the works, hairline cracks were introduced.
However, i'm not sure if these are around the seams, or if these are on exposed on the panels between the standing seams.

We've been told the cracks were now sealed by squirting some form of bonding agent. It would appear no further leaks have been experenced since.

Currently we're not sure how best to proceed with this.


As they have aimed to rebuild the dormer roof (flat section) with a steeper pitch than before. Can you clarify what rainfall issues they havent taken into consideration?

I don't think you have to be an expert in roofing to realise that design will always have a inclination to leak where those two roofs meet. btw, what are 'housing factors contractors'?

I'd like to hear what 'hardmetalking' has to comment since he is a Zinc roof installer, but this is my view; When it rains hard, water will shoot down down both pitches towards that valley area and then just sit in the troughs until it spills over and is able to drain away. When the rain stops, the only way for water to go away is by evaporation or by capillary action through the seams and into the space below.

Whoever designed the original roof was correct in their layout. What was the leak on that part of the roof? The people who who made the modification to raise the flat section haven't taken into consideration the rainfall issue and to be honest, I think it will have to be removed. There will always be leaking at that valley point. It may be possible to bodge it for a few months by squirting something down the joints, but water will always find the tiniest leak point and then the whole lot is compromised.

 

[hardmetalking]

htgeng is spot on.

This is all down to poor design originally and poor installation. I can't believe the contractors went ahead without highlighting the obvious design faults knowing it will eventually leak.

This looks like an aluminium roof to me, which is bad news because if it was zinc it would have been possible to solder the splits/cracks and eliminate the problem for many years. However this isn't possible with aluminium due to it being so thin. This explains the bonding agent being used however this is only a short term fix and one I wouldn't be very happy with.

I'm sorry to have to say this but to do it properly you need to strip the problem area from top to bottom and fit new sheets. I can't see the pitch or build up being a problem as long as it's done properly this time! A site visit always helps but don't be conned into thinking the problem is solved because it isn't.

If you need anymore advice you just have to ask.

 

[htgeng]

As they have aimed to rebuild the dormer roof (flat section) with a steeper pitch than before. Can you clarify what rainfall issues they havent taken into consideration?

Well a practical demonstration is easier than words. Take a hose pipe onto the roof and let it spray onto the roof for 10-20 mins. Take photos of the resulting water that remains at the point were the two pitches meet. Post them here.

 

[hyeung]

I'm afriad i dont have access to the roof. Even if i did i wouldnt be confident walking up there We live in the top floor flat about 5 floors up.

The photos i sent eariler were taken by the contractor and pass to our factors.

The whole situation has been a stressful one. Particularly as the factors are unhelpful in all this. The factors have tried to push me to accept the recent repair i.e seal. But after long arguments the factors have agreed that the contractor will carry out some alternative detail to the repair and pick up the cost. I'm awaiting further information on what exactly they plan to do.

I hope they would replace existing full length sheets laided on the dormer roof and extend slight further up the barelled sections of the roof. However, i'm not sure if they would just cut out a small area of the new sheet where there are cracks, and integrate a new sheet in its place; which in effect would form more joins than before (not ideal)
Would this still be a valid repair or should i refuse anything other than replacing a full one piece sheet?

Any thoughts?

The problem is my lack of knowledge in all this to argue; and not being able to assess the roof itself. The factors are completely useless and are trying to take the easiest route possible. And i've been disappointed with the contractors as they have tried to get out of this and claim all is fine. They have had 3-4 attempts and have only recently discovered the problems of the cracks (the main cause of ingress after their repair)
Does anyone know of any firms in the Glasgow area that would help me assess the situation from a technical point of view. I'm thinking on the worst case i need to take this further to a lawyer, with a view of having evidence at hand?
Any other advice would be appreciated on how best to proceed?

As they have aimed to rebuild the dormer roof (flat section) with a steeper pitch than before. Can you clarify what rainfall issues they havent taken into consideration?

Well a practical demonstration is easier than words. Take a hose pipe onto the roof and let it spray onto the roof for 10-20 mins. Take photos of the resulting water that remains at the point were the two pitches meet. Post them here.