Corrosion beneath roof

[Simon enderby]

hi
We have recently bought a 2011 Cali. I was aware of the roof corrosion issue and looked closely at the paint work on the roof when buying, no obvious signs of paint blistering.
The previous owners had the repairs carried out in 2015.
I have now noticed that what looks like the frame to the underside of the roof has started to show signs of corrosion to the corners. See photos. There are no signs of any issues on the paint surface above, yet.
Is this the first stage that will develop into blistering on the roof itself or will it be limited to the areas it is currently on?

 

[WelshGas]

View attachment 31344 View attachment 31345 View attachment 31346 hi
We have recently bought a 2011 Cali. I was aware of the roof corrosion issue and looked closely at the paint work on the roof when buying, no obvious signs of paint blistering.
The previous owners had the repairs carried out in 2015.
I have now noticed that what looks like the frame to the underside of the roof has started to show signs of corrosion to the corners. See photos. There are no signs of any issues on the paint surface above, yet.
Is this the first stage that will develop into blistering on the roof itself or will it be limited to the areas it is currently on?

The underframe is steel unlike the roof panel and the front section over the windscreen which are made of Aluminium Alloy and suffered from Galvanic Corrosion. VW have done the repair for that as you stated.
What you have is different to that, but could be covered by the 12 yr Perforation Warranty. Basically Corrosion that perforated the paint layer from beneath.

Knowing VW you could have a little battle on your hands, firstly convincing your local Dealership.

 

[Simon enderby]

The underframe is steel unlike the roof panel and the front section over the windscreen which are made of Aluminium Alloy and suffered from Galvanic Corrosion. VW have done the repair for that as you stated.
What you have is different to that, but could be covered by the 12 yr Perforation Warranty. Basically Corrosion that perforated the paint layer from beneath.

Knowing VW you could have a little battle on your hands, firstly convincing your local Dealership.

The issue seems to just be to the corners of the underframe, with the rest of the frame appearing to be of a different material.
Would these corner pieces have been replaced when the roof repairs were carried out?

 

[Jabberwocky]

I notice in the second photo that the seal seems to be dislodged. This will have allowed moisture to accumulate behind/above the underframe. Worth investigating further probably before you start your discussions with VW. Certainly you should make sure this seal is where it should be before letting the VW technicians loose on your Cali. (they will pick up on this displacement and try and blame it for the steel frame corrosion.)
All the best.

 

[Simon enderby]

I notice in the second photo that the seal seems to be dislodged. This will have allowed moisture to accumulate behind/above the underframe. Worth investigating further probably before you start your discussions with VW. Certainly you should make sure this seal is where it should be before letting the VW technicians loose on your Cali. (they will pick up on this displacement and try and blame it for the steel frame corrosion.)
All the best.

Thanks for the heads up. I noticed the corrosion earlier today when I was removing our roof topper, it started to pull the seal off the front when I removed it. I have now re seated the seal and the gap that I think you are referring to in the photo is now closed. The seal doesn’t seem to fit on this curved section as well as it does on the straight section, but the gap is closed.

 

[WelshGas]

The issue seems to just be to the corners of the underframe, with the rest of the frame appearing to be of a different material.
Would these corner pieces have been replaced when the roof repairs were carried out?

No. They are not involved in the repair.
The section above the windscreen is replaced, nothing on the opening roof panel.

 

[Jabberwocky]

Thanks for the heads up. I noticed the corrosion earlier today when I was removing our roof topper, it started to pull the seal off the front when I removed it. I have now re seated the seal and the gap that I think you are referring to in the photo is now closed. The seal doesn’t seem to fit on this curved section as well as it does on the straight section, but the gap is closed.

I'm guessing you are talking about an external topper? If so the seal could have been dislodged for some time without anyone noticing. Getting the topper fitted can be a game of tug of war and its easy to dislodge seals without noticing. It's for this reason we do not have an external topper. If I were you, I'd be disinclined to let VW know a topper has been used for any length of time. (It's an after market product after all)
How do we keep warm on cold nights? An extra glass of wine, an extra blanket and a quick cuddle!!
Good luck.

 

[Simon enderby]

I'm guessing you are talking about an external topper? If so the seal could have been dislodged for some time without anyone noticing. Getting the topper fitted can be a game of tug of war and its easy to dislodge seals without noticing. It's for this reason we do not have an external topper. If I were you, I'd be disinclined to let VW know a topper has been used for any length of time. (It's an after market product after all)
How do we keep warm on cold nights? An extra glass of wine, an extra blanket and a quick cuddle!!
Good luck.

It was the first time we have used the topper. Fitting was easy and not too tight or fiddly but i was lazy and took it off without lowering the roof, hence dislodging the seal.
How do you find the weatherproofness without an external topper? We tend to go out in all weathers.

 

[GrannyJen]

It was the first time we have used the topper. Fitting was easy and not too tight or fiddly but i was lazy and took it off without lowering the roof, hence dislodging the seal.
How do you find the weatherproofness without an external topper? We tend to go out in all weathers.

I camp all year round and have never used a topper.

If sleeping upstairs in wet weather, or any other activity in the wet, just be careful of rubbing the canvas as that will set up water ingress through capillary action. Other than that, no problems at all.

 

[Loz]

These areas can often be a collection point for condensation especially after a wet weekend away. I always try to get the roof up for an hour on the next dry day and wipe away any condensation otherwise this is inevitable.

 

[Simon enderby]

These areas can often be a collection point for condensation especially after a wet weekend away. I always try to get the roof up for an hour on the next dry day and wipe away any condensation otherwise this is inevitable.

Thanks for the heads up on condensation. I’m always conscious of airing the roof thoroughly but will now make sure to dry the corners as well.
From your experience/knowledge is there a risk that this corrosion will develop onto the roof, and specifically external paint work.

 

[Loz]

Thanks for the heads up on condensation. I’m always conscious of airing the roof thoroughly but will now make sure to dry the corners as well.
From your experience/knowledge is there a risk that this corrosion will develop onto the roof, and specifically external paint work.

The different areas are not related but susceptible to corrosion for different reasons.
I also spray those areas with silicone spray as an additional attempt to keep moisture from getting under the paint.

 

[DavidofHook]

It was the first time we have used the topper. Fitting was easy and not too tight or fiddly but i was lazy and took it off without lowering the roof, hence dislodging the seal.
How do you find the weatherproofness without an external topper? We tend to go out in all weathers.

Hi, we had a T4 Westfalia California for 9 years and our present T5 we have had for 6. We have camped mostly abroad but also in the UK in all weathers and never had a problem with water ingress. We sleep downstairs, so upstairs is kept clear and there is no risk of touching the sides. Even in storms in France we have never needed to lower the roof
Hope that helps.

 

[RonB]

Thanks for the heads up on condensation. I’m always conscious of airing the roof thoroughly but will now make sure to dry the corners as well.
From your experience/knowledge is there a risk that this corrosion will develop onto the roof, and specifically external paint work.

Hi, sorry to be a little late in joining the conversation. I have a 2013 Cali and have recently encountered the same issue with flaking paint on the sub-frame corners. Our local VW body shop had treated the roof edge blistering under the extended 6 year corrosion warranty a couple of years ago. As stated previously by WG, the sub-frame is steel and not covered by this, although at the time, this was not a visible fault.

The corner pieces were not replaced at the time of the repair, the flaking paint is probably a result of a combination of condensation and poor paint application at the factory. A claim under warranty however was not accepted by VW for this repair, so body shop have repaired by removing roof, removing flaking paint and respraying subframe including roof-supporting arms with what I believe is a 'hammerite' type of paint.

It looks a very good paint job and hopefully will pass the test of time. Their advice, as others have stated, is to keep moisture to a minimum by drying off, difficult as that may be with our current climate. I would suggest that you do get this sorted, as I would worry about the problem spreading over time.

 

[Beeechke1]

As this thread is now coming up for 5 years old thought it might be worth re visiting this issue. My 2010 T5.1 is now showing some surface corrosion to all four corners of the lifting roof sub frame (pictures below) The corners appear to be distinct individual pieces separate from the rest of the sub roof framing. The corrosion has resulted in a fine white powder under the blistering paint that looks like aluminum corrosion rather than steel to me. Can anyone confirm a) what material are these corner pieces aluminum or steel? and b) what would be the best product(s) to treat the corrosion and repaint?

Thanks in advance Kelvin

 

[ArunAlec]

As this thread is now coming up for 5 years old thought it might be worth re visiting this issue. My 2010 T5.1 is now showing some surface corrosion to all four corners of the lifting roof sub frame (pictures below) The corners appear to be distinct individual pieces separate from the rest of the sub roof framing. The corrosion has resulted in a fine white powder under the blistering paint that looks like aluminum corrosion rather than steel to me. Can anyone confirm a) what material are these corner pieces aluminum or steel? and b) what would be the best product(s) to treat the corrosion and repaint?

Thanks in advance Kelvin

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Pretty sure you will find its ally, check with a magnet. I would just gently remove any flaking paint and dust and wipe over with ACF 50.
My understanding of aluminium “corrosion“ (based on canoes) is that it is surface oxidation so not any real worry.

 

[Beeechke1]

@ArunAlec Thanks that sounds like a really easy fix

 

[ArunAlec]

@ArunAlec Thanks that sounds like a really easy fix

If it’s taken 13 years for yours to corrode that much I reckon the roof is good for a good few decades!