One For TerryTraveller (And Others?)

[Vernon B]

Charlie&me - 2007-09-02 1:42 AM

 

A test.....when you are totally dry, boil a pint of water in a saucepan with the lid off and see if it progresses to your suspect area, this could prove some of us right or wrong.

 

 

 

 

Urika !!!!!!!!!!!!!!!!!!!!!

 

C&m you’ve provided the break through after me and various others have been casting around for over 18 months. The challenge, as you and others have mentioned time and time again, has been to isolate each of the variables and test a series of hypotheses. And as ever the way forward has been staring me in the face …

 

The supposition that the moisture was condensation rather than ingress was always tricky when faced with the question “Why is it occurring on only one side of the roof ceiling?”

 

I never asked the question “Could condensation form on the other side?”

 

By using a version of your boiling water experiment I’ve found out two things:

 

1) Yes condensation forms on this lining (when bonded to GRP) and gives a reading on the damp meter.

 

And most importantly

 

2) To get a moisture reading on the other side of the roof you need to have very considerably more condensation!!!!!! In fact on the problem side just “breathing out” will form condensation but you have to apply considerable amounts of steam to get it on the other side.

 

This is very, very reassuring since it confirms the dealer’s and my own gut feeling. It still leaves the problem of why different parts of the same material are behaving differently and more importantly how it can be remedied without tearing out all roof lining in the cab area.

 

For the moment however let’s just bask in the pleasure of this achievement..

 

[You know this outcome is all down to the years and years of the collective experience represented on this Forum – and the yung uns still ignore us!]

 

Thanks to all who have contributed especially C&m – all we have to do now is fix it – Any thoughts?

 

 

V

 

[Brambles]

Good you have a break through.

 

One reason is the cavity in the roof is saturated with water giving it a higher thermal mass, or heat conductivity. So how do you test? I can only think you now need invasive surgery!!. You could try tapping it with a small hammer or other suitable implement and see if it sounds different to the other side, but I think you need to drill a small hole and have a probe inside the cavity.

Jon.

[Charlieme]

Sounds as though you are nearly there.

 

I dont know what the insulation material is but many are made by injecting two or more substances into one moulding entry point where they either expand or mix to the correct value.

 

Its possible that when the insulation material was formed there was a shortage of one element in the section you have during a 'moulding run' resulting in a variable insulation value.

 

I worked for many years at the 'sharp end' of the Plastic Injection Moulding Trade and have seen many unusual problems. They have mostly been very simple to solve with persistance using a few basic principles of physics.

 

The next stage is what can you do about it

 

 

[Vernon B]

Thanks C&m and Jon

 

Armed with all this me thinks a trip back to the dealer might now be in order.

 

V