Treating rust between roof skins...?

[The Z'eer]

My roof is double skinned, approximately about an inch between the skins. Rust deposits are present, some flakey like debris when poking around. The upper skin topside (painted exterior) shows no signs of rust, although corrosion on the underside of it is apparent and on the interior skin.

Certain areas do allow minimal access to which I wondered if there was any preventative measures of slowing or ceasing the corrosion?

Thanks

 

[the snooper]

cavity wax using a schutz gun with attatchment

 

[cocker]

Waxoyl type stuff

 

[roofman]

Thats condensation causing that mate..whatever you spray in try not to block the exit of the water getting out and actually airflow would be better iff your not able to insulate the top.

 

[Lufbramatt]

Bilt hamber dynax aerosols come with a very thin lance about 50cm long which is great for getting to places like that.

 

[steveo3002]

how about some pics before we get into 2-3 pages of back n forth

is it a bit of light surface rust from 30+ years condensation or is it rotten