Roll mastic sizes, which one to use?

[SmnByt]

Hi everyone,

A quick question, I want to reseal the two joints across the roof, one at the front and one at the back of my van, the sealing strip is 25mm wide so do I use 32mm bedding mastic on a roll? I'm assuming the 19mm mastic would obviously be to narrow to be effective

Simon

 

[Damian]

A quick answer.
Don't use roll mastic on the roof straps, use Soudall Fixall or Sikaflex 512 gunned mastic, and plenty of it.

 

[SmnByt]

A quick answer.
Don't use roll mastic on the roof straps, use Soudall Fixall or Sikaflex 512 gunned mastic, and plenty of it.

Why can't or shouldn't the roll mastic be used on the roof straps, is it strength issue?

 

[DeliDave_]

When ive used the roll sealer its been very stiff and didnt ouze out of the gaps,the gunned sealant seems lots softer and squashes out easily

 

[Damian]

Quote:
"Why can't or shouldn't the roll mastic be used on the roof straps, is it strength issue? "

Because it is the wrong thing to use in the application you describe , simple as that.