Hi,
I've never used the stuff, so I don't really know its properties.
We had new plastic guttering/fall pipes installed ome years ago. People next door (other half of semi) have just had square section system put in, which does not match up with ours. Our round fall pipes have been removed and now replaced with square, without a 'would you mind if...'.
Our half round gutters obviously do not fit the square T at the top of the fall pipe, so the installers instead of obtaining an adaptor, just stuck it in with expanding foam.
The question is, is this adeqaute, or can we expect deterioration and problems later? I suspect the later.