Grunff wrote:
Pecanfan wrote:

It says on the side of Wickes expanding polyurethane foam that, if used
externally, it should be covered (with filler or mortar) within 7 days
since
it's not UV resistant.

Anyone have any experience of exactly *what* happens to this foam if it's
not covered within 7 days?

I've just braved the elements for 3 days moving an external door - the
new
door is finally vaguely weatherproof (with a combination of expanding
foam
and frame sealant) but I really can't be arsed rendering & painting
around
it before the spring. Am I being foolish? If so, as a temporary
measure,
could I just paint the foam with some form oil-based primer?


The foam will initially darken in colour. In a few weeks, it will have
hardened considerably, losing much of its flexibility. In a few months
it will start to break up. A couple of years and it will be gone.

Painting it with a couple of coats of primer will stop this, but will
make it difficult to render later.

I'd agree with all that but I think the 7-day deadline is unnecessarily
short - bit of backside-covering I think! But I wouldn't wait as long
as spring before covering it.

Hey, this sounds like a good excuse to cite Peter Parry's fantastic
Expanding Foam Story, for the benefit of uk.d-i-y newbies, at:
http://www.diyfaq.org.uk/humour.html#foam A must-read!

David

(and NB to newbies: the rest of the uk.d-i-y FAQ is worth a read while
you're in there...)