Adam wrote:
"Phil L" wrote in message
.uk...
Adam wrote:
We had some roofing contractors replacing the flashing on our flat
roof earlier this week. They left the job unfinished, as it was
raining at the time, and said that they couldn't cement the flashing
in place while it was raining. This sounded reasonable, and I
believed them.
They came back today to finish the job. It was raining again this
morning, but they went ahead and did it anyway.

So, were they just looking for an excuse to skive off early when
they were with us earlier in the week, or is the cement they put in
place today not going to set properly?

It depends which way the rain is driving, the other day it could
have been blowing against this wall, today it may be blowing in the
opposite direction leaving this wall relatively dry...cement still
sets in the rain, but running water will cause it to wash out, if it
does this, you will be left with a cementy mess on your roof!


Thanks for that. So does that mean that if it looks OK in a couple of
days' time and isn't a cementy mess all over the roof then it
probably is OK?
Adam

Basiclly, yes, and it doesn't need a few days, if it's alright after 12
hours it's not going to wash out, no matter how much it gets wet.