Hello,

I have got to replace the rotten chipboard on my flat roof. I keep
meaning to do it before summer ends! Every now and again I phone
around timber merchants to see how much wbp plywood is (4' x 8' x
18mm, excuse the mixed units). Over the months the price seems to have
gone up and up but one firm who specialise in "roof supplies" say they
can supply at 17gbp + vat. That seems to good to be true. Should I be
suspicious or should I buy, buy, buy?

Another timber yard recommended osb3. I know that can be used for flat
roofs but is plywood better?

TIA