waterproofing contractor

My brother is a waterproofing contractor, a colleague today, suddenly asked me if I knew waterproofing contractor and I said my brother is doing this, he said his family these days have been renovated house, recently he has been busy buying various building materials but several times to buy some waterproof building materials in the building materials market can always can not find himself in the right, not the price is too high, is the building material of rough work, later a friend recommended him waterproof building materials for the brand, but he has been unable to find the waterproofing contractor so I think asked me if I know the friend.