My block built chimney is leaking a little water into the loft. It is where the haunching at the back of the chimney that covers the lead flashing has blown from the blocks leaving a small gap for the rain to penetrate.
I am going to replace the cement to reseal the flashing but have no waterproof PVA available to create a key. Will I be OK using B&Q multipurpose or Wickes Universal PVA instead? I will be using waterproofed 4:1 cement for the job but imagine is would be advisable to use PVA first for a good key to the leadwork and block.