Quote:
Originally Posted by grumpygrouter  If you are using BAL cement based adhesive, then yes you do. Some adhesive manufacturers say it is not necessary but in any case it would not hurt to do so. priming gives you protection from the possibility of Ettringite Crystalisation forming as the gypsum of the plasterboard can react with the chemicals in the cement based addy. |
Make sure you use an acrylic primer and not PVA, too.