At Melbourne House Check we often see decaying mortar in brick houses during house inspections in Melbourne. This powdery, decaying mortar is called fretting. Essentially, fretting is where the mortar between brickwork begins to ‘fret’ or fall away. There are a few theories on why fretting occurs, but the science of fretting mortar is all about the presences of salts, and basically, fretting is the erosion of mortar by the presence and subsequent evaporation of water, and the growing of salt crystals which corrode the mortar joint. As the brick dries, the salt is left behind and forms salt crystals, which grow in the voids within the bricks and mortar. As more salt is left behind by the evaporation of water, salt crystals grow larger and larger, and the strength of these growing salt crystals can often be stronger than the elements that hold the brick together and subsequently the mortar crumbles away. Fretting mortar is easy to spot during house inspections. Look at the cement joints, and if you see any crumbling or powdery mortar it’s a good indication that the brickwork is fretting. In its advanced stages the mortar will be almost completely missing, and at that point, the rows of bricks may begin to collapse onto the bricks below, similar to the attached photo. Fretting mortar can be hard to stop, so it’s crucial to identify were the salts are coming from in the first place. It may be from within the brick or mortar, or an outside source, like exposed weather or constant watering. In its advanced stages the only real way of rectifying mortar fretting is to re point the brickwork, which can often be an expensive procedure. So, if you are conducting your own pre purchase building inspections in Melbourne, and you come across fretting mortar, call us at Melbourne house Check for free advice on 1300 729 352, or send us an email here. You can view our Google+ post on decaying mortar also.
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