Well let’s start with the facts first shall we, yes - in fact mastic asphalt is one of the very few waterproofing materials that can with the right preparation and application can be rectified easily.
Mastic Asphalt damage can be easily recognised by anyone, yes anyone, once expertly laid by hand crafted tools of an asphalter the final finish of this age-old heritage system leaves a completely seamless waterproofing layer laid to the falls of the roof.
•Bumps on the mastic asphalt surface that are raised and often rounded in shape. Visually to the eye these will appear to be obvious and unnatural in relation to rest of the flat areas. They are generally caused by trapped moisture beneath the surface of the asphalt and can be singular or multiple in number (also referred to as blows or blisters the later being in the final stages of the defects penultimate damage).
•Blisters these are often raised from the flat contours of the mastic asphalt surface circular in appearance to blows/bumps but with the top split or cracked open. To the eye these will appear to be again obvious and unnatural, not unlike small volcanos on the flat areas. They are generally caused by trapped moisture beneath the surface of the asphalt and can be singular or multiple in number.
•Cracks & Splits can be caused by trapped moisture, water seeping into a crack or split can be very damaging. In winter time rainwater in slits/cracks often turns to ice expanding the water volume and as a result pushes against the asphalt increasing the crack. This pushing can cause then wrinkles/creasing cracks or splits often also due to thermal movement in the substrate or impact damage are very clear to see.