Suntuf Access Tape is a purlin tape used when installing polycarbonate roofing. Providing a professional touch, the use of purlin tape between wooden rafters and polycarbonate roof sheets reduces the crackling noise that occurs as the polycarbonate sheeting expands and contracts slightly during weather fluctuations. When purlin tape is used the sheet slides over the PE surface and naturally expands to provide the householder the positive screen they want without the nuisance of a crackling sound.