Crumbly Chipboard

1970’s built deck, chipboard substrate, originally Nuralite asphalt sheet membrane (note black adhesive patches in photos). Replaced at some stage with Butynol Grey rubber. Parts of the chipboard had swollen up where there had been leaks, at the door corner and under the window, also several places in the deck field, possibly caused by nicks/cuts or joint failure. During the replacement of the Nuralite the installers dug out and filled the swollen areas with a cementious compound.
This time: Cut out and remove suspect chipboard and dispose, replace with 19mm plywood incl. new dwang supports where required. Rescrew remaining chipboard with Stainless Steel screws.
Sand deck and install new 1.5mm Black Butynol.
hover cursor over image for text, click image for larger version (600×450 pixels)

first strip of old butynol pulled off closer view showing patching of chipboard another patch of plaster in swollen chipboard chipboard is crumbly (like Wheetbix) area near door in image 3 being removed defective areas are cut out and removed reverse view from previous image new dwangs needed to support 2015 plywood metric sizes overview of the new plywood patches area near door repaired reverse view from image 10 new plywood under window deck tarped up for the night, low temperatures=heavy dew forecast joints are filled and the entire deck sanded joints are filled and the entire deck sanded substrate is primed 50/50 adhesive and solvent mix substrate sheet joints are taped and first sheet of 1.5mm butynol going down second sheet going on reverse view third sheet glued up view along wall edge with upstand before tuckup upstand tucked under wall flashing view of the finished buytnol, looking east at south wall/window view of the finished buytnol, looking west, south wall/door view of the finished buytnol, west, outside railing view of the finished buytnol, east, outside railing new timber batten over turndown new timber batten over turndown view of the deck from below view of the deck on the house