Once you have fixed your roofing trims into position the Joints and Corners will need to be Bandaged with Chopped strand Matting or Chopped Strand Tape. For a really great final look many Fibreglass Flat Roofers will also use a layer of Surface Tissue to create a smooth profile finish, especially on balconies and walkways.
PREPARATION
If you are using Chopped Strand Matting you will need to cut up some 3 inch strips 6 – 8 inches long. You can also tear the CSM off in 6 inch squares for the corner bandage. 1 Layer will be enough for the straight trim joints and 2 layers for the corners to give a little extra strength. At this stage it would be a good idea to placed which pieces of CSM you are going to use at each joint prior to adding your resin. You will also want some surface tissue roughly 16 inches long and as deep as the joint length.
A Small Consolidating Roller and a 2 Inch Brush and a 4 Inch Resin Roller, a Small Mixing Cup and 2 Pairs of Protective Nitrile Gloves are the tools you would need.
It is a good idea to mix your resin in small quantities little and often to avoid wastage using a mixing cup which can hold between Half and 1kg of resin at any time. Another little trick would be to add just 1% Catalyst to your Resin for the bandaging as this will give you an extended working time and help minimise any wastage. At 1% you would be adding just 10g of Catalyst to 1kg of Resin.
Straight Trim Joints
Start with the Straight Trim Joints as these will be the easiest. Making sure you wear your protective gloves, mix the resin and catalyst together and on a piece of cut off OSB board wet out one of your 3 inch by 8 inch CSM Strips. Use the brush or 4 inch roller. Making sure the joint is clean and free of dirt lay your wetted out CSM with your hands over the length of the joint remembering to hook the end up into the bottom tail of the trim. Add additional resin if needed and then stipple the resin into the CSM with the brush before consolidation with the paddle roller. Wipe away any excess resin and make sure the bandage is neat and tidy following the profile of the roof line.
Corner Bandage Joints
For the Corner Bandage use the 6 Inch Squares you have prepared. Again wet out 4 or 5 Squares of CSM and begin to wrap your first piece around the corner and then coming for the opposite side wrap another back towards to first making sure you have a 2 inch overlap. You will find that the CSM once wetted out will follow the contours and shape of the corners easily and can be worked in with the resin roller and brush until the CSM follows the profile perfectly. Remove any excess resin and then use the paddle roller to consolidate the whole area.
Applying the Surface Tissue.
Once you have consolidated your joint you can quickly add your surface tissue which will be very easy to cover and manipulate into the shape of your joint. Using your roller simply push this into place and wrap neatly over and around your joint. Note any areas of the Surface Tissue that needs any additional resin but normally the tissue will absorb enough from the surface of your working area. Once in place and neat, tidy and following the profile of the roof leave your bandages to cure for an hour.
SANDING
Once all your bandages have cured you are ready to sand these back with a 60 grit orbital sander or similar. Denibb your work and sand to the profile of the roof. We find bandaging corners to give a far superior and preferred finish to pre formed corners which often distort under expansion and contraction during hot summer months.
