Maintenance Coating of Existing Decks

John Stallard Most of the aged acrylic Hi Build deck membrane systems that are in need of maintenance are the fibre glass reinforced systems. There are around 5 systems that were promoted heavily in the early 1990,s through to 2005, and in some cases these have become very problematic when installed directly onto a plywood substrate. It is important that a survey is conducted on every deck where there is evidence of water ingress, a registered building surveyor should be engaged to report on the substrate structure. There will be situations where the deck has remained watertight with no issues but just requires re-coating to extend the serviceable life of the existing deck membrane system. Once you have considered all of the above points and the deck is deemed to be satisfactory and ready for re-coating, carefully follow the points below.

Preparation

  1. Ensure all joints and laps are watertight to prevent water ingress while cleaning.
  2. Pressure clean the existing acrylic substrate using clean water and an environmentally safe cleaning liquid. Remove all contamination and wash all traces of the cleaning liquid away and leave to dry.
  3. Prime the substrate with Gripset OP primer with 2 coats onto an existing surface @ 1Lt/10m2 per coat.
  4. Make good any substrate sheet joints using 80mm wide Gripset butylFLASH tape and applying with heat gun. Check all the rainwater droppers and scuppers to ensure all these junctions are watertight. Use a hand roller and over roll the butylFLASH tape with pressure to ensure an absolute bond.
  5. Apply the first coat of Gripset RD at a rate of 1.0 litre per m2 wet film thickness keeping a wet edge at all times. Apply evenly across the entire deck surface. Do not apply in hot and direct sunlight. Best conditions are warm, slightly overcast with a breeze for best application and drying. Leave for a minimum of 24 hours to dry.
  6. Apply the second coat of Gripset RD at a rate of 1.0 litre per m2 wet film thickness keeping a wet edge at all times. Apply evenly across the entire surface in the opposite direction to the first coat to ensure even film thickness across both applications of the deck surface. Do not apply in hot and direct sunlight. Best conditions are warm, slightly overcast with a breeze for best application and drying. Do not use the deck for 7 days to allow curing of the membrane.

Notes

  1. It is our recommendation not to use any liquid membrane system on an external deck substrate with a plywood surface. We recommend to the owners to use fibre cement board as this is the best option.
  2. A trafficable wear coat can be applied in the form of sand blinding over the completed Gripset coating completed.
  3. Do not use deep dye colours. The UV will diminish the colour fastness and thermal heat may cause substrate movement affecting the coating at joints.
  4. Make good any substrate sheet joints using 80mm wide Gripset butylFLASH tape and applying with heat gun. Check all the rainwater droppers and scuppers to ensure all these junctions are watertight. Use a hand roller and over roll the butylFLASH tape with pressure to ensure an absolute bond.
  5. Apply the first coat of Gripset RD at a rate of 1.0 litre per m2 wet film thickness keeping a wet edge at all times. Apply evenly across the entire deck surface. Do not apply in hot and direct sunlight. Best conditions are warm, slightly overcast with a breeze for best application and drying. Leave for a minimum of 24 hours to dry.
  6. For a hard wear surface over the newly finished coating, ABS uncoupling mat can be installed to allow for a tiled finish. Advise the client no direct tiling on Gripset RD is allowed under the NZBC Removable surfaces.
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