Why Coating Assemblies Fail

As a waterproofing contractor specializing in failure, I give little merit to manufactures and their claims regarding the durability or longevity of their deck coating assemblies. All these assemblies have issues and the proof is seen in the photos below which were taken from inspections DeckTech, Inc. has provided to our clients. The key to a durable and long-lasting deck is finding an assembly that meets the specific needs of the project environment and then ensuring fundamentals are sound prior to any application.

Acrylic Coatings

The Acrylic Cement coatings Life Deck, Desert-Crete, West-Coat and numerous others, all fail here on the coast. The expanded hot dip metal lath will rust out, the hot dip protective coating is immediately impacted upon installation when lath is cut and stapled. The lath is rarely stapled to manufactures spec. 22-28 staples per square foot and as lath moves around due to this deficient stapling & Expansion /Contraction of substrates, the acrylic cement is very ridged and fractures. Once you have a fracture in this assembly the moisture enters into lath and then cannot escape. The lath then accelerates with rust and loses additional tensile strength accentuating even more fractures. This condition then leads to total failure and excessive moisture intrusion. The end.

Urethane Coatings

The Urethane direct bond or lath systems Tuff-Flex-Plydeck/MA-Coat are thin wall coatings and many have flashing strips installed over plywood seams. Others have diamond lath. The thin wall coating actually will make flashing sweat, because coating thickness is so thin it allows a certain amount of condensation to enter flashing details in damp environments (Coastal Region) These systems all have issues with flashing failure. The other deficiency we typically see is telegraphing of all plywood seams and nailing. All these assemblies fail at the plywood seams, nailing and flashing edges.

Neoprene Coatings

The Slip-Sheet deck coating Merkote Weather-Deck is a soft Neoprene and as photos indicate they dent and ding easily if items are dropped on them or furniture moved around on them. They also have chronic issues with nail heads backing out and penetrating through the coating. This assembly has been in use for years but very outdated due to new technology in the coating industry. This assembly needs a lot of TLC and if not given this attention will fracture and fail.


Ron J. McKenna

DeckTech, Inc. President

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