There are three types of plywood available in the market; Moisture Resistant Plywood or commercial plywood, Boiling Water Resistant Plywood and Boiling Water Proof or marine plywood. Of all the three types of plywood, marine grade plywood is the best in terms of strength and overall quality. Marine plywood is completely waterproof and is made of superior quality of wood and glue as compared to MR and BWR grades of plywood. There are many types of marine plywood available in the market classified according to grades.
Essential features of marine plywood
A plywood can be called marine grade plywood only if it has the following features.
The glue used to bind the veneers must be waterproof, boil proof and weather proof. The ability of the marine plywood to tolerate boiling water for many hours without delaminating is also dependent upon the quality of the glue. Hence, the glue has to undergo some tests before it can be used to make a marine grade plywood.
Marine plywood must not have voids in it. This is because voids enable water to penetrate the plywood and weaken it significantly.
Face and inside veneers of the plywood must be of the best quality.
BS 1088 grade marine plywood is made of tropical hardwood veneers with natural resistance against fungal growth without treatment. The glue is tested for resistance against boiling water, cold water, steam, dry heat, microbes and weather elements. Face and core veneers are devoid of open defects. The ply is free of bonding defects, overlaps, pleats and gaps in faces. The moisture content is 6% to 14%.
BS 6566 grade marine plywood is made of slightly lesser quality of core and face veneers as compared to BS 1088. The veneers are also thinner as compared to BS 1088 grade marine plywood. The ply is free of voids. The glue quality is same as that used in BS 1088.
AS/NZS 2272 grade marine plywood is a standard structural plywood used in making hulls of boats and other things used in marine environments. Wood veneers used to make this grade of marine plywood are selected on the basis of their density, impact resistance, bending strength and surface finish. Type A phenolic glue is used to bind the veneers. Preservatives are present in the plywood for durability.
These were the marine plywood specifications for different grades of marine plywood.
Size and thickness
The standard size of the marine plywood depends upon its grade and come in different sizes. However, marine plywood sizes should not exceed more than 6mm from the standard size. The standard marine plywood thickness available in the market are 4mm, 6mm, 9mm, 12mm, 16mm, 19mm and 21mm. The extra thickness allowed varies and is between 0.2mm and 1.8mm.
The cost of marine plywood is always more than other kinds of plywood. There are many factors affecting marine plywood price. These factors include type of veneer, size, thickness and composition. Brand name also plays a major role in impacting the price. Marine plywood manufactured by a leading brand will be more expensive. Gurjan marine grade plywood price is the most expensive in India and other countries. The manufacturers usually list marine plywood cost per square feet basis. Thus, the total marine plywood sheet price also depends upon the total square feet area to be covered by the marine plywood.
If you want to buy 18mm marine plywood made of hardwood which is having 5 piles of veneers, you need to spend about Rs 150 per square feet. The price of marine plywood 18mm can also be more if a very high quality of wood such as Gurjan is used. The marine plywood price 18mm by top manufacturers can be even higher.
Let us take some other example of marine plywood price. The 19mm marine plywood price for an 8’ x 4’ sheet can be Rs 110 per square feet. In case of a 20 mm marine grade plywood by a top brand, the price can be about Rs 6000 per sheet.
The starting cost of a laminated marine plywood with thickness ranging between 6-25mm can be Rs 80 per square feet.
The rate of marine plywood can differ from manufacturer to manufacturer. The key is to find the best marine plywood which suits your budget.
Uses of marine plywood
The most common marine plywood uses are in the ship building industry for constructing ships and boats. Marine plywood is also used for constructing floating homes and yachts. Marine plywood is also a preferred material for building docks because there is no need for weatherproofing treatment. Other uses include house decks and bathroom and kitchen walls and subflooring.
The benefits of the best marine plywood are as follows.
Marine plywood does not expand or rot even after prolonged exposure to water.
High resistance against impacts and general wear and tear. Thus, regular maintenance is not required.
High stability under fluctuating temperature and humidity.