This article lists frequently asked questions related to waterproof plywood and provides the answers to them.
What is waterproof plywood?
Most types of wood eventually
become damaged with prolonged exposure to water. However, good quality
waterproof plywood is constructed in such a way that it offers a better degree
of water resistance, compared to natural solid wood or commercial grade MR
plywood. The reason for this is that a phenolic resin (which is a synthetic
plastic resin) is used to bond all of the individual layers together. The use
of such a synthetic plastic resin helps to make the plywood waterproof.
What is the Grade Used to Indicate
Waterproof Ply?
The grading system may vary from
country to country. In India, 'BWR grade' plywood means waterproof plywood.
BWR
- 'Boiling Water Resistant'.
There is also another similar-sounding grade called BWP (Boiling waterproof) Which is commonly used to refer
to blockboards. In waterproof plywood, the BWR grade is indicated on the
plywood sheets.
Is waterproof plywood the same as Marine
plywood?
No, waterproof plywood (BWR
grade) is different from marine plywood. Marine plywood is specially made to
resist prolonged exposure to water.
Quality testing for marine
plywood involves placing a sample piece in boiling water for 72 hours and then
checking its strength and other properties.
Marine plywood is more
expensive than waterproofing and is used for marine applications such as
building boats and ships. For making office or home furniture, Marine fly is
usually overcooked, and good quality waterproof plywood serves the purpose in
most cases.
Is it waterproof plywood exterior grade?
Yes. Plywood is classified as
interior and exterior grade plywood. The interior standard is designed for
indoor use, while the exterior is for outdoor use where the wood is exposed to
natural weather elements (slight rain and sunlight).
In outdoor use, the choice of
marine ply or waterproof is a case-by-case decision, depending on the intended
use. (For the purpose of the roof, for example, marine plywood would be
better).
In India, Commercial MR
(moisture resistant) plywood is for indoor use while BWR standard can be used
for outdoor. Different grade systems are in practice in other countries. E.g.
In the United States, the codes 'INT' and 'EXT' are used to denote these
grades.
What grading system was used to Indicate
Waterproof Ply in the USA?
In the United States, the codes 'INT' and 'EXT' are used to
Indicate Waterproof Ply.
What is the exact difference between
Commercial MR grade and Waterproof BWR plywood?
MR stands for Moisture
Resistance. This means that MR grade plywood can withstand a certain amount of
moisture and humidity successfully. The important thing to note is that
'moisture resistance is not equivalent to 'water resistant' and therefore not
MR grade waterproof plywood.
The key points for comparing
MR and BWR plywood are listed in the table below.
|
BWR
grade plywood |
MR
grade plywood |
|
Boiling waterproof |
Moisture resistant |
|
Better strength and
quality |
Of slightly lesser
quality |
|
Costlier |
Cheaper |
|
Phenol formaldehyde
synthetic resin is used |
Urea-formaldehyde
resin is used for bonding the plies |
|
Exterior grade for
outdoor use |
Interior grade for
indoor use |
Should waterproof plywood be used for home
furniture?
Marine Plywood is better than waterproof BWR plywood and
BWR is better than commercial MR plywood making it a thumb rule. Based on this,
what kind of plywood we as customers choose depends on our scope of work and
cost-effectiveness.
In our opinion, the use of waterproof plywood (BWR) is a
good choice for furniture that is slightly exposed to water, for example, kitchen cabinets or other kitchen furniture. For other furniture that is dry
(e.g. drawing room, bedroom furniture, partitions, wall panels, etc.) it is
sufficient to use commercial MR grade plywood.
Another thing to consider is
that all plywood used in furniture and home decor will in most cases be
laminated, and the laminate surface coating helps to prevent water from
reaching the core of the plywood, increasing the overall water-resistance of
the finished material.
Also Read: What is a Laminate sheet? | Sizes |
Thickness | Types | Manufacturing Process
Can Waterproof Plywood Be Used For Doors?
Instead of plywood, blockboard
and flush doors are the preferred material for constructing doors. Flush doors
consist of solid rectangular blocks of softwood covered on both faces by a
thin layer of tile 2.5 mm thick. Flush doors are lighter in weight, cheaper and
have less sagging and bending compared to plywood. People prefer waterproof
(BWP grade) flush doors instead of waterproof (BWR) quality plywood for their
doors.
What are the sizes and thicknesses in which
waterproof plywood is available?
Waterproof plywood is available in all the standard sizes.
The most common sizes are 8 feet by 4 feet sheets and thickness of 18 or 19mm.
Read the related article on standard plywood sizes and thickness for more
information about this.
Waterproof plywood is available in all standard sizes. The
most common sizes are 8x4ft sheets and 12mm or 19mm thick.
For more information on this, read the corresponding
article on standard
plywood sizes and thicknesses.
Also
Read: Woodworking
Materials Guide for Beginners! | Woodworking Handbook
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