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Plywood for Interior and Exterior Face Core & Back

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Plywood used in Interiors
Plywood is structural wood made from three or more layers of plies or veneer (usually an odd number).
  • These plies are glued together and usually laid with the grain of adjoining plies at right angles.
  • Plywood consists of:
  • a. Face
    b. Core
    c. Back
  • The face is the surface that is visible after installation, while the core lies between the face and back.

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Manufacturing of plywood

Wood used for plywood

Plywood can be derived from:

  1. Hardwood (such as teak or Gurjan wood).
  2. Softwood(such as pine, cedar or mango wood).

Note: Hardwood plywood is generally stronger and of better quality compared to soft wood ply.

Trees used in the manufacturing of plywood:

Alder Arjun Birch Bonsum
Carallia Champ Chaplash Cinnamon
Debdaru Dhup Ebony Elm
Gurjan Hollock Hollong Indian Oak
Laurel Mahogany Maple Mango
Neem Persian Lilach Pine Poplar
Rose Wood Satin Wood Piney Silver Oak
Sissoo Teak Walnut White Cedar

Properties of plywood

1. High Strength

  • Plywood possesses the structural strength of the wood it is derived from.
  • Each ply is usually orientated at a right angle to the adjacent layer in order to enhance strength and stability.
  • Its higher strength to weight ratio compared to wood makes it ideal for flooring, webbed beams, and shear walls.

2. High panel shear

  • Plywood is made with an odd number of layers, making it tough to bend.
  • This cross lamination increases the panel shear of plywood, important in bracing panels and web fabricated beams.

3. Flexibility

  • Thinner veneers are employed to improve flexibility for use in ceiling sand paneling.

4. Chemical resistance

  • Plywood treated with preservatives does not corrode when subjected to chemicals.
  • This makes it ideal for use in chemical works as well as cooling towers.

5. Impact resistance

  • Cross lamination of panels ensures the high tensile strength of plywood.
  • This is especially vital against short term seismic activity or strong winds.

6. Fire resistance

  • Plywood can be treated with a fire resistant chemical coating.
  • More commonly, it is combined with non combustible materials such as plaster board or fibrous cement.
  • This makes it ideal for use in fire resistant structures.

7. Insulation

  • Plywood has high thermal and sound insulation.
  • Heating and cooling costs are greatly reduced by plywood’s insulating properties.

General uses of plywood

1. Structural

  • To make formwork, or moulds for wet concrete.
  • In the construction of portal frames, shear walls, packaging, and roof trusses.

2. Interior work

  • To make floorings, roofs, etc.
  • To make furniture, especially cupboards, kitchen cabinets, and office tables.
  • To make partitions or paneling.

3. Exterior work

  • External cladding
  • Fencing
  • Decking
  • Rails and Balustrades
  • Landscaping elements
  • Stairs

4. Miscellaneous works

  • In the shipping industry.
  • In the manufacture of space and aircraft parts.

Types of ply

1. 3-Ply

  • Composition: This type has three layers of veneer.
  • Application: It is has a better appearance than plywood with more plies,making it useful for indoor use.
 

2. 5-Ply

  • Composition: This type has five layers of veneers.
  • Application: It is used for projects that require less durability and strength.

3. Multi-Ply

  • Composition: It can comprise several veneers; usually seven or more, to create an strong, unyielding frame for a building that can resist winds and external forces.
  • Application: It is mostly for exterior use and roofing.

Types of plywood

a. According to Wood Used

1. Softwood Plywood

Composition: Softwood like pine, redwood, or cedar.
Application: walls, roof sheathing, temporary flooring, crates, boxes, etc.

2. Hardwood Plywood

Composition: Hardwoods like ash, oak, red oak, birch, maple and mahogany,in three to seven layers.
Application: furniture, panelling, partitions, etc.

b. According to Usage

1. Aircraft Plywood

Composition: It uses hardwoods, like mahogany or birch, to create a highly strong finished piece that can also resist heat and moisture. The design incorporates extremely thin veneers that can keep it light and flexible, while strengthening it for handling strong forces.
Application: In projects that need industrial-strength woods, like airplanes,boats, and furniture that’s meant to hold a lot of weight.

2. Lumber Core

Composition: It is usually made with three plies, with two thin veneers (hardwood) on each side and a thick core (strips of wood).
Application: The inner core helps grasp screws, which makes it ideal for projects that require a strong screw hold, such as shelves in cabinets or closets.

3. Structural Plywood: (Indian standards specified in IS: 303)

Composition: It can be made either of softwood or hardwood.
Application: This wood finds use in permanent structures requiring high strength like flooring, beams, form work, and bracing panels.

c. According to Grades

1. Moisture Resistant (MR) Grade or Commercial Plywood:

(Indian standards specified in IS: 303)

Property: It is capable of resisting moisture.

(Note : Moisture resistant does not mean water proof. It only means that the plywood can resist a certain amount of humidity or dampness)

MR grade plywood used for office interiors

2. Boiling Water Resistant (BWR) Grade or Exterior Plywood:(Indian standards specified in IS: 303)

Property: It is capable of resisting water. Phenolic resins adds waterproofing qualities to the plywood.

 BWR grade plywood
Application: It is exterior grade plywood that can be used for indoor, semi-outdoor and outdoor use.It is widely used for making furniture that is likely to get wet.

BWR grade plywood

3. Boiling Water Proof (BWP) Grade or Marine Plywood (Indian standards specified in IS: 710)

Property: It is superior grade plywood which is higher in quality and strength as compared to both MR and BWR grade plywood. This ensures that the glue won’t stop working if the wood becomes damp from weather or wet conditions.

 BWP grade plywood
Application: It is the best choice for marine applications, and finds great use on the shipping and boat making industry. It is used mostly for outdoor furniture and constructions like gazebos,planter boxes, kiosks and benches.

BWP grade plywood outdoor furniture

4. Flexible Grade Plywood:

Property: This type of plywood isn’t stiff and can be rolled easily.

Flexible grade plywood chair

5. Fire Retardant (FR) Grade Plywood:(Indian standards specified in IS: 5509-198)

Property: Its surface is treated with chemicals that retard the burning process of wood.

FR grade plywood
Application: It is used in places where fire risks need to be minimized such as in shopping complexes, public theaters, restaurant, kitchen, etc.

Available sizes and thickness of plywood

Sizes

Plywood size in sq.ft

Plywood size in mm

8 x 4

2449 x 1219

7 x 4

2134 x 1219

6 x 4

1829 x 1219

8 x 3

2449 x 914

7x 3

2133 x 914

6 x 3

1829 x 914

Thickness

1. According to ply

Number of Ply

Plywood thickness in mm

3 – ply

3, 4, 5,6

5 – ply

5, 6, 8, 9

7 – ply

9, 12, 15, 16

9 – ply

12, 15, 16, 19

2. According to grades

Plywood grades

Plywood thickness in mm

MR grade orCommercial Plywood

3, 4, 6, 8, 12, 15, 18, 21, 25

BWR grade or Exterior Plywood

4, 6, 9, 12, 16, 19, 25

Price range of plywood

Type of Plywood

Prices

Commercial Plywood

Rs.40/sq. ft. / Rs.190/sq. ft.

Marine Plywood

Rs.50/sq. ft. / Rs.250/sq. ft.

Exterior Plywood

Rs.50/sq. ft. / Rs.270/sq. ft.

Fire retardant Plywood

Rs.50/sq. ft. / Rs.260/sq. ft.

Note : As shown in the above table, the lowest price depicts the price of minimum thickness of ply whereas the highest price depicts the price of the maximum thickness of ply available in the same type.

Finishing of plywood

a. Laminates:

  • Decorative laminates or others (which are basically a blend of paper and plastic) are glued over the plywood surfaces.

b. Paints:

  • To paint almost any plywood, a primer is first used, which will make the wood surface smooth and allow the paint to adhere to it.
  • It is a low-cost alternative to laminates or veneers and offers a wide range of colours.

c. Polish:

  • Wood polish is usually used on wooden furniture.
  • Wood polish (of darker colours) is used on some furniture parts (such as the underside of tables or the inner planks of single and double beds).

d. Veneer:

  • Wood veneers are thin slices/sheets of quality woods, which can be glued over the plywood surface to enhance its beauty.
  • Veneers are usually the costliest way of decorating plywood.

Tips for buying plywood in India

  • Check for IS: 303 mark on:
  • Commercial plywood or MR grade (Moisture Resistant)
  • Exterior plywood or BWR grade (Boiling Water Resistant)

Advantages of plywood

1. Good uniform strength

  • In plywood manufacture, the grains of adjoining piles are laid at right angles, providing strength to the plywood sheets.

2. Available in large sizes compared to solid wood

  • Uniformly thick 18 mm plywood sheet of size 8×4 is easily available,but it is difficult to get solid flat wood of such a size.

3. Economical use of wood by mixing various woods together

  • The veneers of such woods can be used to form the surface layer of the plywood, while the inner layers may comprise other strong but cheaper woods.

4. Versatile material that has many applications

  • Besides home decor and furniture, plywood has several industrial and structural applications. e.g. Marine plywood for boat-making etc.

5. Durable material

  • Plywood furniture made from good quality hardwood (such as teak, gurjan or eucalyptus wood) is quite durable and lasts several years.

Disadvantages of plywood

1. Water can damage MR grade plywood

  • The layers of plywood can come apart on prolonged exposure to water.
  • This drawback can be overcome by choosing BWR Waterproof grade for plywood furniture that is likely to get wet.

2. Can bend or sag when longer pieces are used

  • Plywood is unsuitable for applications that require longer pieces of wood such as front doors, benches, wardrobe doors or any other place where long panels are required.
  • To overcome this disadvantage, block boards can be used, which are technically better-suited in such cases as also cheaper than plywood.

3. Plywood usually needs additional enhancements

  • Most commercial grade plywood on the other hand, needs to be covered by laminates or other finishes so as to enhance its beauty and durability.

4. Costlier compared to block boards or particle boards

  • Plywood is costlier compared to particle boards or block boards.
  • Carpentry costs in addition to material cost make it relatively expensive.

5. Prone to termite effects

  • Plywood is prone to termite attack and may get damaged once infested.

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