Thinking of building or repairing a deck or balcony? When it comes to the sheathing, in other words, the surface you’ll be walking on, your options have never been so plentiful. Here the main choices available, whether you prefer boards or panels.

Boards

  • Two choices for assembly: Spaced, interlocking
  • Two categories of materials:
    • Wood: White pine, pressure-treated lumber, western red cedar
    • Synthetic: recycled plastic, termoplastic products, composite products

Panelled sheathing

  • Four main types:
    • BC Douglas fir plywood with protective coating
    • Plywood with fibreglass coating
    • Fibre cement
    • PVC membrane

Board sheathing

Boards are perhaps the most traditional choice for balcony or deck sheathing. The days when pine was the sole material used, though, are long gone. Design and durability considerations mean the venerable pine board has been supplanted on the market by other species—not to mention by recycled plastic and various composites. When it comes to the look of your deck, boards work just as well in a spaced or flush design.

Spaced or interlocking?

Open-deck (boards spaced slightly):

Pros

  • The spaces between the boards help the wood last longer:
    • Boards dry faster because water runs off between them;
    • If one board falls victim to rot, its neighbours are less likely to because they aren’t touching it.
  • Easier to install: boards are usually screwed in from the top.
  • Easier to repair: the spaces make it relatively easy to remove and replace individual boards without damaging adjoining ones.

Cons

  • The spaces mean that small objects and debris (e.g., twigs, maple keys, dead leaves) can fall through or become trapped.
  • Parts of the sub-structure (beams and joists) are exposed to the elements.
  • Greater risk of the surface becoming uneven: boards are more susceptible to warping if they aren’t interlocking.

Solid-deck (interlocking or tongue-and-groove boards):

Pros

  • Objects and debris won’t fall underneath.
  • The boards are more likely to produce a level, even surface.

Cons

  • Need to incorporate a 2% slope (2 cm per m, or 1/4 in. per ft.) to keep water from pooling.
  • Needs sufficient ventilation underneath: in case of water infiltration, the underside of the boards and the sub-structure must dry quickly.
  • Installation requires more skill: boards need to be nailed or screwed to the sub-structure at an angle, through the top of the “tongue,” or using hidden fasteners.
  • Repairs are more difficult: the interlocking makes removal and replacement quite complicated, especially for boards in the centre of the deck or balcony.

Wood or synthetic?

Wood

White pine 

Pros

  • Environmentally sustainable.
  • Available in a wide array of formats (thickness, width, length).
  • Easy to repair.
  • The least expensive wooden board option.

Cons

  • Must be painted or stained every 2–3 years.
  • Easily damaged (scratches, dents)

Tip

    • Apply a base coat on all faces of the boards (including the tongues and grooves) at the time of installation or, ideally, beforehand.

Pressure-treated lumber (pine, fir or spruce) 

Pros

  • When properly maintained, offers better durability than white pine.
  • More resistant to rot and insects.
  • Inexpensive.
  • Easy to repair.

Cons

  • Size selection is more limited compared to white pine.
  • Tends to warp and crack (especially fir and spruce).
  • Needs protective coating every 2–3 years after an initial drying-out period.
  • Needs more expensive fasteners (galvanized or stainless steel) to guard against the corrosive effect of its copper-based preservative.
  • Not particularly environmentally friendly because of the chemical preservative.

Tip

  • Treated pine is better than fir or spruce for surfaces that will be walked on.

Western red cedar

Pros

  • Tight, straight grain ensures:
    • A warm look;
    • Excellent dimensional stability.
  • Naturally rot-resistant.
  • Easy to handle and cut.
  • Superior durability when properly maintained.

Cons

  • More expensive than the other two wood alternatives.
  • Scratches easily.
  • Requires galvanized or stainless steel fasteners (unprotected metal can react to the natural preservatives in the wood).
  • Needs periodic application of a preservative to protect it from humidity and UV radiation.

Tip

  • Use only very well sharpened saws and other tools when working with this very soft wood.

Synthetic materials

Recycled plastic

Pros

  • Made from reclaimed materials.
  • Very durable.
  • Offers greater resistance to inclement weather and UV radiation: no protection required.
  • Textured, non-slip surface.
  • 50-year limited warranty.

Cons

  • Very expensive.
  • Very heavy.
  • Fairly difficult to install: pilot holes must be drilled for screws.
  • Limited choice of colours.
  • Cannot be painted or stained.

Tip

  • When installing, take into account the product’s significant expansion coefficient (±3 mm or 1/8 in. per 10°C temperature variation).

Thermoplastic products

Pros

  • Immune to any deterioration due to humidity.
  • Excellent resistance to UV radiation.
  • Can be painted (any paint except oil-based products).
  • Comes with a warranty.

Cons

  • High cost.
  • Fairly difficult to install.
  • Needs special fasteners in many cases.
  • Sensitive to weather extremes (expansion).

Tip

  • Buy some extra boards to be sure you’ll have the same colour and style if repairs become necessary.

Composite products (blends of wood fibre and polymers)

Pros

  • Excellent resistance to rot and insects.
  • Requires no maintenance.
  • Top-end products come with a warranty.

Cons

  • Relatively expensive.
  • Somewhat difficult to install.
  • Often requires special fasteners.
  • Sensitive to UV radiation.
  • Much heavier than wood.

Tip

  • As with thermoplastic products, buy extra boards in case repairs are needed.

Panelled sheathing

Do you prefer a surface with no joints, or only a few? Opt for deck panelling with a protective coating for a perfectly smooth, watertight surface.

Note that panels share some of the disadvantages of interlocking boards:

  • The structure must have a slope of 2% (2 cm/m, or 1/4 in./ft) to allow water to run off;
  • There must be sufficient ventilation underneath so that the underside of the boards and the sub-structure will dry quickly in case of water infiltration.

Four main types of panel

BC Douglas fir plywood with protective coating

Pros

  • The least expensive panel option.
  • The easiest-to-install material: can be nailed or screwed.
  • Available in standard sizes
    • 1.2 m x 2.4 m (4 ft x 8 ft)
    • 1.2 m x 3 m (4 ft x 10 ft)
    • 1.5 m x 2.4 m (5 ft x 8 ft)
    • 1.5 m x 3 m (5 ft x 10 ft).

Cons

  • Painting required.
  • Sealant required at board joints.
  • Regular maintenance and careful use are a must to avoid damage to the thin protective membrane: do not use metal shovels, for example, to clear snow.

Tip

  • Use a non-slip additive with the final coat of paint.

Plywood with fibreglass coating 

Pros

  • Custom manufacturing is widely available.
  • Can be used to cover a large or irregularly contoured surface without joints.
  • Outstanding durability (20 years or more), extendable by refreshing the finish surface.
  • Needs no maintenance.

Cons

  • More difficult to repair than wood.
  • Will degrade rapidly if water gets under the fibreglass coating.
  • Best secured to the structure from underneath, which is more difficult.
  • Any fault in the surface finish must be repaired without delay.

Tip

  • Look for panels with rounded edges; those with sharp edges are more likely to crack.

Fibre cement 

Pros

  • Very good resistance to weather conditions (e.g., sun, rain, freezing) and impacts.
  • Non-flammable.
  • Requires no protection.
  • Can be painted (paint product must be alkali-resistant).

Cons

  • Heavy.
  • Available in one size only: 1.2 m x 2.4 m (4 ft x 8 ft).
  • Care must be taken while handling (carry by sides, not ends).
  • Sealant must be applied to screw heads and panel joints.

Tip

  • Leave a gap of about 3 mm (1/8 in.) between each panel; fill with a quality outdoor caulking product.

PVC membrane

Pros

  • Provides a waterproof, soft and non-slip covering.
  • Can be installed over wood, fibreglass or concrete.
  • Good resistance to UV radiation and climate variations.
  • Hot-welded joints.
  • Product can be repaired and is warrantied.

Cons

  • Membrane must be glued down.
  • Product can stain or get dirty fairly easily because of textured surface and slight unevenness where membrane strips overlap.
  • Needs regular cleaning.
  • Careful use required so as not to damage to the membrane: do not use metal shovels, for example, to clear snow.

Tip

  • To guard against water infiltration, extend a flap of membrane at least 15 cm (6 in.) upward at wall junctions.

 


Questions? Planning to have work done?

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