Can I install Fiberon capped composite over my existing deck frame in Riverview?

You can potentially install Fiberon capped composite over your existing deck frame in Riverview, but only if the frame meets specific structural requirements, the most critical being 12-inch on-center joist spacing, which most older wood decks in the Riverview area were not built with. This is the make-or-break factor. If your existing joists are spaced at 16 inches on center, which was and remains standard for pressure-treated wood decking, you cannot simply lay Fiberon boards on top without modifying the frame first.

All composite decking products, Fiberon included, require 12-inch on-center joist spacing. This tighter spacing is necessary because composite boards are more flexible than wood boards of the same thickness. At 16-inch spacing, composite will flex underfoot, sag over time, and eventually suffer structural failure, particularly under the snow loads that Riverview decks carry through winter. This type of damage from improper joist spacing is explicitly excluded from Fiberon's warranty coverage, so even if the boards hold up initially, you would have no recourse if problems develop.

If your existing Riverview deck was built with 16-inch joist spacing, you have two options. The first is to add sister joists between the existing ones to bring the spacing down to 12 inches. This means installing a new joist between each pair of existing joists, effectively doubling the number of joists. This is a legitimate approach, but it adds material cost and labour. The new joists must be the same dimensional lumber as the existing ones, typically 2x8 or 2x10, and they need to be properly attached to the beam and ledger board with joist hangers. The second option is to tear out the old frame and build new, which is more expensive but gives you a frame that is purpose-built for composite.

Beyond joist spacing, several other conditions of your existing frame need inspection before proceeding. The ledger board attachment to the house is the most important structural element. In Riverview's climate, with its freeze-thaw cycles and Maritime humidity, ledger boards on older decks are a common failure point. The ledger must be securely lag-bolted to the house's rim joist with proper flashing behind it to prevent water infiltration. If there is any rot, water damage, or loosening at the ledger connection, it must be repaired before new decking goes on top.

The posts and beams need inspection as well. Pressure-treated posts set directly in the ground, which was common practice in Riverview builds from the 1990s and early 2000s, may have significant below-grade rot even if they look fine at the surface. Posts should ideally sit on concrete footings with post bases that keep the wood above ground level. The concrete footings themselves must extend below the frost line, which in the Riverview and Greater Moncton area is approximately four feet deep.

The existing deck boards and any rotted or damaged components of the frame need to be fully removed before the new Fiberon boards go down. Composite decking requires a clean, level, structurally sound surface, and any warping or unevenness in the old frame will telegraph through the new boards.

Assuming your frame passes inspection and either already has or is modified to have 12-inch joist spacing, Fiberon capped composite will install over the existing substructure using hidden clip fasteners or face screws depending on the specific Fiberon product line. Fiberon Paramount, the premium capped line, is an excellent choice for Riverview given its moisture resistance and fade performance in Maritime conditions. Budget approximately $45-65 per square foot for materials and installation if you are reusing the existing frame, compared to $55-75 per square foot or more for a complete tear-down and rebuild.

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