Deck and fence construction failures range from aesthetically disappointing to structurally dangerous. A deck that collapses injures people. A fence installed on the wrong side of a property line creates expensive legal disputes. The warning signs that predict these outcomes are almost always visible before the first post is dug.
“The clearest red flag I see is a deck quote that doesn’t specify footing depth. In many regions, that single omission tells you everything — the contractor either doesn’t know the frost line requirements or plans to take the shortcut. Either way, you’ll have a heaving deck in three years and a contractor who can’t be found.”
— Miriam Okello, outdoor structures specialist and fence installation contractor with 12 years of residential fencing experience in the local area
Table of Contents
Red Flags Before You Hire
No footing depth specified in the deck or fence quote. Footing depth is the most consequential structural specification — and the most commonly omitted. Any deck or fence quote that doesn’t specify post depth in inches or centimetres is hiding the most important quality indicator. Ask immediately. If the contractor can’t or won’t answer specifically, move on.
Suggesting permits aren’t required when they are. Decks above 600mm (24 inches) and attached decks virtually always require permits in many regions. A contractor who says permits aren’t required without checking your specific municipality either doesn’t know the requirements or plans to skip the process.
No mention of ledger flashing for an attached deck. Water infiltration at the ledger board is the most common cause of premature deck and house wall deterioration. Any attached deck proposal that doesn’t specifically address flashing is structurally incomplete.
Quote significantly lower than all others. Deck and fence shortcuts are structural — shallow footings, undersized beams, inadequate ledger fastening. These are invisible at installation. A quote far below market almost always reflects one or more of these compromises.
No portfolio of structural framing work. A deck contractor who can only show photos of finished decking surfaces — never framing stages — may not have experience with the structural elements that matter most.
Unable to name lumber species and grade. A professional deck builder specifies lumber by species and grade — not just “pressure-treated.” Grade matters for structural members.
Cash only, no written contract. Particularly concerning in the deck trade, which attracts seasonal operators. A contractor who won’t provide a written contract specifying structural details has no accountability for what gets built.
Utility locates not mentioned before excavation. Digging without your local utility locate service locates is both illegal and dangerous.
Red Flags During the Job
Footings shallower than quoted or agreed. If you measure the footing holes before concrete is poured and they’re shallower than specified, stop the job. Footings that don’t reach the frost line will heave. This is the single most important thing to verify during construction.
Ledger nailed rather than bolted or lag-screwed. An attached deck ledger nailed to the house will separate under load. The ledger must be fastened with lag screws or bolts at the specified interval. Ask to see the fastener before the framing is added.
Framing inspection not scheduled before decking begins. If the contractor starts installing decking before the framing inspection has occurred, the inspection can’t happen — the inspector can’t see what’s underneath. This is a permit violation and a structural risk.
Posts not plumbed before concrete sets. A leaning fence post after installation is a post that wasn’t plumbed before the concrete hardened. Once the concrete sets, this cannot be easily corrected. Watch the post installation and ask to see plumb checks in two directions before concrete is poured.
Railing posts surface-mounted without visible blocking. Railing posts bolted to the outside face of a joist without internal blocking provide inadequate lateral resistance. Ask how railing posts are attached and confirm the method meets the OBC requirements.
Red Flags Specific to Fences
No property line verification before post installation. A contractor who places fence posts without referencing a survey plan or survey markers is guessing at the property line. This is one of the most common sources of expensive neighbor disputes.
Thin-gauge vinyl fence installed without internal post reinforcement. Quality vinyl fence posts in cold climates should have internal steel or aluminum reinforcement. Unreinforced vinyl posts become brittle and can crack in Canadian winters.
Related Questions
- Questions to Ask a Deck or Fence Contractor Before You Hire One
- Questions to Ask a Deck or Fence Contractor About Permits and Inspections
- Questions to Ask a Deck Contractor About Materials and Structural Design
- What to Do If a Deck or Fence Contractor Does Bad Work
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