Decks and fences are among the most common outdoor projects homeowners undertake — and among the most frequently done incorrectly. A deck is a structural element attached to your home. A fence defines your property and in some cases your legal liability. Both are governed by building codes, require permits in most jurisdictions, and when built poorly, create safety hazards, legal exposure, and expensive remediation.
The outdoor construction trades also attract a high proportion of unlicensed seasonal operators who disappear after collecting a deposit. Every spring brings a new wave of deck and fence companies with no portfolio, no insurance, and no accountability when the ledger board pulls away from the house in year two or the fence posts heave out of the ground after the first hard frost.
The questions in this guide are organized by project type. They apply whether you’re building a ground-level deck, a raised deck attached to your home, a composite deck, a wood fence, or a metal or vinyl fence system.
“A deck is a structural element — it’s attached to your house and it carries people. The questions that matter are the structural ones: how is the ledger attached to the house, how deep are the footings, what size are the beams and joists, and is it engineered for the loads it needs to carry? Those questions are what a building inspector asks. They should be what the homeowner asks too.”
— Brendan Tse, licensed carpenter and deck construction specialist with 17 years of experience in residential deck and outdoor structure building in the local area
Table of Contents
Before You Call Anyone
Is this a deck or an outdoor structure that requires a permit?
In many regions and most Canadian municipalities, decks above a certain height or size — typically any deck over 600mm (approximately 2 feet) above grade — require a building permit. Attached decks almost universally require permits, as do decks connected to a structure with an electrical component (lighting, hot tubs).
Fences above a certain height — typically 1.8 meters (6 feet) in most local municipalities — may also require a permit, and fence placement along property lines may be governed by the Line Fences Act or local bylaws.
A contractor who suggests skipping permits on a project that clearly requires them is red flag number one.
What is the primary purpose of this project?
Understanding your priorities before getting quotes helps you evaluate proposals accurately:
For a deck: Is this primarily for entertaining (large, flat, multiple levels)? A hot tub platform (requires specific structural engineering)? A small ground-level platform? Understanding the use drives the structural design.
For a fence: Is the primary purpose privacy (height matters), security (gate hardware and post spacing matter), pet containment (material and gap sizing matter), or aesthetics (material and style matter)? Each priority changes the right solution.
Questions to Ask Before Hiring
Are you a licensed contractor with a registered business?
Deck and fence contractors don’t carry mandatory trade licences in many regions the way electricians or plumbers do, but any legitimate contractor should operate as a registered business with a valid tax-registration number. For deck construction specifically, which involves structural framing and often electrical work, hiring an unregistered operator is a significant risk.
Ask for the business registration number and tax-registration number and verify them.
Do you carry liability insurance and workers’ compensation coverage?
Deck and fence work involves elevated work, power tools, and in some cases excavation equipment. A worker injured on your property without workers’ compensation coverage may leave you liable. Liability insurance covers damage to your property or a neighbor’s during construction.
Ask for a certificate of insurance and a workers’ compensation coverage Clearance Certificate. Verify both.
What a good answer looks like: A registered business with verifiable insurance and workers’ compensation coverage clearance.
Do you pull permits for this type of project?
The contractor — not the homeowner — should be responsible for pulling any required permits. A contractor who suggests you pull permits yourself, or who says permits aren’t required when they clearly are, is a significant red flag.
What a good answer looks like: “We pull all required permits as standard. We know the local requirements and handle the application.”
For a full breakdown: Questions to Ask a Deck or Fence Contractor About Permits and Inspections
Can you show me examples of comparable completed work?
For deck construction, ask to see photos of completed decks with the same structural configuration as yours — attached decks if yours is attached, elevated decks if yours is elevated. Ask specifically whether they can show you how the ledger board is attached to the house in their installations, as this is the most critical structural connection.
For more: Questions to Ask a Deck or Fence Contractor for References and Past Work
Deck-Specific Questions
How will the ledger board be attached to the house?
For any deck attached to a house, the ledger board — the board bolted to the house framing that carries half the deck load — is the most structurally critical element. Improper ledger attachment is the leading cause of deck collapse.
A proper ledger attachment requires:
– Removal of siding and flashing at the attachment point
– Attachment directly to the house’s rim joist or framing with appropriately sized lag screws or through-bolts at the specified spacing
– Proper flashing installed over and around the ledger to prevent water infiltration between the ledger and the house
Ask specifically how the ledger will be attached and what flashing system will be used.
What a good answer looks like: A detailed description of the fastener type, size, and spacing, plus a specific flashing system that integrates with the house’s weather barrier.
How deep will the footings be?
Deck footings must extend below the frost line to prevent frost heaving — uplift caused by freezing soil. In many regions, the frost line is typically 1.2 meters (4 feet) below grade. Footings that don’t reach this depth will heave with seasonal frost, causing the deck to move, crack, and potentially separate from the house.
Ask specifically how deep footings will be installed and whether they’ll extend below the frost line for your location.
What a good answer looks like: Footings at minimum 1.2m depth in many regions, with a specific footing diameter and concrete specification.
What are the beam, joist, and decking specifications?
A properly engineered deck has appropriately sized structural members:
– Beam size determines how far the deck can span between posts
– Joist size and spacing determine the strength of the deck surface
– Decking material and thickness determine the finished walking surface
Ask for the specific lumber species, grade, and dimensions for each structural component. The answer should reference the building code span tables or an engineer’s specification.
For more: Questions to Ask a Deck Contractor About Materials and Structural Design
What decking material are you recommending, and why?
The decking surface material is the most visible and most decision-intensive choice:
Pressure-treated lumber: The most affordable option. Durable when properly maintained. Requires sealing and periodic maintenance. ACQ-treated lumber is the current standard (no arsenic).
Cedar or redwood: Naturally rot-resistant, beautiful, and workable. More expensive than pressure-treated. Requires staining or sealing every 2–3 years.
Composite decking (Trex, Fiberon, Azek, TimberTech): Made from wood fiber and plastic. Low maintenance, doesn’t splinter, resists rot and insects. Higher upfront cost but lower lifecycle cost. Requires specific substructure spacing.
PVC decking: All-plastic product. Maximum durability and moisture resistance. Highest cost. Can expand and contract significantly with temperature.
Ask specifically what decking material is being proposed, why it’s appropriate for your situation, and what the maintenance requirements are over 5 and 10 years.
Fence-Specific Questions
How deep will the posts be set, and how?
Post installation is the most consequential structural decision in fence building. Fence posts must be set deep enough to resist both horizontal loads (wind pressure against the fence) and frost heaving. In many regions, fence posts should generally be set at minimum 900mm–1.2m (3–4 feet) deep, with more depth for taller fences and in areas with significant frost.
Ask specifically how deep posts will be set, whether they’ll be set in concrete, and whether the concrete is being formed to a point at the bottom (to resist uplift from frost) or a flat bottom (which can be pushed up by frost heave).
What a good answer looks like: Posts set below frost line, in concrete that’s formed to resist both lateral loads and frost uplift.
What material are you recommending for the fence?
Wood (cedar, pressure-treated pine): Classic look, workable, relatively affordable. Cedar requires periodic staining or sealing; pressure-treated pine is durable but less aesthetically refined. Both require more maintenance than synthetic alternatives.
Vinyl/PVC: Low maintenance, doesn’t rot or require painting. Quality varies significantly — ask for the material thickness and warranty. Heavy gauge vinyl is durable; thin-gauge vinyl is brittle in cold temperatures.
Aluminum: Maintenance-free, won’t rust, traditionally used for ornamental applications. Not appropriate for privacy fencing.
Chain link: Durable, practical, low cost. Limited aesthetic appeal. Appropriate for utility, pet, or security applications.
Composite: Wood-plastic composite products used in fence boards. Similar to composite decking.
Ask what material is being proposed and why it’s appropriate for your situation, climate exposure, and maintenance tolerance.
For more: Questions to Ask a Fence Contractor About Fence Materials and Design
Questions About Permits, Inspections, and Property Lines
Has the property line been confirmed before the fence is positioned?
Fence placement disputes with neighbors are common and expensive. Before any fence is installed, the property line should be confirmed — ideally through a survey, or at minimum through a review of the property’s registered survey plan. Ask whether the contractor verifies property line placement before installation.
What a good answer looks like: A clear process for confirming property line placement before any post is set.
For more: Questions to Ask a Deck or Fence Contractor About Permits and Inspections
Red Flags to Watch For
Suggesting permits aren’t required when they are. Decks above grade and fences above height thresholds require permits in most local municipalities. A contractor who says otherwise is either wrong or planning to skip the permit.
No ledger flashing specified for an attached deck. Water infiltration at the ledger is the leading cause of premature deck deterioration. Any attached deck proposal that doesn’t specifically address flashing is incomplete.
Footings shallower than the frost line. In many regions, shallow footings guarantee frost heaving. Ask the depth and verify it’s below 1.2m.
No portfolio of structural work. A deck contractor without photos of completed framing — not just finished decking — may not have experience with the structural elements that matter most.
Price significantly lower than all others. Structural shortcuts in deck construction are in the footings, the ledger attachment, and the lumber grade. These are invisible once the deck is finished and dangerous when they fail.
For a full guide: Red Flags When Hiring a Deck or Fence Contractor
Before They Start: A Quick Checklist
- Business registration and insurance verified
- Workers’ compensation coverage clearance verified
- Permit responsibility confirmed and permit applied for
- Ledger attachment method specified (for attached decks)
- Footing depth confirmed (below frost line)
- Structural member specifications (beam, joist, post sizes) confirmed in writing
- Decking material specified with maintenance requirements discussed
- Property line confirmed (for fences)
- Payment schedule agreed in writing
- Warranty terms in writing
Related Questions
- Questions to Ask a Deck or Fence Contractor for References and Past Work
- Questions to Ask a Deck Contractor About Materials and Structural Design
- Questions to Ask a Fence Contractor About Fence Materials and Design
- Questions to Ask a Deck or Fence Contractor About Permits and Inspections
- Questions to Ask When Getting a Deck or Fence Quote
- Questions to Ask a Deck or Fence Contractor During the Job
- Questions to Ask a Deck or Fence Contractor About Warranties
- How Much Does a Deck Cost ?
- Red Flags When Hiring a Deck or Fence Contractor
- What to Do If a Deck or Fence Contractor Does Bad Work
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