100 mm (3 15/16 in) sphereThe test ball for guards: no opening may let a 100 mm (3 15/16 in) sphere pass.
Trade slang calls it the four inch sphere, but a gap of exactly 4 in is wider than the sphere and fails. The usual working gap for wood is 3 7/8 in clear.
Show me on a deck: The 100 mm (3 15/16 in) sphere test
Lessons: Gaps under rails and beside stairs
Answers: How far apart can spindles be, and what is the no climb rule?
Related terms: Baluster , Guard , Climbable
Read more: Uncovered Deck Design Guide, page 14 (City of Edmonton, PDF), Uncovered Deck Final Building Inspection checklist (City of Edmonton, PDF), National Building Code of Canada 2020 (National Research Council, the model code)
Above ground
Also called above ground use category.
The treatment level for wood that stays off the soil and can dry out between rains.
Show me on a deck: Which wood goes where
Answers: Which parts of a deck have to be treated or naturally decay resistant?
Related terms: Ground contact , Heartwood , Incised
Read more: DCA 6, Prescriptive Residential Wood Deck Construction Guide, page 3 (American Wood Council, a US code guide not in force in Canada, PDF), Illustrated Guide for Building Safe and Durable Wood Decks and Balconies, page 27 (BC Housing, PDF), Uncovered Deck Design Guide, page 8 (City of Edmonton, PDF)
Access way
An opening at least 24 in by 24 in to crawl under a low deck and re-level posts on pier blocks.
Edmonton accepts an access way where the joist bottoms are at least 24 in off the ground. Lower than that, leave removable boards over the posts.
Show me on a deck: Pier blocks need access to re-level
Answers: How deep do deck footings have to go?
Related terms: Pier block , Footing , Frost heave
Read more: Uncovered Deck Design Guide, page 7 (City of Edmonton, PDF)
Authority having jurisdiction
Also called AHJ, or building authority.
The office that enforces the building code where you build and has the final word on your deck.
In Edmonton that is the City. It applies the Alberta Edition of the National Building Code and sets its own permit triggers.
Show me on a deck: Which permit this deck needs
Lessons: When an engineer must stamp it
Answers: Do I need a permit to build a deck?
Related terms: Development permit , Prescriptive , Engineer stamp , CCMC evaluation report
Read more: Building codes and standards (Government of Alberta), Deck (Uncovered) permits (City of Edmonton), National Building Code, 2023 Alberta Edition (National Research Council, the Alberta code), Codes Canada (National Research Council)
Baluster
Also called spindle, or picket.
One of the upright pieces that fill a guard; the gaps between them must stop a 100 mm (3 15/16 in) sphere.
Show me on a deck: The 100 mm (3 15/16 in) sphere test
Lessons: A guard on a low deck , Quantities from the shape
Answers: How far apart can spindles be, and what is the no climb rule?
Related terms: 100 mm (3 15/16 in) sphereGuard , Climbable
Read more: Uncovered Deck Design Guide, page 14 (City of Edmonton, PDF), Uncovered Deck Final Building Inspection checklist (City of Edmonton, PDF), Inspecting a Deck, Illustrated (InterNACHI, inspection practice)
Beam
The horizontal member that carries the joists and bears on top of at least two posts.
The joist span it carries, plus any cantilever, and the spacing of its posts pick its size. Never bolted only to the side of a post.
Show me on a deck: Span plus cantilever picks the beam
Lessons: 4x4 or 6x6 post , Post spacing against beam size , Single span or two span beam , Beam overhang past the post , The beam sits on the post , Building up a beam , Two levels, one deck , Inspect from the ground up
Answers: What size beam and post does my deck need?
Related terms: Ply , Post , Drop beam , Flush beam , Cantilever
Read more: Prescriptive Residential Exterior Wood Deck Span Guide, page 10 (Canadian Wood Council, PDF), Prescriptive Residential Exterior Wood Deck Span Guide, page 5 (Canadian Wood Council, PDF), Uncovered Deck Design Guide, page 9 (City of Edmonton, PDF)
Blocking
Short pieces fitted between joists to stiffen the frame and back butt joints, border mitres and guard posts.
Show me on a deck: What blocking is for
Lessons: Blocking under a picture frame , Where board ends meet , Guard posts carry the push
Answers: How high does a deck railing have to be, and when do I need one?
Related terms: Joist , Picture frame border , Guard post , Rim board , Herringbone
Read more: Uncovered Deck Design Guide, page 14 (City of Edmonton, PDF), Illustrated Guide for Building Safe and Durable Wood Decks and Balconies, page 16 (BC Housing, PDF)
Cantilever
Also called overhang.
The part of a joist that runs past the beam, or of a beam past its last post.
Joists may overhang 8 in on a 2x4, 16 in on a 2x6 or 2x8, and 24 in on a 2x10 or 2x12, measured from the centre of the beam. Look up the beam with the span plus the cantilever.
Show me on a deck: How far joists may overhang
Lessons: Span plus cantilever picks the beam , When a cantilever is better , Beam overhang past the post
Answers: What size beam and post does my deck need?
Related terms: Drop beam , Joist , Beam , Span , Fascia
Read more: Prescriptive Residential Exterior Wood Deck Span Guide, page 5 (Canadian Wood Council, PDF), Prescriptive Residential Exterior Wood Deck Span Guide, page 7 (Canadian Wood Council, PDF), Uncovered Deck Design Guide, page 11 (City of Edmonton, PDF), Uncovered Deck Final Building Inspection checklist (City of Edmonton, PDF)
CCMC evaluation report
A Canadian Construction Materials Centre report on a product's uses and limits, for products the prescriptive tables do not cover.
Show me on a deck: Composite follows its own report
Lessons: Glass, cable and aluminum guards
Answers: What decking can I use and how far apart do the joists go?
Related terms: Composite decking , Prescriptive , Guard , Authority having jurisdiction
Read more: About the CCMC Registry of Product Assessments (National Research Council), CCMC Registry of Product Assessments (National Research Council, searchable list), Uncovered Deck Design Guide, page 12 (City of Edmonton, PDF), Uncovered Deck Design Guide, page 15 (City of Edmonton, PDF)
Climbable
A guard with rails or footholds a child can climb. Above 4.2 m (13 ft 9 5/16 in) , nothing between 140 mm (5 9/16 in) and 900 mm (35 7/16 in) above the deck may be climbable.
Show me on a deck: Nothing to climb above 4.2 m (13 ft 9 5/16 in)
Answers: How far apart can spindles be, and what is the no climb rule?
Related terms: Guard , Baluster , 100 mm (3 15/16 in) sphere
Read more: Uncovered Deck Design Guide, page 14 (City of Edmonton, PDF), National Building Code of Canada 2020 (National Research Council, the model code), National Building Code, 2023 Alberta Edition (National Research Council, the Alberta code)
Composite decking
Boards of wood fibre and plastic, or PVC, that follow their own evaluation report for joist spacing.
Show me on a deck: Composite follows its own report
Answers: What decking can I use and how far apart do the joists go?
Related terms: CCMC evaluation report , Joist , Picture frame border
Read more: Uncovered Deck Design Guide, page 12 (City of Edmonton, PDF), About the CCMC Registry of Product Assessments (National Research Council), Uncovered Deck Final Building Inspection checklist (City of Edmonton, PDF)
Corrosion resistant fastener
A screw, nail, bolt or hanger rated for treated wood, usually hot dipped galvanized or stainless steel.
Show me on a deck: Fasteners that match the treatment
Lessons: Metals that corrode each other , Screws, clips and nails , Rust where metal meets treatment
Answers: Which parts of a deck have to be treated or naturally decay resistant?
Related terms: Galvanic corrosion , Joist hanger , Lag screw
Read more: Illustrated Guide for Building Safe and Durable Wood Decks and Balconies, page 28 (BC Housing, PDF), DCA 6, Prescriptive Residential Wood Deck Construction Guide, page 2 (American Wood Council, a US code guide not in force in Canada, PDF), Uncovered Deck Design Guide, page 2 (City of Edmonton, PDF)
Deck height
The biggest drop from the deck surface to the lowest ground beside it, measured at the worst corner.
It decides the guard, the permit and the engineer.
Show me on a deck: Measure height at the worst corner
Lessons: Which permit this deck needs , When an engineer must stamp it , When a deck counts as lot coverage , When a guard is required , What counts as the ground
Answers: How high can a deck go before it needs an engineer?
Related terms: Guard , Development permit , Site coverage , Engineer stamp
Read more: Uncovered Deck Design Guide, page 3 (City of Edmonton, PDF), Uncovered Deck Design Guide, page 5 (City of Edmonton, PDF), Uncovered Deck Design Guide, page 14 (City of Edmonton, PDF)
Deck length
How far the deck projects out from the house; it runs with the joists and picks the joist size.
Edmonton wants drawings for a deck more than 18 ft out from the house.
Show me on a deck: When the city wants drawings
Answers: How far can a deck joist span?
Related terms: Deck width , Joist , Span
Read more: Uncovered Deck Design Guide, page 5 (City of Edmonton, PDF), Uncovered Deck Design Guide, page 4 (City of Edmonton, PDF)
Deck width
The deck measured along the house; on a simple deck it is also the beam length.
Edmonton wants drawings for a deck wider than 30 ft .
Show me on a deck: When the city wants drawings
Answers: What size beam and post does my deck need?
Related terms: Deck length , Beam
Read more: Uncovered Deck Design Guide, page 6 (City of Edmonton, PDF), Uncovered Deck Design Guide, page 4 (City of Edmonton, PDF)
Development permit
Zoning approval for where a structure sits on your lot, separate from the building permit about how it is built.
In Edmonton a deck needs one at 1.2 m (47 3/16 in) or higher, or at any height in a front or flanking side yard.
Show me on a deck: Which permit this deck needs
Answers: Do I need a permit to build a deck?
Related terms: Site coverage , Deck height , Authority having jurisdiction
Read more: Uncovered Deck Design Guide, page 3 (City of Edmonton, PDF), Deck (Uncovered) permits (City of Edmonton)
Drop beam
A beam set under the joists, so they can overhang it and hide the beam behind the fascia.
Show me on a deck: Drop beam or flush beam
Lessons: How far joists may overhang , When a cantilever is better
Answers: What size beam and post does my deck need?
Related terms: Flush beam , Cantilever , Fascia
Read more: Uncovered Deck Design Guide, page 9 (City of Edmonton, PDF)
Engineer stamp
A professional engineer's seal on a design, needed once a deck leaves the prescriptive tables.
In Edmonton: the foundation above 1.8 m (5 ft 10 13/16 in) , or over 55 square metres (592 square feet) on a deck that needs a permit; the whole deck above 3.6 m (11 ft 9 11/16 in) or under a heavy load.
Show me on a deck: When an engineer must stamp it
Lessons: Pier, pier block or screw pile , A hot tub on the deck , A roof over the deck , A second storey deck
Answers: How high can a deck go before it needs an engineer?
Related terms: Prescriptive , Extraordinary load , Screw pile , Authority having jurisdiction
Read more: Uncovered Deck Design Guide, page 5 (City of Edmonton, PDF), Uncovered Deck Design Guide, page 6 (City of Edmonton, PDF), Deck (Uncovered) permits (City of Edmonton)
Fascia
The trim board covering the outside face of the rim joist.
Show me on a deck: When a cantilever is better
Related terms: Rim board , Drop beam , Cantilever
Read more: Illustrated Guide for Building Safe and Durable Wood Decks and Balconies, page 7 (BC Housing, PDF), Illustrated Guide for Building Safe and Durable Wood Decks and Balconies, page 27 (BC Housing, PDF)
Flashing
A formed strip of metal or membrane lapped over the ledger so water runs out, not behind it.
Show me on a deck: Flashing over the ledger
Lessons: Metals that corrode each other , How a ledger fails , What to check each spring
Answers: Should the deck be attached to the house or freestanding?
Related terms: Ledger , Galvanic corrosion , Rim board , Joist tape
Read more: Illustrated Guide for Building Safe and Durable Wood Decks and Balconies, page 22 (BC Housing, PDF), Illustrated Guide for Building Safe and Durable Wood Decks and Balconies, page 21 (BC Housing, PDF), DCA 6, Prescriptive Residential Wood Deck Construction Guide, page 13 (American Wood Council, a US code guide not in force in Canada, PDF), Uncovered Deck Design Guide, page 2 (City of Edmonton, PDF)
Flight
A run of steps between landings, including from the deck down to the ground.
Show me on a deck: When a stair needs a landing
Lessons: How wide a stair must be
Answers: When does a deck stair need a landing?
Related terms: Landing , Riser , Stringer , Handrail
Read more: Uncovered Deck Design Guide, page 13 (City of Edmonton, PDF)
Flush beam
A beam with the joists hung off its side in hangers; it must be at least as deep as the joists.
Show me on a deck: Drop beam or flush beam
Lessons: Hangers need their own fasteners
Answers: What size beam and post does my deck need?
Related terms: Drop beam , Joist hanger , Beam
Read more: Uncovered Deck Design Guide, page 9 (City of Edmonton, PDF), DCA 6, Prescriptive Residential Wood Deck Construction Guide, page 9 (American Wood Council, a US code guide not in force in Canada, PDF)
Freestanding deck
Also called floating deck.
A deck carried on its own posts at both edges, with no ledger on the house.
Show me on a deck: Ledger or freestanding
Lessons: Single span or two span beam , Bracing a freestanding deck
Answers: Should the deck be attached to the house or freestanding?
Related terms: Ledger , Knee brace , Beam , Undisturbed soil
Read more: Uncovered Deck Design Guide, page 11 (City of Edmonton, PDF), Illustrated Guide for Building Safe and Durable Wood Decks and Balconies, page 14 (BC Housing, PDF), DCA 6, Prescriptive Residential Wood Deck Construction Guide, page 17 (American Wood Council, a US code guide not in force in Canada, PDF)
Frost heave
Freezing soil swelling and lifting anything set above the frost line, then letting it down unevenly at the thaw.
Show me on a deck: Footings below the frost line
Answers: How deep do deck footings have to go?
Related terms: Frost line , Footing , Pier block
Read more: Uncovered Deck Design Guide, page 7 (City of Edmonton, PDF)
Frost line
The depth the ground freezes to; footings go below it, at least 1.2 m (47 3/16 in) as a rule in Edmonton, unless the code lets them stay above.
The code lets footings stay above it on rock, on coarse-grained soil that drains well, or under a deck of not more than 55 square metres (592 square feet) with its joists within 600 mm (23 9/16 in) of the ground. Anywhere else they go below it or are designed. The depth depends on the soil, so confirm the one your authority uses.
Show me on a deck: Footings below the frost line
Answers: How deep do deck footings have to go?
Related terms: Frost heave , Footing , Undisturbed soil
Read more: Uncovered Deck Design Guide, page 7 (City of Edmonton, PDF)
Galvanic corrosion
A metal eaten away where it touches a different metal, or modern treated wood, while wet.
Show me on a deck: Metals that corrode each other
Answers: Which parts of a deck have to be treated or naturally decay resistant?
Related terms: Flashing , Corrosion resistant fastener , Joist hanger
Read more: DCA 6, Prescriptive Residential Wood Deck Construction Guide, page 3 (American Wood Council, a US code guide not in force in Canada, PDF), Illustrated Guide for Building Safe and Durable Wood Decks and Balconies, page 28 (BC Housing, PDF)
Graspable
A handrail shape a hand can close around; material up to about 3 1/2 in across counts.
Show me on a deck: Handrail or guard cap
Answers: When does a deck stair need a handrail, and how high?
Related terms: Handrail , Guard , Nosing
Read more: Uncovered Deck Design Guide, page 15 (City of Edmonton, PDF)
Ground contact
The heavier treatment level for wood that touches the soil, such as a buried post.
Show me on a deck: The 6 in treatment zone
Lessons: Treat every cut end , Which wood goes where
Answers: Which parts of a deck have to be treated or naturally decay resistant?
Related terms: Above ground , Post base , Incised
Read more: DCA 6, Prescriptive Residential Wood Deck Construction Guide, page 2 (American Wood Council, a US code guide not in force in Canada, PDF), Uncovered Deck Design Guide, page 8 (City of Edmonton, PDF), Wood Preservation Canada (Canadian industry association)
Guard
Also called railing.
The barrier along an edge that stops a fall; required above 600 mm (23 9/16 in) , and not the same as a handrail.
At least 900 mm (35 7/16 in) high while the deck is under 1.8 m (5 ft 10 13/16 in) , then 1.07 m (42 in) all the way round.
Show me on a deck: When a guard is required
Lessons: Measure height at the worst corner , 900 mm (35 7/16 in) or 1.07 m (42 in)What counts as the ground , Nothing to climb above 4.2 m (13 ft 9 5/16 in) , Can a bench be the guard , Glass, cable and aluminum guards , When a stair needs a landing , A guard on a low deck , Wrapping around a corner , Two levels, one deck , A second storey deck , The final inspection checklist
Answers: How high does a deck railing have to be, and when do I need one?
Related terms: Baluster , Handrail , Climbable , Guard post , Deck height
Read more: Uncovered Deck Design Guide, page 14 (City of Edmonton, PDF), National Building Code of Canada 2020 (National Research Council, the model code), Uncovered Deck Final Building Inspection checklist (City of Edmonton, PDF)
Guard post
The post that holds a guard up, bolted to the rim with blocking behind, never notched and nailed.
Show me on a deck: Guard posts carry the push
Lessons: A 2x8 rim for guard posts , What blocking is for , What to check each spring , Wrapping around a corner , Outlets on the deck
Answers: How high does a deck railing have to be, and when do I need one?
Related terms: Rim board , Blocking , Lag screw , Through bolt
Read more: Uncovered Deck Design Guide, page 15 (City of Edmonton, PDF), Illustrated Guide for Building Safe and Durable Wood Decks and Balconies, page 16 (BC Housing, PDF), DCA 6, Prescriptive Residential Wood Deck Construction Guide, page 19 (American Wood Council, a US code guide not in force in Canada, PDF), Deck Evaluation Guide (North American Deck and Railing Association)
Handrail
The rail you hold on a stair, 865 mm (34 in) to 1.07 m (42 in) above the nosings, needed past 3 risers.
Show me on a deck: Handrail or guard cap
Lessons: How wide a stair must be , The final inspection checklist
Answers: When does a deck stair need a handrail, and how high?
Related terms: Graspable , Guard , Nosing , Flight
Read more: Uncovered Deck Design Guide, page 15 (City of Edmonton, PDF), Uncovered Deck Final Building Inspection checklist (City of Edmonton, PDF)
Heartwood
The darker inner wood of a log; in cedar it is the part that resists decay.
Show me on a deck: Cedar heartwood and sapwood
Lessons: Which wood goes where
Answers: Which parts of a deck have to be treated or naturally decay resistant?
Related terms: Sapwood , Ground contact , Above ground
Read more: Illustrated Guide for Building Safe and Durable Wood Decks and Balconies, page 27 (BC Housing, PDF), DCA 6, Prescriptive Residential Wood Deck Construction Guide, page 3 (American Wood Council, a US code guide not in force in Canada, PDF)
Herringbone
Decking laid in short boards at right angles in a zigzag; every board end needs framing under it.
Show me on a deck: Waste by board pattern
Answers: What decking can I use and how far apart do the joists go?
Related terms: Picture frame border , Blocking , Joist
Read more: Uncovered Deck Design Guide, page 12 (City of Edmonton, PDF), DCA 6, Prescriptive Residential Wood Deck Construction Guide, page 3 (American Wood Council, a US code guide not in force in Canada, PDF)
Incised
Treated lumber with rows of small cuts that let preservative in; it spans a little less than plain lumber.
A spruce pine fir 2x8 at 16 in spans 12 ft plain and 11 ft 5 in incised.
Show me on a deck: Incised lumber spans less
Lessons: Treat every cut end
Answers: How far can a deck joist span?
Related terms: Span , S-P-F , Ground contact
Read more: Prescriptive Residential Exterior Wood Deck Span Guide, page 8 (Canadian Wood Council, PDF), Prescriptive Residential Exterior Wood Deck Span Guide, page 4 (Canadian Wood Council, PDF), Uncovered Deck Design Guide, page 11 (City of Edmonton, PDF)
Joist
The repeating framing member that carries the decking, no more than 600 mm (23 9/16 in) apart and usually 16 in .
Show me on a deck: Deeper joists span farther
Lessons: Closer joists buy span , Where a joist cannot be cut , How far joists may overhang , Board thickness sets joist spacing , Diagonal boards pull joists closer , Gaps let the water through , Where board ends meet , Room for air underneath , Tape on the joist tops
Answers: How far can a deck joist span?
Related terms: Span , Blocking , Rim board , Joist hanger , S-P-F
Read more: Prescriptive Residential Exterior Wood Deck Span Guide, page 7 (Canadian Wood Council, PDF), Uncovered Deck Design Guide, page 11 (City of Edmonton, PDF)
Joist hanger
A metal bracket that carries a joist off a beam or ledger, only as strong as the fasteners its maker names.
Show me on a deck: Hangers need their own fasteners
Lessons: Drop beam or flush beam , Rust where metal meets treatment
Answers: What size beam and post does my deck need?
Related terms: Flush beam , Corrosion resistant fastener , Ledger
Read more: Uncovered Deck Final Building Inspection checklist (City of Edmonton, PDF), Uncovered Deck Design Guide, page 9 (City of Edmonton, PDF), DCA 6, Prescriptive Residential Wood Deck Construction Guide, page 9 (American Wood Council, a US code guide not in force in Canada, PDF), Deck Connection and Fastening Guide (Simpson Strong-Tie, a manufacturer guide)
Joist tape
A self adhesive membrane over the top of each joist that keeps water out of the fastener holes.
Show me on a deck: Tape on the joist tops
Lessons: Gaps let the water through
Answers: How much clearance does a deck need off the ground, and where does the water go?
Related terms: Joist , Flashing
Read more: Uncovered Deck Design Guide, page 2 (City of Edmonton, PDF), Illustrated Guide for Building Safe and Durable Wood Decks and Balconies, page 18 (BC Housing, PDF)
Knee brace
A diagonal brace from a post up into the beam or frame that stops the deck racking sideways.
No column bracing is required while the joist bottoms stay within 600 mm (23 9/16 in) of the ground. Above that it is a design question, and diagonal braces from the corner posts into the frame are usually adequate. Above 3.6 m (11 ft 9 11/16 in) the bracing is engineered.
Show me on a deck: Brace the corner posts
Lessons: Tall decks sway , Bracing a freestanding deck
Answers: How high can a deck go before it needs an engineer?
Related terms: Lateral load connection , Post , Freestanding deck
Read more: Uncovered Deck Design Guide, page 8 (City of Edmonton, PDF), DCA 6, Prescriptive Residential Wood Deck Construction Guide, page 10 (American Wood Council, a US code guide not in force in Canada, PDF)
Lag screw
A heavy screw with a hex head, turned in with a wrench; the usual fastener for ledgers and guard posts.
Show me on a deck: Bolting the ledger
Answers: Should the deck be attached to the house or freestanding?
Related terms: Through bolt , Ledger , Guard post
Read more: Inspecting a Deck, Illustrated (InterNACHI, inspection practice), DCA 6, Prescriptive Residential Wood Deck Construction Guide, page 16 (American Wood Council, a US code guide not in force in Canada, PDF), Illustrated Guide for Building Safe and Durable Wood Decks and Balconies, page 14 (BC Housing, PDF), Illustrated Guide for Building Safe and Durable Wood Decks and Balconies, page 28 (BC Housing, PDF)
Landing
A level floor at the top or bottom of a flight, or where a stair turns; the deck and the ground count.
Show me on a deck: When a stair needs a landing
Lessons: Folding a ramp to fit the yard , The step down from the door , Ramps to an upper deck , Lighting every change of level
Answers: When does a deck stair need a landing?
Related terms: Flight , Guard , Ramp
Read more: Uncovered Deck Design Guide, page 13 (City of Edmonton, PDF), Uncovered Deck Design Guide, page 15 (City of Edmonton, PDF)
Lateral load connection
Hardware that ties the deck frame into the house floor so the deck cannot pull away.
Show me on a deck: Tying the deck to the house floor
Lessons: Tall decks sway
Answers: Should the deck be attached to the house or freestanding?
Related terms: Ledger , Knee brace , Freestanding deck
Read more: DCA 6, Prescriptive Residential Wood Deck Construction Guide, page 17 (American Wood Council, a US code guide not in force in Canada, PDF), Illustrated Guide for Building Safe and Durable Wood Decks and Balconies, page 14 (BC Housing, PDF), Deck Connection and Fastening Guide (Simpson Strong-Tie, a manufacturer guide)
Ledger
Also called ledger board.
The board bolted to the house that carries one edge of the deck; most collapses start here.
Show me on a deck: Bolting the ledger
Lessons: Ledger or freestanding , Flashing over the ledger , How a ledger fails , Tying the deck to the house floor , What to check each spring , Inspect from the ground up
Answers: Should the deck be attached to the house or freestanding?
Related terms: Flashing , Lag screw , Through bolt , Rim board , Lateral load connection , Freestanding deck
Read more: Uncovered Deck Design Guide, page 10 (City of Edmonton, PDF), DCA 6, Prescriptive Residential Wood Deck Construction Guide, page 13 (American Wood Council, a US code guide not in force in Canada, PDF), DCA 6, Prescriptive Residential Wood Deck Construction Guide, page 15 (American Wood Council, a US code guide not in force in Canada, PDF), Illustrated Guide for Building Safe and Durable Wood Decks and Balconies, page 22 (BC Housing, PDF), Inspecting a Deck, Illustrated (InterNACHI, inspection practice), Deck Evaluation Guide (North American Deck and Railing Association)
Nosing
The front edge of a tread that overhangs the riser below, by no more than 1 in .
Show me on a deck: Rise and run limits
Lessons: Handrail or guard cap
Answers: How tall can a deck step be and how deep does the tread have to be?
Related terms: Tread , Run , Handrail
Read more: Uncovered Deck Design Guide, page 13 (City of Edmonton, PDF), Uncovered Deck Design Guide, page 14 (City of Edmonton, PDF)
Picture frame border
Boards run around the deck edge with mitred corners, framing the field boards; it needs blocking under the border.
Show me on a deck: Blocking under a picture frame
Lessons: Waste by board pattern
Answers: What decking can I use and how far apart do the joists go?
Related terms: Herringbone , Blocking , Fascia
Read more: Uncovered Deck Design Guide, page 12 (City of Edmonton, PDF), DCA 6, Prescriptive Residential Wood Deck Construction Guide, page 3 (American Wood Council, a US code guide not in force in Canada, PDF)
Pier block
A precast concrete block on a pad at grade that carries a post on a low deck.
Edmonton has found pier blocks on pads generally adequate near the ground on well drained, undisturbed or compacted coarse grained soil or rock, as long as you can reach the posts to re-level them. On any other soil a way in is required: a 24 in by 24 in access way where the joist bottoms are at least 24 in up, or removable decking.
Show me on a deck: Pier blocks need access to re-level
Lessons: Pier, pier block or screw pile
Answers: How deep do deck footings have to go?
Related terms: Access way , Footing , Screw pile , Frost heave
Read more: Uncovered Deck Design Guide, page 7 (City of Edmonton, PDF)
Ply
One board in a built up beam; a 2 ply 2x10 is two 2x10s fastened together.
Nailed with 2 rows of 3 1/2 in nails no more than 18 in apart. In a 2 ply beam on three posts, the one joint goes over the middle post.
Show me on a deck: Building up a beam
Lessons: 4x4 or 6x6 post , Post spacing against beam size , The beam sits on the post
Answers: What size beam and post does my deck need?
Related terms: Beam , Post , Blocking
Read more: Uncovered Deck Design Guide, page 10 (City of Edmonton, PDF), Prescriptive Residential Exterior Wood Deck Span Guide, page 6 (Canadian Wood Council, PDF)
Post
The upright member that carries the beam down to the footing: a 4x4 or a 6x6.
A 4x4 only under a 2 ply beam, not over 6 ft 6 in tall, on a deck not more than 1.8 m (5 ft 10 13/16 in) up. Otherwise a 6x6, up to 12 ft .
Show me on a deck: 4x4 or 6x6 post
Lessons: Set the post off the concrete , The beam sits on the post , A second storey deck
Answers: What size beam and post does my deck need?
Related terms: Post base , Beam , Footing , Knee brace
Read more: Uncovered Deck Design Guide, page 8 (City of Edmonton, PDF), Prescriptive Residential Exterior Wood Deck Span Guide, page 5 (Canadian Wood Council, PDF)
Post base
A metal bracket that holds a post off the concrete so its end grain can dry.
The pier stands at least 150 mm (6 in) above grade. Never cast the post into it.
Show me on a deck: Set the post off the concrete
Answers: Which parts of a deck have to be treated or naturally decay resistant?
Related terms: Post , Footing , Ground contact
Read more: Uncovered Deck Design Guide, page 8 (City of Edmonton, PDF), Illustrated Guide for Building Safe and Durable Wood Decks and Balconies, page 20 (BC Housing, PDF)
Prescriptive
Built straight from the span tables and standard details, with no engineer, as long as the deck stays inside them.
Show me on a deck: Pier, pier block or screw pile
Lessons: Deeper joists span farther
Answers: How far can a deck joist span?
Related terms: Engineer stamp , Span , CCMC evaluation report , Authority having jurisdiction
Read more: Prescriptive Residential Exterior Wood Deck Span Guide, page 4 (Canadian Wood Council, PDF), Uncovered Deck Design Guide, page 5 (City of Edmonton, PDF)
Ramp
A sloped walkway in place of steps; every inch of rise costs a fixed length of ramp.
Show me on a deck: Slope sets ramp length
Lessons: Folding a ramp to fit the yard , Ramps to an upper deck
Related terms: Landing , Flight
Read more: National Building Code of Canada 2020 (National Research Council, the model code), National Building Code, 2023 Alberta Edition (National Research Council, the Alberta code)
Rim board
Also called rim joist, or band joist.
The joist that closes the ends of the frame; with side mounted guard posts, a 2x8 or deeper is recommended.
Show me on a deck: A 2x8 rim for guard posts
Lessons: Flashing over the ledger , How a ledger fails , What blocking is for , Guard posts carry the push , Squaring the frame
Answers: How high does a deck railing have to be, and when do I need one?
Related terms: Fascia , Guard post , Blocking , Joist
Read more: Uncovered Deck Design Guide, page 12 (City of Edmonton, PDF), Uncovered Deck Design Guide, page 14 (City of Edmonton, PDF), DCA 6, Prescriptive Residential Wood Deck Construction Guide, page 19 (American Wood Council, a US code guide not in force in Canada, PDF)
Rise
The height from one tread to the next, 125 mm (5 in) to 200 mm (7 13/16 in) , and the same on every step.
Show me on a deck: Rise and run limits
Answers: How tall can a deck step be and how deep does the tread have to be?
Related terms: Riser , Run , Tread , Flight
Read more: Uncovered Deck Design Guide, page 13 (City of Edmonton, PDF)
Riser
The upright face of a step. Riser boards carrying the tread fronts let stringers go 1.2 m (47 3/16 in) apart, not 900 mm (35 7/16 in) .
Show me on a deck: The bottom riser trap
Lessons: Rise and run limits , Lighting the stair , The step down from the door , Lighting every change of level
Answers: How tall can a deck step be and how deep does the tread have to be? , How wide do deck stairs have to be and how far apart can stringers go?
Related terms: Rise , Tread , Stringer
Read more: Uncovered Deck Design Guide, page 13 (City of Edmonton, PDF)
Run
The depth from one nosing to the next, 255 mm (10 in) to 355 mm (14 in); the nosing does not add to it.
Show me on a deck: Rise and run limits
Lessons: Tapered treads and spirals
Answers: How tall can a deck step be and how deep does the tread have to be?
Related terms: Rise , Tread , Nosing
Read more: Uncovered Deck Design Guide, page 13 (City of Edmonton, PDF)
S-P-F
Also called spruce pine fir, or SPF.
Spruce pine fir, the common framing lumber in Alberta; each species group has its own span column.
Show me on a deck: Species changes the span
Answers: How far can a deck joist span?
Related terms: Span , Incised , Joist
Read more: Prescriptive Residential Exterior Wood Deck Span Guide, page 6 (Canadian Wood Council, PDF), Uncovered Deck Design Guide, page 11 (City of Edmonton, PDF)
Sapwood
The pale outer wood of a log; even in cedar it has little resistance to decay.
Show me on a deck: Cedar heartwood and sapwood
Answers: Which parts of a deck have to be treated or naturally decay resistant?
Related terms: Heartwood , Ground contact
Read more: Illustrated Guide for Building Safe and Durable Wood Decks and Balconies, page 27 (BC Housing, PDF), DCA 6, Prescriptive Residential Wood Deck Construction Guide, page 3 (American Wood Council, a US code guide not in force in Canada, PDF)
Screw pile
Also called helical pile.
A steel shaft with a helix screwed into the ground to carry a post; in Alberta each one is engineered.
Show me on a deck: Pier, pier block or screw pile
Answers: How deep do deck footings have to go?
Related terms: Pier block , Footing , Engineer stamp , Prescriptive
Read more: Uncovered Deck Design Guide, page 7 (City of Edmonton, PDF), CCMC Registry of Product Assessments (National Research Council, searchable list)
Site coverage
The share of your lot covered by buildings; in Edmonton a deck 1.8 m (5 ft 10 13/16 in) or higher counts toward it.
Show me on a deck: When a deck counts as lot coverage
Answers: How high can a deck go before it needs an engineer?
Related terms: Development permit , Deck height
Read more: Uncovered Deck Design Guide, page 3 (City of Edmonton, PDF), Deck (Uncovered) permits (City of Edmonton)
Span
The distance a member carries load between supports, measured from the middle of one support to the next.
Show me on a deck: Deeper joists span farther
Lessons: Closer joists buy span , Incised lumber spans less , Species changes the span , Where a joist cannot be cut , Span plus cantilever picks the beam , Diagonal boards pull joists closer
Answers: How far can a deck joist span?
Related terms: Joist , Cantilever , Beam , Prescriptive
Read more: Prescriptive Residential Exterior Wood Deck Span Guide, page 7 (Canadian Wood Council, PDF), Uncovered Deck Design Guide, page 11 (City of Edmonton, PDF)
Stringer
The notched board that carries the treads of a stair, 1 1/2 in thick.
Stringers go up to 900 mm (35 7/16 in) apart, or 1.2 m (47 3/16 in) where riser boards support the front of the treads.
Show me on a deck: Stringer depth and spacing
Lessons: Gaps under rails and beside stairs , The bottom riser trap , Where the stringer meets ground , What to check each spring
Answers: How wide do deck stairs have to be and how far apart can stringers go?
Related terms: Throat , Tread , Flight , Rise
Read more: Uncovered Deck Design Guide, page 13 (City of Edmonton, PDF)
Throat
The wood left behind the deepest notch of a stringer, measured square to its bottom edge; at least 90 mm (3 1/2 in).
Show me on a deck: Stringer depth and spacing
Answers: How wide do deck stairs have to be and how far apart can stringers go?
Related terms: Stringer , Rise , Run
Read more: Uncovered Deck Design Guide, page 13 (City of Edmonton, PDF)
Through bolt
A bolt that passes right through the ledger and the house rim, held by a washer and nut on the far side.
Show me on a deck: Bolting the ledger
Answers: Should the deck be attached to the house or freestanding?
Related terms: Lag screw , Ledger , Guard post
Read more: Inspecting a Deck, Illustrated (InterNACHI, inspection practice), DCA 6, Prescriptive Residential Wood Deck Construction Guide, page 16 (American Wood Council, a US code guide not in force in Canada, PDF), Illustrated Guide for Building Safe and Durable Wood Decks and Balconies, page 14 (BC Housing, PDF)
Tread
The flat part of a step you stand on; its thickness comes off the bottom riser when laying out the stringer.
Show me on a deck: The bottom riser trap
Lessons: Rise and run limits , Tapered treads and spirals
Answers: How tall can a deck step be and how deep does the tread have to be?
Related terms: Riser , Run , Nosing , Stringer
Read more: Uncovered Deck Design Guide, page 13 (City of Edmonton, PDF)
Undisturbed soil
Ground that has never been dug, below and beyond the loose backfill around a basement.
How far the basement dig reached is different on every lot, so the fill in the drawing is a drawing convention, not a measured or code value. On a real lot, find where the dig ended and bear past it, or go deeper.
Show me on a deck: Bear on undisturbed soil
Answers: How deep do deck footings have to go?
Related terms: Footing , Frost line , Freestanding deck
Read more: Uncovered Deck Design Guide, page 7 (City of Edmonton, PDF), Illustrated Guide for Building Safe and Durable Wood Decks and Balconies, page 11 (BC Housing, PDF)
