ud83dudcda Wood Deck DIY Guide u2014 3 of 11
u2190 No.2: Why I Built It Myself u00b7 Series Index u00b7 No.6: Floor Material u2014 Why SPF? u2192
Introduction
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Pressure-Treated Deck Lumber
Pressure-treated lumber is the baseline u2014 skip it and you’ll be rebuilding in 5 years.
One of the most common reasons wood deck DIY projects go wrong is starting construction before the overall picture has been defined.
When that happens:
- Materials change partway through
- Structural thinking becomes inconsistent
- The project ends up being patched together after the fact
To avoid this, DIY Dad clearly defined the overall configuration and materials list before any construction began.
This article organizes:
- The overall structure of the deck
- The role of each component
- The materials used and why they were chosen
Breaking Down the Overall Wood Deck Structure
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Deck Stains & Waterproof Sealers
Stain every 2u20133 years. It’s the single cheapest way to double deck lifespan.
The first step is to break the whole into functional zones. This deck consists of the following elements:
Four Major Components
- Foundation and ground-level work
- Floor structure (columns, joists, floor beams, floor boards)
- Roof structure (beams, rafters, purlins, roofing material)
- Accessories (fence, stairs, handrails)
Rather than trying to think about everything at once, each zone is designed separately according to its role.
Component 1: Foundation and Ground-Level Work
This is the base of the entire structure.
Roles:
- Transfer loads to the ground
- Absorb unevenness in the ground surface
- Ensure future maintainability
Configuration used:
- Simple concrete footings
- Adjustable jack bases
- Weed barrier fabric + crushed stone
The emphasis was on avoiding over-fixing u2014 keeping the ability to adjust in the future.
Component 2: Floor Structure (Most Critical)
ud83duded2 RECOMMENDED PRODUCTS
Deck Screws & Fasteners
Use stainless screws only u2014 standard screws rust and stain the deck within one rainy season.
This is what people walk on u2014 the most structurally important part.
Members:
- Columns (posts)
- Main joists (ooiki)
- Floor joists (neda)
- Floor boards
Key design principles:
- Define a clear load path
- Manage spans (distance between support points)
- Make individual members replaceable in the future
The floor structure was designed on the premise that “the parts you can’t see are the most important.”
Materials used (floor structure):
Columns, main joists, floor joists: Single-pipe scaffolding (Super Light 700)
- High strength
- Durable
- Good availability
- Structurally clear load path
Floor boards: SPF 2u00d74
- High workability
- Low cost
- Easy to replace in the future
Component 3: Roof Structure
The roof determines both comfort and long-term durability.
Members:
- Main beams (girders)
- Rafters
- Purlins
- Roofing material
Key design principles:
- Account for snow load
- Be mindful of integration with the adjacent lower roof
- Prioritize water-shedding performance above all
Materials used (roof structure):
Beams and rafters: Single-pipe scaffolding (Super Light 700)
Purlins: SPF 1u00d74
Roofing material: Polycarbonate corrugated sheet
- Lightweight
- Good light transmittance
- Practical to install
- Good cost balance
Component 4: Accessories (Fence and Stairs)
The final step is addressing safety and usability.
Fence:
- Visual screening
- Fall prevention
- Privacy
Stairs:
- Access route
- Safety for children and dog
These were designed as elements that can be added after the main structure is complete.
Materials used (accessories):
- SPF 2u00d74 and 1u00d74
- Louvered lattice panels
- Coarse-thread screws (course screws)
For components expected to wear out or change, easily replaceable lumber was selected.
Why the Materials List Was Finalized First
The reason is straightforward:
- Structural calculations become possible
- Cost estimates become possible
- Construction sequence can be organized
Buying materials before the design is settled almost always leads to waste.
Next Article
The next article takes a deeper look at why steel pipe was chosen as the structural member.
- Why lumber alone was not sufficient
- Pros and cons of steel pipe
- What to watch out for when using it in DIY
NO.4 | Why Steel Pipe Was Chosen for Structural Members u2014 continued there.
That’s all for today u2014 see you in the next article!
ud83dudcda Wood Deck DIY Guide u2014 3 of 11
u2190 No.2: Why I Built It Myself u00b7 Series Index u00b7 No.6: Floor Material u2014 Why SPF? u2192
DIY Renovation Quote Review Manual
How to read, compare, and negotiate contractor quotes. This manual saved me u00a5800,000 on a single renovation project.
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15 years of landlord experience u00b7 3 apartment buildings u00b7 DIY renovations that saved millions of yen. Browse all articles at diytosan.com
