ud83dudcda Wood Deck Build Log u2014 24 of 45
u2190 Detail #8: Decking Board Strength u00b7 Series Index u00b7 Detail #10: Rafter Strength Calc u2192
2026 Update from DIY Dad: Long Planning Period and Final Design Lock-Down
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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.
The wood deck planning phase stretched over a long time. Actual construction didn’t start until about a year after the initial plan. During that time I revisited the design repeatedly. ^ ^
What I Learned from a Long Planning Phase
- No plan is perfect u2014 at some point you have to commit and start building
- Build in flexibility so design changes can be accommodated
- Order materials 2u20133 weeks before construction starts (especially hardwood, which has long lead times)
- Introduce yourself to neighbours beforehand (tool noise and waste disposal)
Beam (u6881) Strength Calculation
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Deck Stains & Waterproof Sealers
Stain every 2u20133 years. It’s the single cheapest way to double deck lifespan.
Hi, I’m DIY Dad. ^ ^
Today: beam strength. Two beams will be installed.
Load Conditions
I’m designing for snow accumulation on the roof. Based on local experience, more than 200 mm of snow is virtually unheard of here u2014 it usually doesn’t even settle. Heavy snowfall exceeding 100 mm might happen once every ten years.
To be safe, I checked the Japan Meteorological Agency records. The historical maximum snowfall depth was:
1917: 300 mm!!
So I’ll use a snow depth of 300 mm for my calculation.
Snow accumulation area = 2,735 u00d7 6,390 = 17,476,650 mmu00b2 (essentially the full roof area). I want the roof to overhang toward the entrance as well, so I’m making it generously wide.
u2191 Snow load area
Snow volume = 17,476,650 u00d7 300 = 5,242,995,000 mmu00b3
Snow load = 5,242,995,000 u00d7 10u207bu2079 u00d7 50 u00d7 9.8 = 2,569 N
(Snow density: 50 kg/mu00b3 dry / 100 kg/mu00b3 wet. I used the dry value.)
Two beams share the load, so each beam carries 1/2 of the total. Snow is treated as a uniformly distributed load.
u2191 Beam layout
Clear span L = 3,590 mm
u03c9 = 2,569 / (2 u00d7 3,590) = 0.358 N/mm (distributed across both beams)
The calculation continues in the next article. That’s all for today! (^^)/~~~
ud83dudcda Wood Deck Build Log u2014 24 of 45
u2190 Detail #8: Decking Board Strength u00b7 Series Index u00b7 Detail #10: Rafter Strength Calc 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.
ud83cudfe0 More from DIY Father
15 years of landlord experience u00b7 3 apartment buildings u00b7 DIY renovations that saved millions of yen. Browse all articles at diytosan.com
