advanced framing advanced wood framing multi-story wood structures advanced wood framing scott...
TRANSCRIPT
Designing Multi-story Wood Structures
Advanced Wood Framing
Scott Nyseth, PE
ADVANCED FRAMING
The Genesis:
“Operation Breakthrough”
(Not a code name for a military offensive)
• HUD sponsorship – started 1969• “stimulate the private housing industry by
promoting volume industrialized housing production, particularly through modular construction. “
• “not a program designed to see just how cheaply we can build a house, but a way to break through to total new systems of housing production, financing, marketing, and land use.”
“Operation Breakthrough”
• Terminated in 1979.
• Positives:• The National Association of Home Builders
(NAHB) along with the USDA Forest Products Laboratory (FPL)
• proposed construction methods for Optimum Value Engineering (OVE) which is also know as the Advanced Framing Method.
Operation Breakthrough How does Advanced Framing fit into our current approach to sustainable design?
LEED for Homes gives credit for using Advanced Framing Techniques
LEED for Commercial gives no direct credit for Advanced Framing Techniques. The benefit will show up in energy savings in the energy model.
There should be some incentive to save the material though…
Some jurisdictions recognize this material saving benefit –
The City of Portland Office of Sustainable Development and the PDC both got it right: The Green Building Resource Manual requires, 24”oc framing, 2 stud corners, engineered lumber, and box headers. These are “threshold” or required strategies which reflect the savings of an important natural resource, as well as energy.
The Building America program is a US Department of Energy (DOE) program which utilizes the Whole Building approach to energy efficiency, where an overall energy consumption savings is targeted, and the details of how you get there do not matter (Energy Star Rating). Advanced Framing is an important tool to achieve energy savings, but it is not required. That being said, almost all buildings in this program utilize Advanced Framing Techniques.
Details of Advanced Framing
Elimination of unnecessary wood framing in a structure
Simply =
Image from Cost Effective Home Building: A Design and Construction Handbook by the NAHB
Not So Advanced Framing
Image from Cost Effective Home Building: A Design and Construction Handbook by the NAHB
Advanced Framing
Image from Cost Effective Home Building: A Design and Construction Handbook by the NAHB
Advanced Framing AlignmentAdvanced Framing
• Studs at 24” o.c.• Two stud corners or other means to fully
insulate corners• One stud is used to support each header• R-10 headers• Fully insulated interior/exterior wall
intersections• 17% of the wall is studs and headers• Conventional = 23% studs/header (�=35%)
Advanced Framing System
• 2 Stud CornersAdvanced Framing System
Advanced Framing System
• Hardware used to eliminate cripples at wall openings
Advanced Framing System
•Single Top Plate
Energy Saving Details
• Insulated headers
• No header necessary at non-bearing walls
Energy Saving Details
• Recessed Header
• Trusses & Joist “Stacked” over studs
Energy Saving Details
• Full and even insulation depth to the outside edge of the exterior walls
• Raised heel or oversized trusses
Energy Saving Details
• Airtight electrical boxes in exterior walls and ceilings
Energy Saving Details
• Seal ALL penetrations to the outside
Pearl Family HousingOwner: Ed McNamara/Turtle Island DevelopmentEngineer: Miyamoto InternationalArchitect: Ankrom Moison Associated ArchitectsContractor: Walsh Construction Company
Fire and Life Safety
Parking Level Meets the definition of a basement , does not contribute to area or height limitation.
Ground Floor Type IA Construction – Occupancy S2, B, E, A2.
Allowable Height - Unlimited
Allowable Stories - One Story
Allowable Area - Unlimited
Podium (2-6) Type IIIB Construction – Occupancy R2
Allowable Height - 55’
Allowable Stories - Four Stories
Allowable Area - 16,000 sf
Modifications to height
Use automatic sprinkler system to add one story and 20’ to allowable height.
Modified height Allowance (fire and life safety) = 75’
Structural height allowance for plywood shear walls = 65’
The Structural height limitation controls the building height!
Type IIIB details
2hr Exterior Bearing Walls – Fire retardant treated wood req’d
• Galvanized or Stainless Steel fasteners required
• Reduce structural properties of wood
Exterior Bearing Wall
Case Study – Advanced Framing Quantify lumber savings for various
Advanced Framing details:
Douglas Fir can produce 1000 bd ft of lumber per year per acre such that every 30 years approximately 30,000 bd ft can be logged.
Wall Studs Wall Studs –
Conventional Advanced Savings
Exterior Walls45,000 s.f.
33,750 BF 22,500 BF 11,250 BF
Interior Walls75,000 s.f.
56,250 BF. 37,500 BF 18,750 BF
Note:2x6 @ 16” o.c. = 0.75 BF/s.f.2x6 @ 24” o.c. = 0.50 BF/s.f.
Top PlatesTop Plates -
Conventional Advanced Savings
Exterior 2x6 Walls
1,200 LF/Floor
2,400 BF/Floor 1,200 BF/Floor1,200
BF/Floor
Interior 2x6 Walls
2,000 LF/Floor
4,000 BF/Floor 2,000 BF/Floor2,000
BF/Floor
Interior 2x4 Walls
4,400 LF/Floor
2,950 BF/Floor 1,475 BF/Floor1,475
BF/Floor
Totals
(5 Floors)46,750 BF 23,375 BF 23,375 BF
Window Trimmers -Conventional Advanced Savings
Under Header (4) 2x6x8’ studs (2) 2x6x8’ studs 1,620 BF/Floor
Under Sill (4) 2x6x3’ studs (2) 2x6x3’ studs 540 BF/Floor
Totals(90 windows/floor)
10,800 BF
Miscellaneous Reductions -
** Savings based on 70 windows / floor @ 5 floors
Conventional Advanced Savings
Headers in NL Bearing Extr.
6x6x5’ (20 BF) 2x6 Flat (5 BF) 5,250 BF**
Wall Corners & Intersections
(3) 2x6x9’ studs (2) 2x6x9’ studs ~10,000 BF
Totals 15,250 BF
Approximate Lumber Savings –
Equivalent to about 2.9 acres of 30 year old Douglas Fir (~ 2x4x23 miles long!!)
Savings
Wall Studs 30,000 BF
Top Plates 23,375 BF
Trimmers 10,800 BF
NL Bearing Headers
5250 BF
Corners/
Intersections10,000 BF
Totals 80,000 bf
Delivery or Disposal?
Challenges (Design Opportunities)
• Application. Advanced framing requires stacked and modular construction to be most effective. This may not work well with certain project types
• Layout Control. Advanced framing requires tighter control of framing layout, which may be difficult to coordinate between subcontractors.
• Different. Advanced framing methods differ from standard wood construction practice. There may be ‘growing pains’ associated with implementation.
• Availability. Custom cut studs (94 1/8” vs. 92 5/8”)
Advantages• Cost Savings. Both upfront and long-term
• Reduction in shrinkage. For multi-story buildings, a single top plate will result in at least one third less total shrinkage
• Reduce waste. Wasted materials are paid for 4x, once to get, once to move around, once to move scrap to dumpster, and once to haul away
• Sustainability. Material and Energy savings
Advanced Framing just makes sense
Contact
Scott Nyseth, PE
Miyamoto International
www.miyamotointernational.com