Construction Details for Green Oak Frames

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Construction Details for Green Oak Frames
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Oak Framing
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Sustainable Design

• Orientation
• Minimise heat loss
• Increase insulation
• Make more airtight
• Improve glazing efficiency
• Passive solar design
• Control ventilation

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Summary

• Shrinkage
• Whether to infill or enclose
• Envelope details
• Glazing details

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The impact of the new Part L1A building
regulations on green oak frames

• The new standards call for a reduction of CO2
  emissions by 20 compared to the 2002 values.
• Reasonable provision has to be made to limit the
  loss of heat through the fabric of the envelope.
• Glazing should be protected to prevent high
  internal summer temperatures.
• Air permeability needs to be kept within
  reasonable limits.

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Shrinkage
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Properties of shrinkage
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Infill verses exterior envelope

• Infill using modern materials
• Advantages include traditional appearance and
  thinner exterior wall
• Disadvantages can be water ingress, air leakage
  and continuing maintenance
• Wrapping the frame in an exterior envelope
• Advantages include improved insulation,
  airtightness and the use of high thermal mass
  materials
• Disadvantages include loss of traditional
  appearance

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Exterior envelope wall details
Softwood Frame
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Sips Panel
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Masonry Construction
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Roof and floor details
Roof
Floor
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Glazing Frames
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Direct Glazing

• Double glazed units are held in place by an air
  dried oak cover
• Shrinkage likely to occur on the inside
• Either a dry or wet glaze method can be used
• Toughened glass should be used throughout the
  system

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Glazing Details

• Glazing horizontal members can be complicated
• Either copper or lead flashings should be used to
  stop water ingress
• Lead should be treated with bituminous tar
• Opening doors and windows should be hung in their
  own stable frame

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Minimising glazing problems

• Protect the glass
• Timber quality should be good
• Keep high heat sources away

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Conclusions

• Shrinkage is the biggest challenge to overcome
  when designing with green oak
• Oak frames can be either infilled or clad
  externally but future regulations may make
  infilling frames unacceptable
• Ideally the fabric of the building should be put
  on the outside of the frame or therefore
  minimising the effects of shrinkage
• Glass should be protected by some form of passive
  solar shading to prevent overheating
• The Future?

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