GBE 1960 Timber Frame Retrofit (Q+A) Q#24728

By July 28, 2019 September 4th, 2019 Code, Encyclopaedia, Q&A

GBE 1960 Timber Frame Retrofit Q+A

GBE > Encyclopaedia > Code > Question+Answer > Q#24728

GBE 1960 Timber Frame Retrofit Q+A
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Hi I am a project management student and a retrofitter of houses

I have just signed up to the discounted Student membership of GBE

Thank you for signing up, it is much appreciated, every little helps GBE to continue to be developed.


As a college project we have to propose a complete retrofit of a 1960’s timber frame house to bring it up to current standards and proposed a new build of the same floor plan to new build current standards.

Q1 What help can you give me?

O1 You are asking an unusual time in July for a college project.

R1 I have had to take time off for Neck Surgery and a long recovery time and now I am trying to get back up to speed and considering when to plan to submit, now within a few days or defer until next year.


Survey Existing

Okay lets go back to basics: Understand what you have got before anything else.

Less sophistication:

  • Timber in framing, windows and doors and stairs and furniture
  • Masonry if any, cavity not solid wall
  • Ceramics: sanitary ware and tiles
  • Metals in accessories and services
  • Less plastics, some in services
  • Unlikely to have vapour barriers?
  • Probably has breather membranes and damp proof membranes and course
  • Insulation unlikely or 2” ≈ 50 mm glass or stone mineral fibre

Timber frame:

  • The timber frame, floor and the roof is likely to be hand cut on site,
  • Spacing at 2’ ≈ 600 mm centres or even 18” ≈ 450 mm centres
  • Timber studs may be as small as 4×2” ≈ 100×50 mm
  • Roof timbers and ceiling joists may be as small as 3×2” ≈ 75×50 mm or 4×2” ≈ 100×50 mm
  • Timber suspended floor: may be ≈ 8×2” 200 x 50
  • (21) Timber Frame (Lecture) G#2117 N#219

Sheathing board:

  • There may be a sheathing board of soft-board or wood fibre board on the outside (contributing a little to the thermal insulation)

Outer cladding:

  • May be timber weatherboarding
  • May be tile hanging
  • May be brickwork outer leaf

Widows and doors:

  • May be unsophisticated EJMA profiled softwood frames
  • Probably single glazing

Internal lining and ceiling

  • May be soft-board lining and plaster skim
  • May be wattle and daub plastering
  • Might even be plasterboard with or without skim

Finishes:

  • If there is any Artex coated surfaces (not by the constructor, usually by the occupant) take care to have an asbestos survey carried out

Services:

  • All electrics should be updated by rewiring to current IEEE standard and consider the accessories for reuse, resale and replacement
  • All plumbing should be checked for lead pipes which need to be replaced with copper or plastic
  • Asbestos cement water tanks
    • Need not be replaced
    • But if they are damaged then get them removed by licensed Asbestos specialists
    • Replace with plastics
  • Boiler efficiency will be very poor by today’s standards
  • Heating distribution may be within an un-insulated concrete floor or cement-based screed dissipating-heat where it may not be well utilized.

Thermal insulation:

  • 1960’s almost no requirements for Insulation,
  • 50 mm in the ceiling?
  • Probably none in the timber frame, if you are lucky, 50 mm in the frame?
  • Framing voids offer little insulating value but they are space of eddie currents and thermal bypass to occur
  • Some soft board sheathing board offers a little thermal insulation

Thermal bridges:

  • In the absence of insulation thermal bridges are potentially more insulating than air, but of little area

Airtightness:

  • Likely to be very poor, well in excess of 10
  • 8 = Noisy wind whistling through gaps, papers disturbed on tables

Proposals: Performance

Approach:

  • Whole house plan, accommodating any phasing of the work
  • PAS 2035/2030: 2019 Design and Installation for Retrofit
  • GBE Retrofit PAS 2035 (CPD) G#21613

Energy Standards

  • GBE Calculator Whole Building Uvalue to In Use Carbon A06 XLS (Shop) G#11095
  • GBE Calculator Whole Building Uvalue to In Use Carbon A05 XLSX (Shop) G#11009
  • Building Regulations Approved Document L1B targets:
    • Existing Domestic Building Refurbishment
    • U value: 0.18 W/m2.K (threshold 0.35)
    • U value: 2.0 W/m2.K Glazing (new build) (no data obtained)
    • Airtightness: 10 or no requirement (no data obtained)
    • Inadequate for UK European Global carbon Targets
  • Scottish Technical standards 6.2 (2010)
    • Existing Domestic Building Refurbishment
    • U value: 0.13 W/m2.K
    • U value: 0.8 W/m2.K Glazing (new build) (no data obtained)
    • Airtightness: 10 or no requirement (no data obtained)
    • Inadequate for UK European Global carbon Targets
  • Northern Ireland: No data collected so far
  • AECB Carbon Lite (Passivhaus for UK Climate and Energy mix)
    • Existing Domestic Building Refurbishment
    • U value: 0.15 W/m2.K
    • U value: 0.95 W/m2.K Glazing (new build) (no data obtained)
    • Airtightness of 10 or no requirement?
    • Adequate for UK European Global carbon Targets
  • Passivhaus EnerPHit
    • Existing Domestic Building Refurbishment
    • U value: 0.15 elements
    • U value: 0.8 W/m2.K Glazing
    • Airtightness: 1
    • Adequate for UK European Global carbon Targets

Other issues:

Moisture management:

  • Consider using a vapour open construction and breathing insulation materials
  • No vapour barriers but intelligent air and wind tightness layers

Solar radiation and solar gains:

  • Existing timber frame (without brick outer leaf) will be subject to solar radiation
  • Solar gains through the opaque fabric will potentially overheat the building
  • Insulation needs to have decrement delay characteristic

Acoustic performance:

  • Existing timber frame (without brick outer leaf) will be subject to acoustic penetration

Consider insulation:

  • between, outside or inside the framing
  • Cellulose flake, cork granules between the framing,
  • Dense wood fibre, cork board, cellular glass inside or outside framing

Proposals:

Accessing the wall and roof framing:

  • Take special care to not damage any cladding or linings to allow salvage and reuse of existing materials
  • Wattle and daub: save and reuse oak wattle, recycle lime plaster
  • Plasterboard will be more difficult to salvage
  • To allow for adding of insulation to stud zones

Framing:

  • Due to existing sections being too small to achieve useful U values
  • Cross batten inside outside or both to create a deeper stud zone
  • Battens at right angles to the studs to minimise thermal bridging to cross overs
  • Add breathing insulation in layers between studs and then between battens
  • Suspending insulation in floor joist zone

Claddings

  • Reinstall breathing sheathing board or install dense wood fibre board to outside
  • Install breathing wind tightness layer outside
  • Re-fix salvaged cladding to wall and roof to outside with battens to form ventilation void

Linings:

  • Install breathing sheathing board or install dense wood fibre board to inside
  • Install breathing airtightness layer inside
  • Re-fix salvaged linings to inside with battens to form services zone void
  • Install services in batten zone, insulate batten zone between services and battens
  • Reinstall salvaged linings or install new linings

Windows

GBE Database (Navigation) G#486 N#498

  • Passivhaus Windows and Doors

Cold water tanks and header tank in loft

Raised access walkway


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© GBE NGS ASWS BrianMurphy
aka BrianSpecMan
28th July 2019 -29th July 2019

GBE 1960 Timber Frame Retrofit Q+A
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© GBENGSASWSBrianMurphy
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BrianSpecMan
28th July 2019

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