Design, Convert And Build Work contd.

Environmental Preference Schedule Of Construction Elements, page 2

ROOF INSULATION

  1. cellulose, sheep's wool or hemp/cotton with thermal broken timber I beams
  2. reused insulation boards
  3. mineral wool and expanded polystyrene
  4. PUR, foam insulation, extruded polystyrene

Choice: 4. 150mm Kingspan 2nds (PU foam)
Reason: Price and practicality - lack of experience with I beams and construction concerns with a thicker roof, which would have been 300mm, if our preferred choice of cellulose had been used.

FLOOR INSULATION

  1. Mineral wool,(glass wool & rockwool) Expanded polystyrene
  2. Foamed glass
  3. Perlite
  4. Extruded polystyrene PUR

Choice: 4. 90mm extruded PU foam.
Reason: We had planned to use expanded polystyrene but problems with floor levels left us with the choice of major amounts of underpinning or saving hight with the more efficient PU.

WALL INSULATION

  1. cellulose, cork, wood fibre boards or hemp/recycled cotton
  2. Mineral wool or EPS
  3. Foamed glass
  4. PUR, extruded polystyrene

Preferable to insulate outside existing structure and clad
Choice: 1,2 & 4. Granary south facing walls; 140mm Pavatherm wood fibre boards
Outside east & north sides; Kingspan seconds. New build; 100mm of mineral wool
Reason: Practicalities with Pavatherm proved quite testing and expensive. Though this experience would help with another project. In places space was very tight and this also influenced choice.

WALLS (new) External

  1. Cob or earth, durable wood
  2. reused brick or stone
  3. new brick or concrete blocks made with recycled aggregate
  4. concrete blocks, aerated autoclaved concrete blocks, strong cement mortars, tropical wood, preserved wood

Choice: 1 & 2. Reclaimed brick outer skin and Stranlite concrete blocks inner skin which are made with selected aggregates including graded bottom furnace ash and pulverised fuel ash.
Reason: Principally the aesthetics of remaining in keeping with the associated buildings which the planners were keen on but also cost and experience with alternatives. We experimented with construction of the new lobby to WholeHealth using a timber frame with hemp lime in fill panels finished with lime and would like to try a Cob or straw bale construction next.

WALLS (new) Internal

  1. Timber frame, clay block, cob or earth
  2. Sand lime blocks, flue-gas gypsum blocks
  3. Cellular Concrete blocks, natural gypsum blocks
  4. Concrete, strong cement mortars

Choice: 1 & 4. We had chosen to use some new clay blocks from NTB but unfortunately they failed building control tests and we fell back to using concrete block and insulated timber frame with plasterboard.
Reason: Clay block where thermal mass required otherwise timber stud.

TIMBER FRAME EXTERNAL WALL FINISHES

  1. Rain screen of durable timber from sustainable source
  2. Lime sand render on lightweight lath
  3. Fibre/cement sheet rain screen
  4. hard cement render/new brickwork screen

Choice: 1. Feather edge English Larch boards single nailed onto timber frame
Reason: Ist choice, practical and affordable

INTERNAL WALL FINISHES

  1. Local timber finish or lime-washed earth walls
  2. Lime or clay plaster on masonry, timber lath or wood wool slab
  3. Gypsum (natural or flue gas derived) plasterboard and plaster skim
  4. MDF, plastic boards

Choice: 2 & 3. About half of the Granary was finished with lime plaster on either brick panels or woodfibre boards and half was plasterboard with gypsum skim.
Reason: Our builders had reservations about using lime plaster but we found a local lime plasterer who did a great job and put to rest any fears. We used lime from Mike Wye in Devon who offered great support.


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