NCC 2016 Volume One
Search the National Construction Code editions
Classification
Building class 1a Building class 1b Building class 2 Building class 3 Building class 4 Building class 5 Building class 6 Building class 7a Building class 7b Building class 8 Building class 9a Building class 9b Building class 9c Building class 10a Building class 10b Building class 10c

Filter

Classification
Building class 1a Building class 1b Building class 2 Building class 3 Building class 4 Building class 5 Building class 6 Building class 7a Building class 7b Building class 8 Building class 9a Building class 9b Building class 9c Building class 10a Building class 10b Building class 10c
Specification J1.6 Floor Construction

Specification J1.6 Floor Construction

1. Scope

This Specification describes the thermal performance of some common forms of floor construction.

Intent

To clarify that outlines the thermal performance of some of the more common forms of floor construction.

2. Construction Deemed-to-Satisfy

Figure 2 details the R-Values considered to be achieved by some common forms of floor construction.

Figure 2 TYPICAL R-VALUES FOR FLOOR CONSTRUCTION

Floor construction description Item Item description R-Value
Up Down
(a) Timber internal floor, 10 mm internal plaster
v1_SpecJ16a_2005.svg
 1. Indoor air film (still air) 0.11 0.16
2. Particleboard flooring (19 mm, 640 kg/m3) 0.15 0.15
3. Floor airspace, 100 mm to 300 mm (non reflective) 0.15 0.22
4. Plasterboard, gypsum (10 mm, 880 kg/m3) 0.06 0.06
5. Indoor air film (still air) 0.11 0.16
Total R-Value 0.58 0.75
(b) Timber, suspended ground floor, open subfloor
v1_SpecJ16b_2005.svg
 1. Indoor air film (still air) 0.11 0.16
2. Particleboard flooring (19 mm, 640 kg/m3) 0.15 0.15
3. Outdoor air film (7 m/s) 0.04 0.04
Total R-Value 0.30 0.35
(c) Solid concrete suspended slab
v1_SpecJ16c_2005.svg
 1. Indoor air film (still air) 0.11 0.16
2. Solid concrete (150 mm, 2400 kg/m3) 0.10 0.10
3. Outdoor air film (7 m/s) 0.04 0.04
Total R-Value 0.25 0.30
(d) 150 mm hollow-core concrete planks
v1_SpecJ16d_2005.svg
 1. Indoor air film (still air) 0.11 0.16
2. Concrete topping (60 mm, 2,400 kg/m3) 0.04 0.04
3. Hollow-core concrete planks (150 mm, 1,680 kg/m3, 30% cores) 0.14 0.14
4. Outdoor air film (7 m/s) 0.04 0.04
Total R-Value 0.33 0.38
(e) 100 mm solid concrete slab-on-ground
v1_SpecJ16E_2013.svg
 1. Indoor air film (still air) 0.11 0.16
2. Solid concrete (100 mm, 2400 kg/m3) 0.07 0.07
3. Ground thermal resistance - -
Total R-Value 0.18 0.23
(f) 150 mm solid concrete slab-on-ground
v1_SpecJ16F_2013.svg
 1. Indoor air film (still air) 0.11 0.16
2. Solid concrete (150 mm, 2400 kg/m3) 0.10 0.10
3. Ground thermal resistance - -
Total R-Value 0.21 0.26

Notes:

  1. The R-Value of an item, other than an airspace, air film or air cavity, may be increased in proportion to the increased thickness of the item.
  2. TheTotal R-Value of a form of construction may be increased by the amount that an individual item is increased.
  3. For floor types (c) and (d) that are located over an internal space, the Total R-Value can be calculated by replacing the value for outdoor air film (R0.04) on the underside of the floor with the value for indoor air film (R0.11 for heat flow up or R0.16 for heat flow down).
  4. For floor types (b), (c) and (d) located over ground with an enclosed perimeter, the Total R-Value can be calculated by replacing the value for outdoor air film (R0.04) on the underside of the floor with the value for indoor air film plus ground thermal resistance (i.e. R0.11+R0.56=R0.67 for heat flow up, or R0.16+R0.58=R0.74 for heat flow down).
  5. Where reflective building membrane is attached beneath the floor with a 100 mm reflective airspace, add R0.38 for heat flow up and R1.14 for heat flow down.
  6. Where ground floor construction with an enclosed perimeter makes the airspace adjacent to the ground reflective, the face down subfloor air films will be R0.23 instead of R0.11 for heat flow up, and R0.80 instead of R0.16 for heat flow down.
  7. The addition of 10 mm of render to the ceiling of a suspended internal concrete floor will increase the Total R-Value by 0.02.
  8. Solid concrete slab includes concrete beam and infill floors and concrete precast permanent formwork panels. For the purposes of calculating the Total R-Value of a floor, the R-Value attributable to an in-slab or in-screed heating or cooling system is ignored.
  9. Where an airspace is filled, the R-Value listed for the airspace must be deducted from the Total R-Value of the floor construction.
Intent

To detail the Total R-Values considered to be achieved by common forms of floor construction.

For a material that is not listed as an item in Figure 2, other than air, the R-Value may be determined by dividing the thickness of the item in metres by the thermal conductivity in W/m.K (typical values are described in ).

For the purposes of calculating the Total R-Value of a floor, the R-Value attributable to an in-slab or in-screed heating or cooling system is not included.