All H1 changes now in place

The final transition date for the updates to Clause H1 of the Building Code has passed and, as a result, windows and doors in climate zones one and two now require an R-value of R0.46.

Suppliers, specifiers and builders in the country’s two warmest climate zones were given a year longer than the rest of the country to achieve the second R-value in what was a two-step process for all climate zones.

On 3 November 2022, windows and doors in houses in all areas of the country required a rating of R0.37 – up from R0.26. On 1 May 2023, the required R-value for climate zones three, four, five and six increased to R0.46 (three and four) and R0.50 (five and six).

Now, the final transition date will bring zones one and two in line with the rest of the country.

Increased R-values impacts construction methods

From 2 November 2023, if using the Schedule Method, compliance can only be achieved through the use of thermally broken aluminium, uPVC or timber window framing with double-glazed Low E IGUs – aluminium framing will no longer suffice.

For door construction, a common first step to meet the required R-value is to use a thermally broken aluminium or composite door, while timber, uPVC or fiberglass insulate doors can also significantly increase the R-value. If the door includes glazed sections, or is fully glazed, then low-emissivity, argon-filled double-glazing provides the highest R-value performance.

Intent of H1 changes

The update to Clause H1 of the Building Code intends to make new buildings warmer, drier and healthier, as well as to reduce the energy and environmental impact of heating them. There are different requirements for Buildings more than 300m² , Buildings less than 300m² and Residential. Changes apply to wall, floor and ceiling insulation, as well as the thermal performances of windows and doors.

For Buildings less than 300m² and Residential, R-value requirements for roofs increased from R2.9 and R3.3 (depending on zoning) to R6.6. Walls R-values have been increased from R1.9 in zone one to four to R2.0. Current wall depth will not have to change to accommodate the increases and the new R-value of R2.0 is achievable using standard 90mm wall framing.

Unheated slab-on-ground floors were lifted to R1.5 to R1.7 from R1.3, depending on the climate zone from 1 May 2023, while heated ground floors require an R-value of R2.5-R3.0 – an increase from R1.9.

While the increase in R-value for slab-on-ground floors appears to be small, the change to the method of calculation has changed and the increase is more like the equivalent of going to R2.0 under the previous approach – says BRANZ.

Builders may need to consider a change in installation methods for floors. For example, insulation added to non-slab-on-ground floors can’t be held in place with stables due to its increased thickness.

To find out more about changes and the products that can be used to achieve the new R-values, check out PlaceMakers ‘All Over H1’ website.