The changes to the building code that could impact your build

Changes to the Building Code are coming. Here’s how they’ll impact you if you’re planning a new build

Every year the Ministry of Business, Innovation and Employment (MBIE) works alongside those working in the building and construction sector, as well as the public, to review proposed changes to the Building Code with one common goal in mind: to ensure we are building homes that are warmer, drier, healthier, and cheaper to heat.

This year, the focus has been on new builds in particular. The three areas consulted on this year are plumbing and drainage, hollow-core floors, and fire protection. The submissions for these three are under review, whereas the previously consulted changes to energy performance and insulation requirements from 2021 have been approved and we are currently in a transition period to action these changes.

H1 Energy efficiency

Clause H1 of the Building Code deals with the energy efficiency of, in this case, a home. It does this in two ways.

  • By requiring adequate thermal resistance (explained below) to enclosed spaces that are temperature and humidity controlled, such as the inside of your home, and how well it retains heat through windows, doors, floors and so on.
  • By limiting uncontrollable airflow, meaning how well your home seals to assist with heat retention.

When are the changes being made?

The H1 updates come with new wall, floor and roof insulation performance requirements, including windows and doors.

Currently we’re in a transition period to ensure compliance on new-build projects by the end of this year, however that transition period has recently been extended by six months to 1 May 2023 for wall, floor and roof insulation due to the current pressure on the residential construction sector.

All windows and doors have an ‘interim improvement level’ that needs to be achieved by November this year, with final upgrades actioned by May and November 2023 depending on where
in the country you are.

The most important date to keep in mind is 3 November 2022. Building consents submitted before this date can show compliance with the previous requirements, whereas those submitted after need to show compliance with the new requirements.

Who’s impacted?

The country has been broken up into ‘climate zones’ labelled 1-6, starting from the upper North Island with zones 1 and 2. These zones reflect and acknowledge
the different climates experienced across New Zealand, and enable the Building Code to address each climate uniquely in a way that best supports its needs.

What are the changes?

Within the ‘climate zones’, minimum R-values need to be achieved for all types of insulation and joinery. An R-value is a measure of ‘thermal resistance’, which is just a fancy way of communicating how well a window or door keeps heat in the home. The higher the R-value, the better the window or door performs in terms of heat retention, or lack of heat transfer out of the home.

Wall insulation

In-wall insulation for walls in a new build needs to achieve an R-value of R2.0 – the current requirement is R1.9 so it’s not much of a change. The plus with this is that it means it can still be achieved within a common 90mm wall frame. Homeowners don’t need to wear the cost of framing wider walls to take a thicker insulation.

Floor insulation

Previously all floor types were treated in the same way; with the changes to H1 floor insulation requirements not only separated by the new climate zones, but also by
the type of construction: either slab on ground, or other such as pile foundations which is what most villas, bungalows and cottages are on.

The required R-values for each zone varies but Zone 1’s slab on ground floors is 1.5 and 2.5 for other floors, whereas Zone 6’s slab on-ground floor is 1.7 and 3 for other flooring types. Remember, higher R-values are for colder climates. The reason why slab on ground floors can get away with lower R-values, however, is because the insulating effect of the ground under the slab is now taken into consideration as well.

Suspended timber floors or piled foundations currently only need to achieve an R-value of R1.3 so to now be R2.5-3.0 depending on location is a reasonable increase. A lot of new builds have slab foundations though, so if you’re one of them, then the increase is only to R1.5-1.7.

Roof insulation

The changes call for a doubling the amount of roof insulation required, from an R-value of R3.3 to R6.6, while also introducing flexibility to the insulation rules for a 500mm strip around the perimeter of a low-pitched roof. Insulation in this 500mm strip only needs to achieve an R3.3 rating whilst the rest is R6.6.

Alex McGregor, business development manager for Greenstuf says the R-value that needs to be achieved is for the whole system, not the insulation in isolation. “Putting an R6.6 insulation roll into the ceiling will not achieve R6.6 as a system because you lose heat through all the timber/steel framing,” he explains.

“The most cost effective and high performing solution is a double layer of GreenStuf R3.6 (280mm thick). This can be done in a cross-lapped design in trussed roofs, where you eliminate heat loss by 90 percent. The R-value achieved in this scenario is R7.”

Window and door joinery

R-values that windows (excluding skylights, which require even higher R-values of .54 and .62 in Zones 3/4 and 5/6 respectively) and doors in Zone 1 needs to be 0.46 by next November, with Zone 6 needing an R-value of 0.50 by next May. The focus for the change is to require higher upgrades to colder climate zones – specifically 5 and 6.
These improvements will require the window and door joinery to be fabricated differently, but the physical installation will remain the same.

Moving forward

Shane Walden, the Group Design & Innovation general manager from APL Window Solutions, who supply Altherm, First and Vantage, says the window and door manufacturer has spent the past couple of years readying itself with investment into new machinery to meet demand for the new legislation.

In fact, it’s been making windows and doors that are compliant for some time and these have been used in many new builds already.

“The whole idea here is warmer, more comfortable homes that are more energy efficient that require less heating in winter and cooling in summer,” says Shane. “You get higher performing glass with a low-e coating, which is a good thing because you get more bang for your buck.”

Remember, these changes only apply to new builds at this time, but that doesn’t mean you should ignore them if you’re renovating or extending. Replacing window and door joinery throughout your home, as well as ensuring your extension is of the highest quality possible, even if you’re not required to do so under the Building Code, will almost always pay off.

Words by: Jen Jones  Photography by: Swell Productions for Vantage

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