A small footprint doesn’t have to mean small thinking. Discover how Prolam glulam can bring more space, light and architectural character to modern granny flat design – while keeping construction straightforward.

Key takeaways:

• A well-designed granny flat can add real value to a property – creating space for family, guests, rental income or work.
• Glulam can help architects and builders make better use of a compact footprint, with options for raked ceilings, wider openings, longer spans, exposed structure and outdoor living.
• New Zealand’s 2026 granny flat consent exemption can be met using lightweight timber-framed construction, including Prolam glulam beams, posts and bracing solutions.
• Prolam supports the design and specification process with the Prolam Specifier, technical documentation and engineering support where required.

Changes to New Zealand building legislation have put granny flats in the spotlight – and prompted fresh conversation about how these small-footprint buildings are designed and built.

We spoke to architects and builders about what the new legislation means in practice, what clients are asking for and where glulam can offer design and construction advantages over traditional timber or steel.

The modern ‘granny’ does more 

‘Granny flat’ may be the familiar term, but they serve a much wider variety of purposes in today’s property market: independent living for ageing parents or adult children, guest accommodation, rental income, a home office or studio.

That broader role is changing expectations too. Modern granny flat designs need to make every square metre count, while creating a stand-alone dwelling that feels considered in its own right and sits comfortably alongside the main residence.

Prolam glulam fits that brief – helping create space, light and architectural character without complicating construction.

Where Prolam glulam fits within New Zealand’s granny flat rules

New Zealand’s granny flats building consent exemption, which came into effect in January 2026, allows small stand-alone dwellings up to 70m² to be built without a building consent where all exemption requirements are met.

A simple design with light timber framing and light roof and wall claddings are key criteria. Other key exemption criteria include (but are not limited to):

• single-storey construction, with no mezzanine
• a maximum building height of 4m above floor level.

Prolam glulam beams, posts, lintels, PLX Portal and PLX Column can all form part of a light timber-framed design.

The exemption doesn’t remove all compliance requirements. You’ll still need:

• a PIM
• licensed building professionals
• Certificates of Work and Records of Work
• full Building Code compliance
• resource consent, if required by the relevant planning rules.

The Prolam Specifier, Prolam's online tool for engineered timber design and specification, helps provide the supporting evidence trail, including product technical data, connection details and PS1 documentation for council.

Small footprint. Bigger design possibilities.

Granny flats require smart use of space within a compact footprint. The Prolam range of glulam structural timber products supports architects and builders to achieve this, from creating more open layouts, wider openings and expressive roof forms to stronger indoor–outdoor connections. 

1. Create a greater sense of space with raked and vaulted ceilings

Raked, vaulted and skillion ceilings can make a compact interior feel taller, lighter and more generous. 

Prolam glulam beams used as rafters and ridge beams provide long, straight and consistent structural members to support these roof forms and achieve clean architectural lines. 

With the exemption capping overall height at 4m above floor level, beam depth becomes a real design consideration. Glulam can achieve the required span with a shallower member than solid timber in some applications, helping preserve ceiling height and make more of the available space.

2. Maximise light and views with wider openings

Large ranchsliders, bifolds and generous glazing can visually extend the living space and strengthen the connection between inside and out.

The right solution depends on what the opening needs from the structure. A Prolam glulam lintel carries the load over the opening, while PLX Portal and PLX Column provide compact bracing where wall lengths beside a large slider or glazed opening are limited.

3. Open up the floor plan with longer spans

In a granny flat, every square metre (or millimetre) matters. The span capability of engineered timber beams can reduce the need for intermediate structural supports, giving architects greater freedom to create open and flexible living areas.

Where space above an opening is limited, a glulam lintel can often achieve the required span with less depth than an equivalent solid timber member (as outlined above).

4. Make structure part of the design with visual glulam

Structural timber does not always need to disappear behind cladding or linings. Visual grade Prolam beams, posts and exposed trusses can do ‘double duty’, providing the structural performance the building needs while also becoming part of the interior and exterior architecture – adding warmth and character, while keeping architectural lines simple and layouts functional. 

Prolam provides technical guidance on treatments, finishes and coating requirements to help achieve the required durability and finished look.

5. Extend the design outdoors with pergolas and verandas

Pergolas, verandas and covered outdoor areas can extend the way a granny flat is used well beyond its internal floor area.

Prolam’s H3.2 treated beams and H5 posts can carry the same timber language outdoors, creating shade, shelter and stronger indoor–outdoor connections while continuing the architecture beyond the granny flat’s building envelope. 
For exterior applications, the appropriate treatment and coating are important to protect the timber from exposure to moisture.

6. Pair glulam with engineered timber panel systems

For projects looking to simplify more of the structure, Prolam glulam beams, posts and bracing systems can work alongside engineered timber wall, floor and roof panel systems such as Potius.

The two systems perform different but complementary roles. Together, they create an integrated engineered-timber approach that can support efficient design, prefabrication and faster construction on site.

Great design. Uncomplicated construction.

The advantage of glulam is not only what it makes possible in the design. It can also provide a simpler construction solution than steel or solid timber in the right applications. 

• Compared with steel: Prolam glulam is light, can be cut and trimmed for a precise fit, and installed using standard tools and connections – avoiding the need for specialised steel fabrication, trades and lifting equipment. 
• Compared with solid timber: stronger and more dimensionally stable, glulam can achieve longer spans and, in some applications, reduce the number of members required. 
• On tight sites: lighter members and timber construction are practical advantages where access beside or behind an existing home is limited. 

These advantages keep more ambitious granny flat designs practical to build, without adding unnecessary complexity on site. 

How to specify Prolam for a granny flat

The Prolam Specifier helps architects, designers and builders move from granny flat design requirements to engineered timber specification – performing design calculations, identifying suitable beams, posts and structural solutions, and generating the technical and compliance documentation needed for the project.

That documentation is particularly important for consent-exempt granny flats, which will not receive council inspections or a Code Compliance Certificate.

Where the project involves a pergola, more complex beams and bracing portals or requires Specific Engineering Design, Prolam’s engineering team can provide project-specific design support and technical advice.

Ready to design your granny flat?

Bring more architectural flair to a compact stand-alone dwelling, without complicating the structure.

Explore Prolam Architectural solutions for granny flats or start your design  with the Prolam Specifier.