Why HardiePlank® is a Popular Cladding Choice for Garden Rooms & Annexes

Q: Can HardiePlank® be used on any garden room or annexe?

Yes, it can be fitted to most core structures — whether that’s a timber frame, SIPs system, or steel frame. However, not all garden room companies offer HardiePlank®, as it takes different skills to install compared with timber cladding. It is most often available from companies that offer a bespoke design service.

Q: Are there alternatives to HardiePlank®?

Yes, Cedral cladding is a similar fibre cement product that some designers also specify.

Published: 10 September 2025
Reading Time: 3 minutes 30 seconds

Over recent months we’ve featured a growing number of garden rooms and annexes finished with HardiePlank® fibre cement cladding. It’s easy to see why designers and buyers are opting for this option. With a choice of profiles, colours, and textures, along with long-lasting durability and minimal maintenance, HardiePlank® is becoming a go-to alternative to natural timber.

Cosy Garden Rooms are low maintenance with Hardie Plank cladding and uPVC doors and windows

Cosy Garden Rooms project finished with HardiePlank® cladding – read more about this project.

What is HardiePlank®?

HardiePlank® is a fibre cement weatherboard made from a blend of cellulose fibre and cement. The boards are engineered to resist moisture, pests, and insects, with the surface treatment designed to repel water before it penetrates the core structure. Unlike natural timber, HardiePlank® doesn’t warp, rot, split, or suffer from insect attack, and it retains its dimensional stability through seasonal changes.

There are two profiles in the range:

HardiePlank® – a traditional lap board available in smooth or wood grain textures.
Hardie® VL Plank – a contemporary option with an interlocking tongue-and-groove joint that hides the fixings for a crisp finish.

Both profiles can be fitted horizontally or vertically, giving designers flexibility. While the horizontal layout offers the familiar timber-clad look, vertical installations create strong, modern lines that elongate the building.

Low maintenance finishes have been used including composite cladding and aluminium doors and windows

Timber Rooms used the Anthracite Grey HardiePlank® cladding with the same colour windows for a smart monochrome look– read more about this project.

Colours, Textures & Finishing Touches

The range is available in an impressive colour palette:

21 colours for HardiePlank®
8 colours for Hardie® VL Plank

Thanks to ColourPlus™ Technology, the boards come with a multi-coat, baked-on finish that resists fading and does not require repainting. Buyers can choose between smooth and wood grain textures, depending on whether they prefer a crisp minimal look or a more natural timber effect.

Specialist corner trims and window profiles are also available, ensuring a streamlined finish with neat detailing around doors and windows.

Hardie Plank cladding comes in a woodgrain texture

Hardie Plank cladding comes in a smooth texture

Low Maintenance & Lasting Appearance

One of the big advantages over timber is that HardiePlank® maintains its colour and finish without the need for regular staining or painting. Timber claddings, if left untreated, weather down to a silvery grey; HardiePlank® retains its chosen colour, whether you opt for soft neutrals or bold modern tones.

Maintenance is minimal, often just a soapy wash once a year. When combined with low-maintenance roofing systems such as EPDM coverings and aluminium or uPVC doors and windows, the result is a building that requires very little upkeep. And because the boards are engineered for durability, your garden room or annexe will keep its appearance for decades.

5m x 3m garden office by Miniature Manors with Boothbay Blue Hardie Plank cladding

This Miniature Manors project shows how coloured HardiePlank® cladding can enhance a contemporary design – read more about this project.

Fire Safety & Building Regulations

HardiePlank® has a non-combustible fire rating of A2-s1, d0. This makes it a particularly popular choice when compliance with Building Regulations is required, including:

Garden rooms between 15–30sqm positioned within 1m of a boundary.
Larger garden rooms over 30sqm.
Garden rooms or annexes that include sleeping accommodation.

Garden Rooms with HardiePlank® Cladding

We’ve showcased a range of projects that highlight the versatility of HardiePlank®. Some owners choose bold contrasts, pairing light cladding with dark window frames, while others go for a dramatic monochrome effect by matching Anthracite Grey cladding with frames in the same shade.

The choice of vertical or horizontal installation also changes the look — from a New England painted building aesthetic to a sharper, more architectural finish.

Garden Rooms with HardiePlank® Cladding Examples

Durability & Warranty

James Hardie products come with a 15-year warranty and are designed with a life expectancy of around 60 years. That means garden rooms and annexes clad in HardiePlank® will maintain their appearance and integrity for decades, outlasting many timber alternatives.

Frequently Asked Questions

Does HardiePlank® need painting?

No, the ColourPlus™ finish is baked on, so it doesn’t need painting. A gentle wash with soapy water once a year is usually enough to keep the cladding looking fresh.

Can HardiePlank® be used on any garden room or annexe?

Is HardiePlank® more expensive than timber cladding?

Yes — HardiePlank® generally costs more than softwood options like Thermowood or Siberian Larch, but it is usually slightly cheaper than Western Red Cedar. Installation costs may be a little higher due to the specialist skills required, but it will pay for itself in lifespan and lack of maintenance, often lasting far longer than natural timber alternatives without the need for ongoing treatments.

Are there alternatives to HardiePlank®?