Lime and loam: How interior walls can tackle humidity

Written by

22 February 2022


4 min read

New Zealand's summers seem to be getting muggier and muggier. Some traditional tools help, like dehumidifyers, but there's a much simpler and more efficient solution.

Humidity in New Zealand can be a challenge, from the deep South to the subtropics of the mid-upper North Island. For a country with a largely temperate climate, for example; in Auckland and Northland alone, the average annual humidity levels are relatively high at 82% and 84%, respectively. And for the almost two million people who live across these regions, this can make for some hot, sticky, muggy summers.

Humidity can be especially uncomfortable indoors, and more noticeable in particular rooms such as bedrooms, kitchens, at the workplace — and over time contribute to an unhealthy interior space. To combat this, we can bring out the dehumidifier, turn our fans on, or pump out the air conditioning, all to mixed results based on the situation. But there’s another, more fixed solution — a solution embedded in the interior walls of the home or workplace.

Sto NZ's StoCalce Functio is a state-of-the-art humidity management system that seeks to create a comfortable and healthy ambient interior climate through the use of loam and lime. It’s a plaster system applied to interior walls that regulates indoor humidity, offering a natural alternative to other wall finishes, and one that boasts many more additional benefits.

The porous plaster structure utilises loam to store humidity temporarily, and then release it back into the environment when suitable, with the potential to absorb more than 90 g water/m2 in eight hours. Meanwhile, the lime offers durability, design and application advantages that have stood the test of time.

Sto NZ marketing manager Ben Andersen says, "For new builds or for renovations, the unique characteristics of the plaster system make it a popular choice not only as an agent for humidity management but as an aesthetic and natural alternative to other interior wall finishes."

“The fact that it’s got a number of different functions as a plaster system makes it pretty unique,” says Ben. “Not to mention it’s a completely natural product.”

StoCalce Functio is simultaneously a stylish option for interior walls and a humidity control tool.
StoCalce Functio is simultaneously a stylish option for interior walls and a humidity control tool.

A sustainable option

StoCalce Functio’s materiality is equally one of its biggest draws: it is naturally alkaline, which makes it possible to completely dispense with the anti-microbacterial preservatives that would otherwise need to be used under storage conditions. In other words, it’s a product that is nothing but natural.

Ben says the product is an especially good choice for those looking for interior finishes without harmful chemicals or other additives.

“We are all very aware of the importance of natural, sustainable solutions,” he says. “Many projects do require that products specified contain no harmful substances or emissions — and StoCalce Functio really does tick that box.”

Of course the materiality isn’t the only thing that’s sustainable about the product. Its status as a natural, fixed means of tackling humidity means it’s a substitute for other solutions, like dehumidifiers and air conditioning, which require electricity to function.

“Lime and loam’s porous structure and its capacity for associated diffusion makes it a sustainable and innovative improvement for interior spaces and climates, contributing to a lower carbon footprint," says Ben. "It's climate-regulating properties also help to prevent damage associated with moisture, extending the life-cycle of the building's interior, inhabitants, health and wellbeing.” 

StoCalce Activ finishing plasters  open up a range of design options and unique surface finishes.
StoCalce Activ finishing plasters open up a range of design options and unique surface finishes.

A bold aesthetic

Of course, interior finishes and coatings are often one of the most significant aspects of the interior design and decor of a home: colours can make the design more cohesive, for example; colour and texture should suit surrounding furniture and fixings, and wall materiality should assimilate into the wider cladding systems used in the building.

Walls are an important style statement, and Sto kept this in mind when developing StoCalce Functio: the offering includes many different application techniques, textures, and colours to achieve a variety of sophisticated interior wall finishes.

"In fact, StoCalce Functio may be specified without the humidity regulating base-coat and be applied for its unique aesthetic character, for example; StoCalce Functio Activ finishing plasters can be applied directly over plasterboard, there are a wide range of options to suit your project requirements," says Ben.

StoCalce Activ finishing plasters are naturally tinted with a selected range of StoCalce Color tints and applied by a registered Sto contractor, guaranteeing compliant materials are used and application meets the highest quality of standards. Plus a 7½ Year StoWarranty, says Ben.

“The plaster, is all hand-applied, and under different environmental conditions and lighting influences, it really does provide each project its own uniqueness,” says Ben. “A bit like StoCalce Functio as a whole.”

Learn more about Sto NZ and StoCalce Functio.