General Questions

Who is Stellaria?

Stellaria NZ Ltd is the NZ distributor for all Wienerberger, Internorm, BOEN and MST Marbles products.

Who is Wienerberger?

Wienerberger, Europe – is one of Europe’s largest multinationals producing clay construction blocks, clay roofing tiles, clay facing bricks, clay facing tiles and clay pavers & piping systems. Founded in 1819, Wienerberger was publicly listed in 1901. Wienerberger now exports worldwide with 202 plants in 30 countries and is the global market leader for clay facing bricks, roof tiles and pavers. Wienerberger stands for high-quality natural clay products, which are marketed under the brands KORAMIC, POROTHERM, TERCA, PENTER and ARGETON. Wienerberger produces roof, wall, façade and paving from pure natural clay. Brick is one of the oldest building materials in history and therefore sets a perfect example for the modern concept of sustainable products. Wienerberger is exemplary for its environmental & business ethics, diverse designs and creations, energy-efficient construction and durable quality, holding their value for a very long time. Building with Wienerberger therefore, represents an economically and ecologically sound investment for the future.

About Porotherm

What is Porotherm?

Porotherm is a natural fired, solid clay construction block. It is available in a range of sizes, complete with accessory blocks (Lintels & Portals) in accordance with the climatic/thermal requirements for each project and/or region. Solid clay construction now forms up to 80% of the building material choice throughout Europe. Clay & lime have been used for hundreds of years and is now used extensively throughout the world.

Is Porotherm suitable for seismic zones?

Clay construction is design-engineered to be twice as strong as conventional construction methods. POROTHERM, in it’s current form, has been used extensively throughout Europe for the over 50 years and is now used worldwide in many high seismic zones such as Russia, China and Europe. Rigorous shake table testing documentation is available to show the extent of tests carried out by Wienerberger Engineers, meeting the highest Euro standards. This construction method is extremely earthquake resistant.

What is the acoustic value of Porotherm?

The acoustic rating for R25 is Rw + C 42. LR42Th+ is Rw + C 44.

Is Porotherm waterproof?

Due to the thermal matrix design of the clay block most commonly used in NZ, R25Th+ at 250mm wide and kiln fired at temperatures of 1200c, water penetration is minimal. A breathable plaster system being waterproof and organic with mineral paint exterior finish is applied to meet E2 requirement.

Does Porotherm need a Flashing System?


How are the fixings attached to the walls?

Standard masonry fixings or Hilti Screws available in NZ.

How is the plumbing piping & electrical cabling installed?

Chases are cut in the walls at a depth of 30mm. This is easily and quickly achieved by a builder, blocklayer, plumber or electrician using a double saw chase cutter with a vacuum.

How many blocks do I need per sq/m?

A standard 250 Th+ Porotherm block requires 8 blocks per m2. By comparison, standard concrete blocks require 12.5 blocks per m2.

What is the speed of construction - how many sq/m per man hour to lay?

Porotherm is 4 times faster to lay than traditional concrete building methods being a confined masonry system. The steel & concrete is only required, depending on the engineering in the lintels over the openings and the portals installed up to 5m increments along the wall. This has a significant impact on the end cost to build. Labour cost is the largest component of costs to any construction company or builder. Porotherm significantly reduces this.

What is the comparative cost to timber frame and concrete block?

We have prepared a wall comparison chart to show the comparative costs. A finished Porotherm wall is comparative to a high-end 140 timber frame wall with brick veneer cladding.

What is the design and/or life expectancy of Porotherm?

The design life of Porotherm is 150 years. The life expectancy of the clay block is many generations.

Does it have a guarantee or warranty?

Porotherm Clay blocks have a guarantee of 100 years. Installers are certified by Stellaria NZ.

Is Porotherm eco-friendly and sustainable?

Yes, absolutely. Totally natural clay construction. The Wienerberger sustainability story is at the heart of all their operations. To offset the carbon footprint required to transport from Europe to NZ, Stellaria offers 5 native or specimen trees (of your choice) to everyone building in Porotherm. We believe this gives something back to the environment the only element Stellaria NZ takes from the environment – the cost to ship it here!

What green ratings or certifications does Porotherm have?

DECLARE accreditation.
Sentinel-Haus Institut, the European centre for healthy building skills.
EMISSIONS DANS L’AIR INTERIEUR – Volatile Substances in Indoor Air.
AVEC LA TERRE CUITE means with clay, No Development of Mould.
NATUREPLUS – Respect for Saving Non-Renewable Resources.
QUALITEL – Acoustics & Thermal certificate Lower Energy & Maintenance.
AFNOR NF – characteristics certified by the French NF norm for clay blocks.
EXCELL ZONE VERTE – Green Certificate.

What fire-proofing system is required?

None. Porotherm 250 Th+ has a F.R.R of 3 hours minimum.

What cladding or plaster system can I use?

A lime-based plaster system is highly recommended to retain breathability of the block. Any cladding system can be used on Porotherm.

What heating or cooling system is required for a Porotherm house?

Minimal heating and cooling is required. Porotherm has significantly reduced thermal leakage compared to timber and concrete block construction. Testimonials report heating bills are dramatically reduced due to the passive nature of this block system.

Which blocks do I need for my project?

Depending on your climatic zone in NZ and personal preference for thermal retention, the standard block R25 will meet NZ climate zones 1 & 2 and R25 Th+ in zone 3. If you want a warmer or passive home, apartment or office you can use any of the higher R-value blocks, CLIMAmur. You will also need the portal, lintel and rebate blocks to complete the building system. Quantity estimates can be calculated for you from your finished architectural drawings.

Do I need a specialised block layer?

No. Porotherm can be installed by any licensed blocklayer or builder with minimal upskilling by our Wienerberger-Stellaria NZ certified installers.

Do I need an architect/designer or engineer?

Yes. Licensed architect or designer for permit drawings and qualified structural engineer.

How easily will I get a permit?

Stellaria NZ Ltd has assisted the consent process for clients and architects with 12 local Councils from Queenstown to North Auckland.

What is your Codemark?

Currently, Stellaria NZ is undergoing accreditation with BRANZ for all POROTHERM products.

What mortar do I need?

We recommend Dry-Fix – a special cartridge-applied mortar developed by Wienerberger which is 50% faster and again, cleaner to use, no mixing of mortar on site.

How much reinforcing steel is required?

Depending on design complexity, generally x1 D20 reinforcing steel bar is required at 5m centres and each side of major openings, installed in the Porotherm column or Portal block. Cages comprising 4 D12’s and ties at 300 centres are required at top bond beam and foundation level. These are also required at lintels – no further horizontal reinforcing is required.

How are the windows and doors installed?

Standard masonry fixings and flashings are used. We recommend Hilti continuous screws.

How much water is required for construction?

Porotherm block construction uses 95% less water when laying compared to concrete block construction.

How much waste is produced in construction?

Porotherm wastes 45% less than concrete block construction. Any waste is organic – it can simply be crushed and returned to your garden or soil.

What climate zone is best suited to Porotherm?

Any climate. Porotherm is used in Panama in +45 degrees temperatures and in Russia -45 degrees.

What technical or on-site support is there available for my builder?

Stellaria NZ Ltd is committed to on-going technical support for all architects/designers or builders specifying Wienerberger products.

What countries in the world use Porotherm?

Wienerberger has 202 plants in 30 countries around the world and exports worldwide including China, Russia, America and others.

How heavy are the blocks?

The blocks range from 14.7 – 20kgs each. The benefit being contractors only have to lift 8 p/sqm as opposed to 12 for concrete construction. In total, a blocklayer would lift 144kgs p/sqm of Porotherm and 225 kgs p/sqm of concrete block.

What is the carbon footprint to produce clay construction blocks?

As part of Wienerberger’s corporate responsibility, Wienerberger are committed to reducing the CO2 emissions 100% by 2020. Stellaria NZ offer 10 trees of the owner’s choice to off-set the cost to transport to NZ from France or Germany.

How easy are the blocks to cut and install?

We recommend a De Walt Alligator saw or bench saw. Cutting is simple, quick and clean with minimal waste.

How do I estimate the quantity of blocks required for my project?

The Stellaria NZ team will help you and/or your architect or builder to estimate the blocks and quantities you will need for your project. Prior to ordering, we provide a full wall by wall block count to assist accuracy of delivery. Very little waste is required for a skilled builder or blocklayer.

Can Porotherm be used for multi-level or commercial construction?

Yes, absolutely. Porotherm is easily engineered for apartments and commercial buildings. Speed of construction, reducing labour costs, reduced heating and cooling costs is of particular interest to commercial developers worldwide.

What is the R-value?

Wienerberger has developed an extensive range of Porotherm blocks to suit all climates and personal requirements for heating and cooling. For example, Porotherm R25Th+ has an R-value of 1.7, Porotherm CLIMAmur42 has an R-value of 5.4. Porotherm CLIMAmur36 has an R-value of 4.64. There are many different blocks to suit your climate and personal preferences – without the need for add-on insulation systems i.e strapping & lining, direct fix insulation, panel etc.