Frequently asked questions

1. Why is Ytong considered a ‘green’ building product?

Ytong is well known as an environmentally friendly construction material. The production of Ytong requires only a fraction of the energy compared to other materials. The manufacturing process emits no pollutants and creates no by-products or toxic waste products. Ytong is manufactured from common and abundant natural raw materials. The finished product is up to five times the volume of the raw materials used, making it extremely resource-efficient and environmentally friendly.

Non-polluting manufacture – Ytong manufacturers use a closed-loop manufacturing process, so that nothing is ever released other than clean steam. Product trimmings, slurry and water are reprocessed, and steam is reused whenever possible.
Resource efficiency – The end product is approximately 80% entrapped air and 20% mass. Thus 5 parts Ytong are produced from just 1 part of raw materials.
Low energy consumption throughout life-cycle – The total energy consumption to produce Ytong is 1/3 to 1/2 that of comparable building materials. When installed, Ytong results in tremendous energy savings for heating and cooling the building.
Healthier indoor air quality – Ytong products are an excellent choice for the chemically sensitive because Ytong Autoclaved Aerated Concrete does not off-gas. Ytong does not promote the growth of mildew and mold, and cannot be infested by termites. Rats and other pests find no home, since there is no cavity in an Ytong wall. Pesticides can be reduced, and the occupants can breathe a little easier.

2. How safe is Ytong?

Ytong is probably the safest building product available. Ytong is a non-toxic product that does not pollute the air, land or water. During the manufacturing process, waste from the cutting process is recycled back with raw materials and used again. During construction, there is virtually no waste generated. Ytong products were designed to respond to the urgent need to conserve and protect the earth’s precious natural resources.

3. Will a Ytong building last as long as other buildings?

Yes, in fact it will last longer. The durability of Ytong has been proven in every type of climate in the world for over 75 years.

4. How durable is Ytong and can it be used in cold climates as well as hot climates?

Ytong has proven to be a very durable material. There are numerous structures in many different climates worldwide, many over 75 years old, in excellent condition. Ytong will not rot, warp, rust, corrode, or otherwise decompose. Termites and other pests do not eat it. Ytong will not burn. The millions of tiny cells in Ytong cushion buildings from major force, preventing progressive collapse. Ytong has withstood earthquakes in Japan, the frigid temperatures of northern Europe, the harsh salt air of the French Riveria, and the hillside fires of San Francisco.

Ytong provides a very low maintenance building, saving considerable time and money in upkeep over the life of the building. Although damage to a Ytong wall is unlikely, repair is simple using an Ytong repair mortar. The durability of finishes, both exterior and interior, plays an important role environmentally.
Ytong provides excellent thermal insulation due to the ideal balance between low thermal conductivity and available mass. A material’s mass and thermal properties are important measures of its capacity to store energy and resist heat transfer. The degree of benefit of thermal mass depends on the climate, building type and use.

5. Is Ytong a new product?

No. Ytong was first commercially produced in 1923 in Sweden. Since then, Ytong construction systems such as masonry units, reinforced floor/roof and wall panels and lintels have been used on all continents and every climatic condition. Today Ytong is used all over the world in places such as the Far East (Japan, Australia, South Korea, Taiwan, Malaysia, Indonesia and Thailand), in the Middle East (Israel, Kuwait and Turkey), in Europe (Germany, France, Netherlands, Italy, Greece, Belgium, Switzerland) and in both North and South Americas (United States, Mexico, Chile, Brazil and Argentina).

6. Is Ytong better than standard construction materials such as wood and concrete?

Ytong outperforms concrete and wood. Ytong is the only durable, structural, thermal and fire rated material all in one product. For example, in wood construction, insulation and drywall must be added to make the wall fire rated and thermally compliant. In addition, insulation must be added to masonry to obtain reasonable thermal values. Unlike wood and concrete, Ytong is lightweight, has superior acoustic absorption, is a non-organic material that will not decay or rot and is moisture and pest resistant. In nearly every situation, Ytong is the best building material choice.

7. Is Ytong material resistant to growth of mildew and mold?

As a non-organic mineral based material, Ytong products do not promote the growth of mildew or mold. Mildew may appear over finishes if material used for finishing promotes the growth of mildew.

8. How has Ytong been used?

Ytong has been used worldwide in the following applications:

• Hospitality; hotels, motels and restaurants
• Retail and warehouses
• Industrial
• Office Buildings
• Education
• Medical, clinics and offices
• Religious Buildings
• Single family homes
• Multi-family projects
• Specialty application such as fire walls and sound walls

9. How do you hang heavy items like cabinets or shelves on Ytong walls?

Fasteners are available that easily drive into Ytong walls and are capable of securing heavy items. These fasteners are similar to standard concrete “spread-fast” anchors. Since Ytong is less dense than standard concrete, fasteners can be driven in with a hammer. Specialty drills are not required. Unlike stud walls, fasteners can be placed anywhere in Ytong walls. No need to explore to find studs for hanging heavy objects.

10. How is Ytong finished?

Standard mineral based paint, traditional or synthetic stucco, thin brick facing, tile, siding materials or any other building finish can be used on the outside of Ytong walls. Inside, Ytong walls can be finished with plaster, textured paint, gypsum drywall or any other mineral based interior finish.

11. How much does Ytong cost?

Ytong pricing is very competitive with other quality building materials. Installed cost and operating cost must be considered as well. These costs are all affected by project size, location, labour market, current freight rates, building codes and the particular application. Ytong typically pays for itself within 3-5 years.

12. Do Ytong walls require insulation?

Never. Ytong walls are insulated by millions of tiny air cells which reduce thermal conductivity. The thick walls also benefit from high thermal mass, much like a log home.

13. How is wiring installed in Ytong walls?

Easily. People often imagine that wiring will be a challenge due to the solid structure of Ytong blocks. When they discover how versatile and workable Ytong really is, they are pleasantly surprised. There are 2 standard methods for installing wiring in Ytong Autoclaved Aerated Concrete walls. Many installers use a combination.

Routing: Build the walls first. The electrician draws directly on the block to indicate where the wires will go. The Ytong installer uses a manual or electric router to cut channels on the inside of the walls. After the electrician installs the wiring, the wall is plastered. Requires no pre-planning, and changes are easily made. Conduit usually required.
Inside the Wall: With this method, the majority of the conduit is installed as the wall is built. Wiring may also be run in the vertical cores. Pre-wired conduit is typically used to reduce the hassle of pulling wires. Wiring is deep in the wall and surrounded by a fire retardant material. Extra switches and receptacles can still be added by the routing method.

14. What are possible exterior finishes that can be used over Ytong?

Many of the conventional exterior finishing systems such as one coat plastering (sometimes referred to as a hard coat system) and two coat systems can be used over Ytong as an exterior finish. Other options such as brick veneer, stone and siding can be used and have been used in many residential projects.

15. What are possible interior finishes that can be used over Ytong?

Typical interior finishes such as plastering, mineral paint, ceramic tiles, and wood panel can be used over Ytong walls. Vinyl wall covering should not be used since it creates a vapour barrier, which may lead to growth of mold and delaminating of the wall covering.

16. What is the thickness of the finish systems?

Depending on the manufacturer and type of system, thickness for exterior finishes range from 3mm to 10mm. Finish coats such as textured paint or a mineral coating are applied over a base coat on the first pass. Regarding the interior finish, the approximate minimum thickness is 3mm to 10mm over Ytong standard masonry units. Again, paint or other surface finishes such as wall covering are applied over the base coat.

17. Can Ytong be used with standard concrete blocks (CMU)?

Although the mix of Ytong material and CMU blocks is not required in most cases, there is no technical restriction to prohibit the use of both products.

18. Why is a vapour barrier not required in the exterior wall assembly of Ytong wall?

As solid monolithic Ytong wall system, the enclosed non-connected cellular structure and exterior finishes provide the healthy balance between resistance to moisture penetration and vapour diffusion. This balance is adequate to maintain a dry system, prevent moisture condensation and allows vapour diffusion when and if any presence of vapour occurs within the wall system.

19. What is the R-value for the Ytong system?

R-Value Calculation

The Lambda  (λ) values, combined with thickness of product, give the thermal resistance – or R value – of each element in a structure. R value is a measure of thermal resistance, measured as:

Thickness divided by λ

The higher the R value of any element, the better its ability to resist the transmission of heat.

Other elements included in calculation would be cavity air spaces, surface air films, and the reflective capacity of aluminium foil surfaces.

We supply standard B04 blocks with the λ of 0.11 and a thickness of 250mm.

0.250 / 0.11 = 2.27

Then add 10-12mm external render 0.36 plus internal plaster 0.11.

Estimated to add 0.47

Final R value estimate 2.74

Note: R–value = R outside air (0.17)+ R ext plaster (0.36)+ R AAC + R int plaster(0.11) + R inside air (0.68)

Ytong wall, floor and roof systems provide an innovative combination of excellent low thermal conductivity, thermal mass and low air-infiltration. This practical combination of properties in one system provides an excellent thermal insulation material and permits peak energy usage in the building to be shifted to off-peak hours, thus reducing operation cost for building users and owners, improving comfort of living and reducing the demand on power generation facilities.

It is important to remember that thermal performance of any building material is the result of several factors and may not be assumed either effective or ineffective on the basis of any one factor.

Typically, most people refer to the steady state R-value as a measure of the material resistance as tested under steady and constant climatic conditions. In the “steady state” where thermal values are obtained from laboratory testing, it is assumed that temperatures at both sides of a wall are constant and remain constant for a period of time, unlike what actually occurs in normal conditions. In actuality, the temperature levels on both sides of walls may change during a 24-hour period. In many cases, the exterior temperature may experience large temperature swings. These changes may cause a reversal in direction of the heat flow or at least “delay” the heat flow to the point where it substantially reduces the heat transfer to the inside the building envelope. In this case, the combination of the heat capacity and the excellent thermal resistance exceeds the performance of a high “steady state” R-value. This dynamic process is known as the “thermal mass benefit” or “mass-enhanced” R-value.

Ytong block walls correctly constructed using blocks of 600 x 250 x 250 (length x height x width) and with a suitable external render give an approximate R-value of between 2.7 and 2.8.

20. Do exterior walls have to be weather protected?

All cement or mineral constructing products should be protected from moisture during construction and before finishing. Ytong is a cement material, but also a thermal insulating building material. Therefore, Ytong must be protected against moisture to preserve the high thermal property of the material.

21. Can gib board be applied directly over Ytong walls?

Gib board can be applied directly to the Ytong with construction adhesive and screws or attached to furring over Ytong walls. However, one should be aware of the fact that gypsum board may promote the growth of mildew. We recommend the use of mineral-based finish to prevent such a problem.

22. What kind of roofing material or system can be used over Ytong roof panel?

All commercial available roofing systems can be used over Ytong roof. Generally speaking, when Ytong roof panels are used flat or near flat, they are covered with a membrane system such as built-up or EPDM. On a pitch, they are often covered with concealed fastener metal roofs or shingles.

23. How efficient is Ytong?

The Ytong building system provides an airtight envelope, which is critical in controlling a comfortable and healthy indoor environment. A major emphasis in heating and cooling system design is to minimize “uncontrolled” ventilation air. By providing an airtight building envelope, Ytong minimizes the “uncontrolled” air changes and allows the ventilation air to be “controlled”. Overall, the volume and quality of ventilation air can be easily and accurately controlled in an Ytong building – thus providing a comfortable, economical and healthy environment.

The excellent thermal protection properties of Ytong exterior walls were confirmed in a study by the Centre of Renewable Energy Sources of Greece for Ytong. The study proved that if you build your house with Ytong blocks, you can achieve a 6.6% reduction of the energy you spend in order to heat the building and 41.4% reduction of the energy you spend to cool the building. When you also combine Ytong Blocks (masonry) and Ytong Panels (ceiling) you can achieve 13.4 % reduction of the energy spent to heat the building and 54.2 % reduction of the energy spent to cool the building.