Fastening a roof to aerated concrete walls: choosing fastening elements for a wall plate

Aerated concrete construction and renovation require careful roof security to ensure the stability and longevity of your building. To ensure that everything stays in place securely, the process of fastening a roof to aerated concrete walls requires careful selection of the appropriate elements.

Because of its lightweight and insulating qualities, aerated concrete poses special difficulties when it comes to attaching parts like roof plates. Selecting the right fastening components is crucial to supporting the weight and preserving the roof’s structural integrity.

We’ll look at the best methods for choosing fastening components that complement aerated concrete in this guide. To guarantee a solid and long-lasting bond between your roof and the aerated concrete walls, we’ll go over a variety of options, their benefits, and how to pick the best ones.

Types of fasteners for the roof of an aerated concrete house

The first thing you should be aware of is the components that are used to fasten an aerated concrete roof. Primarily, this concerns the sturdy attachment of the Mauerlat, which is the foundation of the roof structure resting on the ventilated concrete wall, to which the rafters are fastened.

Ample educational resources are available these days regarding the construction of aerated concrete roofs for homes. Including the video that is featured in our article, "Aerated concrete, construction, roof."

On the other hand, the fastening components receive less attention. Thus, let’s examine the most widely used components and their attributes in more detail (if there are any instructions with a photo on the manufacturer’s packaging, they typically don’t cover all the issues and need to be clarified).

Types of fastenings for the mauerlat of an aerated concrete house

Mounting type	Peculiarities
Steel wire

1. 3-4 crowns before the end of the masonry, a wire of sufficient length is left between the blocks.
2. When the masonry is completed, its ends are twisted together, threaded through the holes in the mauerlat.

It is advised that such a fastening be made beneath each rafter for optimum reliability.

• Sturdy mount.
• Does not require large amounts of time and labor.
• Inexpensive.

• Over time, the wire can stretch or rust, and the blocks can wear out under the influence of wind load.
• Aesthetic improvement of the building"s appearance is required.

1. The last crown of the wall is made of gas blocks with a U-shaped cavity.
2. After the wall has gained enough strength, all the cavities in the blocks are combined into one – for the installation of a reinforcing frame.
3. A frame is made from thick reinforcement (10-12 mm) and anchors are attached to it.
4. The number of anchors should be equal to the number of rafters.
5. To fix them to the reinforced frame, it is better to use wire.
6. All anchors must be located strictly in a vertical plane.
7. After installing and fixing all anchors, the cavity is filled with concrete.
8. The Mauerlat elements are threaded through the holes and installed on the wall.
9. Mauerlat fixation occurs due to a threaded connection at the end of the anchors, washers and two nuts.

The upper portions of the threaded anchors must extend at least 40 mm past the edge of the wall plate in order to provide dependable fastening.

1. The roof of a house made of aerated concrete is fastened as firmly, rigidly and reliably as possible.
2. The entire structure of the house is significantly strengthened in the upper part.

• A rather complex, labor-intensive and time-consuming method.
• Additional financial costs and material consumption.

Although dowels, studs, and anchors come in a variety of forms, their basic functions and designs are the same.

• A hole is drilled with a diameter equal to the diameter of the outer part of the dowel.
• The entire dowel, if it is non-separable, or its outer part is driven in.
• A self-tapping screw is inserted into the plastic or metal part of the dowel driven into the wall and screwed in until it stops.

The structure is fixed in the mass of the aerated concrete block by the unique teeth, segments, and petals in the lower part of the fastening elements, which expand greatly when they are tightened and rest (the entire lower part of the dowel/anchor can also expand conically).

• A fairly strong method of fastening for a roof made of aerated concrete.
• Does not require large financial investments (low price of fasteners).
• A wide range of fastening elements.
• Can be used for roofing of any complexity.

• Mechanical anchors are not as reliable as concreted or reinforced ones.
• If fixed incorrectly or under excessive load, the fastening may break.

An extension, an L-shaped bend, or a T-shaped branch are required in the design of this type of stud (the portion that will be concreted); an ordinary bolt with the cap down can be used as an example.

• A hole is drilled, the diameter of which is a couple of cm larger than the diameter of the bolt head or the dimensions of the bend.
• The stud is inserted and filled with mortar.
• It is necessary to ensure the vertical position of the stud, or immediately install a part of the Mauerlat.

When fastened in this manner, an aerated concrete block roof is strong enough to support various kinds of loads and strong winds.

• A hole is drilled and thoroughly cleaned from aerated concrete chips.
• Then it is filled with a special filler.
• The anchor is screwed into the filled hole.
• After the time required for setting, the wall plate elements are mounted.

• The connection is quite strong and without the natural gap typical for a mechanical fastener.
• High waterproofing performance.
• The method is not difficult, cheap and accessible to everyone.

• Although the fastening itself is very rigid, compared to a cemented or reinforced anchor it is still not as reliable.
• It is impossible to dismantle such an anchor without destroying part of the gas block.

Selecting the appropriate fastening components is essential for guaranteeing a sturdy and safe connection when attaching a roof to aerated concrete walls. Specialized anchors and screws made for aerated concrete are the best choices because they provide a firm grip without causing any damage to the material. Choosing the right components adds to the roof structure’s overall durability and safety by preventing problems like shifting or detachment.

Mauerlat material

Wood

The material of the Mauerlat has an impact on the roof’s flawless performance in addition to the kind and technique of fastening. Wood is generally given preference. Here, coniferous wood species that are resistant to water are selected, like larch.

This is typically a well-dried beam measuring 100 by 150 or 180 mm in cross-section. A board with a thickness of 40–50 mm can be used as an alternative for a small aerated concrete house whose roof does not place a significant load on the base.

Please note! It will not be superfluous to pre-treat all elements of the Mauerlat in several layers with an antiseptic and waterproof protection or varnish. In this case, the beam should not directly contact the wall, no matter what method of fastening is chosen. A layer of sealant and waterproofing should be placed under the beam, for example, in the form of roofing tape. It may seem that such layering reduces the strength of the connection and is not reliable. However, the upper edge of an aerated concrete wall is never perfectly smooth. Therefore, without a seal between the Mauerlat and the wall, the cracks will form, which will reduce heat, noise and moisture insulation of the structure.

Metal

The primary component of the roof frame is frequently metal. It is typically a steel angle. Of course, the mauerlat needs to be thick and made of metal as well. Next, its base is made up of an I-beam and a channel.

The fastening elements, techniques, and principle are still the same. In an aerated concrete wall, however, it is better to use a fixed connection with a reinforcing belt using bolted or welded fastening.

Aerated concrete

The roof of an aerated concrete home may have a partial continuation of the primary material, just like any other stone, brick, or wooden structure. Aerated concrete roofs are stronger and easier to maintain, but they also call for part of the wall plate to be fixed at an angle to the horizontal plane.

Making a reinforcing belt in this situation is challenging. Consequently, it is preferable to fasten the wood using chemical or mechanical fasteners.

Requirements for fasteners for aerated concrete blocks

We must not overlook the fact that aerated concrete is a highly hygroscopic porous building material. Moisture formation occurs when metal surfaces come into contact with cellular concrete.

Naturally, the connection will weaken quickly if the metal is not resistant to corrosion or does not have an external rust-proof layer. Catastrophic outcomes are possible, including a powerful wind gust tearing off the roof.

As a result, the following factors need to be considered when choosing fasteners for an aerated concrete roof:

• Corrosion resistance. Aerated concrete has a slightly alkaline reaction of the environment, and due to its porosity, it is not able to protect fasteners from corrosion.
• Resistance to wall cracking. According to the requirements of GOST 31360-2007, aerated concrete has virtually no resistance to tensile stress. Therefore, when choosing the type of fastener and the method and place of its installation, it is necessary to take into account that the aerated concrete block can easily burst. Cracks can also appear during operation after the roof has been installed.
• Dimensions. Anchors, studs and dowels must be immersed in the mass of the aerated concrete block by at least 2/3 of their length. Otherwise, the point of contact of the fastener with the aerated concrete will constantly loosen and weaken under the influence of various deformation loads.
• Dowel material. If the screw must be galvanized or otherwise protected against corrosion, then its outer part must have either the same protection or be made of an inert material – plastic.
• Environmental safety. This parameter applies more to chemical anchors. The composition of the fixing substance must be approved not only by SNiP, but also by the Ministry of Health.
• Resistance to changes in external conditions. Here, first of all, requirements are imposed on the resistance of materials to temperature and humidity changes. They should not expand and contract excessively, get wet, melt and become excessively brittle when cooled.
• The need for a specialized tool for installation. Depending on the type of fastening element, its installation can be done either with your own hands using simple tools (drill, hammer, screwdriver), or using specialized construction equipment by a professional team.

Type of Fastening Element	Description
Expansion Anchors	Suitable for aerated concrete, these anchors expand when tightened, providing a secure grip. They are commonly used for wall plates due to their strong hold.
Plastic Anchors	These are easy to install and work well for light to medium loads. They fit into pre-drilled holes and expand as screws are inserted.
Concrete Screws	Designed specifically for use with concrete, these screws offer a strong hold without needing additional anchors. They are ideal for heavier loads.
Metal Anchors	These offer high load-bearing capacity and are suitable for heavy-duty applications. They require precise installation to ensure a secure fit.

Securing a roof to aerated concrete walls requires careful consideration of the appropriate fastening components. Knowing these options can help ensure a stable and long-lasting installation because each type of fastener has advantages and disadvantages of its own and works best in certain situations.

You can make sure the roof is securely fastened and resilient to different weather conditions by choosing the right fastening components. This decision improves the structure’s overall durability and safety while also enhancing its long-term performance.

In conclusion, taking the time to learn about and choose the appropriate fasteners will pay off by offering a safe and dependable roofing solution. For your building to remain structurally sound and long-lasting, the roof must be securely fastened to the aerated concrete walls.

Video on the topic

How to fasten a Mauerlat / Fasteners for a Mauerlat / Mauerlat on aerated concrete / How to assemble a roof

Reinforcing the fastening of the Mauerlat to a wall made of aerated concrete

To prevent the roof from moving! 3 ways to fasten the Mauerlat