When installing a railing, it is crucial to select the correct screws and fastening methods to ensure stability and long-lasting durability. The choice primarily depends on the material in which the railing will be mounted.
Which material will you mount the railing on?
Wood
Concrete
Lag screws
Ø10 mm lag screws
minimum length of 60 mm.
Expansion bolts
M10 expansion bolts
minimum length of 65 mm.
Plugs & lag screws
Ø12 plugs and
Ø10 mm lag screws
minimum length of 60 mm.
When installing a railing, it is crucial to select the correct screws and fastening methods to ensure stability and long-lasting durability. The choice primarily depends on the material in which the railing will be mounted.
Which material will you mount the railing on?
Wood
Lag screws
Ø10 mm lag screws
minimum length of 60 mm.
Concrete
Expansion bolts
M10 expansion bolts
minimum length of 65 mm.
Plugs & lag screws
Ø12 plugs and
Ø10 mm lag screws
minimum length of 60 mm.
This guide serves as a general recommendation for selecting screws and fastening methods for DOLLE railing systems. However, construction structures and materials can vary significantly, and the correct fastening method depends on the specific conditions of the project.
The user is fully responsible for assessing
The load-bearing capacity and quality of the material (e.g., concrete strength, wood hardness, etc.).
Whether the length and diameter of the screws are sufficient to ensure a stable and durable installation.
Whether longer screws, larger plugs, or an alternative fastening method is needed.
That the installation is carried out correctly and in compliance with applicable building regulations and safety requirements.
DOLLE cannot be held responsible for incorrect installation, improper selection of screws/plugs, or damages resulting from inadequate fastening or failure to assess the substrate properly. If in doubt about the choice of fasteners, consulting a professional is recommended.
What are lag screws, expansion bolts & plugs?
Lag screws
Description
A lag screw is a heavy-duty screw with a hexagonal head, which is tightened with a wrench or socket.
Application
Typically used for fastening in wood or in combination with plugs for masonry and concrete.
Advantages
Provides a very strong connection, ideal for heavy structures such as railings and fences.
Expansion bolts
Description
An expansion bolt consists of a bolt and an expanding metal sleeve. When the bolt is tightened, the sleeve expands and wedges itself firmly into the material.
Application
Typically used for fastening in wood or in combination with plugs for masonry and concrete.
Advantages
Extremely strong and suitable for installations that need to support heavy loads and endure significant forces.
Plugs
Description
A plug is a small plastic or metal sleeve inserted into a pre-drilled hole in masonry or concrete. When the screw is driven in, the plug expands, creating a strong anchor.
Application
Used together with lag screws in masonry and concrete.
Advantages
Provides a very strong connection, ideal for heavy structures such as railings and fences.
Screw size and plug size
To ensure a correct and stable fastening, it is important to choose the right combination of screw and plug. The size of the screw and plug depends on the load as well as the material in which the screw is being mounted.
Relation between screw and plug size
A general rule of thumb is that the plug should be slightly larger in diameter than the screw so that the screw can expand the plug and create a strong anchor.
Calculating screw length
Plug length + railing base thickness + 5 mm = screw length
Example:
Calculating plug length
Screw length - railing base thickness - 5 mm = plug length
Example:
Choice of screws for indoor or outdoor use
Indoor use
Electro-galvanized screws are sufficient.
Outdoor use
Hot-dip galvanized or stainless steel screws (A2 or A4) are recommended to prevent corrosion.
Preparation of drill holes
To ensure a strong and durable fastening of expansion bolts or anchors, it is important to drill and clean the hole correctly.
Drilling the hole
Use a drill bit with the same diameter as the anchor (e.g., Ø12 mm drill bit for a Ø12 mm anchor).
Drill to the full depth to ensure sufficient space for the anchor/screw.
When using expansion bolts, the hole should be slightly deeper than the bolt to allow for expansion.
Cleaning the hole
Use a vacuum cleaner, compressed air, or a brush to remove all loose material.
Ensure the hole is completely clean and dry before inserting the anchor or expansion bolt.
Edge distance when mounting in concrete
When installing railings in concrete, it is important to consider the edge distance, i.e., the distance from the drilled hole to the edge of the concrete element. If the fastening is placed too close to the edge, the concrete may crack, leading to a weakened installation and potential safety risks.
Minimum edge distance of 8 cm in concrete slabs to ensure sufficient strength and to prevent the concrete from cracking under load.
For expansion bolts, the larger the bolt, the greater the recommended edge distance – preferably at least 8 cm for M10 bolts.