How to attach timber fence rails to steel fence posts?

Ripley

Hi, we are building a 1.5 metre picket fence and have the steel posts cemented into position. Posts are SHS (square hollow section). Can anyone suggest the best approach for attaching horizontal timber fence rails to the steel posts please? Also, which fittings/brackets etc would be best for the job? Thanks in advance for any hints.

EricL

Hello @Ripley 

A common and reliable way to fix timber fence rails to SHS steel posts is to mechanically fasten the rails directly to the face of the post using galvanised or stainless steel fixings, rather than relying on light brackets. For a 1.5 metre picket fence this is typically done by pre-drilling the steel posts and then fixing the timber rails with self-drilling metal screws or bolts designed for steel. 

Tek screws with a hex head and drill point are very common for residential fencing, as they go cleanly through 1.6–2.0 mm SHS without needing heavy drilling and give a strong connection. If you want a neater or more adjustable result, drilling the post and using galvanised coach bolts with washers through the timber rail is also widely used, particularly for hardwood rails.

Another approach is to weld short flat steel tabs or angle cleats to the SHS posts before painting or galvanising, then screw the timber rails to those tabs. This keeps the rails slightly off the post face, helps with drainage, and reduces the chance of water being trapped between timber and steel, which can shorten the life of the timber. 

Purpose-made fence rail brackets are available, usually galvanised pressed steel or powder-coated types, but they are less common for picket fences and are more often seen on pool fencing or modular systems. Whichever method you choose, it is important to use galvanised or stainless fixings suitable for treated timber and to keep the bottom rail clear of soil to avoid moisture problems.

If you need further assistance, please let us know.

Eric