Different fixings and fasteners placed side by side

Pay Attention To



– Interior screws have less corrosion resistant coating than exterior screws. If you use interior screws in exterior environment, they will start to rust and may ruin the design.

– There are several types of exterior environments depending on how much salt is in the atmosphere. It is important to understand that exterior fixing for low salt atmosphere is not suitable for aggressive salt atmosphere.

– TIMco has separated its screws into five environment categories:

(1) Clean, Dry and Low Humidity Environments

(2) Occasionally Damp/Wet, Rural and Sheltered Areas

(3) Urban and Industrial Areas with a Low Salt Atmosphere

(4) Industrial Areas with a Moderate Salt Atmosphere

(5) Industrial and Coastal Areas with An Aggressive Salt Atmosphere

– Interior environments can also be very different. In wet rooms humidity can go very high and fixings for exterior environment should be used there.

– In rooms where chemicals are used, fixings must be chosen with special care considering environment.


– Fixing length must consider the thickness of fixture and penetration length.


– Some drives take more torque than others.

– Some drives have better installation convenience than others.

– Read more info about drive types from here.


– When using countersunk heads with solid materials like steel, they need pre-drilled phases / countersunk holes.

– Read more info about head styles from here.

Timber Screws


– Usually timber screws are with Coarse Thread, but also Fine Thread and Hi-Lo Thread are used.

– Metrical Thread is not suitable for timber.


– Timber should be pre-drilled when the density of the timber is greater than 500 kg/m3 and/or diameter (side dimension) of the screw exceeds 6 mm.

– Pre-drilled holes are not needed when using special screws where the manufacturer has pointed out that they don’t need pre-drilled holes.


– Screws pointside penetration length should be at least 6x diameter.


– The wrong sizes and locations of the load-bearing screws could crush the wood and reduce the load capacity.

– In load-bearing connections, it is important to consider screws distances from timber sides and at the end.

Metal Screws


– Usually metal screws are with Fine Thread and Metrical Thread.

– Coarse Thread is not suitable for metal connections.


– Some screws may need pre-drilled holes when they don’t have Self Drilling Point.


– Self Drilling screws have different drilling capacities. Most accurate info will be got from the manufacturer data.

 THREAD WITH WINGS – For Fixing Timber to Metal!

– When fixing timber to metal with self drilling screws, it is important that screws have thread with wings.

– Wings are designed to ream out the timber, so the screw can drill into metal without burning timber out. When the wings hit the metal, they will break off to permit the thread to self tap into the metal.

Drywall Screws


– Screws with Coarse Thread are designed for using in timber frames.

– Screws with Fine Thread are designed for using in metal frames.

– Fine Thread screws can also be used for timber frames.


– Drywall screws have usually a bugle head. It is designed to prevent damaging the plasterboard during installation.


– Drywall screws have Phillips Drive. It is designed to prevent over-tightening the fasteners.


– Self Drilling screws for metal frames have different drilling capacities. Most accurate info will be got from the manufacturer data.