Helifix Drilling Guide
Helifix remedial wall and pinning tie installation procedures will regularly involve the use of power drilling tools to drill holes into masonry walls and through wall cavities. In all cases it is important to use the correct drilling technique to avoid causing excessive damage to the substrate materials and to ensure the accuracy of each hole's diameter.
Drilling
Wherever possible rotary percussion drilling should be used to keep disruption to the masonry to a minimum. In particular, rotary percussion drilling should be used as standard whenever drilling into delicate materials or cavity brickwork to promote accuracy and avoid appreciable spalling.
When SDS-type drills are used, the size of the machine should be kept as small as possible and the operator must avoid leaning or pushing heavily on the drill during operation. Use of SDS machines may increase spalling and damage and lead to an increase in hole diameter beyond the recommended size.
Drilling into brick or mortar?
Where drilling through the brick or block face is not acceptable then it will be necessary to consider inserting the remedial wall or pinning tie through the mortar bed.
Remedial ties designed to produce a dry, mechanical fixing, e.g. DryFix ties, may be installed directly into the mortar provided that this is strong and in good condition. Angled drilling through the masonry may also be used in some circumstances.
Systems that generate a partially or fully bonded fixing, e.g. RetroTies, ResiTie or CemTies, may be used in different situations where the mortar is in poor condition and drilling through the brick face is not acceptable.
Health and safety
Drill operators may face a number of different hazards when using power tools to drill into or through masonry and when installing Helifix remedial wall and pinning ties.
Electricity, gas and water pose immediate and dangerous hazards. Thus it is important that, prior to drilling, appropriate measures are taken to locate, identify and isolate any electrical, water or gas services which may be present in the wall under repair or wall cavity.
In addition, it is important that all necessary safety precautions be taken while drilling. Electrical safety gloves and appropriate safety footwear, eyewear and hearing protectors should always be worn and only well insulated, quality tools be used.
Further notes and guidelines that site managers and product users may choose to refer to when designing safe work strategies are presented in our Remedial Wall and Pinning Safe Installation Guide.
Drill types
Rotary hammer drills
Rotary hammer drills, otherwise known as Special Direct System (SDS) drills, are designed to hold SDS drill bits and use a weight to create the impact force on the bits when drilling. The design enables efficient drilling into hard masonry and is particularly well-suited to the drilling of large diameter holes. The direct hammer action also means, however, that rotary hammer drills fitted with SDS bits can contribute to excessive masonry damage and spalling when drilling into delicate or soft materials. Accordingly, SDS drills should only be used when drilling into dense materials such as reinforced concrete, hard brick, some limestone and sandstone and when drilling blind holes in strong material. Generally, the drilling of all holes should be tried first with a rotary percussion, 3- jaw-chuck type drilling machine (see below) and the SDS method should be seen as a "last resort".
Note. A 3-jaw-chuck adaptor fitted to an SDS machine must NEVER be used in place of a rotary percussion drill. Fitting a 3-jaw chuck attachment to a rotary hammer drill does NOT alter its performance and is NOT suitable for percussion drilling.
Rotary percussion drills
Rotary percussion drills use a 3-jaw rotating chuck to clamp and rotate straight-shanked drill bits. The hammer action of rotary percussion drills is provided by the rapid pulsing, backwards and forwards, of the chuck. The design provides a much gentler transfer of energy to the hammer action to that provided by the SDS and permits fragile masonry substrates such as brick, terracotta, mortar, hollow concrete block to be drilled without damage. This kind of drill will commonly have a chuck speed up to 2500 rpm with 10-40,000 percussive pulses per minute.
