Site Safety and Handling

Fyfestone Site safety and handling skewed picture of a buildingFyfestone Site Safety & Handling picture of a building

Collar jointing is laying units back to back in normal aspect with a 10–15mm mortar joint between the adjoining faces of the units. The two leaves may be tied together. If tied either normal ties or bed joint reinforcement may be used. Collar jointed walls are not suitable for separating walls in dwellings.

To reduce the risk of injury, the project design, site conditions and the way in which the work is organised should be properly planned. Practical advice on these matters should help designers, specifiers and those managing work on site as well as those handling the blocks.

Handling Building Blocks

This guidance by the Construction Industry Advisory Committee (CONIAC) covers the safe handling of architectural masonry, by which the committee means all masonry units and blocks, including those made of clay, concrete, reconstituted stone or any similar man-made or natural material.

Handling of heavy building blocks can give rise to a wide range of injuries, including serious injuries where the damage is gradual and progressive over a substantial period of time.

Risk Assessment

1. To minimise the risk of injury:

  • All hazards involved need to be identified
  • The significant risks estimated; and
  • Suitable precautions to avoid or reduce these risks incorporated into safe systems of work

 

2. The main hazards are:

  • Heavy loads and poor posture: excessive stress and strain causing injury to muscles and tendons, particularly where handling involves bending, twisting or other difficult postures;
  • Slips, trips and falls: including damage caused by dropped blocks;
  • Sharp edges: cuts and abrasions to the skin;
  • Skin hazards: dermatitis, burns and similar conditions caused by contact with mortar (see HSE construction information sheet No. 26 Cement).

 

3. With block handling, the risk of injury is largely determined by the weight of the block – the heavier the block, the higher the risk of injury.

 

4.After taking account of expert opinion and the long history of complaints over handling heavy blocks, CONIAC has concluded that there is a high risk of injury in the single-handed, repetitive manual handling of blocks heavier than 20 kg (44 lbs).

 

5.If a single person handling is needed, either blocks of 20 kg or lighter should be specified and used or other precautions should be taken to reduce the risk by, for example, the provision of mechanical handling. This would contribute to the risk assessment required under the Manual Handling Operations Regulations 1992.

 

6.With blocks weighing less than 20 kg. Manual handling risks are still significant and suitable precautions should be taken to minimise these risks as much as possible.

Precautions

 

Designers and specifiers should take the weight guideline into account at the design and specification stage of the project. Where it is not reasonably practicable to avoid specifying blocks heavier than 20 kg, provision should be made for mechanical handling or for laying by two people.

 

Project planners and contractors should follow the weight guideline and ensure that the precautions listed below are taken into account when planning the work and when devising safe systems of work. Contractors should also give instruction and exercise supervision to ensure that workers follow these plans and systems of work.

The Task

Handle and lay building blocks in accordance with the following:

  • Plan to stack blocks close to where they will be used.
  • Stack on a level, firm base and wherever possible without double stacking of block packs
  • Keep man-handling of blocks to a minimum and use mechanical lifting and handling aids as much as possible, such as cranes, fork-lift trucks with pallets, trolleys and telescopic handlers.

Note: Ensure that the landing area of scaffolding is adequate for the temporary loading of blocks.

  • Always use mechanical lifting and handling or operate a two-person system for blocks weighting more than 20 kg
  • Arrange work to avoid over-reaching or twisting when handling blocks
  • Ensure good grip and secure foot placement in the working area when handling blocks

 

Arrange the work so that blocks only need to be handled up to shoulder height. Go higher by using staging, for instance. (Note: further protection against falls may be necessary if the effective height of guard rails is reduced). Particular care and attention is needed for higher risk block laying such as when head room is restricted, under soffits or below working platform level.

The working environment

Prepare roads and hard standing first and before blocks are on site. In areas where blocks are carried or handled, keep the site clear of obstacles or tripping hazards, such as discarded block wrappings or stack ties. Uneven, slippery or unstable ground conditions increase the risk of injury. Blocks should be protected from the weather to avoid them getting wet and increasing in weight.

Training

Workers should be given information and training on the systems of work and procedures to be used on that site to ensure safe manual handling of blocks. Suitable training will also be necessary for designers, specifiers and those managing contracts.

Personal Protective Equipment

When handling blocks the normal protective equipment needed for use on building sites should be provided by employers and worn by individual workers; in particular, safety helmets, safety footwear with protective toe caps and suitable gloves.

Wall Ties

Serious injuries have occurred when building double skin walls due to contact with the sharp ends and edges of some types of wall ties. The exposed sharp edges should be covered or safer wall ties used.

SAFE HANDLING AND USE OF CONCRETE BLOCKS

Consideration of the points listed below will contribute significantly to working and manual handling.

  • Minimise manual handling by delivering units as close to the place of use as safety considerations permit
  • Move units in packs and by mechanical means whenever possible
  • Load units out to above knee height
  • Ensure that normal protective equipment appropriate to construction sites is both provided and used
  • Ensure that appropriate eye protection and dust suppression or extraction measures are provided when mechanically cutting or chasing units

 

Additional considerations include:

  • Manual Handling Operations Regulations requires employers to carry out a risk assessment on all manual handling tasks
  • The Construction (Design & Management) Regulations places duties in the form of a mandatory Health & Safety system, on clients/designers/contractors.

In an attempt to provide practical guidance for meeting the requirements of these two regulations the Health & Safety Executive (HSE) has issued Construction Sheet 37 ‘Handling Building Blocks’ which advises that:

  • There is a risk of injury in the single-handed repetitive manual handling of blocks heavier than 20kg
  • Units of greater than 20kg should be handled mechanically or using a two person team if they have to be handled repetitively

 

NOTE: It has been industry guidance for several years that two person teams should be used for handling heavy units.

 

The HSE guidance does not prevent an individual handling manually small numbers of units of greater than 20kg. In particular, ancillary units such as quoins or reveals would fall into this category and would not be expected to be handled by a two person team.

The guidance given in Construction Sheet 37 is not mandatory, but gives a method of meeting the requirements of the regulations.

Units of greater than 20kg may be specified and used to meet particular design requirements provided that appropriate handling methods are used.

For users who, for design reasons, would otherwise select units of greater than 20kg but would prefer not to, a number of options exist. The appropriate choice from the options available will depend on the unit or wall properties dictated by the application.

 

Choices include:

  • Using lighter solid units having sufficiently similar properties
  • Using cellular/hollow units instead of solid units (having almost identical properties to solid units)
  • Using alternative construction techniques such as:
  • i) Laying units flat to form a 190 or 215mm width wall (suitable for finishes such as plastering or drylining)
  • ii) Collar joining* units to form a 190 or 215mm width wall (particularly suited to facing applications).

Whenever making the choice of units it is essential to ensure that the desired performance characteristics of the finished wall are not compromised.

SITE WORK

Storage on site

  • Pallets should be stored on flat, level ground at a safe distance from other trades, they should not be stacked on top of one another.
  • Products should be unpacked immediately prior to using as they can be damaged once the packaging materials are removed.
  • Remember that masonry units can be easily damaged by transport or mobile plant moving around the site area. Ensure the pallets are stored at a safe distance from roadways, access and exits points.
  • It is important that opened pallets are covered to prevent the ingress of water, dirt or dust.

Blocklaying

To maintain the natural appearance of the finished wall, it is recommended that blocklayers should use blocks from several packs whilst proceeding with construction.

During heavy rain blocklaying should be discontinued unless the work is protected. Protect the top of the work against rain, snow and frost when stopping work an hour or more and especially overnight. The face of the work should also be protected against splashes from the ground, scaffolding and other construction activities.

  • Masonry units should only be laid by suitably experienced operatives
  • Unprotected scaffolding poles, planks etc; should not be supported by the cast stone units
  • Brace constructions to prevent damage to freshly assembled materials
  • All units should be laid and adjusted to their final position while the mortar is still plastic.
  • Mortar exuding from joints should be cut away avoiding smearing the face of the unit
  • Installation should not be carried out during heavy rain unless the work is protected. When work stops for more than an hour or two, especially overnight, the top of the work should be protected against rain, snow and frost. The face of the work should also be protected against splashes from other construction activities
  • Masonry construction should not be carried out in frosty or freezing conditions, or if the temperature is at or below 3 ºC, unless precautions are taken to ensure that the mortar has a minimum temperature of 4 ºC when laid and is protected until this has hardened. Precautions may also be required if the temperature is 3 ºC when the mortar is laid but could subsequently fall below freezing point before the mortar has hardened, e.g. overnight
  • During construction it is advisable to protect finished work using appropriate gauge polythene sheeting. This prevents mortar drips, mastic, paint and other construction materials staining or adhering to the masonry. Mortar, in particular, is very difficult to remove

 

If the temperature is at or below 3ºC then blocklaying should not be carried out unless precautions are taken to ensure that the mortar has a minimum temperature of 4 ºC when laid and is protected until it has hardened. Precaution may also be required if the temperature is 3 ºC when the mortar is laid but could subsequently fall below freezing point before the mortar has hardened (e.g. overnight).

Chasing

A rotary chasing machine or mechanical disc cutter is recommended where the use of hollow blocks is not possible and chasing is necessary. Vertical chases should not exceed one third of the wall/leaf thickness and horizontal chases should not exceed one sixth of the wall/leaf thickness. In load-bearing walls the effect of a reduced section area caused by chasing should be checked. Chases should not impair the strength or stability of the wall in any event.

 

Transporting the UnitsDuring transit the following points should be considered:A suitable vehicle e.g. rigid or articulated trailer preferably with air suspension should be used for transport.Units should be covered during transit to protect them from saturation and staining.Bearers should provide adequate support to prevent incidents of point loading of the units.

 

Palletised deliveries of Architectural Masonry should be unloaded either by grab or forklift, using suitable forks. Under no circumstances should scaffold poles, timbers etc. be used to carry or support the pallets.When using grabs, these should grip the pallet, not the product.Slings should not be used unless previously discussed with the manufacturer.Where slings are used to lift individual units, the arrises of the unit should be protected and the sling positioned to provide an even support.

 

Site HandlingThe safe handling of Architectural Masonry components is essential in order to ensure that they remain undamaged. Where handling information is not clear, contact the supplier for further recommendations.A manual handling assessment should be carried out before the units or pallets are moved.Where units are supplied with lifting sockets or eyes these must be used.

 

Avoid side loading to sockets by using a lifting beam where necessary.Always use suitable plant for moving the product around site and ensure wherever possible that units are delivered to the work area before any obstructions are put in the way.Units should be adequately supported to ensure ease of handling. Care must be exercised not to drop the product. Re-use interior packing to protect faces, arrises etc during site handling.Care should be taken not to slide the units across each other.Don’t store pallets on sloping or uneven ground. Make sure storage area is flat, level and dry.

 

Never stack pallets and large units on top of each other.When unpacking products, do not burst open the wrapping either by hand or with site tools. It should be cut open with a knife, taking care not to damage the faces.When moving pallets of Architectural Masonry units, always re-use interior packing to prevent damage to faces, arisses and profiles.

Site Storage

All Fyfestone architectural masonry is banded, shrink wrapped and banded onto pallets.

Once the product is on site, the following guidelines should be followed:Palletised products should be stored on flat, level, dry ground at a safe distance from other trades, roadways, etc. to prevent damage to the aesthetics and structure of the product. Runners should be used to support pallets on soft ground.Never stack pallets of products on top of one another.

 

Individual units should not be stacked face to face without appropriate interface material (manufacturers packaging and protective materials should be used for this).Individual units should be suitably supported by timber or plastic bearers.Products should remain packaged until immediately prior to use.When unpacking the product, strapping/packaging should be carefully cut, not ‘burst open’.

 

Ensure that care is taken when cutting the packaging so that the face of the unit is not damaged by the knife blade.It is important that opened packs of Architectural Masonry are covered with polythene sheeting to prevent the ingress of water, dirt or dust.

Protection

All blockwork should be protected from rain as much as possible. At the end of each day blockwork should be covered, this is particularly important in the case of hollow blocks to avoid saturation. Prevention of excessive moisture will reduce the risk of efflorescence or lime bloom, which is generally attributable to a build up of moisture somewhere within the wall.

 

Consideration should also be given to propping high or long walls where they are not properly restrained until completion of the walls. This could also apply to internal walls, originally not designed for wind loads, being constructed before the envelope of the building is complete.

 

Good protection should be maintained throughout the construction of the project, including the use of toe boards on scaffolding and polythene sheeting to plinths and cills to prevent staining from mortar splashes.

 

Sheeting should be left in place until completion and further protection given to areas exposed to site traffic or following trades.

 

Unless the work is protected when proceeding there is always the risk that sudden Frosts or showers will cause damage.

 

NOTE: The appearance of finished masonry may be affected by failure to protect the work during construction.

Cutting

The general tolerance on cut dimensions is +2, -2mm, although in certain circumstances it is not possible to achieve this, e.g. where a shallow cut is less than 25° to a face.

The general tolerance on cut angles is ±1.5° and taper-to-cut faces will be within +1, -1mm.

Cutting Masonry on site

The range of specials Fyfestone produce to aid the construction process significantly reduces the amount of cutting needed on site. However, when faced with limiting situations, it is not always possible to manufacture a unit to accommodate every situation and therefore site cutting of units may be necessary. It is advisable to cut blockwork on a clipper bench station with a Diamond-tip blade and a fresh supply of lean, uncontaminated water.

 

The size and thickness of blade is also very important. For instance if cutting a full block into two halves, a 10mm blade is necessary to ensure that 2 x 215mm blocks are achieved, thus eliminating any extra length by using a thinner blade, (i.e., a 4mm blade will give 2 x 218mm units).

 

The cutting slurry produced is unavoidable and needs to be washed away from the face of the units immediately after cutting. The chemical reaction caused by cutting reactivates the cement, which hardens onto the first material it, makes contact with after cutting. The heat generated in the cutting process accelerates this. Dry cutting is not recommended because of this reaction.