- Adequate points for fixing drop rods for suspended services: additional steel may be required if this has been overlooked at the design stage. Fixing of primary brackets to steel beams before fi re spray/cladding.
- Design changes: additional pipe runs or equipment may put an unacceptable load onto the steel work or a floor etc.
- Drawings: execute work only to drawings marked ‘For Construction’. Always read the drawing thoroughly. Elements omitted can be very costly to put right. Always ask the designer for missing information. If a pipe size is missing, do not guess. You are bound to be wrong.
- Anchor/thrust blocks for underground water pipes: these must always be installed to approved detail drawings. Casually dumped concrete will not pre vent pipework under pressure buckling and rising out of the trench. This is expensive to remedy.
- Access: it may be essential to provide access panels in plaster ceilings, vertical shaft enclosures for commissioning or future servicing, therefore the panel positions need to be known to ensure the space is not occupied by air diffusers, sprinklers, fi re detectors or some other service equipment.
- Existing services should have been located and plotted, but:
– Be observant—think!
– What buildings were on the site previously?
– Where were the buildings located?
– Ask the local people. Are buildings to be demolished?
– Double check!
– Substations located inside buildings sometimes serve others as well. Check with the local electricity supply company before any demolition work proceeds.
– Buried cables can be owned by the local electricity supply company or a national distribution company.
– If buried cables are indicated, keep on digging carefully until you find them.
They are often deeper than you think.
– Enquire from voice and data cable providers what telecoms cables are on or near site. Contact Highways Department regarding any traffic control cables around site. Often these are located below pavements and can be damaged by hoardings.
- Gas and water mains operate at varying pressures. Damage to medium- and high pressure mains which pass through a site could cause widespread disruption to users located well away from the site.
- Site access: heavy loads such as packaged boilers, transformers etc., require good access to the point of unloading if programme dates are to be met.
Access will be necessary for large pieces of equipment to be brought into the building and to final positions. This will necessitate walls being left down in some cases.
Identify the sizes and weights of the equipment and prepare a method statement on how the equipment is moved into position. The most troublesome areas are staircases with applied finishes, which require closing to foot traffic.
Remember that other trades require access at all times and early agreement on this is essential. If ignored, claims from subcontractors for excessive walking time may ensue.
In tall buildings the same problem can arise if lifting facilities are not available when required or are inadequate.
- Datum lines and levels: clearly identify and protect those areas where successive trades rely on them for setting out. Remember that any setting out is only as good as the reference points and levels that are provided. Bad setting out leads to costly remedial action, e.g. if walls, ducting and false ceiling grids in cellular spaces are not set out from the same datums (structural grids) ducting spigots and holes in ceiling for diffusers can be seriously misaligned.
- Adherence to drawings: ensure that ‘Builder’s Work’ activities are carried out in accordance with the issued drawings. Preferably get the subcontractor to check the main contractor setting out. Areas to watch out for are:
– inserts or pockets in plant bases
– plant bases, especially if the pipework
– cable entry points, especially long radius bends—Cables cannot be pulled if the bends are too sharp or tight.
- Tile and support grid dimensions must be known at the outset to ensure that the underside of luminaires and air terminal devices are positioned at the correct level. If changes occur, tell the other trades.
- Coordination: if the services have been coordinated the sequencing of the various activities can be identified, but site management must also take into account the main contractor element as well.
- Service shafts need access to install the various services, DO NOT make access difficult or impossible by getting the main contractor work out of the way and letting the subcontractor sort out his own problems.
- Trenches obviously come before the installation of the services but to limit the time any trench is open, liaise with the subcontractor and utility companies about the date they can actually start the work.
- Soils and wastes, when made of cast iron, require space for jointing. They are also governed by the fi ttings available. These services need to go in first.
- Who does what? Check the division of responsibility at trade interfaces, they are often specified for design rather than construction convenience.
– Electrical feeds to HVAC plant and electrically operated doors, lifts etc., are often ‘by others’.
– Final electrical connections are often omitted. The electrical feed usually terminates in an isolator, leaving the cables from the isolator to the piece of equipment to someone else or no one!
– Installation of recessed luminaires is often omitted by the services subcontractor leaving the job to the ceiling subcontractor.
– Steelwork gantries for plant and equipment are omitted on the grounds that the services subcontractor does not design steelwork.
– Access stairs, ladders and guard rails are generally ‘builder’s work’, but it must be clarified at an early stage.
– Steelwork for pipe supports should be included in the services subcontractor’s tender. Vertical shafts create problems when a steel floor to a service shaft has to be installed at each level after the services have been completed.
– Access doors and panels in walls, partitioning etc., must be such that the services equipment is also accessible.
- Earthing pits: soil conditions affect the location and depth of such pits. Monitor such work carefully as a lot of time and money can be wasted in obtaining the required resistivity levels.
- Mock-ups: these can be of great benefit especially where repetition occurs. Costs may not have been allowed by the subcontractor but even if they have not, mockups are worth investigating as potential savings can be made by all concerned.
Note: Cosmetic (aesthetic) mock-ups without all of the services installed may ultimately be proven unacceptable and unachievable.
- Electricity supply company: requirements for their incoming switch rooms vary one to another.
Watch out for grano floors to 2mm level. Access doors to the supply company’s own specification—but provided by the main contractor.
- Shafts and pits for lifts, scissor lifts and dock levellers: these must be built square and vertical. Tolerances should be say 10 mm but should always be – nil.
Shafts and pits too small of square or plumb will require remedial work before installation on the equipment can start.
- Lift shafts: all entrances have to be installed relative to the plumb of the shaft.
Fast-track construction requires the entrances to be fitted before the front wall of the lift shaft can be constructed.