DE LA UNIDAD REVOLUCIONARIA NACIONAL GUATEMALTECA A LA LEGALIDAD

The social housing directorates and asset manager have to develop strategies that assist them in deciding whether the identified activities are assigned as periodic maintenance at fixed intervals or carry out regular inspections or simply respond to user requests after failure has occurred (El-Haram & Horner 2002a).

The general definitions for the various forms of maintenance classifications are given in BS 3811 and are illustrated in Figure 3.6. According to BS 3811 (1984) operational maintenance includes developing:

• Planned maintenance; • Scheduled maintenance;

• Condition based/predictive maintenance; and • Unplanned maintenance.

There two broad classifications, namely Planned Maintenance and Unplanned Maintenance. Although this is not within the remit of this research to deal with any detail, but it would be imprudent not to consider problems generated within the complete maintenance framework.

69 3.6.1.1 Unplanned Maintenance.

Unplanned maintenance is also called day-to-day maintenance on ad-hoc basis (Vijverberg 2000; El-Haram & Horner 2002a), corrective maintenance (Tsang 1998 and Horner et al. 1997) breakdown maintenance (Organ et al. 1997, Tsang 1999) and reactive maintenance (Pitt 1987; Duffuaa et al. 1998; Duffuaa et al. 2000). Unplanned maintenance is the simplest type of maintenance, where a component / element in a building are used until it fails. The provider simply responds to the complaints of the users after failure has occurred (David & Arthur 1989; El-Haram & Horner 2002a) or failure has been detected during a regular inspection of the building (Antunes & Corvacho 2002).

Figure 3.6: Classification of Building Maintenance

Source: BS 3811 (1984)

Because unplanned maintenance is associated with the correction of unexpected failures, according to Colen & Brito (2002), it has and almost is always an urgent character, which may lead to unavoidable extra costs (compared to planned maintenance). In reality, however, no maintenance strategy is totally unplanned. Even an unexpected breakdown of an item would require some form of planning of how to execute the necessary repairs to the required standard / cost. The term unplanned maintenance is thus misleading, as it does not correctly describe the phenomenon it purports to depict.

70 3.6.1.2 Planned Maintenance

Planned maintenance is also known as forward maintenance and is based upon the assumption that the service life of an element or component can be predicted with some degree of certainty and will involve forecasting of maintenance needs (Pitt 1987, 1997). The reality, however, is that maintenance cannot be totally planned because the failure prediction for a building component is not an exact science and therefore, planned maintenance is based on statistical evidence - information from suppliers or through experience. It is however not an exact science many variables such as weather and workmanship have an effect. Any plan requires regular updating, but an unforeseen breakdown or failure can occur requiring an unplanned maintenance response, Mirghani (2001).

Planned maintenance was introduced to overcome the disadvantages of unplanned costs associated with unplanned maintenance and to reduce the cost of inspection, repair and unplanned equipment down time (Mann et al. 1995). Planned maintenance may sometimes be referred to as ‘forward maintenance’ and is based on the assumption that elements or components have a life span which can be predicted. This information allows to ‘plan’ to be drawn up forecasting maintenance needs with associated costs.

Planned maintenance can be broadly grouped into three types: time-based maintenance, condition-based maintenance (Duffuaa et al. 1998) and improvement maintenance (Colen & Brito 2002).

In time-based maintenance, maintenance tasks are performed on an item in accordance with a predetermined plan at regular fixed intervals, regardless of its actual condition (Saranga 2002; Tsang 2002). Such a strategy is based on the adoption of renewal cycles for certain items and frequently applies to external and internal painting (Horner et al. 1997).

Condition-Based Maintenance (CBM) is defined as “Maintenance carried out in response to

a significant deterioration in a unit as indicated by a change in a monitored parameter of the unit’s condition or performance” (Kelly & Harris 1978; Nezhad et al. 2007). Under the

CBM concept, a change in condition and or performance is the primary reason for carrying out maintenance on an item. Thus, the optimal time to execute maintenance work is determined from a condition survey, which shows the actual state of each constituent item in

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a building. In this approach, maintenance tasks are determined and planned by monitoring the building’s elements such as walls, floors and roof, plumbing and electrical installations and other equipment to identify which element or piece of equipment requires maintenance before a major failure occurs (Horner et al. 1997).

Refurbishment means different things to different people, depending on their perspectives (Mansfield 2002). Thus, to a homeowner refurbishment could encompass everything from changing a light bulb to repairing the roof, while to a building contractor it is the gutting and reconstruction of an interior. In the investor’s perspective, it is any improvement that leads to an increase in rental values while from a purely economic view, it is any investment designed to forestall the capital depreciation of a property. It is not surprising therefore that attempts by many authors (Bone 1987; CIOB 1987; Industrial Market Research 1987; Seeley 1985, 1997; Quah 1988; Wunderlich 1991; Aikivuori 1996; Egbu et al. 1998; Hardcastle et al. 1990; Vijverberg 2000) and many others, to provide an inclusive and concise definition acceptable to all have not succeeded.

Mansfield (2002) suggested that the most comprehensive definition so far is given by RICS (1998), which defines refurbishment as: “The extensive repair, renewal and modification of a

building to meet economic and or functional criteria equivalent to those required of a new building for the same purpose. This may involve the installation of current standards of building services, access, natural lighting, equipment and finishes, using historic fabric as the carcass of what is, effectively, a new building”.

Against the background of this terminological confusion, Colen and Brito’s (2002) view is that the general focus of all the different terms and perspectives is the replacement of existing element / components for others with better characteristics in certain service conditions. Thus, the overall purpose of the refurbishment is to extend the beneficial use of an existing building by providing a cost-effective alternative to redevelopment.

Each of the above three categories will contain two types of maintenance work i.e. Corrective or Preventative maintenance.

Corrective maintenance, also known as failure-based, unplanned maintenance or reactive maintenance (Pitt 1987; Duffuaa et al. 1998; Duffuaa et al. 2000) is the most basic strategy

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involving merely repair or replacement of a building element once that element has failed. Since the strategy is an unplanned response to failure there are inherent disadvantages. Firstly, there can be secondary damage to other parts of the building as a consequence of the failure, which can in some cases be more costly to address than repair or replacement of the particular failed item. Secondly, failure can occur at a time, which is inconvenient for the owner and the user of the building.

Preventative maintenance, also encompassing time-based, planned or cyclic maintenance or proactive maintenance (Pitt 1987; Duffuaa et al. 1998; Duffuaa et al. 2000), can address some of these disadvantages. Being planned, the objective is to predict failure and thus avoid the emergency situation caused by sudden failure. The strategy which is carried out according to a predetermined plan has a number of advantages: maintenance tasks can be undertaken at more convenient times, maintenance should be more cost-effective and the risks to health and safety should be reduced since unexpected failure should be less likely. Furthermore, deterioration of the condition of the building should be minimised, maintenance operations are conducted in the most logical, and efficient sequence and the strategy provides a tool for financial management (Chanter & Swallow 2007). However, because planned maintenance anticipates rather than responding to failure, building elements may be replaced prematurely. In this respect, the strategy can be considered wasteful.

In order for the planned preventative maintenance programme to be successfully managed and implemented it will rely on the social housing provider developing a system of reporting and maintaining accurate data records for the issues as to What? How? When? Figure 3.7 illustrates a typical planned maintenance system.

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Figure 3.7: An Overview of Planned Maintenance Management System

Source: BS 3811 (1984)

The successful maintenance operation has to take into account all 3 of the different types of maintenance as this will prevent repairs being undertaken just prior to any refurbishment of the dwelling house.

3.6.1.3 Deterioration Phenomena and the Concept of Maintenance

There are many facets of building maintenance problems which have been researched over the past 4 decades (PSA 1976; Seeley 1985; BRE 1998; Carrillion 2001) to understand the nature, causes, effects and the remedies of building defects. Although this is an extremely interesting topic and will, often form part of the wider issues evolving around building pathology, it is outside the scope of this research in terms of examining the relationships between design detailing and workmanship. However, it suffices to say that there are a number of variables that interact together on a random basis and influence the incidence of defect occurrence. This is summarised in Figure 3.8.

It is clear from Figure 3.8 that there is a huge range of variables that have an impact on maintenance at any point in time and the inherent randomness in itself creates logistical challenges during the life of the building. The repair process is further exacerbated by the

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manner in which defects are identified, reported, classified into a priority order and then the decision whether to repair or replace, given constraints on available budgets and the impact that it may have on minimum standards of fitness. Ultimately, the aim of any social housing provider is to preserve the functional utility of the assets to a level that satisfies the needs of the tenants (customers) and also the legal obligations of the social housing provider.

Figure 3.8: Agencies Influencing the Incidence of Building Defects

Source: BRE Digest 176

Some defects are simply cosmetically unacceptable whilst others seriously impair the function of an element of the building and the building as a unit, possibly even endangering “life and limb”. The procedures for identifying defects and classifying them into priority order for repair are the keys to the managers’ problem. The subjective nature of decision making as to when a defect has entered into a ‘limit state’ of unacceptability is a major contributor to maintenance management problems.

3.7 Critical Factors Affecting Maintenance