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A Guide to Construction Risk

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This blog post will provide an overview of the primary areas of risk associated with construction projects, in addition to outlining the various methods to manage these risks. We’ll also investigate contract structure and procurement strategy, which includes the essential decision on what form of contract to use.

TYPES OF RISK IN CONSTRUCTION CONTRACTS

Construction contracts involve multiple types of risk. These risks can range from financial to legal and health and safety risks. Contractors might also be at risk of disputes with clients, suppliers, or subcontractors. All of these potential problems can have a significant impact on the completion and cost of a construction project.

It is essential to analyze the numerous available risks in construction projects and classify them accordingly. Unfortunately, such analyses are scarcely done. Generally, the wide range of risks can be construed into a few standard categories like time, cost, performance/quality, health and safety and environmental risk. The following examples provide insight into multiple risks.

  • Management, direction, and supervision may be marred by greed, ineptitude, ineffectiveness, favouritism, unreasonableness, insufficient communication, mistakes within the paperwork, malfunctioning designs, inadequate guidance briefings or the identification of stakeholders; non-compliance with statutory requirements; unclear stipulations, incorrect selection of contractors or consultants; and variations in requirements.
  • The land, any man-made barriers, the climate: all of these factors play a role in physical work.
  • Faulty materials or craftsmanship; assessing and examples; onsite organization; lacking staff, labour, machinery, items, period or funds.
  • Delay and disagreements about the ownership of the site, as well as procrastination in providing information and inefficiencies in carrying out tasks, have all been causes of delays that were outside both parties’ control. Layout has also been an area of dispute.
  • Negligence or breach of warranty can cause damage to persons and property, and some matters such as accidents, uninsurable risks and consequential losses may be excluded from insurance cover due to exclusions, gaps or time limits.
  • The external environment can significantly impact operations. Environmental regulation, government policy on taxes, labour, safety and other laws, planning approvals and financial constraints can all affect the business. Additionally, energy or pay restraints, price increases due to war or civil commotion, malicious damage may also need to be taken into consideration.
  • Intimidation and labour disputes are two unfortunate realities in the workplace. These conflicts can cause strife between workers, employers, and unions, leading to potentially hazardous outcomes.
  • Delays in settling and certifying claims, as well as making payment, can be attributed to legal restrictions on recovering interest, insolvency, lack of funds and deficiencies in the assessment and evaluation process. In addition, fluctuations in exchange rates and inflation are also influencing factors.
  • Law and arbitration are both processes that aim to resolve disputes, yet can often be marred by lengthy delays, injustices and uncertainty due to inadequate recordings or unclear agreements. Furthermore, the cost of getting a decision made and then enforcing that decision is not always predictable. Changes in statutes and different interpretations of common law can make this even more complicated.

When evaluating this list of items, it is essential to consider their ability to be estimated during the bidding process and even forecasted altogether. Still, empirical data has demonstrated that, in actuality, contractors do not usually perform thorough analyses as they prepare bids for their regular tasks.

The development of a good risk management strategy is based on assessing and responding to risks. Extensive research has been done in this area, which resulted in the practice of creating ‘risk registers’ being widely adopted as a measure of good practice. Risk registers list potential risks and allocate either a numerical or qualitative probability and magnitude to each one – if numbers are used, multiplying them will give an indication of the risk score. These measures should greatly affect how risks are responded to.

A risk register is meant to identify steps taken to mitigate the phenomena and any contingency actions needed in case it occurs. Who is responsible for such actions and when they should be taken are also common items noted. This practice, however, is often accepted uncritically; Drummond (2011) notes that even so, risk registers cannot eliminate surprises but rather, provide an illusion of control. Furthermore, only those risks that are not already allocated in the contract are likely to be included on a contractor’s risk register, which can lead to it being more a means of communication from the contractor to the project manager about residual risks than an effective list of how risks will be managed or who is responsible for them. In this sense, risk registers may simply contain low frequency/high value risks instead of what was initially promised.

Dealing with risks

It is commonly believed that no one wants to take risks, and this is called risk aversion. But dealing with uncertainty is an issue that must not be overlooked, as the very point of getting into construction in the first place is to assume calculated risks. Doing business entails taking on challenges that others may shy away from, so it is important to acknowledge these potential perils and make them manifest in order to stay ahead.

Rational commercial decisions can be made determining who should bear risks, and by taking on several risks, the degree of uncertainty becomes less of a factor.

Having a clear grasp of this concept helps construction advisors to counsel their customers on how to assign the risk. The objective of selecting a contract should always be to delineate responsibility for risks unambiguously. Regrettably, the industry has long neglected this imperative, leading to an abundance of claims and legal disagreements.

Following the convention of risk registers, there are three steps to managing contractual risk: first, assessing the potential issues; second, addressing those concerns; and finally, monitoring any changes.

Identifying the risks is paramount before beginning a project. The list presented in the blog serves as an illustrative checklist to facilitate discussion of any potential dangers. As part of this process, clients should be clearly informed on their priorities for the project. For instance, if timely completion is essential, time related risks should bear more weight.

The second step in the process is to analyse each of the risks – examining their probability of occurring, how often they are engaged with, the potential severity of their impact and the range of possible values. This can be fairly subjective, but it is crucial for raising awareness about risk exposure. Some risks may need more detailed quantitative analysis than others since they have higher priority; however, due to their lower priority, many are dealt with more subjectively. A word of warning must be offered with regards to analysing risks: many projects have gained off-ground momentum due to an ‘optimism bias’, whereby risks, costs and programmes are typically undervalued.

Respond to the risk: To identify the optimal contract strategy, the previous steps provide a basis on which to consider the client’s priorities and any major risks. The next step is to determine who is best equipped to handle such risks – employer, consultant, contractor or insurer. Any decision about relinquishing responsibility must take into account both how often an event might occur and how much premium will be paid for shifting it. It is also essential that control over a risk should be assessed. For example, designers would be most capable of mitigating design-related risks; as such, liability for design flaws is usually allocated to them. Furthermore, diverse procurement options allocate different levels of accountability to subcontractors’ associated risks.

It should be obvious that it’s pointless to dispute which standard-form contract or procurement system is superior; each has its place depending on the situation. A consultant who routinely suggests one option too quickly, without evaluating any potential hazards isn’t fulfilling their duties as a professional.

We can now look closer at the range of potential responses to contractual risks; transfer, acceptance, avoidance, insurance or even not taking any action.

Transfer of risk

The transfer of risk occurs when responsibility for the goods is passed from the seller to the buyer, who then assumes all risks associated with the delivery of the goods. The responsibility will pass upon arrival at the designated location and this should be clarified in advance by both parties.

The inevitability of risk means it cannot be entirely eradicated; however, it can be shifted. In line with the fundamental maxim, this usually requires payment of a fee. Therefore, attempting to impose unmanageable risks on other parties is ill-advised.

Understanding the transfer of risk is a critical factor when studying building contracts. To comprehend the extent of risk allocation, one must evaluate the legal position enabled by contractual clauses — both with and without them. This book’s purpose is to assist in developing such an understanding, which is a fundamental requirement of this field.

It is not prudent for employers to try and transfer a risk that is difficult to evaluate. Reliable, proficient contractors will factor in these risks into their bids while careless ones may skirt around them, leading to an unwelcome surprise down the line. Should this occur, they may try and reclaim the cost through the employer. If unsuccessful, it might put them into bankruptcy, which won’t benefit anyone in the end.

Acceptance of risk

The risk of loss is accepted by the parties, and they agree that neither of them will hold the other liable for any damage or injury caused by said risk. They acknowledge that the responsibility of evaluating and managing risk lies with them both, and they hereby agree to accept said risk.

Clients should be careful not to put too much or unfair risk upon contractors. Stealing an advantage over them in this way is bad business practice. Taking risks may seem profitable in the short term if they don’t have to pay a premium, but eventually someone has to suffer the consequences. In the long run, this could result in creditors being taken on by those who have been overloaded with risk and unable to cope. This could also mean that fewer contractors will be able to tender for work due to their competition’s collapse.

The employer should bear any risks which cannot be managed or reduced by project participants, as any attempt to shift them may incur costly premiums. Conversely, if a client continues to engage in development procurement, they are essentially paying extra for someone to take on an unnecessary risk. Therefore, it is more sensible for the employer to assume highly uncertain and badly calculable risks.

Risks that can’t be predicted or estimated, like those of war, earthquakes and invasions, are defined risks. Without considering these variables in the tender process, you may end up with results that are too high to accept.

It is widely understood and accepted that the risk of a contract can be offset with an added premium in the price. However, Shash (1993) found that even if a project’s risk profile impacts contractors’ mark-ups, it does not appear to influence their willingness to bid. Even more shockingly, Laryea and Hughes (2011) concluded estimators don’t consider the operational risks when formulating bids for construction work. Moreover, contractor must bid without knowing who the competition is, and therefore do not know if the opposing company has professionalism or experience to set a reasonable price for risk. As a result, this creates a threat of contractors losing out due to pricing their work too high as part of an effective risk related bidding strategy.

Avoidance of risk

Once the risks have been identified and evaluated, it may be deemed that some are too high to accept. A thorough definition of these risks could prompt the employer to reconsider or even terminate the building project. Examining the financing limits of a project and potential outcomes of more probable risks can determine if a project is viable. An alternative way to avoid risk is by redefining the venture. If finance for the endeavour depends on a particular government grant and there is possible legislation that could end this subsidy, then reconfiguring the project to no longer rely on it could be advantageous.

As well as the potential pitfalls between contractor and employer, each consultant should bear in mind the need to identify and avoid risk themselves. Cecil (1988) suggests that a RIBA report on avoiding risk for architects is to make sure that the responsibilities, payment, and expenses are all agreed on and understood at the start of any project. This will help consultants avoid many issues later on.

Insuring against risk

It is important to mitigate potential losses by having an insurance policy in place. Taking out a policy can provide protection against unexpected events and avert financial difficulty if something goes wrong. It is prudent to ensure that you have coverage for any potential risks associated with your business. Insurance provides peace of mind and safeguards against possible mishaps, ensuring that you are covered in the event of a disaster or crisis.

When managing ‘acceptance of risk’, insurance and laying off risks have similar outcomes. Insurance is an available option in some scenarios, and many standard contracts demand a form of insurance. Common insurable risks are protecting against third party injury claims and fire. It is also possible to insure against losses due to liquidated damages or other forms of consequential loss. Before deciding on the correct type of insurance for any project, it should be thoroughly thought out and consulted on. For instance, consultants will usually get professional indemnity insurance in order to protect themselves and their clients from potential failures in completing tasks with the necessary skill and care.

Doing nothing about risk

Not acting on risk is the same as exposing oneself to danger. Ignoring the potential harm that can come from not dealing with risk can have serious consequences. Therefore, it is important to not overlook any risks and take steps to manage them accordingly.

It’s common for project teams to overlook risks from the get-go. If clients are not well-informed, and advisors fail to take into account any risks that may arise, then any disasters that materialize are a total shock. However, consultants may choose to stay quiet and do nothing even if they’ve considered the balance of risk and deemed it’s best left with those who can manage them. It could look like the same course of action in either case, but it’s advisable for those involved to make their decisions clear so they can be debated openly.

A further instance of omission occurs in the standard-form contracts. It is easy to assume that such occurrences are not addressed by these documents, however, this does not mean the parties are absolved from risk. In fact, the contract does assign it – even if unintentionally. This can be problematic as misunderstandings and uncertainty may arise, which can inevitably lead to litigation and claims.

Allocating risk through methods of payment

Payment methods can be used to allocate risk between the buyer and seller. Using different payment methods can help determine who carries any potential risk associated with the transaction, either the buyer or seller.

One of the key elements when apportioning risk is how prices are calculated. This encompasses deciding who takes responsibility for discrepancies between estimated and actual prices. Typically, construction contracts involve pricing related to costs with an addition for overhead and profit. The contractor’s work is usually quantified in a bill of quantities that he/she is expected to quote on. Two kinds of prices are generally used: ‘fixed price’ or ‘cost reimbursement’. Both categories have different implications and must be understood before the contract is signed.

Fixed price items are paid for on the basis of a contractor’s predetermined estimate, including risk and market premiums. The employer pays the estimated rate and it does not matter what amount the contractor spends.

Cost reimbursement items are those charged based on the amount the contractor expends while completing the job.

It is unusual to find a contract that is exclusively fulfilled with one method. Generally, both methods will be used together, with one being more dominant. This can be seen by the items in a bill of quantities for a JCT SBC/Q 2011 job – most are fixed priced and need to be multiplied by the quantity listed in the bill.

In terms of an NEC3 Option B contract, payment is based on the contractor’s estimate and the rate in their bill, multiplied by the quantity fixed. This kind of contract is known as a fixed price one, but may have cost reimbursable components such as fluctuations linked to actual changes in market prices.

A fixed fee prime cost contract establishes provisions for payment according to the contractor’s expenses. While that portion of the contract is cost-reimbursable, the contractor’s attendance and profit margin are determined by a pre-set ratio of the prime cost, not related to actual costs, thus resulting in a fixed price format. This shows how each type of agreement incorporates aspects of the other.

When considering the sharing of risk, it is essential to bear in mind that in fixed-price contracts, the contractor agrees to provide an estimation for their work and be held accountable for it. In this case, any amount saved will be beneficial for them, whereas any excess spending will not. On the other hand, with cost reimbursement arrangements, any variance from the original estimate will be carried by the employer; they would gain from reductions but must pay for increases.

When considering cost-based pricing in construction contracts, it is important to consider the context. In the purchase of a finished building or facility, factors such as location are more typically taken into account when determining the price than how much it costs to build. This is also observed in other markets, such as those for cars, computers, furniture and plant and equipment, where value rather than cost decides the price. Therefore, distinguishing between cost, price and value is essential; cost refers to the expense of obtaining something; price determines what must be paid for it; and value reflects its worth to the buyer. For successful transactions, the manufacturer or contractor must balance price so that it is higher than cost but lower than value delivered, thereby satisfying both parties involved.

In this context, firm price contracts should be distinguished from fixed price ones; the former often lack a fluctuations clause, making it more likely that the tender sum and the ultimate cost are one and the same.

Final account / Certificate Template in Excel

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You can download a template of our final account in excel, this is great when closing construction accounts.

Quick note on the final account certificate

The final account certificate can signify both the contract administrator’s satisfaction with the work and the amount finally due to the contractor, depending on the conditions of the contract. According to JCT SBC 11, clause 4.15 dictates that an obligation is established to issue a certificate within two months after rectification is complete – though it often takes much longer. This can be for a variety of reasons: perhaps the last portion of retention isn’t significant enough for the contractor to chase; alternatively, there may be other projects deemed more lucrative than one that only offers the final part of the fee account; or when it’s issued, changes in premiums to professional indemnity insurance may be required.

Download the final account certificate template here

Accounts
Accounting

What is two stage tendering?

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Two-stage tendering is a procurement strategy where the construction project is split into two stages. 

In the first stage, one or more contractors bid on a design-build contract, framework or alliance to complete a portion of the total scope of work (under the design and build) or help in the early stages of the contract, such as design and tendering at the agreed rates, and these will also help in getting budgetary figures for the construction activities.

In the second stage, these same contractors bid on another contract to complete the rest of the scope of work. This helps ensure that costs are kept in check because only part of the work needs to be done at once. It allows contractors more time to come up with bids for each phase separately (rather than having them all down at once).

Two-stage tendering is a type of procurement method for construction projects.

Two-stage tendering is a type of procurement method for construction projects. It can be used in government and private sector projects and is typically employed when it is necessary to have multiple contractors deliver a project. The first stage is the invitation to tender, or IT, which occurs before plans are drawn up for the project. This allows companies bidding on the work time to understand what exactly they’ll be responsible for and have some cost certainty about future projects by getting an idea of how much money will need to be spent upfront. Once all bids are submitted, all parties involved examine them with a fine-toothed comb (and possibly even some magnifying glasses) until they find one that best suits their needs—and then proceed with them.

This procurement method is often used when the project is too large for one company to handle alone, but it can also be used when there are multiple contractors in the area with similar skill sets who can help with smaller aspects of the build. 

Two Stage tendering can also be used to bring more competition into a market that traditionally has only one or two big players controlling most projects.

When to use two-stage tendering

Two-stage tendering is a good choice for projects that are large or complex. It’s common for a project to be too big or complicated to complete in one contract, especially if there are multiple phases, each with its own requirements. In these cases, two-stage tendering can help break up your work so that you can get your foot in the door and then proceed with more confidence. Two-stage tendering also allows you to take on risk in manageable chunks—if something goes wrong at any point, you won’t end up losing all of your investment for the entire project. Finally, two-stage agreements allow both parties (the buyer and seller) more time to understand each other’s needs and expectations before making commitments.

This is particularly important when dealing with a new buyer or seller.

The benefits of two-stage tendering

  • Cost savings
  • Time savings
  • Reduced risk in the project’s execution phase
  • Improved contractor performance due to early involvement during the design phase. This can lead to better quality work, reduced subcontracting, and lower costs for materials and equipment. In addition, two-stage tendering offers cost certainty on some aspects of a project because you can be reasonably sure of the final contract price at an earlier date than if you were working with only one tenderer at that time.

What you need to know about two-stage tendering

Two-stage tendering is a type of procurement method for construction projects. It is used when the scope of work still needs to be fully defined, and it’s also an effective tool used in situations where there are multiple contractors who can do the work.

The two stages of two-stage tendering are:

  • The first stage is the submission of a tender based on the scope of works available at the time (for example, a design contract). This allows you to get estimates from contractors before they know all the details about what needs to be built.
  • The second stage is when you put out another tender request once more information has been gathered (for example, an invitation to submit bids). This allows contractors interested in bidding for your project before but weren’t given enough information about what was needed—such as pricing details or technical requirements—to resubmit their bids for consideration after getting more details about your project’s complexity and expectations from them.”

Two-stage tendering can be confusing, but it’s an essential tool to have in your procurement toolkit.

Conclusion

We hope this article has helped you understand what two-stage tendering is, why it’s useful and when it might be appropriate. I

Construction technology behind Demolition works

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In this blog post I’ll be covering the construction technology aspect of demolition and what to consider when undertaking demolition for your construction project. This is a required competency if you’re on your RICS APC. This would be useful for quantity surveyors and land surveyors.

Do I need planning permission for demolition?

Excavator working at the demolition of an old industrial buildin
Demolition

In short yes you do need planning permission for demolition work, read more here:

When you want to start demolition work on your property, Public Health Act 1961 makes it necessary to notify the local authority (i.e. you need a planning permission before any demolition) . The Inner London area also has by-laws related to demolition and they require notification to be deposited with the district surveyor. In Scotland, a warrant is required from the building authority of the burgh or county in which the proposed demolition work is taking place. It is also necessary in Great Britain to inform the Health and Safety Executive of the appropriate local authority that governs your project.

Before any building demolition work can begin, the building owner or their agent must notify the public utilities companies (e.g. gas, electricity, water and drainage authorities), as well as telecommunications services and other business that have installations in the building.

It’s the contractor’s responsibility to make sure that all services and installations that they’re working on are either safe or have been removed by the appropriate authority.

demolution
Building demolition

What is demolition?

This is a skilled and dangerous operation, so unless the job is very small, it’s best to leave it to a specialist contractor. Demolition can be broken down into two main categories:

  • partial demolition of a structure
  • complete removal of the entire structure.

Before any demolition or remodeling, you must carefully remove all saleable items such as copper, lead, steel fittings, and many others.
The original sentence is difficult to read because it is overly technical and contains many uncommon words.

As a general rule, taking down requires a thorough knowledge of building construction so you can identify and support load-bearing members and walls. Partial demolition usually requires manual labor with tools like hammers and picks. These types of operations involve the removal of smaller parts of a building, such as bricks to create new openings or rafters to add dormer windows.

Preliminary considerations

SURVEYS

Before any demolition work is started, a detailed survey and examination should be done on the building or structure and its surroundings. Photographs are then taken so that the state of affairs can be considered in the future.

All existing problems on neighboring properties should be inspected, observed and safely stored in a distinct place. The relationship and condition of adjoining properties that may be influenced by the demolition must also be considered and noted, given the existence of easements, wayleaves, party rights and boundary walls.

  • The roof and framed structure. Make sure the order of demolition won’t cause unbalanced thrusts to occur during the work.

Inspect all load-bearing walls and then assess their condition and thickness to determine whether they can be demolished or will need to be rebuilt.

It’s crucial to ensure that these extend beyond public footpaths, as well as past the boundaries of the property.

  • Before construction, get a second opinion on your balconies, heavy cornices and stairs.
  • Services
  • drainage
  • electrical supply;
  • service pipes and gas mains
  • water mains and services pipes;
  • telephone cables, underground and above ground;
  • radio and television relay cables;
  • district heating mains.

Prior to demolition, you should survey the entire site to ensure hazards are removed. You’ll want to make sure there are no oil drums or gas cylinders laying around. If the building’s construction is unclear, study all available drawings and analyze them carefully. Alternatively, conduct a detailed survey of a building under the guidance of an experienced surveyor.

INSURANCE

Insurance companies and underwriters usually regard demolition work as especially hazardous. As a result, the demolition process is typically contracted out. Even minor work such as removal might not be covered under a general contractor’s insurance policy. In other words, where demolition or removals form part of a contract for additional work, builders should make sure that their insurance will cover all issues, including claims from operatives and other parties involved with these aspects of the work. Insurance must also cover any third party risks, such as damage claims to property and business, public utilities, and local authority maintained roads and paving.

your business, public utilities, and roads. We also cover damage to your property, as well

SALVAGING

Salvage is an old practice of using materials or parts that are no longer needed. They are often resold, though they can also be avoided if they’ll fit well with the new building. This can be a cost benefit towards the project but also avoids sending the waste to land fills. For example, when building an extension to an existing structure, salvaged roof tiles may go unnoticed and blend right in. They are usually cheaper new if they’re not rare due for being discontinued by the manufacturer. Other examples include fireplaces, roofing slates, stairways, London Stock bricks and useful lengths of structural timber.

Buildings are designed to last, but over time new ones will be built and older ones will be demolished. Because of this, it’s important for us to re-purpose such old architectural features as salvage.

When quoting for demolition work, contractors will consider the salvage potential. They will also consider a balance between the time and costs factors for careful reclamation and resale, against simply demolishing without regard. The latter will still require transportation of surplus materials from site, as well as attracting tipping costs at licensed receiver businesses. These must be highlighted carefully in the contract as to who owns the salvage of the demolition as if this is not clear from the tender stage disputes can arise.

HOARDINGS

A site survey can help determine whether a location should be designated as historically significant, so that special protection for pre-existing properties, public highways, or other places used by the general population is granted.

Consultation with the local authority will be required to determine their requirements for temporary works, not least the health and safety aspects. The local authority usually requires a formal application, licensing fees and possibly financial deposits against damages, particularly if the work abuts a public thoroughfare and highway.

Long blank hoarding with space for advert mockup on construction site
Hoarding

ASBESTOS SURVEY

In the UK there are many laws and regulations relating to the use, handling, and management of asbestos. This is understandable because inhaling asbestos fibers can result in lung cancer. Much of our existing building material contains large amounts of asbestos. It was introduced for various reasons, including its fire retardant properties and resistance to damage caused by insects.

Asbestos was often sprayed onto the steelwork of buildings to protect them from fire, used as a pipe insulation and in board form as a cladding or lining. This is why before making alterations or demolishing any buildings, it’s essential that an asbestos appraisal is done. The major legislation includes:

The Asbestos (Licensing) Regulations of 1983 require a license to be held by an employer who carries out work on sprayed finishes that contain asbestos and where asbestos insulating board is used.

  • The Control of Asbestos at Work Regulations 2002. These relate to all work with asbestos, and affect anyone liable to exposure. The regulations provide a specific requirement for the identification and management of any asbestos products in non-domestic buildings when maintenance is required. This means they must document any up-to-date specialist surveys that were carried out, their location, condition and assessment of their risk of exposure.
  • See also the Health and Safety Executive (HSE) publications Methods for the Determination of Hazardous Substances (MDHS 100); Surveying, sampling and assessment of asbestos containing materials – 2001. If you’re selling your home or considering renovations, an asbestos survey is a must-have. There are a few types of asbestos surveys:

Presumptive Survey: A method of identifying asbestos products in a space is by conducting a presumptive survey, which typically involves inspecting the building for materials that might contain asbestos. This type of evaluation is mainly used by building owners and facility managers, who take responsibility for ensuring that the asbestos material does not pose any harm to building occupants.

A Sampling survey: It can be difficult to identify the type of asbestos when there’s a potential for it being present. A sampling survey is usually given before a presumptive survey in order to positively identify the substance, depending on where your material has been exposed.

Asbestos is a mineral that has been linked to a number of serious health problems, including mesothelioma. Some types of asbestos, such as chrysotile, have been banned under the Asbestos (Prohibition) Regulations 1999.

  • Sampling and identification survey: The assessment of samples and identification surveys This type of survey is a prerequisite before any demolition and refurbishment work can commence. It can serve as the basis for specialist contractors to tender for asbestos removal.

The Personal Protective Equipment Regulations 1992 and the Control of Substances Hazardous to Health Regulations 2002 require employers to take necessary steps to protect their employees. For asbestos surveys and removals, one of these steps might be limiting your breathing through a respirator.

Stamp with finger on plan of house background.
Planning permission for demolition

FURTHER PLANNING AND RISK CONSIDERATIONS

  • The method of construction, including design, health and safety requirements and the structural integrity of components.

Our asbestos assessment results in a diagram for wet or dry removal, with an explanation of the various materials used (with strengths and weaknesses), their hazards as health or safety risks which are relevant to your work activity (see subsection on Asbestos Survey), and material reuse possibilities (see subsection on Salvaging).

  • Occasionally, facades are retained as part of a preservation order: therefore, temporary supports may be required (see Chapter 5.1 on shoring).
  • Find a way to isolate the effects of demolition, like preventing dust and debris from spilling onto people and buildings. Protection would include things like putting down a dust sheet or using a tarp to cover the area.
  • Exposure of hazardous materials. Along with building materials and previous occupancy, contamination from iffy soil can happen. Consider taking soil samples to your lab for an analysis.
  • Move as much of the existing infrastructure as possible to the new site. Ensures that all utilities are addressed and provides notice for any exclusions.
  • Regulations from local planning authority and Health and Safety Executive. Check restricted hours of work, noise levels, and dust levels as well.
  • Debris Disposal – Most debris generated in construction projects will need to be disposed of properly. We’ll discuss different methods to do this, such as rubble chutes and skips.

METHODS OF DEMOLITION

When choosing how to demolish something, there are a few different methods to consider. Factors such as location and material will help determine the best way.

  • Types of Structures: For example, a two-storey framed structure.
  • Type of construction element: example masonry wall, prestressed concrete, or structural steel.
  • Location of buildings For example, a building in an isolated location with a border more than twice the height of the building to be demolished. A confined site has borders less than twice the height of the building to be demolished.

Every site is unique, and the demolition process should take this into account. The techniques and procedures given below are intended to provide general guidance.

HAND DEMOLITION

Whenever demolition is necessary, it’s important to use the least disruptive method possible. This could involve utilizing hand tools or other items that are hand-held. You’ll also want to carefully evaluate the impact on the surrounding area. If the debris will fall onto a public roadway or another piece of land, for example, you are better off using a chute or skip.

PUSHER ARM DEMOLITION

This method is only advised to be used on buildings with a firm level base. Make sure you take the appropriate safety precautions when using this machine.

When an operator encounters a building whose height exceeds 6.0 m, it is better to lower the building by hand. The pusher arm should not be overloaded.

A qualified operator is required to work from inside of a reinforced vehicle. The vehicle should be able to withstand the impact of flying debris, and have shatterproof glass in their windows. When adopting this method of demolition, the structure being demolished should first be detached from adjoining structures by manual means.

DELIBERATE COLLAPSE DEMOLITION

This method is the complete collapse of a building, which will then be removed by experts. Expert engineering advice should be sought before this technique is used on buildings with other buildings or very steep sites.

DEMOLITION BALL TECHNIQUES

To demolish a structure, a crew of workers drives a demolition ball into the building from one side. In some cases, this can be done by swinging it from above using a crane-type appliance. Workers can use three different techniques to do this:

  • vertical drop;
  • swinging in line with the jib;
  • slewing jib.

Whenever possible, a skilled operator is essential.

A wrecking ball can only be used for a vertical drop technique when it comes to the use of a normal-duty mobile crane. Any other techniques need to use heavy duty machines such as convertible dragline excavators. And an anti-spin device should be attached to the hoist rope in all cases. It is advisable to reduce the length of the crane jib as the process goes on, but it’s never okay for the jib head to dip below 3 metres at any point in time.

Pitched roofs need to be removed by hand down to the wall plate level. This means at least 50-70% of the interior needs to be cleared. Next, demolition should proceed floor by floor, starting with the lowest one.

Do not use any demolition ball techniques on buildings over 30,000 meters, because the fall of debris is uncontrollable, and you won’t have enough space if you do. You should always separate attached buildings by hand to leave a space around the perimeter of the building. This space needs to be at least 6,000 meters, or half the height of the building; whichever one is greater.

WIRE ROPE PULLING DEMOLITION

The size and circumference of the steel wire ropes should be appropriate for the task at hand, but not less than 38 millimeters. The ends should be firmly attached with a gradual pulling tension to avoid sudden and violent release of their load. No person should be more than 3/4s of the distance from the winch to either side of the rope.

If the technique of pulling doesn’t cause the structure to collapse after a few tries, it might be weakened and should not be approached. One way to avoid this is by demolishing it with an alternative means like demolition balls or pushers. Care should be taken to ensure the vehicle or winch you’re using stays grounded – don’t lift off the mountings or wheels!

DEMOLITION BY EXPLOSIVES

This is a specialist method that involves placing explosives within the fabric of the building, then detonating them to cause partial or complete collapse. It should never be attempted by a building contractor without the advice and supervision of an expert.

OTHER METHODS

If site conditions are not ideal for you to use explosives, then the following specialist methods may be used:

-Gas expansion burster In a prepared cavity, a steel cylinder filled with liquefied gas is inserted. Once fired, the expansion of the gas causes the fabric to break into large chunks.

  • Hydraulic burster: A steel cylinder with your number of pistons, which are forced out radially under hydraulic pressure.
  • Thermal reaction: the method requires to cut out and remove a steel structural member, a mixture is applied around the member. The mixture is usually ignited by electric current, which results in a large amount of heat that causes the metal to become pliable. This heat causes a small wire rope attached to a winch to be sufficient enough to cause collapse of the element.
  • Thermic lance This method involves a steel tube, sometimes packed with steel rods, through which oxygen is passed. The tip of the lance is heated to around 3,500 °C by preheating it when the supply of oxygen is introduced. It will melt all the materials it encounters and cause very little damage to anything else.

It’s important to remember that all demolition works have inherent dangers and risks, so specialty contractors should be employed to complete those types of tasks.

Reference:

Advance Construction Technology 4th edition

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