Building Investigation

Link work with a range of developer, owner, tenant and contractor clients in different sectors to provide structural engineering design services to allow existing buildings to be modified or extended. This may include consideration through feasibility, detailed design and construction of:

• Upward extensions
• Sideway extensions
• Removal or demolition of parts of structures
• Use of existing floors for new purposes
• Modifying roofs
• Installing new floors or heavy equipment
• Repairs to defects

Structural defects in buildings can take many forms and can occur in combination. There may be obvious structural defects where members fail, grossly distort or fall down off buildings. Less obvious structural defects can cause damage to finishes, machinery not to operate properly or doors not to close. Structural defects can be caused by poor design or construction (including modifications) or can be a consequence of deterioration over time or changes in building use or environmental conditions. Link engineers have extensive experience of undertaking structural appraisals of defects to existing buildings. These appraisals can include consideration of issues such as:

• Building movement including foundation settlement.
• Cladding materials failing and falling away
• Corrosion of steel frames or members
• Degradation of aging concrete structures including carbonation, chloride ingress, sulphates.
• Degradation of aging timber members.
• Cracking associated with thermal movement
• Defective, under-designed or poorly detailed, framing, floor or roof members in steel, concrete, timber.
• Inadequate provision for lateral stability.

In each case our appraisals consider the available information and findings of building investigations to identify, in a staged process, the probable nature and causes of observed defects and strategies for future investigation, monitoring or repair.

As well as the appraisal of the nature and causes of observed structural defects to buildings our Link engineers consider and discuss with clients appropriate strategies for future investigation, monitoring or repair. In some cases (such as extensively fire or impact damaged structures) repairs may include wholesale replacement of damaged parts of the structure. In those cases the engineering design challenge may be determining where the junction should be between replacement and repair. Do foundations to fire damaged superstructures need to be replaced? Are there commercial (building value) non-structural considerations associated with retaining parts of partially damaged structures? In other cases, repairs may include local repair of particular damaged members such as welding plates to corroded steel beams or columns or remedial reinforcement and concrete repairs to deteriorated concrete members. In each of these cases the repair may also include provision of appropriate corrosion protection coatings or modified protection against water ingress or provision of electrolytic (often cathodic) protection. Whatever the appropriate form of structural repair it is important that the works are undertaken diligently and properly by appropriately experienced contractors. Our Link engineers are experienced in working with client teams to specify and design remedial works and assist with procurement of specialist repair contractors. We expect to work with clients and contractors to identify appropriate methods of working (often including further investigation as works proceed) to ensure adequate quality and commercial control of the works. Our engineers are often involved in site inspections and review of repair works as they progress.

Typically, when a structurally significant fire occurs in a building the fire brigade will attend and take whatever steps they consider necessary to extinguish the fire and substantially remove the threat of re-ignition. At some point in the fire fighting process – depending on building location – a local authority Building Inspector may also attend and comment immediately on the safety of the damaged structure. Normally, the building owner or tenant will advise their insurers of the fire while it is still happening or immediately afterwards and the insurer will appoint a Loss Adjuster. One of the first questions the Loss Adjuster and building owner want to address is “How bad is the structural damage and what are the immediate safety steps that need to be taken?” It is often at that point that our Link engineers are requested to attend the site of the fire and undertake an initial structural appraisal of both the extent of the structural damage and the need for urgent demolition or propping. Sometimes the Link engineers are on site while smoke is still in the air and the building still warm. Our initial structural appraisal draws on our experience of different types of structural forms and our assessment of their residual robustness in the damaged condition where some elements may have completely collapsed and others may remain standing. We are primarily considering two separate issues.

• What needs to be done immediately to make the building safe? This needs an urgent answer. (This may be a different opinion to that provided by the Building Inspector and liaison may be necessary)
• What, if any, parts of the building might be saved to remain in a repaired building. This may involve a phased approach to investigation as debris is removed as well as appreciation of commercial considerations by discussion with Loss Adjusters and Building Owners.

Our Link engineers are frequently involved in specifying the scope of appropriate immediate demolition and temporary works as well as identifying the strategy for further investigation as part of the building become safely accessible.

Water ingress into buildings can cause damage to structures (as well as rot, damage to finishes, and damage to services etc). In particular water ingress is a primary cause of corrosion to both steel framing members (beams and columns) and reinforcement in concrete (floors, beams columns, walls). Water ingress is also a primary cause of deterioration of timber members. The effect of water damage can be exaggerated if the water which is involved can contain road salts especially for structures which are directly trafficked by road vehicles. Chloride induced corrosion of steel is a different form of electrolytic reaction to normal atmospheric corrosion and can cause steel elements (reinforcing or beams and columns) to pit. This pitting can mean that corrosion of concrete reinforcement does not manifest as a volume increase which cause visible concrete spalling and can therefore be associated with weakening of members with no visible signs. Link engineers are experienced in undertaking appraisals of the consequences of water ingress into structures. As well as direct assessment of the impact of the ingress on structural elements Link engineers consider the causes of the water ingress and nature of the construction details which have allowed it to occur.

Link provides services to both landlords and tenants associated with various stages of commercial leases. This has included acting for either side with regard to licence to alter applications and start and end of a lease. Also at the time of specification of new developments the Practice has acted for both landlords and tenants in specifying the developer requirements and input into negotiation of development agreements.

Heritage buildings can present a variety of structural engineering challenges which are not normally associated with more modern buildings. Link engineers have experience of addressing these challenges to develope innovative cost effective solutions. Heritage buildings are considered by Planners and society more widely to contain elements (fabric and finishes) which should be preserved in-tact, so far as is practical, during any works to maintain or modify their structure. However, as Heritage buildings are invariably ageing their structure is often deteriorating over time sometimes resulting in loss of strength, instability or damage to valuable finishes. Also many Heritage buildings have outlived their original function and need to be re-purposed to allow them to be usefully maintained. Sometimes fires have occurred while Heritage buildings have been vacant causing partial damage. Link engineers have experience of undertaking structural appraisals of existing Heritage buildings which include timber, steel and concrete frames with stone, masonry and composite (e.g. timber and infill) elevations. Typically such appraisals will include an initial assessment the structural integrity of either the whole or parts of the building structure and address the nature of any defects identified. The appraisals may then be extended to consider structural options for repair or modification of the structure. Each such option considered is necessarily required to address issues of buildability while retaining as much as necessary of the existing building fabric. Often construction options are considered alongside Heritage advisors to clients and local authority Planning officers. As well as more orthodox repair techniques some structural solutions include the introduction of new structures in between damaged existing structures which are to be retained in the fabric in future even if they have no ongoing structural function.

Link engineers have are accustomed to providing a range of other structural engineering appraisal and consultancy services which include:

• Confidential Expert Advisor services
  • in cases of disputes about defective structures appointed by one of the parties and providing technical advice on the structural issues involved often alongside solicitors.
• Expert Witness services
  • appointed by courts in cases of legal disputes about defective structures which are to be adjudicated by a legal process. In this instance there are strict rules about non-partisan technical advice on structural issues.
• Structural Engineering Advisor Services (Licence to Alter)
  • Review of structural engineering technical submissions made by tenant or landlord on behalf of the other party as part of legal agreement.
• Structural Engineering Advisor Services (Purchase, Sale, Lease End)
  • Technical advice to landlords or tenants or vendors or purchasers on structural matters which may affect proposed future building uses, building values, lease end payments. Sometimes including design of remedial or modification works.
• Structural Engineering Advice with regard to Damaged structures
  • Fire, ground movement, impact, structural deterioration (rot, corrosion etc) can create structural damage which may have a significant impact on the stability and integrity of building elements. Sometimes these can have urgent health and safety implications which may require structures to be taken out of use, propped or demolished.”