Modern Basement interior

Why it’s important to get the right survey

Olympic Construction Olympic Construction News, Uncategorised

Many companies offer building surveys. So how do you recognise a qualified company that can provide the right survey you need?

Olympic Construction are a RICS- CABE & PCA accredited company, with experienced Chartered Building Engineers and Certified surveyors, ready and able to undertake your surveys and provide you with a bespoke quality Report.

Accreditations to look for

RICS

Olympic Construction Ltd is a registered RICS (Royal Institute of Chartered Surveyors). RICS are a globally recognised professional body. To hold RICS registration, a company must have a RICS qualified surveyor and have passed a stringent code of ethics.

CABE 

Our managing director and head of surveying is a Chartered Building Engineer and Fellow member of ‘CABE Chartered Association of Building Engineers’ Fellow Chartered Building Engineer is the highest level of CABE membership and reflects the knowledge, expertise and experience of the industry’s most experienced professionals and a commitment to furthering the ethics and professionalism of building engineering.

PCA 

Olympic construction Ltd have been a full member of the Property Care Association (PCA) for over 20 years. The PCA is the only remedial trading association covering remedial works and has been established over 90 years (formally the BWPDA) and is the recognised standard by both RICS and the NHBC in remedial and waterproofing works and advice.

Which type of survey do I need?

What type of survey you will need is subject to your circumstances.

Dampness surveys

CondensationRising Damp

There are many forms of dampness that can affect property in different ways:

  • Rising dampness
  • penetrating dampness
  • salt dampness
  • mould
  • condensation
  • flooding

Dampness is amongst the highest incorrectly identified defects in property surveying.

A reading on a damp meter is simply an indicator of a problem. The meter will not identify the source or provide the solution.

A damp survey must consider the property as a whole, taking into account the period of the property, type of construction and any changes made to the property from its original design.

The surveyor should have a complete in-depth knowledge of how the property is constructed and behaves in relation to structural and atmospheric moisture and moisture vapour movement through the various mediums that form the structure.

A lack of understanding of these areas can lead to misdiagnosis and incorrect treatments being recommended.

Your damp/ timber surveyor should hold a minimum CSRT qualification and have the experience to correctly identify the reason for the defect occurring and provide you with the correct solution.     

Waterproofing or Tanking

This is the term that refers to preventing water from entering the property, which is located below ground level, i.e. a basement or cellar, waterproofing systems are not required to structures located above ground level.

Undertaking a basement- cellar conversion will require building regulation due to the change of use and may require planning permission.

It is essential that the surveyor who is undertaking your survey is both qualified, holding the minimum ‘CSSW Qualification’ and having the knowledge and experience to determine how the waterproofing installation will affect your property both structurally and how it will affect the internal environment within the existing property.

The surveyor instructed must completely understand the building regulations relating to a basement/cellar conversion. Getting this wrong will prevent your building regulations application from being accepted.

Water can penetrate a structure below ground level in two ways:

  1. Where the ground is not saturated, it will move through the capillaries of the ground and structure by capillary suction. When this form of moisture comes to the internal surface of the building, surface dampness is evident, but there will be no free flow (flooding) of water. Capillary moisture can enter a structure laterally, such as when a wall is earth retaining, and/or it can rise from the ground through floors or freestanding walls, appearing as rising dampness.
  1. Where the ground is saturated, and hydrostatic pressure occurs, water will be pushed through the capillaries of the ground and structure. Where the water comes to the surface, the pressure behind it will force it into the property in the form of liquid water, and flooding will occur.

Where a wall is earth retaining, penetration will be lateral through the retaining soil. If the water table is high (such as when water is trapped in a clay sump created when the foundations are excavated) or if rainfall is percolating down through the soil, then this water will be under hydrostatic pressure and could flood the property internally. If there is no water pressure present, then penetration will be through capillary action, and the property will not flood internally.

Fungal decay

wet rotDry rot

Dry rot and wet rot can affect all areas of your property.

Correct identification and, more importantly, why it occurred is paramount to correcting and preventing reinfestation.

Fungal decay affects your properties structure due to the timbers becoming wet. Dry timbers with a moisture content below 20%MC do not become infested by fungal decay.

Establishing the moisture source and correcting this is the most essential part of any timber survey and recommended remedial work. Failing to get this right will result in the fungal decay reinfesting your property as the timbers will again become wet.

Insect infestation- ‘commonly termed woodworm’ wood-boring insects and there are many which can affect your property, some require treatment and some do not, the flight holes are what generally alert people to the insect infestation, this is where the insect has left the timber, the important point with insect infestation is establishing and knowing how the insect affects the timbers and if it is still active or historical and not requiring treatment.

Your instructed damp/ timber surveyor should hold a minimum CSRT qualification and have the experience to correctly identify the reason for the defect occurring and provide you with the correct solution.     

Wall ties

wall ties

Cracks. Structural movement. What do these terms mean?

The first time most people hear the term ‘Wall ties’ is when they receive a pre-purchased report as part of their mortgage, or a structural engineer requests an inspection of this element of the property.

What are cavity wall ties, and why are they important to the building structure?

A cavity wall is normally constructed of two skins, the inner skin can be constructed of a similar material, usually brick or blockwork, but also possibly in some cases timber. The internal skin benefits from lots of support, which cancels out the slenderness and makes it rigid. These include the floors, ceiling, and wall constructions within the property, which brace it, the roof too, dependent on the type of construction this can be and is used to securely strap the upper areas by means of the wall plate, these points all provide horizontal lateral restraint.

So, with a cavity wall, we have a very stable inner wall, which has load bearing structures providing stability. But to provide better protection from the elements, it is encased within the external envelope, which in comparison is a very unstable independent structure, which only has its 'self-weight' and little or no bracing to provide lateral restraint.

Wall ties provide the lateral support and stability for the outer skin. Spaced horizontally and vertically at regular intervals, the cavity wall ties are braces that are fixed within the mortar beds of both the internal and external leaves of the walls when the walls were originally constructed. The wall ties provide stability for the outer leaf by providing fixed points back to the inner supported leaf. In effect, when correctly tied, the outer leaf forms part of the overall thickness of the wall, reducing the total slenderness ratio significantly.      

A correctly undertaken wall tie inspection will also consider other elements of the building structure, including the roof. Roof spread will apply additional outward pressure to the top of the walls, resulting in the upper levels of brickwork being turned off the horizontal mortar bed. In this case, the defects resulting in the roof spread must be addressed and the affected upper courses of brickwork taken down and reconstructed.

A full inspection to the external face of the property must be undertaken to establish if there are underlying defects to the structure, subsidence, settlement incorrect building works as these will influence the structural stability of the property, a wall tie system will not correct these defects, in these situations we would need to provide further advice.

An effective wall tie installation must have been installed to the correct pattern and density. The external elevations are scanned with a metal detector to identify the pattern and density of the installed ties.

The wall ties are visuality inspected for corrosion within the wall cavity using an endoscope and sometimes brick removal where retrofit cavity wall insulation has been installed.

Cracks around the openings to a property are not always related to wall tie failure. In some cases, this is related to corroding steel installed to provide support to the masonry over the opening.

As the installed steel corrodes, it oxidises (Rusts) this results in the steel increasing in thickness and volume, as the steel is encased within the structure of the building fabric, the increase in volume results in pressure being applied to the surrounding masonry, the weak point being the horizontal bonding between the bricks, this results in lifting of the masonry and opening of the joint, resulting in further water ingress and corrosion, eventually resulting in cracking and distortion of the surrounding masonry.

Properties with solid wall construction can also be affected by structural movement resulting from incorrect lateral support. This can be a defect within the original design or the removal of structural elements as part of renovation works.

In the cases listed above, remedial lateral stabilisation works can be undertaken by installing a Theohelical lateral restraint system designed by our Chartered Building Engineers, who have undertaken the Theohelical remedial design engineering courses, so are able to develop a restraint system that will provide stability to the property using the various system and existing elements of the property.

Get in Touch ?

The Chartered Building Engineers and surveyors at Olympic Construction Ltd have the knowledge, qualifications and surveying equipment to inspect your property from the roof to the basement level and provide you with a compressive written report with the answers you or your lenders are looking for
Tel - 0161 633 9860 & 01625 900 800 or contact us.