Building Pathology Flashcards
Tell me about a report you have prepared relating to the causes of failure, likely results of failure and apprpraite remedial measures.
I carried out an inspection and developed a report on damp issues within a flat in Oxford. From my inspection, completing both visual internal and external inspections, protimeter and relative humidty checks I determined that the damp was likely a result of condensation. I advised that there was not appropraite ventilation in the property, with the windows being rarely openeing, extract fan not working and 1 bedroom flat having 1 resident and two dogs occupying. I recommended that heat retaining vents be installed into the external walls and a new extract fan installed in the bathrooom with an exract capacity of 16l/s.
Why would you use non-technical language in a report?
As an expert reporting on the field, I should assume that the reader will not have the level of tehcnical knowledge I do. Non technical language ensures that the reader will understand the information within the report and communictes its contents first time.
Tell me about BRE guidance you have applied and the reasoned advise you provided as a result?
When compelting my inspection of Esmond Road and developing the report I used the BRE crack classification system. The cracks that I inspected were between 5 and 15mm and classified as BRE 3. I was able to advised that internal remedials could completed with some minor opening up and patching by a mason. The classification also gave me confidence in that the cracks were not structural but could affect the weatehr tighness of the property.
Keyworker Showers, Hillingdon
How did you deal with the supporting of shower trays where the showers had less damage?
For showers that did not require full refurbishment I included within my specification for the contractor to ensure that the trays have 3 shower feet that were fit correctly and tight to reduce the change of further dropping.
Keyworker Showers, Hillingdon
What mastic did you select and why did you choose it?
I specified a high quality water proof and mould resistant mastic from unibond. The reason was that I wanted to minimise risk of seals compromising that were more likely to happen from a cheaper mastic. Also during the survey stage, I noticed many of the residents were sufferening with bacteria/mould growth, I specified a mould resistant in an aim to reduce the occurence of mould or bactiera.
Keyworker Showers, Hillingdon
What advice did you give to your client about the risk of replacing the mastic only?
I advised that although the bathrooms assigned to mastic replacement were currently not suffering from severe water damage there was a risk that damage could occur if the problem of support is not addressed. This would involve removing the show unit and ensuring the chipboard floor structure was supported appropriately via noggins/joists. I was aware of the budget constraints of the client, so I recommended that a monitoring survey be completed yearly of showers with mastic reparis to ensure the remedial works were suitable.
Keyworker Showers, Hillingdon
Did you comply with British Standard bs 5385-4, if not why?
This British Standard relates t the installtion of tiles. The specification for the bathroom did not involve the use of tiles, the shower unit was comprised of hygenic wall panels.
Magdalen damp report, Oxford
What advice did you give your client about their legal responsibilities regarding damp
I advised the client that under section 11 of the Landlord and Tennant Act that they are legally responsible for maintaining the water tighntess of the structure. If the damp was a result of penetrating or rising damp it would be their responsibilty to rectify the issue. Also if unaddressed, this could result in a disrepair claim from the resident.
Magdalen damp report, Oxford
Did you consider the possibility of wet insulation affeceting the temperature of the wall
The wall that was showing signs of damp had creduly installed vents at low level. I was able to carefully remove a vent and assess the condition of the cavity wall insulation. Polystyrene bead insulation was present, from touch it was not wet.
Magdalen damp report, Oxford
Did you determine what type of insulation was within the wall?
The wall that was showing signs of damp had creduly installed vents at low level. I was able to carefully remove a vent and see that polystyrene cavity wall insulation had been installed. This eluded to the fact the freeholder had tried to improve the thermal capacity of the property, anc combined with the vents pointed toward condensation.
Magdalen damp report, Oxford
As the nomral protimeter pins only penetrate the plaster how could you assess whether the inner skin of the wall was dry or damp?
From my desk top study of the instruction before my inspection I understood there would be value in bringing a protimeter with deep probes to allow me to check the dampness of the skin inner skin of the brickwork.
Magdalen damp report, Oxford
What additional inspections did you recmmond to your client should be undertaken?
I recommended that an intrusive investigation of the external wall should be undertaken to ensure that interstitial condensation had not occurred.
Magdalen damp report, Oxford
Did you consider increasing the static ventilation of the property?
My recommendations included installing passivents into the external walls. The sytem I recommended removes hot humid air from the property to the outside using pressue, a permeable membrna allows for the moisture to be removed without allowing a draught inside.
Magdalen damp report, Oxford
What external inspection did you undertake?
I followed a six step inspection process. 1) Understand the construction and occupancy of the property. 2) Pinpoint the area of damp and key features of its presence. 3) Inspect externally for defects. 4) Test the moisture content of walls. 5) Surface temperature check 6) Check the ventilation of the property.
SBHG Window Replacement programme
Why was the problem with piers not picked up at the intial survey stage?
The list of the properties that were placed on the programme were derived from my clients stock condition survey data provided by a third party. I was instructed to complete surveys of the properties on the programme to pick up additional extneral repairs that could be picked up during the programme. This is when I noticed the issues with the piers and the lintel.
SBHG Window Replacement programme
If the problem had occurred after the windows had been installed, what could have been the cause?
The lintel cracking or piers leaning after the new windows had been installed could be a sign that the old windows were supporting the load of the building more than the new windows had been specified to do so.
SBHG Window Replacement Programme
Why could you not speak to a lintel i.e. catnic, for advice and recommendations for the lintel?
Although the symptoms of the defects were related to the lintels of the property, it was not clear the the defect was a cause of a broken/damaged lintel. I was able to determine that the issue was structural, but as this was outside of my area of expertise I reocmmended that a structural engineer was appointed.
SBHG Window Replacement Programme
Why did you think the lintel had cracked, what checks did you complete?
I completed checks on site, including measuring the crack width to categorise it in category 3. I checked the surrounding area and internally for more cracking. The cracks were localised only to the lintel. From the location of the cracking and their width I formed the opinio that the crack was likely due to failure of the structure and not movement of the ground.
Prestwick Road Subsidence
What did you consider caused the problem? And what inspections did you complete to come to the conclusion?
Before we carried out t he inspection I compelted a review of the historical documentation, this included a report from a loss adjuster, arboricultural report and trial pit. On site I completed an inspection of all damage internally. The repaired cracks had previously opened up, with the resident advising it had occured over the previous summer. Cracks were wider at the top, trial pit information included evidence of roots adjacent from the foundations, damge was seasonal which all pointed to soil shrinkage.
Wigston Close, Structural Works
What immediate measures did you take for the safety of the occupants and the others?
Due to the wall being deemed as a dangerous structure, immediate works involved decanting residents, proping the walls with accrow props and steel beams and hording the external wall to secure the property.
SBHG Window replacement programme
How did you determine that the defects you noticed were structural?
During my inspection I noticed that the elements that were effected were the mullions and the lintel. Victorian properties of the nature typically have a construction of timber lintels above bay windows that are supported on the mullions. As both of these areas were showing signs of defect I concluded this issue was structural.
SBHG Window replacement programme
How did you determine that the issue was structrural and was not caused by subsidence or settlement?
The cracking and bowing was localsised to the mullions and the lintels. I completed an inspection to the ground floor bays and they were not showing any signs of deflection or cracking.
SBHG Window replacement programme
Why did you instruct the client to appoint a structural engineer for the repairs?
Although I was able to determine that the defects I observed were structural, prescribing and designing the repairs were outside of my experince and competence
What are the typical defects associated with lintels in victorian properties?
Timber lintels are typical with mortar facing
Insufficient depth to be safe from damp penetration
Also vulnerable to insect attack
Can cause for reduction in strength and failure of lintel
SBHG Windows
What repairs did the structural engineer presribe?
Install a new steel lintel to the inside which mortar concrete would be supported from
New steel posts installed to mullions
What is the relevant legislation relating to limitation periods and what does it include?
The limitation act 1980
6 years limitation period underhand contract
12 years if the contract is signed as a deed
Keyworker Showers, Uxbridge
What was the construction of the floors at the Hillingdon keyworker accomodation and how did this cause the defects?
The floors were constructed of timber joists with a tounge and groove chipboard. The loose edges of the chipboard were not supported by noggins and end joints were not all supported joists. The floor was then unable to resist the load of occupant using the shower.
Keyworker Showers, Uxbridge
Where you prescribed a full refurbishment what did the repairs include?
Removal of all water damaged chipboard
Installation of noggins at loose ends of chipboard
Use of moisture resistant grade chipboard
All chipboard junctions to be supported on joists
How can cavity wall insulation cause for damp in cavity walls?
In proper installation can cause for the cavity to be bridged
Water repellent systems must be installed to manufacturers guidance
If mortar gathers on the insulation it can allow for water to travel inside
Batt at gable ends should be taken up to verge, or a cavity tray should be installed to prevent water travelling across the top of them
Retrospective cavity fill can prevent evaporation in external skins, make the wall more vulnerable to frost attack and if mortar falls onto the fill can cause for cold bridging.
What are the methods for testing dampness in a material?
The oven method - drying and comparing to wet weight
Conductivity testing
Carbide testing
What are the issues with oven and carbide testing?
They are destructive methods of inspection
Require samples from material
Inpracticial to use on site
A range of samples is required
What are the issues with conductive testing?
Does not register low levels of moisture
Is calibrated to moisture content percentage of timber
Only test the surface/just below the surface of material
Magdalen Damp Report, Oxford
Explani your pcoess diagnosing the damp at Magdalen.
1- Understand the construction and occupancy of the property
2- Pinpoint areas of damp and mould/identify key features
3- Inspected externally for any obvious defects
4- Test moisture percentage of walls using protimeter
5- Complete temperrature check of wall surface
Can you give me a definition of damp within buildings?
The presence of unwatned moisture within the structure or elements of a buldinsg, either as a result of intrusion from outside or condensation from within the structure.
How does a protimeter test for moisture?
Probes inserted into wall
Meaures electrical current between two probes
Higher the moisture, the greater the current
What is condensation within buildings?
Moisture that gathers on surfaces
Warmer air can hold more moisture than cool
If air contacts a surface that is cold enough it will increase its relative humidity to 100% and water will condense. This is the due point.
Mould and staining can then develop from the moisture on the walls
How does condensation occur within buildings?
Moisture is produced by people living in properties and the activities they carry out
Areas such as bathrooms and kitchens produce more moisture into the air
Condesnation will then occur on cold parts of walls i.e. where there is a cold bridge
It will also occur in areas where there is little ventilation
Magdalen Damp Report, Oxford
How did you determine that the damp was likely to be as a result of condensation?
The areas where damp was forming were to low level and areas of low ventilation, i.e. behind furniture and curtains. I tested the walls with the protimeter and they did not give a reading of excess moisture, there was also no sign of relevant defects externally. The property also had crudely installed vents that did not retain any heat. The resident also lived in the property with three dogs indicating high levels of moisture int he air.
