Pathology

Question 1

What are the main kinds of damp?

Answer 1

There is typically understood to be 3 main causes of damp:
* Penetrating damp
* Rising damp and
* condensation.

Question 2

What is the main difference between wet and dry rot?

Answer 2

Wet rot is caused by continued exposure to moisture. The timber breaks down and and fungal growth can form. Damage will typically be isolated to the area of exposure.

Dry rot is caused by exposure to moist air, where there is a lack of ventilation. Dry rot is identifiable by cuboidal cracking caused by a breakdown of cellulose in the timber. Dry rot can spread from the initially affected area seeking out a food source with long mycelium strands. Large fruiting bodies may also appear which will spread spores.

Question 3

What is nail fatigue/sickness?

Answer 3

Nail fatigue/sickness is when ferrous nails, used to hold down roof tiles/slates, corrode and cause slates to crack or slip.

Question 4

What is roof spread?

Answer 4

Roof spread is caused by a roof structure’s inability to support it’s load. This is often caused when sections of roof structure are damaged or removed, e.g. through remodelling, or when heavier roof tiles are installed. E.g. replacement with concrete tiles instead of original slates.

It can be identified by bulging to the head of walls, where the roof is pushing outwards against the walls in a scissor like motion.

Question 5

What is High Alumina Cement? (HAC)

Answer 5

High Alumina Cement gained popularity in the 1950s due to it’s rapid curing time. It’s use has since been banned in structural applications as it had a tendency for structural failure and was more susceptible to moisture and sulphate attack.

Question 6

What is a defect?

Answer 6

A defect refers to a flaw, fault, or imperfection that deviates from the intended design, construction standards, or performance expectations of a structure.

Building defects can occur due to various factors, including design errors, material issues, construction mistakes, environmental influences, or aging and deterioration over time.

Question 7

How would you remediate wet rot?

Answer 7

• The source of moisture would need to be identified and remediated
• The area should be dried
• Cut out rotten timbers
• Treat remaining timbers with fungicide to kill any remaining spores
• Install/splice new timbers

Question 8

How would you remediate dry rot?

Answer 8

• Identify and remediate the source of moisture
• Dry the area and improve ventilation
• Remove any fruiting bodies, mycelium and clean down any spores
• Remove all affected timber and any local timbers which show signs of contamination
• Apply fungicide to the surrounding timbers
• Install new timbers

Question 9

How would you identify asbestos?

Answer 9

Asbestos is invisible to the eye, but it is possible to identify materials which may contain asbestos. Asbestos can be found in any property built pre 2000. It can be found in many materials including:
* Floor tiles
* Pipe lagging
* Insulation
* Roofing sheets
* Textured finishes
* Rainwater goods

Question 10

How can Portland Cement cause issues in older properties?

Answer 10

Portland Cement mortar is much harder than traditionally used lime and isn’t naturally breathable. When applied to older properties where lime would have been used it can cause dampness in walls, spalling to bricks and cause cracking.

Question 11

What causes fungal growth?

Answer 11

Fungal growth can be caused by a variety of factors, including:
* Excess moisture
* Poor ventilation
* Condensation
* Lack of sunlight

Question 12

How would you remediate a beetle attack?

Answer 12

• Identify the kind of beetle and extent of infestation
• Dispose of very damaged wood
• Treat damaged and surrounding timber with appropriate insecticide
• Monitor and review

Question 13

Can you describe some typical cavity barrier defects?

Answer 13

Cavity barrier defects would typically be either the wrong specification of type/rating, e.g. using open state instead of closed state. Or installing them with gaps or a lack of compression.

Question 14

What is interstitial condensation?

Answer 14

Interstitial condensation is caused by warm moist air, coming into contact with cold surfaces and condensing, however within a structure itself, e.g. within a wall. This risk can be eliminated through the design of the wall and the introduction of a Vapour Control Layer.

Question 15

How would you calibrate a disto?

Answer 15

I would check it against a tape I knew to be accurate or a fixed reference point previously used to calibrate distos.

Question 16

What is a hygrometer?

Answer 16

Hygrometers measure the humidity levels in the air.

Question 17

What is a stone end repair?

Question 18

What is a frost damage?

Answer 18

Front damage is caused by the moisture within a building material, e.g. a brick, freezes and expands causing the material to break apart.

Question 19

What causes lintel failure?

Answer 19

• Structural overloading,
• Or more commonly deterioration through rot or chloride attack etc
• A timber lintel behind a stone lintel for example could have failed causes the stone lintel to be overloaded and crack

Question 20

How would you calibrate a Protimeter?

Answer 20

You can use your hand to check the calibration. it should read 18% WME.

You can also buy a tool which will do the same.

if the reading is out, it could be that the pins are dirty or the battery is low. If there is nothing obviously wrong then it would be advisable to replace the protimeter.

Question 21

What is Carbonation in Concrete?

Answer 21

Carbonation is a chemical reaction in concrete which typically occurs in the presence of moisture and is a slow, ongoing process that can take months or even years to progress significantly. It starts from the concrete surface and gradually advances inward, reducing the alkalinity of the concrete.

Question 22

How do you remediate carbonation?

Answer 22

Methods include:

• Re-alkilization compound, chemical recation reduces carbonation
• Electronic re-alkinization, current reducued rate of carbonation
• Carbonation-resistant coatings
• Cut and repair

Question 23

What is chloride attack?

Answer 23

Chloride ions can enter the concrete through various pathways, including exposure to seawater, deicing salts, marine environments, or chloride-rich groundwater. Once chlorides reach the reinforcement, they can depassivate the steel and initiate corrosion, leading to the formation of rust. The rust occupies a larger volume than the original steel, resulting in internal pressure that causes cracking, spalling, and deterioration of the concrete cover.

Question 24

How do you remediate chloride attack?

Answer 24

• Protective coatings, Applying appropriate coatings or sealants to the concrete surface can act as a barrier, preventing chloride ingress and protecting the reinforcement.
• Corosion inhibitors, these can be applied to the surface and can provide a positive chemical reaction which reduces the rate of corrosion
• Cathodic protection, anode systems can be installed to provide an electrical current that suppresses the corrosion process and protects the reinforcement from chloride-induced corrosion.

Question 25

What are deleterious materials?

Answer 25

In the context of building surveying, “deleterious materials” typically refers to substances or materials present in buildings that can be harmful to human health or the structural integrity of the property.

Question 26

What are some deleterious materials?

Answer 26

• Asbestos
• lead paint
• Woodwool slabs
• Calcium silicate
• High alumina cement

Question 27

What is sulphate attack?

Answer 27

Sulphate attack is chemical between sulpahtes and water in concrete.

Can be caused by sulphate inclusions within the concrete if exposed to moisture or to sulphates in the ground/substrate.

Remediation requires removing and replacing the concrete.

Question 28

How do you calibrate a protimeter?

Answer 28

If you put your hand on the prongs it should read 18%.