Building Pathology T006

Question 1

What is Dry Rot

Answer 1

Dry rot (also known as serpula lacrymans). Dry rot requires unprotected timbers to become damp with a moisture content of approximatly 20% to thrive.

Question 2

What are some symptoms of dry rot

Answer 2

Damp musty smell, Large concentrations of fine brown dust (spores), The presence of Hyphae, fine strands of fungal growth that combine together in order to spread, Mushroom like orange fungus, the fruiting body is often found in warm, damp, dark unventilated places such as under floorboards,

Question 3

What is Wet Rot

Answer 3

Wet rot (also known as coniophora puteana). Wet rot thrives at a moisture content between 30% - 60%. Wet rot can cause severe structural damage if not treated.

Question 4

What are some symptoms of wet rot

Answer 4

Damp musty smell, Affected timber will appear discouloured often darker, Affected timber will be soft and spoungy, Fungal growth will appear near the moisture source as the fungus does not spread over masonry, Mine Fungus

Question 5

What is mine fungus

Answer 5

Mine Fungus (also known as fibrovaillantii). A form of wet rot often mistaken as dry rot. The fungus grows on coniferous trees such as pine. The fruiting body is an irregular white plate with a thickness of 2-12mm. White cotten like mycelium can grow, in newly formed mycelium fine drops of clear liquid maybe present.

Question 6

How do you treat rot

Answer 6

Stop the moisture source in order to dry out the affected area. Remove damaged area in order to prevent any further spread. Rot treatment of neighbouring material such as fungicidal paste to form a protective chemical barrier. Damaged timber replacement with preservitive treated timber.

Question 7

Methods of detecting high moisture content

Answer 7

Electronic damp meter, Speedy carbide meter,

Question 8

What is an electronic damp meter

Answer 8

damp meters usually work by measuring the electrical resistance between two pins. Often displaying the moisture content as a pecentage.

Question 9

What is a carbide speedy meter

Answer 9

carbide speedy meter requires a small drilled sample of material is mixed with a weighed quanityiy of calcium carbide inside a pressure vessel.

Question 10

What are the limitations of an electronic damp meter

Answer 10

Meters are only calibrated for timber, Hygroscopic salts can exaggerate reading (it is important to test for salts), Different species of timber have different resistances, The following can provide exaggerate readings; - Copper, Chrome or Arsnic treated timber - Foil lined wallpaper - lead paint

Question 11

What are the limitations of an carbide speedy meter

Answer 11

Destructive technique, Danger of fire/explosion if the regent is exposd to moisture, Generally not as quick as other methods,

Question 12

What are some crack monitering techniques

Answer 12

Crack width gauge, Plastic tell tale, Glass tell tale, Brass screws and callipers, target and total station

Question 13

What is crack monitering

Answer 13

Observing crack width changes is one technique used to monitor structural damage due to movement.

Question 14

What is a Crack width gauge used for

Answer 14

Steel ruler is simple instrument used to monitor crack width variation. The crack can be measured to the nearest 0.5mm. Typically used at the start of a crack investigation.

Question 15

What are Plastic tell tales used for

Answer 15

The plate with scales marked in millimeter units of measurement is fixed on one side of the crack and the other plate marked with cursor is fixed on opposite side of the crack. Pros include; They can measure cracks along two axis, can get corner crack monitors. Cons include; fixings can come loose expecially if stuck on with adhesive or if knowcked. Typically 1.0mm degree of accuracy.

Question 16

What are Glass tell tales used for

Answer 16

This technique used to measure crack width variation in the past, but it is not popular any more. It basically consists of strip of glass cemented on to the cracked structural element. This method is no longer used because there is no way of measuring the extent of the movement or direction.

Question 17

What are Brass Screws and Calipers used for

Answer 17

In this technique of monitoring crack width variation, two screws are fixed on each side of the crack at 90 degrees. The screws will guarantee the correct measurement of the crack width and prevent errors. Digital calipers often have a resoloution of 0.01mm. In some cases discs are glued onto the wall.

Question 18

What are targets and total station used for

Answer 18

Typically used to monitor larger scale movement i.e. bridge subsidance. Recorded from a known datum to ensure co Accuracy up to 1.5 at a distance of up to 1,500 meters. This can also be achived by laser reflective targets fixed to the structure. This is typically more expensive and time consuming.

Question 19

What are common types of wood boring insects

Answer 19

Longhorn beetle, Deathwatch beetle, Powderpost beatle, Common furniture beetle, Wood boring weevil.

Question 20

What is the lifecycle of woodboring insect

Answer 20

Egg - Laid in or on the surface of the wood Lava - 4 weeks to years feeds within the wood Pupa - 1-4 weeks+ lava is nearlly fully grown and begins to surface Adult - 1-35 days fully grown mates and lays eggs

Question 21

What are signs of wood boring insects

Answer 21

Flight holes, Frass, Damp timber,

Question 22

What are flight holes

Answer 22

Flight hole are where the lava emerge from affected timber. Typically sized 1-3mm, can help identify the type of insect e.g. longhorn beetles have flight hoels between 6-9mm. Typically round the shape can help identify the type of insect e.g. weevils create jagged holes, Longhorn beetles create oval holes.

Question 23

What are some factors that impact wood boring insects

Answer 23

Location some insects are exclusive to a reigion or country e.g. termites are not found in Northern Europe, Longhorn beetles are restricted to surry Types of timber certain types of insect prefer certain types of timber. Some only attack soft wood or hardwood e.g. Powderpost beetle. Some attack only rotten timber e.g. weeviles. Some only attack sapwood.

Question 24

How do you erradicate woodworm

Answer 24

The application of insecticide is ussually sufficent to erradicate woodworm. Application of a liquid formulation to the surface of affected timbers by brush or typically low pressure spraying of permethrin, cypermethrin and cyfluthrin. Bat friendly gels and pastes are avalible.

Question 25

What is mundic block

Answer 25

Blocks produced from waste rock worked from mining, quarrying and beach gravel. The blocks breakdown overtime. The blocks typically degrade from the inside of the cavity to the surface.

Question 26

What are the classifications of mundic block

Answer 26

A1 - Sound concrete in satisfactory condition A2 - Concrete suitible subject to protection and maintenance A3 - Stage 3 tested containing less than 30% possible problem aggregates B - Contains more than 30% possible problem aggregates although appears sound C - Clearly unsound from examination Options A1-3 are morgagable, B-C are not.

Question 27

How is mundic block tested.

Answer 27

Routine testing is taken in a 50mile radius of Tavistock. Preliminary test screening - serveral 50mm core hole samples are taken from various locations. Stage 2 examination will test the percentage of possible problem aggregates Stage 3 examination will employ a petrographer to access if the material has no visible deteriation.

Question 28

What are RAAC planks

Answer 28

Reinforced autoclaved concrete planks. BRE issued an Information paper on planks designed before 1980 following the collapse of a collapse in 2018.

Question 29

What are the concerns with RAAC planks designed before 1980

Answer 29

Rusting of embedded reinforcement, Ecessive deflection, Ponding of rainwater increasing the imposed load, Surface colour, e.g. dark bitumen increases thermal movement compared to reflective solar paint.

Question 30

How do you manage RAAC planks designed before 1980

Answer 30

Conduct a risk assessment, Consider the long term plan for th RAAC roof, Check with maintainance staff, facilities managers, contractors and those who have access to the building, Ensure that staff know to report any leaks, cracks or other potential defects.

Question 31

You have been instructed by an institutional investment client to inspect three units on a small industrial estate.

Your inspection shows the units to be steel portal framed with either exposed aggregate or colour coated steelcladding panels that you notice are relatively thin.

The manager of one of the units mentions during your inspectionthat the cladding panels are foam insulated.

Please explain what you understand by the expression ‘foam filled cladding panels’, and the issues associated withthe use of such panels (Level 1)

Answer 31

In simple terms foam insulated cladding panels are composite panels with an inner insulating element of some type of foam. The foam used is generally Polyurethane or Polyisocyanurate, with a foaming agent to expand the material to fill the internal cavity. Knowledge of related product issues In the past the potential use of HFCs or similar compounds as a foaming agent in the product manufacture has resulted in some buildings being clad with panels that couldhave significant environmental hazards if damaged or destroyed in a fire.Knowledge of survey limitations Because of the changing composition of the foam infill used over timehas arisen from various legislative revisions it is difficult to ascertain the exact nature of the foam in a particular panel infill without intrusive sampling and testing.

Question 32

You have been instructed by an institutional investment client to inspect three units on a small industrial estate.

Your inspection shows the units to be steel portal framed with either exposed aggregate or colour coated steel cladding panels that you notice are relatively thin.

The manager of one of the units mentions during your inspection that the cladding panels are foam insulated.

Please explain what you understand by the expression ‘foam filled cladding panels’, and the issues associated with the use of such panels (Level 2)

Answer 32

Reasons for use of product: Such panels were generally used because of their lightweight characteristic,coupled with good sound and thermal insulation properties.

Building modifications & compliance with current standards: It must be remembered that some of theearlier panels, whilst they complied with Building Regulations at the time, will not measure up to current requirements, and these panels may prove to be difficult and costly to remove and dispose of in order to facilitate upgrading to current standards.

Deleterious materials & investment: Modern foam filled cladding panels are, in the main, produced withcolour coated steel panels either side of the infill. Such panels would comply with modern regulations, andcan be specified with confidence, although only too often products that were in recent common usage become today’s deleterious material. The candidate should be able to discus what is viewed as deleterious and explain why some investors have their own lists of deleterious materials.

Question 33

You have been instructed by an institutional investment client to inspect three units on a small industrial estate.

Your inspection shows the units to be steel portal framed with either exposed aggregate or colour coated steel cladding panels that you notice are relatively thin.

The manager of one of the units mentions during your inspection that the cladding panels are foam insulated.

Please explain what you understand by the expression ‘foam filled cladding panels’, and the issues associated with the use of such panels (Level 3)

Answer 33

Greater knowledge should then be demonstrated by demonstrating anawareness of how specific types of panels have been identified as potentially having a contributory role in theconsequences of recent fire events in the UK.

These issues include their role in the speed at which firespreads and further discussion into the subject regarding the concerns of some fire fighters regarding theintegrity and stability of certain panels under fire conditions. British Cladding Council advice The British Cladding Council called for a moratorium on the use of foamfilled cladding panels in 2000, until more research was undertaken on their performance in a fire. Indeed the Council went so far as to urge the use of ‘only built up systems or composites containing mineral fibre untilthe risks associated with foam filled panels have been fully investigated and quantified.’ Investment advice Because the client in this instance is an institutional investor, careful investigations would need to be carried out to determine when the panels were manufactured, the nature of the infill andbudget costs for their removal and replacement.Insurance implications Other potential concerns such as insuring such buildings also needs to be flagged to the client as the property is being considered for institutional investment purposes.