Building Pathology Flashcards

Question

What is Japanese Knotweed?

Answer 1

- A herbaceous perennial plant that is a non-native, invasive species in the UK. - First introduced for ornamental purposes in the mid 1825 century but now very invasive due to lack of enemies such as insects, bacteria and fungi that are only present in it's country of origin. - JK grows through spreading of rhizomes laterally. - Causes circa. £165m per year. - Commonly found around public waterways and railway tracks.

Answer 2

- Green, shield shaped leaves with flattened bases. - Hollow, bamboo-like stem which is light green with speckled red colouration. - Small, clustered creamy-white flowers. - Thick and extensive rhizomes which are orangey-yellow internally.

Answer 3

- Rhizomes can exploit cracks and structural weaknesses in building fabric or existing cracks causing progressive cracking and loss of structural integrity. This can occur in foundations, walls, retaining walls, hardstandings (through movement joints and weaknesses in incorrectly laid hardstandings). - Rhizomes can also physically move and block underground services such as drainage and water pipework in addition to affecting buried cables. - Can prevent homebuyers from gaining a mortgage from a preferred lender and some do not cover JK. - Can cause diminution in land / property value. - Can spread very easily to neighbouring property - 0.02g of rhizome needed to allow regrowth.

Answer 4

- Spring: emerging stems that can range from green to red and purple with rolled leaves. - Late summer / early Autumn: Creamy-white flowers form in drooping clusters. - Autumn / winter: Stems only present and turn various shades of brown, sometimes with orange tinge.

Answer 5

- Excavation and disposal: Excavation can extend up to 3m vertically and 7m horizontally from the above ground growth. Is then taken to appropriately licenced waste management facility. - Onsite burial and encapsulation with membranes: Excavated then buried on site, if can't be covered with 5m of overburden a specialist root membrane must be installed or the Japanese knotweed will be completely encased with root barrier if it cannot be completely buried. - Chemical control with use of specialist herbicides applied by mixture of stem injection and localised spraying. - Biological control: introduction of a 'pest' species that will attack the JK. Trials currently being undertaken with Japanese sap sucking insects. However will not control infestation on its own.

Answer 6

- Wildlife and Countryside Act 1981 - it is an offence to plant of otherwise cause Japanese Knotweed to grow in the wild. - The Duty of Care Regulations 1991 - Japanese Knotweed is classed as controlled waste and therefore owners owe a duty of care when handling and disposing of it.

Answer 7

Herbicidal treatment: + Cost effective. + Carried out in situ - less risk of accidental spread. + Quickly reduces ability of JK to spread and impact structures. - Can take years to complete treatment (3 year course then monitoring). - Not appropriate where development is planned - will cause spreading. - Continued monitoring required 2 years post treatment to confirm rectification. Burial: + Work can continue immediately after burial. + Quick. - May not be possible to burry on site - buried services etc. - Not possible if water table is high. - Rhizomes can be accidently spread. Excavation and offsite disposal: + Quickly removes JK. + No restrictions left on site. + Works can continue immediately. - Expensive. - Reduces valuable landfill capacity. - Increased risk of spread. - Should be used as a last resort measure.

Answer 8

- Explained that the client had a statutory obligation to prevent its' further spread under the Wildlife and Countryside Act 1981. - Stated the implications if left to spread - could spread to where site incoming water and outgoing drainage were and near security hut. - Recommended that although I had identified it, a Japanese Knotweed specialist surveyor should be instructed to map the area and provide recommended remedial options and reasoned professional advise. Herbicidal treatment was chosen on the basis that: - Water table was particularly high on site - couldnt burry. - Chemical treatment would take longer but reduced chance of disturbance and spread of JK. - Land was an existing site and not going to be developed in the foreseeable. - 10 year guarantee was issued - this was a condition of the new incoming tenant looking to let the property on a 10 year FRI lease.

Answer 9

- Whereby the level if moisture inside a building reaches a level that causes building defects such as staining of decorative finishes, mould growth, frost damage and sulphate attack.

Answer 10

- Condensation. - Rising damp - Penetrating damp

Answer 11

- It is the result of water being drawn up through porous masonry from wet ground via capillary action. - It can be detected by horizontal tide marks up to 1.3m in height (any further vertical movement is prevented by gravity), blown plaster and spoilt decorative finishes. - Causes include: 1. No DPC. 2. DPC bridged (render, soil, raised external paving, covering, removed or blocked vents to suspended floors, poor underfloor ventilation). - Remedies include: 1. Installation of DPC. 2. Electro-osmotic damp proof course. 3. Chemical injected DPC. 4. Increase internal ventilation and heating.

Answer 12

- Horizontal lines observed on decorative finishes or building fabrics which show the vertical extent of rising damp. Below which there will be discolouration and general darkness and might be general deterioration to decorative finishes. Hydroscopic salts tend to be concentrated in the tide mark which originate from the ground and are left after evaporation of the ground water.

Answer 13

- Occurs when water penetrates the a building's envelope. - Causes can include: 1. Saturation of walls exposed to prevailing winds, usually south or south-westerly. 2. Defects with masonry walls that allow penetration e.g damaged masonry and lack of pointing. 3. Leaking rainwater goods: can saturate the masonry leading to frost damage which then allows water ingress, can also enter into the loft space if sarkiing is too short and guttering overflows due to blockage. 4. Defective or missing cavity trays. 5. Failed roof coverings (slipped tiles and defective flat roof coverings). - Remedy includes: 1. Find and rectify the source of the leak. 2. Promote rapid drying (through heating and ventilation or dehumidifier and restricted ventilation).

Answer 14

- The process whereby water condenses from water vapour to liquid water when the temperature of air containing the water drops to, or below the dew point (temp at which air becomes saturated with water vapour). - There are two forms of condensation: 1. Interstitial: Occurs within the structure at interfaces between materials and tends to be hidden by construction and surface finishes. 2. Surface: Occurs on surfaces and therefore easier to observe.

Answer 15

Surface condensation - Causes: 1. Cold internal surfaces such as external walls, single glazed windows, cold-water pipes, wall-to-floor junctions, lintels and window reveals. 2. Large amount of excess moisture produced from human activity including cooking in kitchens, bathing, drying clothes inside. This moisture condenses in the rooms where the activities occur but also migrates to where vapour pressure is reduced in areas such as unheated rooms. 3. Excess moisture from unvented or defective flues from paraffin or butane heaters or tumble driers. - Affects: 1. Mould growth - usually more prevalent to areas with restricted air movement such as behind furniture or inside cupboards. 2. Damp patches and spoiling of decorative finishes. - Remedy: 1. Mixture of increasing heating and ventilation. 2. Modifying human behaviour - heat all rooms of the property and reduce activity that causes excess moisture - shorter showers, dry clothes outside etc. 3. Fix any defective flues. 4. Increase insulation. 5. Install windows with trickle vents.

Answer 16

Issues: - Can cause dampening of insulation materials which can lead to reduction in performance and eventual physical deterioration. - If forming against timbers, can promote rot and insect attack. Rectification: - Changing of the building detail if there is an inherent defect. - Replacement of insulation if penetrated such as in a cold roof build up - insulation penetrated by fixings, vapour then passes through vapour control barrier and then into the very cold roof void allowing condensation to form on structural timbers.

Answer 17

* Blocked air vents to ground floors, causing dry rot * Failed or lack of damp proof course – rising dampness, penetrating damp, efflorescence on plaster, decay to skirtings * Delamination of brick skins – bulging of brickwork * Over notching of floor joists for retrofit of services – deflection of floors, reduction in load bearing capacity * Poorly fitting sash windows, risk of decay within window reveals, water penetration beneath sub-sills, draughty or dangerous operation, decay in concealed areas, lack of security * Roof covered with concrete interlocking tiles – overloading of roof structure, bowing of rafters and purlins, roof spread * Settlement of bay windows – internal cosmetic damage, distortion in load-bearing elements * Wall tie failure (particularly in black ash mortar) * Heave or subsidence of shallow foundations * Nail sickness – ferrous nails corroded

Answer 18

* Water paths through parapets, hidden valleys and gutters * Springy floors resulting from decaying timber floor joists. mainly caused by poor cross-ventilation. heel drop test to test the springy floor. * Rotten or stuck sash windows * Blocked internal gutters. * Damp penetration in solid walls * Corroded cast iron railings bursting stonework * Bowed brick walls, caused by the practice of lightly bonding high-quality facing bricks in with poorer quality bricks of the main wall, unbonded party walls and front walls and decaying coursed timbers buried in walls * Failure in roof trusses caused when roof ties rot and begin to spread. Dislodged joists and ridges caused by bomb blast damage. * Leaning chimneys/over-tall stacks/damp penetration via stacks * Perforated lead work or splitting caused by over-beating or poor maintenance * Missing or badly altered load-bearing timber partitions * Damp basements * Failure of timber lintels * Poorly applied or painted stucco limiting water evaporation from walls * Downpipes decanting on to lower roofs from roofs above, causing temporary flooding in heavy rainfall

Answer 19

* Sulphate attack can cause serious damage to brickwork and concrete by creating expansive force that are, or can be, sufficient to disrupt mortar and create significant expansion, bowing and cracking of concrete floor slabs together with related collateral damage. * In some subsoil there can be a problem with sulphate attack. It occurs when the fill material (hardcore) beneath the slab contains sulphates and these migrate into the concrete. The sulphates react with the concrete causing it to expand. * Calcium, magnesium and sodium sulphates occur naturally in some clays and other sub soils * The sulphates dissolve in the groundwater and permeate the concrete. * This leads to an aggressive chemical reaction between the sulphates in solution and one of the chemicals in the cement. * The resulting compound expands rapidly as it forms and this can crack the foundation concrete. * If sulphate attack is a possibility it is wise to use sulphate resisting cement.

Answer 20

* Spore * Hyphae * Mycelium * Fruiting Body

Answer 21

A generic term that is used to commonly describe the larva stage of wood boring beetles. A number of insects, mainly beetles, are able to use wood as a food source and some of them can cause serious damage to building timbers.

Answer 22

• COMMON FURNITURE BEETLE (WOODWORM) 3-5m long, dull brown Lines of pits on wings Found on or around damaged timber LATE MARCH – EARLY AUGUST (particularly warm weather. Softwood, European hardwoods 1-2mm dia. Circular flight holes Flight holes random orientation, mainly in direction of grain. Bore dust, cream coloured, lemon shaped pellets. Life cycle 2-5 years • LONG HORN BEETLE Adult 10-12mm, black or dull brown. Sapwood or softwoods particularly roof timbers. South-west of London mainly surrey. Flight holes, few large oval, 6-10mm largest dimension. JULY to OCTOBER Cream coloured, sausage shaped. • DEATHWATCH 6-9mm long, chocolate brown MARCH to JUNE Bore dust, disc shaped cream pellets Flight holes circular 3mm diameter Mostly oak and elm (hardwoods) • WEEVIL 3-5mm long, brownish black. Distinctive long snout. All year around. Flight holes, small ragged, 1mm diameter. Decayed softwood and hardwoods in damp conditions. Mostly found in below ground conditions.

Answer 23

* Asbestos * Calcium chlorides * Calcium silicate bricks * CFC’s * Formaldehyde * HAC (High Alumina Cement) * Hollow clay pot floors * Lead * Nickel sulphides

Answer 24

Used as a permanent shuttering. Formwork is used to contain concrete in order to mould it to the required dims and to support it until it can support itself. It may be left in place for the lifetime of the building.

Answer 25

* Concrete does not adequately get compacted. * Risk of poor cover to the steel and hence loss of durability, possible reduction in strength, and loss of fire resistance. * Voiding and honey combing due to vibrations. Poor bond or failed bond between the wood wool and the hardened concrete. * Buildings constructed from 1950 to the mid-1970s are most likely to be affected by this form of construction. * If permanent shuttering is discovered, intrusive investigations may be needed to determine the adequacy of concrete cover to the steel reinforcement. If voiding is present, the affected area can be exposed and repaired using hand-fixed concrete repair methods or, if over a larger area, sprayed concrete.

Answer 26

* Concrete Carbonation * HAC * Alkali Silica Reaction * Chloride Attack * Sulphate Attack

Answer 27

A generic term that is used to commonly describe the larva stage of wood boring beetles. A number of insects, mainly beetles, are able to use wood as a food source and some of them can cause serious damage to building timbers

Answer 28

* Spore * Hyphae * Mycelium * Fruiting Body

Answer 29

Occurs in glass production. Microscopic imperfections in the glass. When the glass is tempered, the nickel sulphide inclusions do not return to the normal low-temp state for several years and expands in the process which can cause cracks with no obvious cause.

Answer 30

* Chrysolite – most common asbestos in buildings. Corrugated asbestos cement sheets. * Amosite – found in fire retardant materials * Crocidolite – pipe insulation, plastics, cement products.

Answer 31

* Features include shrunken wood with cuboidal shapes. Cotton wool type mycelium on the surface. Timber crumbles under finger. Fruiting bodies are red/brown in colour and pancake shaped. * Identify the rot and where it is at its worst. Remove the cause and strengthen the joists as required or fully replace. If the dry rot has passed through the masonry, this will need sterilisation too.

Answer 32

When used as permanent shuttering for concrete, it may lead to grout loss, honeycombing or voids which can reduce fire resistance, corrosion protection and loss of strength. It is adequate for use in flat roof decking.

Answer 33

* Asbestos – Fiberous material used for a variety of reasons from roof sheets to insulation and fire stopping. It is carcinogenic and needs to be removed if there is a risk of release of fibres. * Lead – Risk of lead poisoning when used for pipes or paint. Contaminates drinking water and risk of inhalation of paint dust or potentially ingested when children chew on painted products. * Machine Made Mineral Fibres – Potential Carcinogenic. The evidence leads to show there is a high risk and should be treated as such but has not yet been proved. * Wood Wool Slabs – When used as permanent shuttering for concrete, it may lead to grout loss and inadequate coverage of steels which leads to inadequate fire protection. If used for roof decking, it is not considered deleterious. * Calcium Silicate Bricks – Shrinks after construction with further movement from wetting. Thermal movement more likely than with clay bricks. Construction details must allow for movement and if designed and used correctly, performs well. * High Alumina Cement – Gives high early strength and used in maritime buildings. Porosity is increased and resistance to chemical attack is reduced. Where water and chemicals are present in the mix, it can lead to the concrete becoming friable and lead to loss of strength.

Answer 34

Any material that is harmful to health, safety, environment, not suitable for their purpose or pose a risk for where it is used.

Answer 35

* Crazing - Surface crazing caused by lack of protection from UV exposure. No treatment is required if in small localised patches but should be monitored. * Ponding - If the gradient is not sufficient and there are dips in the roof finish, it can lead to pools of water. It can lead to water ingress if there is a gap in the roof finish. * Thermal Movement * Cracks and splits can occur when there is thermal movement between the substrate and membrane. Usually requires localised repair to the area around the crack. * Blistering - Caused when water vapour beneath the roof finish increases. The source of moisture should be traced and the blister opened and allowed to dry before patch repairing. * Flashing and Falls around openings- Defective lead from deterioration or poor workmanship around openings causing water ingress. Depending on the issue with the lead, there are different repairs. * People - Punctures caused by people from impact damage. * Cracks and tears along the line of joists - Caused by thermal movement or saturation of insulation or sagging decking. Repaired by cutting felt back and allowing it to dry before patching over."

Answer 36

As they are not protected with a DPM when they comes into contact with a water source they expand and can transfer this up into the slab above

Answer 37

That as a roof ages the fixings which are often iron nails start to fail resulting in tile or slate slippage especially in windy weather conditions. Replace existing iron nails with copper nails, these do not corrode.

Answer 38

- House Longhorn Beetle - only found in Surrey, Berkshire and Hampshire.

Answer 39

- Incorrect application of cement pointing: In solid wall buildings, if lime based mortar is replaced with cement mortar the mortar joints cannot release the interstitial moisture within the wall, it therefore is released through the brickwork which leads to spalling due to excess moisture release and makes the bricks more susceptible to freeze thaw as they have a higher moisture content. - Freeze thaw: Water absorbed through the porous surface of the bricks and then expands upon freezing. - Crystallisation of salts (cryptoflorescence): this occurs just below the surface of the bricks leading to spalling. Occurs from large build up of salts and usually occurs where older, weaker bricks are re-used inappropriately in areas of excess dampness (at ground level which is susceptible to splashback - should use engineering bricks).

Answer 40

Carbide meter: - Sample of mortar, plaster or brick taken and weighed. - Sample then placed in one chamber, a weighed amount of calcium carbide powder is placed in a separate chamber. - Container then shaken to allow mixing of two materials. The amount of acetylene gas produced indicates the amount of moisture present. - Pros: accurate. - Disadvantages: intrusive, more time consuming that protimeter. Moisture meter: - Measures level of conductivity, water has high conductivity so increases the reading when present. - Pros: Quick, non-intrusive (relatively). - Disadvantages: Calibrated for timber, can give false high readings from highly conductive materials such as salts, foil backed plasterboard and black ash mortar. Deep wall probe: - Essentially a long protimeter than can measure conductivity deeper within the wall.

Answer 41

- Dead load: load imposed by the structure itself. - Live load: load imposed by occupants and objects in a structure. - Environmental load: load imposed by rainfall, snow and wind.

Answer 42

- I actually recommended that some opening up works were conducted internally to determine the extent of the water ingress and extent of damage to the structural timber and roof deck. - After inspection it was apparent the entire roof deck was saturated and rotten in widespread areas and would require wholesale replacement. - As the existing reinforced bitumen felt roof covering showed widespread developed crazing and isolated blistering it was clear that it was at the end of its life and would therefore require replacement too. - I consulted the BRE Good Repair Guide - Flat Roofs: making repairs to bitumen felt and mastic asphalt roofs.

Answer 43

- Giant Hogweed. - Horse tail. - see conors slides.

Answer 44

- Property Care Association Code of Practice.

Answer 45

**_Dig and dump (excavation of the plant and roots)_** * JK infested soil excavated (up to 3m vertically and 7m horizontally from the area of growth), removed off site and disposed in an appropriately licenced waste management facility as it is classed as controlled waste under the Environmental Protection Act 1990. * **Benefits**: quick, no restrictions on site for development, works can continue on site immediately. * **Drawbacks:** Expensive (£70 per tonne), reduced valuable landfill capacity (should be last resort), increases risk of spread (disturbing the plant through excavation) **_On-site burial_** * Trench is excavated on the site in suitable location and JK then excavated and buried in the trench which will need to have at least 5m of overburden. Unless JK can be buried with 5m of overburden then a specialist root barrier membrane must be used to partly or full encapsulate the JK. Area is then monitored for at least two successive growth seasons and treated with herbicides if needed. * **Benefits:** More cost effective than dig and dump, works can continue immediately, quick to remove. * **Drawbacks:** Need suitable set aside area where the JK will not be disturbed, can't be used if water table is high (allows distribution of JK into waterways), if root barrier used it needs to be installed correctly as any weaknesses / tears can be exploited by JK, JK can be accidently spread during excavation. **_Herbicidal treatment_** * Herbicides applied to JK usually combined application of spraying and stem injection. * **Benefits:** Cost effective, can be carried out in situ (less risk of spread), quickly reduces spread and ability to impact structures, can be used on restricted sites that don't have a set aside area. * **Drawbacks:** JK remains in situ do could be disturbed and spread (particularly if works being carried out), not appropriate for sites where there is planned development (excavation), take several years to achieve complete eradication with two years of monitoring to ensure growth has ceased. **_Other options:_** * Biological control - testing being undertaken - still not used. * Screening / sifting - JK excavated along with soil which is then sifted to separate rhizomes which are disposed of appropriately, the soil is then screened and stored on site in a suitable location, treated with herbicide and monitored.

Answer 46

Cold roofs: - As the roof void is cold there can be issued with interstitial condensation as warm air from inside the building enters the unheated roof space allowing condensation to form on the timber roof joists and deck - this make them susceptible to rot and therefore structural failure eventually. Require vented 50mm gap between bottom of roof deck and top of insulation to try and prevent. - More complicated to construct - insulation between the joists rather than just on top of roof. - Greater chance of thermal bridging - ceiling joists are not insulated. - Benefit: as insulation is between joists there is no change to roof height - this could affect roof height relative to the parapet walls - may need to extent them etc Warm roofs: - Easier to install. - Can be retrofitted. - Less chance of thermal bridging. - Drawback - external roof height will be raised.

Answer 47

* It was clear to see that the roof covering had failed in numerous areas and water could be seen dripping through the underside of the roof deck. There was also staining and areas of plasterboard soffit that were saturated and had fallen in isolated areas. * Rising damp would have been localised to the walls and tide marks would have likely been present to a height of circa 1.3m with spoilt decorative finishes, staining and blown plaster below. * Condensation was present to the internal windows but I believe this was a result of the building being unheated, unventilated and having excess water vapour from the penetrating damp.

Answer 48

* I advised my client that if the JK was not treated it could continue to spread and damage the adjacent hardstanding and security hut by exploiting structural weaknesses and causing cracking in addition to causing cracking of mains water and drainage pipework which I know were in close proximity to the infested area. * I also advised that the client that under the Wildlife and Countryside Act 1981 they were obligated to control its spread and prevent spread onto neighbouring properties. * I then considered the potential remedial options but recommended that herbicidal treatment should be utilised on the basis that the site had a high water table and no suitable area to dispose of the JK to allow on site burial and also that excavation should be used as a last resort, would be considerably more expensive and may lead to further spread of the JK. * I advised that the client that as JK had been identified, the client should instruct a JK contractor to map the entire site to confirm the extent of the growth and make sure there were no other areas of infestation. * I also advised that the client should ensure that they had a 10-year guarantee with the treatment to give comfort to the incoming tenant on a 10 year FRI-lease.

Answer 49

* Environmental matters, i.e. trees in close proximity * Neighbouring dwellings * Engineers structural survey * CCTV Drainage survey

Answer 50

* The staining and deterioration to the internal plasterboard / decorative finishes was patchy and concentrated in numerous areas along the length of the elevation. If it was rising damp I would expect to see a linear tide line around 1.3 m max height. * I was lucky that the second time that I visited the property there had been a sustained period of rainfall and I could see that the areas of staining observed previously had darken.

Answer 51

* **_Solid walls:_** leaking mortar joints (need to be raked out to a depth equivalent to their height and then repointed), masonry water repellent to less exposed elevations, defective jointing details around windows etc. * **_Cavity walls:_** Rarer but could have bridging of cavity by wall cavity ties sloping inwards (will see regular spots of ingress), bridging of the cavity wall by it being blocked above the DPC from mortar droppings and other debris, missing cavity trays.

Answer 52

* Carbonation * HAC * Sulphate attack * Regent's Street disease

Answer 53

**_Residential_** **Georgian** * Water ingress through parapet walls and valley gutter details. * Missing or poorly altered load-bearing timber partitions. * Failure of roof trusses * Poorly applied or painted stucco limiting water evaporation from walls * Rotten or stuck sash windows **Victorian** * Defective slates and nail sickness. * Deflection of roof timbers caused by installation of heavier concrete tiles (cheap). * Blocked air vents to suspended timber floors from removal or raising of external pavement level. * Lack of lateral support between terrace houses (known as the book end effect); joists run parallel with part walls. _Modular - Post Second World War_ * Use of asbestos sheets to roofs. * Corrosion of steel frames used. * Alkali Silica Reaction affecting concrete frames (gel **General housing (modern)** * Cracking and movement of walls due to timber frame being wet and then shrinking once dried out. * Heave / subsidence. **_Industrial_** * Impact damaged cladding. * Cut edge corrosion. * UV degraded roof lights. * Asbestos roof sheets. **_Office Buildings (60s-80s)_** * Hollow clay pot floors - can exhibit loss or strength due to honeycombing of the structural concrete ribs of the floor system which reduces structural integrity and fire stopping capabilities. Incorrect removal of topping screed if structural to gain floor height can lead to structural failure. * Wood wool cement board - WWCB is formed of softwood shavings which are coated and bounded by Portland cement. WWCB was commonly used as permanent shuttering in flat slab or ribbed reinforced concrete floors. There is risk of poor concrete cover to the steel structural members therefore reduces durability, structural integrity and fire resistance. If discovered the shuttering be removed to determine coverage and parch repairs undertaken by hand if necessary.

Answer 54

* Found in early 20th century load bearing steel framed buildings clad externally with stone, brick and terracotta that is notched around the steel frame and then the void filled with low grade mortar. Corrosion of the steel frame due to oxygen and moisture causes corrosion and expansion and with no void space causes cracking of the mortar and overlying cladding. * Can usually diagnose from cracks delineating the frame. * 2 main ways to rectify: 1. Exposing the steel, cleaning it and protecting it and then create a void around steel frame to allow movement. 2. Use cathodic protection: system relies on concealment of discrete anodes into the stone joints and electrical connection to the steel frame and the introduction of an electric current to reverse the corrosion process. Requires detailed design to ensure harmful currents arnt produced and maintenance.

Answer 55

**_Heave:_** * The upward movement of the ground beneath a building as a result of the soil expanding. * **Causes:** Tree removal (increase in soil moisture), frost heave, burst sub terrain water pipes. **_Subsidence:_** * The ground beneath a building sinks, pulling the property's foundations down with it. * **Causes:** Prolonged dry spells particularly with clay rich soils, trees drawing moisture and collapsed mines. **_Settlement_** * Downward movement due to compression of soil due to weight of building within 10 years from construction. * **Causes:** occurs after construction.

Answer 56

* Asbestos. * Concrete carbonation of the concrete frame. * HAC.

Answer 57

* Radon is a natural, colourless, odourless, radioactive gas formed by the radioactive decay of uranium that occurs naturally in rock and soil. * Exposure to particularly high levels of it may increase risk of developing lung cancer. * Some areas of the UK have higher concentrations due to geology and soils e.g Cornwall, Devon and Sommerset. * Radon can build up in some underfloor areas and enter a building. Youhttps://www.brainscape.com/l/dashboard/building-surveying-apc-19728728/decks/11173470/cards/376263225/edit can take some of the following steps: 1. A well installed damp proof membrane (radon barrier). 2. Air vents (with fans if needed). 3. Radon sumps. 4. There are others.

Answer 58

**_Type A:_** Basement tanking used internally or externally (applied during the construction process). Any defects to the membrane will have damaging consequences and those defects to external tanking systems will be impossible to rectify. Internal tanking systems can be penetrated by fixings and can be displaced by build up of hydrostatic pressure. **_Type B:_** Structurally integrated protection whereby waterproofing is provided by walls themselves (reinforced / prestressed concrete). Need to carefully consider jointing details as they can leak. **_Type C:_** Drained cavity system whereby water is allowed to pass through the external skin into the cavity and is then pumped away by an electric pump. Can be problematic when there is a high water table and failure of pumping system (usually due to accumulation of fine silts etc).

Answer 59

**_Subsidence cracking:_** Usually diagonal, runs through masonry and blockwork and usually wider at top than bottom. **_Heave cracking:_** Usually wider at base and as above. Appoint a structural engineer!

Answer 60

* Can pull more moisture of soil, particularly during dry seasons causing subsidence and then once removed can lead to excess moisture and heave of soils. * Roots dont usually directly affect buildings, they damaged water and drainage which then cause issues. * Oak and Poplar have strong root activity. * Safe building distances vary but good rule of thumb is to limit proximity of tree equivalent of that of its full maturity height.