Materials Used In The Building


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1.Roofing slates:


---Asbestos cement slate


Appearance similar to natural slate therefore has advantage as cheap replacement for this material. Non-combustible.


---Glass reinforced cement


Appearance similar to natural slate therefore has advantage as cheap replacement for this material. Testing indicates durability will be comparable with asbestos cement. Non-combustible.


Requirements:


Waterproof over lapping roof covering. Durable, impervious, rot and frost resistant. Must be resistant to ignition from fire exterior to the building.


2.Troughed sheeting;


---Asbestos cement


Good long-term durability. Limited colour range. Strength may be poor. Non-combustible.


---Calcium silicate with various non-asbestos fibers


Recent development as replacement for asbestos cement. Long-term durability claimed to be comparable. Similar performance. Good fire properties. Some varieties. Non-combustible.


Requirements:


Generally applied to side part of the building. Durable, imperious, rot, frost resistant material. Must permit site drilling for fixing and be compatible with fixing and sealants. Good fire properties.


3.Eaves soffit:


---Plywood


Should be exterior, decoration required for protection, easy to cut and fit.


---Softwood


Made up from single board or T&G boarding for wider soffit configuration. Decoration required for protection. Easy to cut and fit.


---Calcium silicate board


Good workability characteristics and fire properties. Some are non-combustible. Board quality determines performance so selective.


Requirements:


Close off space at eaves between fascia and top of external wall. Span between and nail fix to rafers at normal space, 400-600mm centers, without excessive shrinkage or sag.


4.Verge of the roof:


---Softwood


Made up from single board or T&G boarding for wider soffit configuration. Decoration required for protection. Easy to cut and fix. Only suitable for over-hanging verge details where protected from weather. Must be decorated for protection.


---Glass reinforced cement board


Good workability characteristics and fire properties. Board quality is selective.


Requirements:


Board material to provide neat joint at junction of roof and gable wall. Water and rot-roof, frost resistant material required. Over-hanging verge detail requires nail ability for fixing. Flush verge detail shown requires key with mortar.


5.Rainwater pipes:


---Unplasticized polyvingyl-chloride


Lightweight easily worked material. Wide range of proprietary system now available. Improved products now appear to offer adequate durability. Painting not required.


---Aluminium


Durable lightweight material. Normally available only though specialist fixers. Seamless pattern. Painting not required.


Requirements:


Pipes must span recommended bracket spacing, provide easy jointing and cutting permit decoration if required. Jointing system must cope with thermal movements.


6.Gutters:


---Timber


Regular painting required to ensure durability. Timber should be vacuum impregnated with preservative. With support loads from ladder.


Requirements;


Gutters must span recommended bracket spacing. Ability to support ladder during maintenance an advantage as is resistance to impact at base of down-pipe. Must be compatible with most building materials.


7.Flashing:


---Lead


In many ways the idea material combining good malleability and workability with excellent proven durability.


---Aluminium


Malleable grades of aluminium alloy now available. Care needed in selection of quality of aluminium as it can be attacked by water run-off from cementitious material. Electrolytic action possible in polluted atmospheres, particularly when in contact with ferrous metals.


Requirements:


Impervious material to close off gaps at junctions of roof covering. Malleability a big advantage but non-malleability can be offset to some extent by the availability of a range of performed sections. Must accommodate movements in the roof. Flashing should not detract from the main roof covering or cause unsightly staining.


8.Roof insulation


---Minerai wool quilt


Non-combustible. Material compacts overtime thereby reducing insulation value.


---Cellulose fibre


Must have insecticidal and fungicidal protection for long-term durability. Combustible. Available with various fire properties.


Requirements:


Rot-proof insulation for laying over ceiling between joists to provide overall minimum roof value. Water resistance and non-combustibility an advantage. Must be dimensionally stable.


9.Cavity wall insulation:


---Polystyrene bead-board


Combustible, but protected by wall. Available with various fire properties.


---Polyisocy-anurate board


Offers slightly higher standard of insulation for equivalent thickness to other materials. Waterproof material. Combustible, but protected by wall. Available with various fire properties.


Requirements:


Rot resistant insulating material which combined with other wall materials must give a minimum temperature. Material to be water resistant, not encourage moisture penetration. Compatibility with masonry materials and mortar essential. Must not cause premature corrosion of wall ties.


10.Roofing felt:


---Textile fibre base


Very poor durability, not used for roofs of good quality.


---Glass fibre base


Fibre base is not proof giving improved durability. Not suitable for mechanical anchorage to deck.


---Asbestos fibre base


Fibre base is not proof. Main advantage is improved resistance to flame penetration, but this requirement can be achieved by other types using mineral aggregate solar protection.


Requirements:


Water proof flexible material normally in 3 layer combinations set in hot bitumen compound. Durable,