Waterproofing is the process where objects became unaffected by water or resisting water passage, or which are covered with a material that resists or does not allow water passage. Water proofing is important to ensure that the building structure will not be destroyed by water leakage. All buildings and houses contain areas in which there will be the presence of water either as the result of washing or showering. Wet areas are those rooms which provide accommodation of water usage. The Australian Standard 3740 defines two degrees of wetness of such areas. These categories are as follows:
Category 1 – Areas like the shower compartments where there is a large amount of free water.
Category2 – Areas around fixtures such as baths, basins, sinks, toilets and laundry tubs.
Wet areas include bathroom, toilet, laundry and kitchen. The building code requires that these areas be lined with water resistant finishes and that the floors must be equipped with drainage to dispose of free water. The shower and bathrooms are critical areas to ensure that free water will not penetrate the building structure. Authorities have reported that the failure in water proofing is among the main problems of new home owners.
Most of the areas in houses have floors made up of concrete block on ground, suspended concrete floor block, suspended timber floors and with walls constructed of timber or steel studs sheeted in fibre cement or plasterboard. The most common lining materials are water resistant plasterboard (Aquachek, Watershield) and fibre cement sheeting (Villaboard). Water Resistant Plasterboard is similar to normal plasterboard except that its core is impregnated with a wax to inhibit the normally absorbent characteristic of plaster. Fibre Cement Sheeting is a cementaceous board reinforced with cellulose fibres. Both board types are manufactured with a recess along the long edge to allow them to be taped and set. The lining of wet areas with plasterboard should be carried out with the sheets laid horizontally. An exception to this rule is where the whole wall can be covered with a single sheet. Where the sheet is not to be tiled, water resistant plasterboard can be fixed using the normal combination of nails or screws and adhesive. Where the surface is to be tiled, adhesive fixing must not be used and the board must be fixed with nails or screws at 200crs and 150crs at butt joints. Screws are the industry preferred method of fixing. If the tiles are more than 6.5 mm thick, all mechanical fixings shall be at 100 mm centers.
Jointing shall be carried out with paper tape set in base-coat (2 coats). Areas not to be tiled are finished with one coat of top coat. Top coating under tiled areas is unsuitable because the surface can be raised providing an unsuitable surface for tiling. Also top coats are water soluble.
In lining, it is important to ensure that the appropriate noggins are provided in above sinks, baths and shower trays. Check also location of angles and skirtings
In fiber cements, sheeting shall be carried out horizontally in domestic construction. Vertical sheeting is use in some commercial work. Fixing shall be by screw or nail at 200crs. All joints shall be made with paper tape bedded in base coat (2 coats) under tiles. In having construction floors like concrete it is normal to leave a recess in the slab under shower trays or where the finished floor is laid so that it falls towards the floor waste. Suspended timber floors in wet areas are commonly surfaced with fully compressed. Fibre cement sheet must be 15mm thick for joists at 450crs and 18mm thick for joists at 600crs. The sheet is screw fixed at 450crs to all joists. Where sheets are jointed, the joint shall be bonded with Hydra Epoxy 501 applied to the edges to ensure complete bonding. Hydra Epoxy 501 is a two part, water based epoxy resin, mixed immediately prior to use.
If suspended blocks are constructed, the block design frequently does not allow for recesses and any shower trays or falling finishes will need to be accommodated above block level.
Australian Standard 3740 lay down where solid surfaces, flashings and membranes shall be installed in relation to showers, baths and wall-mounted fittings. The perimeter of all walls of a wet area shall have a flashing which extends 75 mm up the wall and 50mm across the floor.
If showers are constructed into or adjacent to a corner, a flashing shall be installed from the membrane to a height of 1800. The flashing shall extend 40mm each side of the corner for external trays and 75mm for internal membranes.
If showers are enclosed, a solid surface shall be provided to a height of 1800 above the floor level within the shower enclosure. If showers are not enclosed, a solid surface shall extend 1500 (horizontally) from the furthest extension of the shower rose and to a height of 1800 above floor level. A water-proof membrane shall be provided over the floor area of an enclosed shower and extending 75 above finished floor level. A water-proof membrane shall be provided over the floor area and 1500 (horizontally) from the furthest extension of the shower rose and extending 75mm above finished floor level. Baths, basins, tubs or other vessels fixed to a wall shall have a waterproof flashing or membrane applied to 150 above the vessel.
The definition of a solid surface in Australian Standards 3740 is satisfied by the application of ceramic tiles, fixed with approve waterproof tile cement over fibre cement sheet or water resistant plasterboard. Tiles should be finished with an approved waterproof grout.
Perimeter flashing can include pre-formed PVC fibreglass reinforced plastic (FRP), corrosion resistant metal or flexible synthetic material such as Hyperlon. The angle can be formed on site from fibreglass reinforced plastic, epoxy resin or acrylic emulsion.
References
1. Australian National Training Authority, Wateproofing to Wet Areas [Online] Available at: http://www.atpl.net.au/sample/pdf/atpsample_1552.pdf [Accessed 23 Feb 2010]
2. Lafarge Plasterboards, Wet Areas Using plaster Boards [Online] Available at: http://www.lafargeplasterboard.com.au/systems/wet-areas.php [Accessed 23 Feb 2010]
Credit:ivythesis.typepad.com
0 comments:
Post a Comment