wet area text -...

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©TAFE NSW Construction and Transport Division1

WET AREACONSTRUCTION

This text introduces subject matter related to the preparation and installation of wetareas and fitments.Reference may be made to “Basic Building and Construction Skills”, produced by TAFE and Addison, Wesley, Longman Australia Pty Limited, to re-examine andreinforce these basic skills.

The text addresses the preparation of wet areas ready to receive linings and theinstallation of fittings and fixtures. This includes the framing required for support andfixing of fittings and fixtures.

Focus is placed on the frame preparation to allow building-in of moulded bath/spaunits, pre-fabricated shower bases and sink/vanity installation.

Reference is made to the current Australian Standard for waterproofing internal wetareas.

Methods are outlined for determining wall lining material quantities and any associatedflashings.

A comprehensive ‘Glossary of Terms’ is included at the end of the text, which provides a detailed description of trade terms, technical content and some trade jargon.

WET AREA CONSTRUCTION


WET AREAS

Definition:

A wet area is any area within a residential structure, which will be affected by water usage.These areas include bathrooms, ensuites, laundries, kitchens, pool areas, photographic/hobbyroom, partly enclosed balconies, etc.

Wet areas must be designed and constructed to avoid water damage and/or penetration of theinterior linings and coverings. This is achieved by following procedures contained within theAustralian Standard 3740.

Australian Standard

The current Australian Standard applicable to wet areas is AS 3740 - 1994, which wasintroduced in 1989 by a standards committee for the industry to address poor waterproofingpractices. This standard is currently under review with an updated version due for publicationin 2002.

The standard sets out requirements for waterproofing internal wet areas and the preferredconstruction materials and methods to be adopted. It should also be noted that allmanufacturer’s requirements and recommendations be followed to ensure ultimate performance of their products, which in turn reduces the necessity of call-backs and rectification work.

Fig. 1 Typical residential wet area

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Wall Frame Preparation

Wall framing to wet areas may be of a steel or timber construction. Ideally where timberframing is selected, it is preferable to use well seasoned materials with section sizes as small aspossible to reduce the effects of shrinkage. One of the most common problems encountered inwet areas is as a result of material shrinkage or movement.

Stud spacings should not exceed 600 mm with a row of noggings placed in-line, not staggered,behind all horizontal sheet joins for full edge support.The studs may need to be checked out to a maximum depth of 20 mm to accept and support thelip of a bath or spa. This allows for wall linings to run down over the lip to provide adequateflashing.

The assembled frame should be rigid and not rely on the wall sheet lining fixing for strength.All internal and external wall stud connections should have a nest of three studs, which are wellfixed and blocked at 600 mm vertical centres. Alternatively, the internal corners may bereinforced with a metal 32 x 32 mm plasterer’s angle running from bottom to top plate.

Additional nogging fixing should be included in the following areas:

150 mm up from the floor around the base of a shower recess to provide sheet fixing and/or tray edge support;

Additional stud/s for shower screen fixing; Trimmer on flat for shower head support and shower tap bridle-piece mounting; Trimmers on flat for toilet cistern fixing and toilet control cock fixing; and Additional trimming/noggings, as required, for other fittings and fixtures such as a vanity

cabinet, towel rails, wall mounted heaters/dryers, shaving cabinets, paper holders, etc.

Fig. 2 Preparing the wall frames

600 c/c Max.

Top wall plate

Trimming studwhere required forshower screenfixing

Common studs

Noggings

Trimmer on flat toallow for fixing ofcistern

Trimming on flat toallow for support ofWC control cock,where requiredBottom wall plate

Additional trimmersto support showertray/flashing, asrequired

Additional trimmerson flat to support hot

and cold waterbridle piece

Additional trimmerto support showerhead, whererequired

Corner or end stud



Flashings and Sealants

Flashings

Perimeter flashings must be used at the floor/wall junction in all general wet areas and mustextend a minimum of 25 mm above the finished floor surface.

Alternatives

A PVC flashing 75 to 100 mm x 50 mm, similar to‘Viplas’, is adhered to the floor onlywith a two-part water-based resin, similar to‘Hardies HydrEpoxy 505’, which allows thewider upturn to move independently of the wall frame and linings.These angle flashings are available in 3.0 m lengths and should be lapped at all jointsaround the perimeter. It is preferable to cut the narrow side only at internal and externalcorners, which allows the wider upturn to be folded into the corner in a continuous form.

A 130 mm wide chlorosulphonated polyethylene flashing, similar to‘Hypalon’, may beadhesive fixed to the floor with a two-part water-based resin, similar to‘Hardies HydrEpoxy 505’.

A 150 mm wide fibreglass mat strip may also be used around the perimeter and over floorsheet joins sealed with compatible manufacturer’s approved sealing compounds.

The vertical internal shower recess corner/s may have a 32 x 32 mm metal plasterer’s angle fixed to the studs at 600 mm centres behind the wall linings or a 50 x 50 PVC anglemay be used as an alternative. In both cases the angle should extend into the shower trayor onto the pre-formed shower base and be at least 1800 mm high above the recess floor.

Sealants

Sealants may be used in a variety of situations for wet area applications:

Junctions between wall linings and floors; Around baths; Around taps if PVC aprons are not used; Cut outs and penetrations.

Suitable sealants should beflexible, similar to the siliconetypes, and specify their use suchas brick and concrete sealant,mould resistant tile sealant orother acrylic water resistantsealant.

Fig. 3 Typical tube of sealant

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Wet Area Lining Materials

Typically, wet area linings are either water-resistant plasterboard or fibre-cement sheeting.

Plasterboard (Main types available)

‘Boral Wet Area Plasterboard’ is manufactured with recessed edges for water resistantjointing in tiled areas and normal jointing beyond tiled areas. The board has face andback liners, which are resistant to moisture penetration as well as a moisture resistantgypsum core. The board is available in both 10 mm and 13 mm thicknesses. Sheetlengths range from 2400 mm to 4200 mm. The board is a distinctive green colour.

‘CSR Aquachek’ is a gypsum plasterboard with the core, face and back treated duringmanufacture to make it resistant to moisture and humidity. Available in both 10 mm and13 mm thickness, with 1200 mm wide sheets available in 2400 mm to 4200 mm lengthsand 1350 mm wide sheets available in 3600 mm and 4800 mm. The board is a blue-greycolour.

‘Lafarge Watershield’ plasterboard. Conforms to ASTM C630. Has a water resistantgypsum core and a specially treated heavy duty linerboard. The board is a bluishcolour.

Fibre-cement Sheet

‘Hardies Villaboard’ is manufactured to conform to Australian Standard AS2908.2 -1992 Cellulose - Cement Products.

Villaboard is composed of Portland cement, ground sand, cellulose fibre and water andmanufactured in three thicknesses, e.g. 6 mm, 9 mm and 12 mm.

The 6 mm board is commonly used as a tile substrate for internal walls. The thickersheets are recommended where there is a requirement for impact resistance. The 6 mmboard is available in the following sizes:

Mass:

6 mm Villaboard has an approx. mass of 8.5 kg/m2

Width mm Lengths mm

900 2400, 3600, 4200

1200 1800, 2100, 2400, 2700, 3000, 3600, 4200

1350 2400, 3000, 3600



‘CSR Fibre-cement Wallboard’ is an autoclaved, cellulose fibre reinforced cement sheet,which is immune to water damage and will not rot. It conforms to the requirements ofAS2908.2 -1992, ‘Cellulose-Cement Products Part 2: Flat Sheets’.

It is manufactured in 900 mm, 1200 mm and 1350 mm widths with lengths ranging from1800 mm to 4200 mm.

The sheet thickness is 6 mm and the mass is approximately 9 kg/m2.

Fibre-cement sheeting

Fibre cement sheeting is produced by two companies CSR and James Hardie.The following details provide a broad overview of cutting and installation methods.

Cutting

Cutting fibre-cement sheeting can be achieved in four different ways. The most traditionalmethod is to use the Hand Guillotine, as shown below. The guillotine produces clean, straightedges, while cutting on the off-cut side of the line to allow for thickness of the blade.

Fig. 4 Cutting along the line with a hand guillotine(‘Fibro cutters’)

Hand guillotine

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A more popular method now used is ascore and snap knife with a tungstentipped edge.

Score the face side of the sheet againsta straight edge. Score 4 to 5 times toabout ½ of the thickness.

Support the scored edge and snap thesheet upwards for a clean break.

Hardies have produced a third methodfor cutting using electrical poweredshears for both straight and curvedcuts.

Hand sawing can also be used forgeneral cutting but is best confined tosmall cuts as it is labour intensive andhard wearing.

Small rectangular or circular holes canbe achieved by drilling a series ofholes around the perimeter of the holeand tapping out the waste piece fromthe sheet face.

Fig. 5 Score, lift and snap

Fig. 6 Methods used to create holes

Tungsten-tippedscore & snap knife

Straight-edge

Drill holes aroundcircumference

Support edges,then punchthrough withhammer



Larger rectangular holes or openingsare formed by scoring around theperimeter of the opening, forming alarge hole in the centre as shownbelow.

Saw cut from the centre hole to thecorners of the opening, support theedges and snap away the off cuts.

Installation

Sheets should be fixedhorizontally across studs.

Only a single width sheets shouldbe placed vertically in a confinedspace.

Sheets should be fixed with nailsor screws only in tiled area. Donot fix with adhesive when thewalls are to be tiled.

Internal angles in a Villaboardsystem should be tied togetherwith a continuous metalplasterer’s angle fixed at 600 mm centres.

Fig. 7 Score, lift and snap

Fig. 8 Reinforce internal corners

Score betweencuts

Saw cut

Lift to snap

Straight-edge

Continuousgalvanisedmetal angle

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In shower recesses, or otherregularly wetted areas, cornersshould be flashed with Hardiesflash-strip.

The flashing strip must extendinto the shower tray. Metalexternal angles or paper tape mustnot be used.

CSR Wallboard in a showerrecess requires a 50 mm x 50 mmPVC angle in the internal cornerbefore sheeting.

Flashing should be installedaround the wall/floor junction innormal areas (when required byregulations). Flashing must beinstalled in shower recesssystems. Flashings should beepoxy glued to the floor only.

Sheets should be measured and cut to suit the wall sizes. Tap penetrations etc should becarefully located and cut out.

Fix sheets to framing allowing a 6 mm gap along the floor. Nail sheets at 200 mm c/c atsheet edges, ends, internals, externals and in the body of the sheet.

Fig. 9 Flash the internal corner

Fig. 10 Typical sheet fixing

Metal angle

Hypalonflashing

Fibre-cementsheeting

12 mm min.

Fix 50 mm min. from edge ofsheet at corners

600 mm max. c/c

Noggings must be fixed ina straight line behindhorizontal sheet joints12 mm min.

200 mmmax.

Butt joint

200 mmmax.

200 mmmax.

6 mmgap

Bearers Compressed fibre-cement floorsheeting



BATH INSTALLATION

Types of Baths and Spas

Most baths and/or spas are manufactured with a fall in the base and a moulded lip around thetop to provide a finish and a flashing.The closed side/s are normally recessed into the wall frame to allow the wall lining to pass overthe raised lip. This in turn provides a horizontal barrier to water and therefore prevents passageof the water into the wall cavity. As they are permanently built into the structure they areclassed as‘Fixtures’, as opposed to‘Fittings’, which have fixings and may be easily removed.

Common materials used for their construction include:

Moulded fibreglass or acrylic; Pressed metal with a baked enamel surface; Stainless steel; and/or Cast iron with a baked enamel finish.

Pressed metal baths and spas need to be supported around the perimeter only, whereasfibreglass/acrylic baths and spas need perimeter and base support. Most fibreglass/acrylic spasare manufactured with a steel tube cradle for permanent support under the shell. The base isusually packed with a dry sand/cement mix to provide a solid platform for load strength.

Handling/Protection

The surface of these fixtures is easily damaged, therefore the utmost care must be taken afterinstallation to prevent chipping, scratching or cracking, which would lead to an expensiverepair or replacement.There are some patent type repair kits available for cracked or chipped fibreglass/acrylic types,which are quite successful, however enamelled touch-ups rarely work as well. Some companiesoffer a complete enamel surface re-coat, in-situ.

The best practice is to avoid damagein the first place by completelycover the unit with plastic,cardboard or a sheet of ply andavoid standing in the base duringfinishing work.

Keep gritty materials, such as sand,off the surface at all costs.

Fig. 11 Providing temporary protection

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Preparing the Wall Frames

The height of the bath is the most critical position in relation to the size of the tiles. Therefore,once the size of the wall tiles is determined the bath lip may be located on the side walls.

Note: Most bathroom wall tiles are150 mm square and the depth of theaverage bath/spa is around 450 mmor approximately 3 tiles high underthe perimeter lip.

Set out the height of the bath lipallowing the bottom edge of the 4thcourse of tiles to sit over the beadonto the step in the rim.

Where the tiles on the support sidemust align with the main wall tiles,the wall height should be determinedby working down from a full tile fittedonto the flat section of the bath lip.This will ensure horizontal tile jointcontinuity around the bathroom andallow the cut tile edge on the supportwall top course to be hidden underthe rim of the bath.

Fig. 12 Setting the height of the bath

Top and bottom platesare out of 35 mmmaterial

35

2

150

150

150

22

491



Supporting the Rim on the Closed Side

It is preferable to have continuous edge support where the bath lip is recessed into the studwall. Also, the bottom edge of the wall lining needs continuous support between the studs.

The simplest method of achieving this is to recess timber battens, one above and one below thelip, flush with the wall frame to a depth of 20 mm. This will allow the bath edge to slide intothe wall and allow the wall lining to pass over the lip to provide a flashing.

The batten on top provides support and fixing for the length of the sheet between studs.

An alternative method is to cut and fix noggings between the studs, as shown below:

Fig. 13 Method 1

Fig. 14 Method 2

Nogging ortrimmer

5 - 15 mmflexible sealant

3 - 5 mmflexiblesealant

Continuoussupporttrimmer

Water resistant walllining

Wall tiles

Continuous topribbon batten forfixing and support

Water resistant walllining

Wall tiles

5 - 15 mmflexible sealant

3 - 5 mmflexiblesealant

Continuousbottom ribbonbatten forsupport

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Supporting the Rim on the Open Side

Supporting frames for the open sides of the bath/spa are usually constructed from seasonedtimber.Note: Treated pine is not necessary, provided the correct amount of ventilation is provided asper AS/NZS 2023 - 1995.

Alternative materials may also be used such as brickwork and‘Hebel’ block.Which ever materials are used, the structure must be rigid to prevent movement during use.Any movement may lead to bath/spa damage and tile damage to the perimeter.

Common Timber Framing methods

Method:

STEP 1 Determine the overall size of the frames by plumbing down the outside edge of thebath lip on all open sides.

STEP 2 Measure in from these marks a distance equal to the thickness of the rim, plus thethickness of the wall tiles, plus the thickness of the wall lining, e.g.

3 + 10 + 6 = 19 mm

STEP 3 Measure the overall width and length of the frames.Measure the height from the floor surface to the underside of flat support section of thebath rim.Now construct the frames with stud spacings at Max. 450 mm centres.

Note: The top plate should be placed on edge to allow a clear fit under the rim.

Fig. 15 Supporting the open side



The two methods shown below are used to support the open side of the rim when:

The rim sits onto a tiled hob section; or The tiles fit under the rim.

Fig. 17 Tiles finish up under the rim

Fig. 16 Rim resting on a tiled hob

Flexible beddingand sealant

Bath lip ontotiled hob

Tile corner trim

Waterproofwall lining

Tiled supportwall

Floor tiles andmortar bed

70 mm supportwall framing

Support battenunder bath lip

Flexible beddingand sealant

Bath lip overface of tiledsupport wall

Waterproofwall lining

Tiled supportwall

Floor tiles andmortar bed

70 mm timber supportwall framing

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Providing Adequate Ventilation

Once the frames are complete and sheeted with Villaboard, prepare at least two openings totake tile bath vents to allow sufficient ventilation under the bath to dry out any trapped conden-sation. AS/NZS 2023 - 1995 states, “Every enclosed air space under a bath should be pro-vided with ventilation openings having an aggregate clear area of not less than 5000 mm²”.

Note: Where spas are used, access to the pump may be from outside, therefore the access panel may bea permanently vented metal plate, which will provide the necessary ventilation. This negates the needfor vents internally.

Fig. 18 Fitting vents under the bath

150

75



Baths and Bath Framing

The details below outline a typical bath profile and the completed framing required to supportthis type:

Fig. 19 Typical bath detail

Fig. 20 Completed bath framing

PLAN

ELEVATIONEND ELEVATION

Nogging/trimmer forwall lining supportand fixing

Support battenunder bath lip

Notch forbath lip

Open-sideframing

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Hobs and Hob Walls

Hobs are generally raised or flat tiled sections at one or both ends of a bath. The main purposeof a hob is to close off the area left between the length of the bath and the walls.A raised hob is usually formed between the end of the bath and a shower to provide closurebetween them. It may also be used to fix the side panel of a glass shower screen and/or tomount the taps for the bath.

Set Out / Construction

Fig. 21 Flat hob end Fig. 22 Raised hob wall

The height of a raised hob wall should be setout to suit full wall tiles. The raised sectionof the hob wall is usually one tile courseabove the bath to provide a flashing and afinish between bath and shower.

A gauge rod is used to set the height of thewall to allow full tiles from finished floor tothe top edge. This rod is also used to set theheight of the bath, so the top of the bath willwork full tiles.The hob wall may be constructed fromtimber framing and lined with Villaboard,similar to the support side of the bath, or itmay be of masonry. Brick, concrete blockand Hebel block are suitable materials.

Note: The width of the hob wall should also be set

out to suit full tiles where possible, howeverthis is usually determined by the width of thebath.

Timber must not be used for shower recesshobs.

Fig. 23 Set height using a gauge rod

Bath

Raised hob wall

Gauge rod setout to top oftile courses

Finishedtiled floor

Finished showerrecess floor

Shower screen



SHOWER BASE INSTALLATION

A shower base may be described as:“A pre-formed, pre-finished vessel, which is installed as the finished floor of a showercompartment and which is provided with a connection point to an approved sanitary drainagesystem.”(reference AS 3740)

Fig. 24 Critical measurements

The internal corner where the shower recess areais to be formed must be prepared prior to the wallframes being erected. Valuable time is wasted,tools are readily damaged and the task is mademore difficult if the frames are modified aftererection.

STEP 1 Mark the height of the base from thebottom of the wall plate, plus anadditional 15 mm to allow forinstallation and bedding on a sand/cement ballast.

STEP 2 Mark the thickness of the lip in fromthe face of the stud.

STEP 3 Cut out the waste from the studs and ripthe plates, to form the recess.

STEP 4 Cut and fix noggings between studsaround the top of the base to providewall sheet fixing.

Fig. 25 Critical measurements

A shower base may be used as analternative to a shower tray, orwaterproof liner, which is tiled on asand/cement bed with a fall to thewaste.The pre-formed shower base may bemanufactured from: Pressed metal with a baked

enamel finish; Polymarble/Acrylic; Concrete; or Stainless steel.

Before installation, the shower baseshould be checked for size to allowaccurate positioning for the wasteconnection and check out depth forwall frames.

Prepare Wall Frames

To allow base lip to fitbehind face of stud

Height of base plusclearance for mortarbedding

(915 x 915preformed

base)

Check length

Check width

PLAN

Check position ofwaste outlet

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Positioning the Base

Concrete Slab

Care should be taken to accurately position the shower base in the wall frames to ensure thewaste pipe will drop into the sewer pipe cast into the slab. A 100 mm diameter cap with anopening to take the shower base waste pipe is placed over the sewer pipe end and rotated toensure alignment.

Note: It is critical that the drainage is accurately placed prior to slab placement, as modifyingthe position with elbows and offsets later is very time consuming and costly.

Timber Platform Flooring

The advantage of a suspended timber floor allows the drainage to be easily fitted under the baseafter the base is installed, or the drainage is more easily modified if inaccurately positionedbefore base installation.To locate the opening in the floor for the base, before bedding the base, place the base in itsfinal position and mark the centre of the floor waste through the hole in the base.Once the preparation is complete, the shower base may now be installed on a bed of sand/cement ballast to allow for levelling and full support for the internal area of the base.The walls are now ready for lining, as shown below: (Note: plumbing has been omitted)

Fig. 26 Base bedded into position



INSTALLATION of SINK/VANITY UNITS

Wet area fitments include the following:

Laundry tubs; Bathroom/Ensuite vanity units; Bathroom/Ensuite wall cabinets; Laundry benches; and Laundry cabinets.

Many plans come with a bathroom or wet area layout plan for fitments. The size of the units,position within the room and the finished height of bench tops is usually noted on these details.These details are useful for the preparation of wall frames so additional studs, noggings and/orfixing blocks may be positioned for future fixing.

Fig. 27 Wet area fitment details

VIEW 1 VIEW 2 VIEW 3

VIEW 4

PLAN of Bathroom and Ensuite

BATHROOM

ENSUITE

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Installing Vanities and Benches

Normally bathroom vanities and laundry benches are installed after the floors are tiled.A levelled base or plinth is fastened to the tiles to provide a sound level surface for the vanitycarcass to sit on. Some vanities are constructed with the plinth as part of the cabinet.The water resistant kickboard facing lifts the carcass off the floor and away from contact withsurface water. It is normally set at 75 to 150 mm high.

The vertical face of the carcass is checked for plumb and the top checked for level in bothdirections. The back is fastened to the wall through a batten at the top and the base is fixeddown to the plinth. Screws are used to hold the vanity tightly into place.

Fig. 28 Installing the vanity and checking for position

Unit checked for level

Unit checked for plumb

Screw fixing to plinth

Screw fixingthrough batten



Once the carcass has beenplumbed and levelled, theback rail of the cabinet isscrew fixed to the stud wall.

It is advisable to use at leasttwo fixings in the length ofthe rail, to provide solid andstable attachment.

The bottom rail, if present, isalso screwed to the stud wallor the base of the cabinetmay be screwed to the solidplinth underneath.

Fig. 29 Fixing the rail to the stud wall

If the vanity top does not have abuilt-in or moulded upturn at theback, to prevent water passingbehind the cabinet, then a flashingshould be installed.

The flashing may be in the form of: An ’L-shaped’ non-corrosive

metal or plastic flashing stripfitted to the wall on top of thecabinet fixing rail, before thetop is secured;

An ’L-shaped’ non-corrosivemetal or plastic flashing stripcut into the back edge of thetop, before the top is fitted; or

A full length bead of flexiblewaterproof sealant appliedbetween the fitted top and thewall lining.

Fig. 30 Typical flashing methods

Sealant between walland fixing batten

‘L-shaped’ flashing let into back edge of top

Sealant between walltiles and top

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Fig. 31 Vanity with splashback - Flashed during assembly

Fig. 32 Moulded top vanity with built-in upturn - no additional flashing required



Fasteners

Fixing to Timber Frames

Standard countersunk wood screws aresuitable for general carcass fixing,however particleboard screws may be usedfor additional holding power or whenattaching particleboard tops to the carcass.Round head screws and cup washers maybe used where the fixings are exposed.Due to loads imposed by wall-mountedfixtures the diameter or gauge of thescrews should be at least 8 to 10 gauge toprevent shear. The screws should penetratethe timber frame by at least 30 mm toresist pulling out.

Note:Toggle bolts may be used for fixingthrough wall sheeting for light loads.

Fig. 33 Suitable screw fixings

Fixing to Steel Frames

Steel wall frames require special fasteners,which are capable of drilling and tapping inone go.Suitable fasteners for this application wouldbe ‘Wing-tek’ screws, commonly used for general steel frame construction andconnection.

Fig. 34 Wing-tek screw fixings

Fixing to Masonry Walls

For light fixing, a plastic ‘Star plug’ and fully threaded screw would be suitable.

For heavy duty fixing where loads areexpected to be great, a masonry anchorwould be suitable.

Fig. 35 Star plug and screw Fig. 36 Masonry anchor

Countersunk head Raised head

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Installing Laundry Cabinets/tubs

Most laundry cabinets, with a 45 to 60 litre top mounted stainless steel tub, are made of metalfinished with a baked enamel or powder-coated surface. (plastic cabinets are also available)

They have metal rails, top and bottom, at the back to allow the cabinet to be screw fixed to thewall and the tub is fitted after.

The stainless steel tubs have an upturn along the back edge, approximately 15 mm high, whichis also screw-fixed to the wall. The wall tile splashback is then laid over the top to form awaterproof joint, which prevents water running down the back.

Note: Where tubs are fitted to an internal corner of the laundry, a flexible waterproof sealantshould be run between the tub and wall before the splashback is laid.

Fig. 37 Typical laundry tub installed to a corner



Water Damage, Decay and Fungal Growth

Water damage may occur due to poor flashing practices, poor ventilation or using materials,which don’t provide adequate resistance to water penetration.The result of this water penetration may be:

Timber decay in wall framing; Timber decay in floor framing; Fungal damage to surrounding materials; Swelling of manufactured boards such as particleboard; Musty odours from enclosed spaces; Damage or staining to fitments.

Fungal Growth

Timber decay is caused by fungal growth feeding on the lignin and cellulose, which makes upthe bulk of the timber’s structure.To exist the fungi will require suitable conditions, as follows:

A food source, such as timber; Water or a high moisture content, i.e. above 18%; and Oxygen.

The fungi, unlike plant forms, does not need light to exist therefore, dark moist places are verysuitable for it’s existence. Fungi produce fruiting bodies, which develop spores. These spores are dispersed and becomenew fungal growths having an appearance like a surface root system, known as mycelium.Most fungi or ‘rot’ require high levels of moisture, at least 18% to start, however there is one species, Sepula lacrymans(commonly called ‘Dry rot fungi’), which requires only humid conditions to survive.

(refer to Building Materials and Hand Tools for more details relating to Fungi)

Fig. 38 Typical result of leakage from a poorly flashed fitment

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GLOSSARY OF TERMS

Carcass -The main body or frame of a cupboard or vanity. Consists of the sides,back and base.

Fittings -These include any item in a wet area, which may be easily removed.They normally are fixed to the wall surface with screws.

Fixtures -These include any item in a wet area, which is built-in or permanentlyfixed into place and not designed for easy removal.

Hebel -This is a lightweight, autoclaved, aerated sand/cement product, whichincludes aluminium paste reacting with water to form a gas and createtrapped air bubbles in the finished product. Used in wet areas in blockform under baths to support sides.

Hob -A raised, narrow section of wall forming a partition between fitmentssuch as a bath and a shower recess or as a raised edge across the front ofa shower recess to keep water in.

Hypalon -A trade name for a chlorosulphonated polyethylene flexible angle foruse up the vertical corner of a shower recess, behind the wall linings tocreate a waterproof seal.

Patent -This is a term used to describe a product which has had its designregistered with the Patents office. It is the original idea of a person orpersons, which cannot be copied without consent.

Polycarbonate -A plastic material, which is tough, flexible, waterproof, and resists thebreakdown effects of the suns UV rays. It is used for roof sheetingmaterial, as it is very durable and under most circumstances, hail proof.It may be formed into corrugated, ribbed or sandwich panel profiles.

PVC -Polyvinyl chloride. A plastic product commonly used for sewer pipeand fitting production.

Staggered -This refers to the placement of solid bridging, noggings, trimmers, etc.by offsetting every piece from the previous one, when placed in a row.

Viplas -A trade name for a PVC waterproofing angle product.

Wet area -Any area within a residential structure, which will be affected by waterusage.



FURTHER READING

Australian Standards Committee, 1994, AS 3740–Waterproofing of wet areas withinresidential buildings, Standards Association of Australia Homebush, Sydney.

Note: (also refer to 2002 update to this standard)

Boral and CSR manufacturer’s brochures for the installation of wall linings to wet areas.

Hadlington, P., and John Gerozisis, 1995, Urban Pest Control in Australia, NSW UniversityPress, Kensington, NSW, Australia.

Teachers of Building, 1996 Reprinted 1997, 1998, Second Edition 1999, Basic Building andConstruction Skills, Addison Wesley Longman Australia Pty Ltd, South Melbourne.

Ward-Harvey K., 1984, Fundamental Building Materials, Sakoga Pty Ltd, Mosman NSW.

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