What should I look for?

We look at risk areas and how to identify if your home or a home you are thinking of buying is at risk of being a leaky building.

What should I look for?

Certain design or installation practices contribute to leaky buildings. We look at factors common to all types of cladding, and others specific to particular cladding systems.
The claddings prone to cause leaky building problems are:

• Stucco.
• EIFS (Exterior Insulation and Finish System).
• Texture coated fibre-cement.

Leaky buildings are not caused because these cladding types are unsatisfactory, but these claddings are often found on leaky buildings and have sometimes been detailed, fitted or finished poorly.

Factors common to all cladding types

The following factors are common to stucco, EIFS and texture coated fibre cement. How they are addressed may be slightly different according to the cladding. If you think you have a leaky home, you should seek professional advice before making any major repairs. See what to do if you have a leaky home for more information.

Intersecting roofs that direct water behind the cladding
Check where the apron flashing terminates within a wall surface that the end is stop-ended, to divert water into the gutter, and not allowed to flow behind the cladding at this point. A sealant joint at this point is not satisfactory.

Where the roof ends within a wall a kick-out flashing is required (Photo:BRANZ Ltd)

Poor maintenance of paint coatings
The waterproof coating must be maintained in very good condition, and will require re-coating long before it loses its decorative appearance. All of these cladding types rely on the waterproof coating to protect the non-waterproof substrate. Paint coatings will weather and wear, often requiring recoating in the most exposed areas at least every five years. Wear and stress failure is likely to occur in corners and at sharp exposed edges. Also check the body of the wall for narrow cracks causing breaks in the waterproof coating. The remainder of the coating in general wall areas may appear in good condition, but if signs of hairline cracking or thin areas are noticed, repainting is the only option.

Gaps in waterproof coatings behind spoutings or other fixtures attached to the cladding
Any fixtures (such as facings, fascias or light fittings) must not be attached to the cladding before the waterproof coating has been completed. The cladding relies on the waterproof coating being continuous and gaps can cause leaks to occur.

Penetration of the cladding by spoutings and fascias
It is important that the spouting or fascia was not fitted before the cladding was completed. If the spouting and cladding are fitted first and the polystyrene is merely plastered around the spouting or flashing, water will enter behind the polystyrene. If spouting disappears into the cladding, it should be removed, the cladding completed and the spouting shortened and refitted.

Adding decorative elements that penetrate the cladding can cause leaking (Photo:BRANZ Ltd)

Claddings penetrated by fixings or decorations allowing water to enter
Fixings through the waterproof coating and cladding need protection such as neoprene gaskets. Pipe penetrations need a sleeve and a formed sealant joint (not just sealant smeared on the surface) to prevent water getting behind the EIFS. Pergolas or decorative timbers attached to the timber frame penetrating the EIFS need waterproof protection otherwise they will track water along their top surface and into the house interior.

No step down at doorways/decks
In addition to providing clearance for claddings it is important that rainwater cannot back up and enter at doorways. Even at entranceways with a verandah there must be an adequate fall away from the doorway to remove rainwater and avoid flooding. Enclosed decks without a roof require a 100mm step at the doorway. Provision must be made for splashing from the deck surface and if an outlet becomes blocked, water must not enter under the sill to the interior.

Insufficient height to flashings where roofs or decks join. The Acceptable Solution E2/AS1 requires an upstand behind flashings of:

• 35mm over windows.
• 75mm behind claddings where they meet a roof.
• 115mm behind the cladding over a waterproof deck.

Leaks can occur where these minimums have not been met. For EIFS it is very important that the cladding does not wick water up through the cladding to the interior.  The solution to leaks at these points is to remove sufficient cladding and fit a flashing with sufficient height. Smearing sealant to the junction is not a satisfactory solution.

Reliance on sealant for waterproofing
A formed sealant joint made to a prepared gap can provide a good weathertight joint (e.g. movement control joint) and may continue to work well for 10-15 years. Such joints still need to be checked annually to ensure that the sealant is still securely attached to each surface and remains flexible. Sealant joints will deteriorate in the sun and must be able to be inspected and preferably protected from sunlight. Joints formed by smearing sealant over or into a gap or failed joint will not last well.

They are unable to flex as correct movement control joints are designed to. They are likely to separate from the surface of the material they are attached to. They can then attract quite large amounts of water because of the narrow gap formed and capillary action that will draw water in. As a primary means of weatherproofing they should not be relied upon.

Insufficient clearance of cladding to the ground or over a deck or roof surface

The wall cladding has been finished down to the deck surface and is soaking up water (Photo:BRANZ Ltd)

Acceptable Solution E2/AS1 requires any cladding to be 100mm above a paved surface and 175mm above grass, garden or other non-paved surfaces. Over decks, flat roofs or any other sloping roof, there must be a 35mm clearance from the bottom of the cladding. If this gap is not maintained then water can splash up the cladding. Where the cladding touches the ground or roof surface moisture can wick up behind and through the cladding and reach the framing. The solution is to either lower the ground surface or cut the cladding to ensure there is clearance. Ensure there is a 50mm overlap to any framing at the base of the wall.

Problems specific to stucco

Insufficient movement control joints
Movement control joints prevent the cladding cracking when it expands or contracts due to natural moisture or heat variations. For stucco no continuous wall area should be greater than 10m2. Wall surface areas greater than this will place stress on the stucco cladding. Movement control joints should also be formed:

Position of movement control joints

• Vertically at the side of openings such as windows or doors.
• At each floor level.
• At not more than 4m centres vertically or horizontally to break up large expanses of wall that are smaller than 10m2.
• At changes in the height of the wall area.
• At any point where natural flexing of the structure may occur, such as at the top plate level of a gable wall or where a cantilevered deck is attached to the building.

You can recognise a movement control joint as a straight horizontal or vertical join either in the wall’s surface, alongside a window or doorway, or where the wall changes height. It will be a formed sealant join, or may look like a deliberately made straight-line crack in the wall surface.

Insufficient movement control joints will always cause stucco to crack. The solution in extreme cases is to remove the plaster and install control joints when re-plastering. Where the cracking is confined to one area only, control joints can be cut into the plaster and cracked areas repaired. Seek professional advice from a building consultant before carrying out this work.
 
Inadequate curing of plaster coats
Allowing the plaster coat to dry out too quickly causes it to shrink before reaching full strength, leading to random cracking. The surface will appear crazed. This shrinking can break the surface of the

Random cracks in wall

waterproof coating and provide narrow cracks that will allow water to penetrate into the plaster and possibly into the structure.

Serious cases of random cracking will require the stripping of the plaster cladding and re-coating. In less serious cases the cracks can be raked out and patched. Hair-line cracks can be re-coated with a waterproof paint coating.

Parapets without cappings
No stucco cladding should have a parapet where the plaster is carried over the top of the parapet. Whether the plaster surface is sloped or flat, the plaster will allow water to get in and will crack at corners and junctions. The only solution to this problem is to provide a metal cap flashing, correctly installed and jointed.

Inappropriate waterproof coatings
Coatings to stucco must be waterproof. Cement or lime based coatings are not waterproof. The recommended coating is an acrylic paint, which allows the stucco to breathe, while excluding rainwater. High-build paints are not recommended as any water that gets in behind the cladding is trapped and cannot dry out.

Recessed windows allowing water to penetrate flat sills
It has been common to recess windows to create the impression of a ‘solid’ construction. Stucco used on a flat or near flat surface (as in B in the diagram) is not waterproof and will allow water to enter. A metal flashing should be used that extends over the sill and over the face of the cladding. It must have an upstand at A or a membrane flashing

Check point A for signs of cracking and ensure there is a full flashing under the sill at B

(synthetic rubber or uPVC) under the plaster coat. The plaster is prone to cracking at the corners and this detail is no longer allowed under the Acceptable Solution E2/AS1. If recessed sills have not been fitted with a flashing, or water is entering at the corner the stucco must be removed and the sill repaired.

Flashings missing from windows and doors
All windows and doors must have a system to keep water out. At the very minimum there must be a head flashing that extends up behind the cladding and slopes out over the aluminium window or door facing, extending past the end of the window or door by 20mm and lapping the aluminium by 10mm. If flashings are missing the only remedy is to cut out a section of stucco to allow flashing to be inserted.
 
Lack of additional reinforcing mesh at corners of windows and doors
Where stucco is finished around a window or door, stress builds up at the corner. A movement control joint is usually inserted at this point to relieve this stress, or additional mesh or netting reinforcement is provided. If the mesh has not been provided, a tell-tale crack is likely to occur, radiating out from the corner. The solution is to cut a movement control joint, or replace the stucco.

Junctions that crack

Saddle flashing required at A

Any place where there is a sudden change of direction, such as where a solid handrail meets a wall surface, (see diagram), cracking may occur. Saddle and cover flashings are essential at these junctions. You may not be aware that there is no flashing beneath the stucco until it fails.

Intersecting roofs that direct water behind claddings
Check where the apron flashing ends within a wall surface that this is stop-ended, to divert water into the gutter, and not allowed to flow behind the cladding at this point. A sealant joint at this point is not satisfactory.

Penetration of the cladding by spoutings and fascias
It is important that the spouting or fascia was not fitted before the cladding was completed. If the spouting and cladding are fitted first and the stucco is merely plastered around the spouting or flashing, water will enter behind the stucco. If spouting disappears into the stucco, it should be removed, the stucco completed and the spouting shortened and refitted.
 
Gaps in waterproof coatings behind spoutings or other fixtures attached to the cladding
Any fixtures (such as facings, fascias or light fittings) must not be attached to the cladding before the waterproof coating has been completed. The stucco relies on the waterproof coating being continuous and gaps can cause leaks to occur.

Stucco penetrated by fixings or decorations allowing water to enter

This pipe has not been flashed properly where is enters the wall (Photo:BRANZ Ltd)

Fixings through the stucco need protection such as neoprene gaskets. Pipe penetrations need a sleeve and a formed sealant joint (not just sealant smeared on the surface) to prevent water getting behind the stucco. Pergolas or decorative timbers attached to the timber frame penetrating the stucco need waterproof protection otherwise they will track water along their top surface and into the house interior.

No step down at doorways/decks
In addition to providing clearance for claddings it is important that rainwater cannot back up and enter at doorways. Even at entranceways with a verandah there must be an adequate fall away from the doorway to remove rainwater and avoid flooding. Enclosed decks without a roof require a 100mm step. Provision must be made for splashing from the deck surface and if an outlet becomes blocked, water must not enter under the sill to the interior.

Insufficient height to flashings where roofs or decks join
Acceptable Solution E2/AS1 requires an upstand behind flashings of:

• 35mm over windows.
• 75mm behind claddings where they meet a roof.
• 115mm behind the cladding over a waterproof deck.

Leaks can occur where these minimums have not been met. For stucco it is very important that the cladding does not wick water up through the cladding to the interior.  The solution to leaks at these points is to remove cladding and fit a flashing with sufficient height. Smearing sealant to the junction is not a satisfactory solution.

Reliance on sealant for waterproofing
A formed sealant joint made to a prepared gap can provide a good weathertight joint (e.g. movement control joint) and may continue to work well for 10-15 years. Such joints still need to be checked annually to ensure that the sealant is still securely attached to each surface and remains flexible. Sealant joints will deteriorate in the sun and must be able to be inspected and preferably protected from sunlight. Joints formed by smearing sealant over or into a gap or failed joint will not last well.

Such joints are unable to flex as correct movement control joints are designed to. They are likely to become detached from the surface of the material they were originally attached to. They can then siphon quite large amounts of water because of the narrow gap formed between the surface and the detached sealant and consequent capillary action that will draw water in. As a primary means of weatherproofing they should not be relied upon.

No drip edge at bottom of cladding
Horizontal surfaces of stucco that form the soffit above windows, at the bottom of walls or over flashings should not be formed flat. Water can track and be blown across these surfaces as it clings to the horizontal surface by surface tension. A groove (6mm wide and deep) set back from the edge or a sloping underside forming a sharp edge at the front surface will cause any water to drip off.

Problems specific to EIFS

Common problems with EIFS claddings and detailing include:

Insufficient movement control joints
Even though EIFS is able to absorb movement and the base coats have some flexibility, movement control joints are still required to prevent cracking. Proprietors of the specific system you use will stipulate how frequently movement control joints are required. They should also be provided:

• At each floor level.
• At junctions with other materials.
• At the junction between solid balustrades and the wall surface.
• Where EIFS continues over a change in foundations (e.g. concrete floor slab to timber piles).
• Where adjacent wall areas vary greatly in height.
• Next to lintels over garage doors, where the lintel supports an upper floor.

Using non-proprietary base coating systems
Extensive cracking will generally indicate that an incorrect base coating system has been used. The proprietors of EIFS systems specify very carefully which coating systems to use but there have been cases of alternatives being used by non-certified workers or to save money. Extensive cracking to the base coats will require the complete removal of the plaster coats and replacement with an appropriate plaster system.

Parapets without cappings
It is possible to construct a solid handrail without any flashing being visible on the outside. A flexible membrane can be inserted under the polystyrene sheets that will prevent any water entering the supporting timber structure. If doubts exist it may need to be established by checking the consent documents held by the council, asking the

The tops of the parapets must be sloped and incorporate a flashing

person who applied it or checking the timber structure for high moisture content. Of particular concern would be the junction of the handrail with the wall of the house.

Horizontal surfaces to parapets and handrails
The top of all handrails or parapets should be constructed with a slope of at least 15 degrees. This will drain water off the surface quickly, preventing water lying on the surface and increasing the risk of water entry. A shaped piece of polystyrene fitted over a membrane flashing can be used for this purpose, but must be installed by a professional.
 
Penetration of cappings by handrail fixings
If the top of a solid balustrade has been penetrated by fixings for a handrail, or by the handrail itself, it is very difficult to prevent water entering. In the new compliance document, E2/AS1 cappings are required and must not be penetrated through the top. Fixings for handrails and other accessories must always be through the vertical face of a wall or solid handrail. This will allow this junction to be sealed against water entry.
 
Inappropriate waterproof coatings
A waterproof paint coat must be applied to all monolithic claddings. Cement based coatings do not provide a waterproof coat. Coatings should be as recommended by the proprietor of the EIFS cladding system.

Recessed windows allowing water to penetrate on flat sills
Where EIFS has been correctly constructed to the proprietor’s details there will be uPVC flashings fitted at the head, jambs and sill. Where a deep recessed window has been constructed using the polystyrene sheet the plastic flashings may have not been fitted. The window will require re-fitting using the correct flashings.

Poorly fitted polystyrene sheet
Polystyrene sheets that have been fitted with gaps (proprietors allow only 3mm maximum gaps) will cause problems later. The base coats are likely to penetrate into these gaps and crack along the lines of the joint. These failures are easily identified as they will form straight cracks at sheet joints. Stripping the coatings back to the polystyrene, filling gaps with slivers of polystyrene and re-coating is the only long-term solution. Sheets not firmly fixed back to the framing are also likely to cause cracking.

Weathered polystyrene sheet
Prolonged exposure of the polystyrene to the weather prior to coating will cause oxidation of the surface of the sheet. This must be removed before applying the base coat or adhesion will be seriously weakened. This will show up later as de-lamination of the base and finish coats from the polystyrene surface.
 
Lack of additional reinforcing mesh
Polystyrene sheets can be joined above or below windows and doors or other openings, but strips of additional reinforcing mesh must be inserted to strengthen this joint against the stresses that will occur at the corners. Telltale cracking will not radiate from the corner but will tend to follow the joint line or may form a hairline crack in the corner of a window head or sill, allowing the entry of water.

Cracked junctions
Some junctions require a saddle or other flashing, either in metal or a waterproof membrane, as cracking almost inevitably occurs. One such junction is where a solid balustrade meets a wall surface. You may not be aware that there is no flashing until the cladding fails.

No drip edge at bottom of cladding
Horizontal surfaces of EIFS that form the soffit above windows, at the bottom of walls or over flashings should not be formed flat. Water can track and be blown across these surfaces as it clings to the horizontal surface by surface tension. A groove (6mm wide and deep) set back from the edge or a sloping underside forming a sharp edge at the front surface will cause any water to drip off.

Problems specific to texture coated fibre-cement

Common problems with texture coated fibre-cement claddings and detailing have included:

Insufficient movement control joints
Movement control joints are required to prevent cracking. Manufacturers of the specific system you use will stipulate how frequently movement control joints are required. They should also be provided:

• At each floor level.
• At junctions with other materials.
• At the junction between solid balustrades and the wall surface.
• Where adjacent wall areas vary greatly in height.
• Next to lintels over garage doors, where the lintel supports an upper floor.

Using non-proprietary jointing systems
Extensive cracking of joints generally indicates that incorrect jointing compounds have been used or have been poorly installed. The manufacturers of fibre-cement sheet specify very carefully the jointing systems to be used. Extensive cracking at joints will require the complete removal of all jointing compound and joints being reinstated.

Parapets without cappings
Texture coated fibre-cement is not a suitable cladding for the tops of handrails or parapets or any near flat surface. A metal cap flashing must be provided for all parapets and solid handrails clad with fibre-cement.

General parapet tops should be sloped and capped or otherwise protected against water entry (Photo:BRANZ Ltd)

Inappropriate waterproof coatings
A waterproof paint coat must be applied to all monolithic claddings. Cement based coatings do not provide a waterproof coat. Coatings should be those recommended by the manufacturer of the fibre-cement.

Lack of sealing of sheet edges or backs
Fibre-cement is absorbent so manufacturers recommend that the bottom edges and backs of sheets should be sealed to prevent moisture absorption. Unsealed sheets will allow water to be absorbed causing swelling, breakdown of flush joints or separation or bubbling of the waterproof coating. It is important to make sure the joints remain waterproof.

Sheets not cut to waste around openings
Fibre-cement sheets should not have joints above the edge of an opening, such as a window jamb. The sheets should be continuous around the corner of the opening with the joint 150-200mm in from the corner. Joints formed directly above or below an opening are likely to open up because of the stress caused at the corner. Failed joints should be cleaned out and re-formed.

Intersecting roofs that direct water behind the cladding
Check where the apron flashing terminates within a wall surface that the end is stop-ended, to divert water into the gutter, and not allowed to flow behind the cladding at this point. A sealant joint at this point is not satisfactory.

Gaps in waterproof coatings behind spoutings or other fixtures attached to the cladding
Any fixtures (such as facings, fascias or light fittings) must not be attached to the cladding before the waterproof coating has been completed. The fibre-cement relies on the waterproof coating to be continuous and gaps can cause leaks to occur.

Fibre-cement penetrated by fixings or decorations allowing water to enter
Fixings through the waterproof coating and fibre-cement need protection such as neoprene gaskets. Pipe penetrations need a sleeve and a formed sealant joint (not just sealant smeared on the surface) to prevent water getting behind the cladding. Pergolas or decorative timbers attached to the timber frame penetrating the cladding need waterproof protection otherwise they will track water along their top surface and into the house interior.

No step down at doorways/decks
In addition to providing clearance for claddings it is important that rainwater cannot back up and enter at doorways. Even at entranceways with a verandah there must be an adequate fall away from the doorway to remove rainwater and avoid flooding. Enclosed decks without a roof require a 100mm step. Provision must be made for splashing from the deck surface and if an outlet becomes blocked, water must not enter under the sill to the interior.

Insufficient height to flashings where roofs or decks join
Acceptable Solution E2/AS1 requires an upstand behind flashings of:

• 35mm over windows.
• 75mm behind claddings where they meet a roof.
• 115mm behind the cladding over a waterproof deck.

Leaks can occur where these minimums have not been met. For fibre-cement it is very important that the cladding does not wick water up through the cladding to the interior.  The solution to leaks at these points is to remove sufficient cladding and fit a flashing with sufficient height. Smearing sealant to the junction will not provide a satisfactory solution.

Fungal growth can be a sign of more serious failure (Photo:BRANZ Ltd)

Reliance on sealant for waterproofing
A formed sealant joint made to a prepared gap can provide a good weathertight joint (e.g. movement control joint) and may continue to work well for 10-15 years. Such joints still need to be checked annually to ensure that the sealant is still securely attached to each surface and remains flexible. Sealant joints will deteriorate in the sun and must be able to be inspected and preferably protected from sunlight.

Joints formed by smearing sealant over or into a gap or failed joint will not last well. They are unable to flex as correct movement control joints are designed to. They are likely to separate from the surface of the material they were originally attached to. They can then attract quite large amounts of water because of the narrow gap formed between the surface and the detached sealant and consequent capillary action that will draw water in. As a primary means of weatherproofing they should not be relied upon.

Initial swelling in this stripped balcony was a sign of failure (Photo:BRANZ Ltd)