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Can rain blow into my house through weep holes in windy weather causing damp and moisture problems?
No, as long as the flashing in your wall has been properly installed this is not possible. The only exception is where a poorly designed pathway, concrete slab or garden has been constructed next to the wall. In this case storm water can dam up above the level of the flashing and flow in through the weep holes.
There are many possible causes for damp and moisture problems in walls including:
1. Poorly installed waterproofing and flashing.
2. Faulty roof installation or corrosion.
3. Faulty plumbing.
4. Unintended conduits from the outer skin to the interior such as incorrectly installed brick ties or incorrectly drained air conditioning units.
Under no circumstances should you block the weep holes as whatever the problem is this will make it worse, possibly much worse. You can also find information about independent research on whether extreme weather can cause rain to blow into weep holes and up through the wall cavity.
What does AS3959:2009 say about requirements for weep holes at levels BAL-12.5, BAL-19, BAL-29, BAL-40 and BAL-FZ when building in bushfire prone areas?
Excerpts from AS3959:2009 relating to weep holes:
Clauses 5.4.3, 6.4.3, 7.4.3 Amdt 3-2011 (relating to BAL 12.5, BAL-19, BAL-29)
"Vents and weepholes in external walls shall be screened with a mesh with a maximum aperture of 2mm, made of corrosion-resistant steel, bronze or aluminium, except where the vents and weepholes have an aperture less than 3mm (see clause 3.6), or are located in an external wall of a subfloor space."
Clauses 8.4.3, 9.4.3 (relating to BAL-40, BAL-FZ)
"Vents and weepholes in external walls shall be screened with a mesh with a maximum aperture of 2mm, made of corrosion-resistant steel or bronze, except where the vents and weepholes have an aperture less than 3mm (see clause 3.6)."
How can the High Performance Bushfire Weepa achieve Bushfire Attack Levels BAL-LOW, BAL-12.5, BAL-19, BAL-29, BAL-40 (and even BAL-FZ under some circumstances) when some of its components are made of plastic?
Fine stainless steel mesh screens the weep hole 15mm inside the cavity. The secret is the plastic grate that you see at the front of the High Performance Bushfire Weepa. Under extreme heat attack it resists melting and chars like burnt toast. This fixes the stainless steel mesh screen in place protecting the cavity against ember attack.
How can I retrofit weep holes with metal mesh screening as required by AS3959:2009 BAL 12.5 and above for buildings in bushfire prone areas?
This is a difficult and time consuming job. Weepa has released the Protector Weep Hole Screen for exactly this purpose. It can be easily installed after the house is built and will be suitable for all levels of bushfire protection.
Otherwise you will need to place metal mesh into the weep hole so that it screens the whole aperture. Do not use screwdrivers or other sharp objects as this will puncture or distort the metal mesh. At Weepa we have previously made up a little smooth wooden tool to do this job. It is easy to tear the mesh if the bricks are rough.
Please feel free to call our office if you need more information or a sample or two to experiment with.
Can the fine stainless steel mesh in the High Performance Weepa stop termites entering the wall cavity through weepholes?
The fine stainless steel mesh has an aperture of 0.415 which is smaller than any termite. However, no weep hole cover or guard, plastic or metal, can protect your house against termites as there are inevitably tiny cracks in the mortar around the bricks which are large enough for these determined creatures. To be safe you must use the usual termite prevention procedures, get regular professional inspections and keep vegetable matter and timber away from brick walls so the weep holes are not bridged.
My house is already built. Can I retrofit your weep hole formers for vermin exclusion?
Weepa has a range of products, some of which are only suitable for installation during construction and others that can be retrofitted to your house after construction.
The Protector Weep Hole Screen can be easily retrofitted for vermin exclusion and bushfire protection. It is DIY and comes with a simple tool for installation. It complies with AS3959 for all Bushfire Attack Levels. Unlike other solutions it has been designed to ensure adequate airflow so the cavity remains well ventilated. Please be aware that no weep hole guard can exclude termites, so other measures must be taken for termite prevention (refer to question above).
The solid plasterer or renderer has rendered over the weep holes in my house. Does this matter?
Yes. Without weep holes your home is at risk of Leaky Building Syndrome. You should get professional advice without delay about how to recreate the weep holes.
Why do I need weep holes?
Weep holes serve two important purposes.
1. Ventilation of the internal wall cavity - Without ventilation, mildew, dry rot and damp reduce the life of the internal wall studs and other building materials within the cavity. Inadequate ventilation is the main cause of "Leaky Building Syndrome".
2. Drainage - Water that enters the cavity due to capillary action, condensation, damage, or accidental flooding needs to escape somewhere. In tropical and sub-tropical areas of Australia it is not unusual to see water flowing from the weep holes on the prevailing side of well constructed houses after a 'gully raker' or monsoonal storm.
What weep hole spacing do I need?
Typically weep holes are included in the external leaves of cavity walls in the course directly above damp proof courses, flashing and cavity fill, and at the bottom of the infill cavity at spaces not to exceeding 1200mm.
However, your architect or building designer will specify weep holes according to the needs of your particular project. We recommend that when designing for damper climates and air-conditioned buildings closer spacings should be used. This gives greater airflow to dry cavities.
Do Weepas impede air flow?
To answer simply, No. Independent testing by Dr Daniel James at Griffith University showed that Weepas cause "no significant restriction of the airflow under typical, normal and extreme operating conditions".
Be sure to remove the mortar guards after installation. We've witnessed a number of building where the mortar guard has not been removed after the job is complete. This is likely to restrict airflow.