A Cavity Wall Tray is to prevent water ingress through the outer wall of a property entering the inside living area, it is sometimes seen as a “Fix all cure” for leaks, which is actually incorrect.
Over the last 25 Years of Installing Cavity Wall Trays we have come across many common problems that can lead to water ingress in to a property. In an attempt to advise and hopefully enlighten people we have drafted up a list of the most common areas where we found water ingress due to defective or in adequate maintenance of the property.
The list below will hopefully give some pointers that may even in some cases remove the need for a cavity wall tray installation, as a professional organisation we don’t want to mislead customers or do unnecessary works if we don’t feel a cavity wall tray is the only answer. We will always bring to the customers attention any obvious issues we see either at the point of pricing from photographs, or when we are actually installing the cavity wall trays, that said any small areas of concern such as split sealant on windows we would do anyway whilst working in the area as a courtesy to the customer.
- The first and most common issue we come across is failed sealant around window/door openings above the area where the water has leaked in to the property.
We regularly find Silicone sealant that has shrunk back and cracked or simply split, allowing driven rain directly in to the cavity area. This usually occurs when inferior sealants such as high modulus silicones are used, these type of sealants tend to cure to a quite rigid state and don’t allow for much movement for thermal expansion and contraction of the frames and structure. A low modulus silicone will flex far more and is less likely to split or shrink back. This becomes a greater problem when the windows or doors are fixed behind the outer wall instead of between the opening, as the frame is then already inside the cavity area and any splits of the sealant allow water ingress readily in to the cavity. This can sometimes be remedied using upvc D beads to match the windows, set and sealed using a quality low modulus silicone sealant. A final point regarding water ingress through windows, we have also occasionally noted windows that are fixed downwards in to the cill area, what happens with time water entering the hollow section of the frame eventually rusts the fixings and causes water ingress usually with a tell-tale rust staining taking place. In these cases the glass can be removed along with any fixings and sometimes the holes sealed up effectively , but ideally you would change the window and fix at the sides instead to prevent breaking the drainage channel section of the frame as this is where the water that bridges the glass gasket will run too, then it would usually exit through a weep vent or out on to a upvc cill.
- Missing /Damaged or inadequate lead flashings/soakers.
Quite often when installing cavity trays over conservatories or extensions we find the lead flashings or soakers to be inadequate and as such water is entering the structure under or behind the lead. Sometimes lead can become holed or worn, or slip out of position due to thermal contraction, this to can also cause water ingress in to the property. Moss growth on roofs around the lead soakers or tile overlaps can cause water to traverse sideways and subsequently enter the property, this is really a general maintenance issue but worth mentioning as we have come across properties that have had water ingress through moss obstructing water ways.
- Property main roof issues, Very occasionally water can enter the cavity area and inside the property from the properties main roof area.
This can be something as simple as a broken tile, eaves slate or blocked gutter even, or sometimes the under tile felt has perished at eaves level allowing driven rain to enter the cavity area at the top of the wall. This can be remedied usually by fitting a propriety upvc eaves protector which covers the exposed cavity and supports the felt. All the above defects and issues are what we have found to be the main problem areas relating to water ingress in to the cavity wall area along with the ongoing soaking of the outer wall of course, this information is drawn from over 25 years of installing cavity wall trays to every possible type of application, we have always kept an open mind regarding water ingress as each situation is different from the last, but we will continue to learn and improve our service through these experiences. In the words of my Grandfather 'You only stop learning when they put the lid on'. We may expand on this section at a later date and we will continue to strive to keep properties free from water ingress through the cavity area.
Assuring you of our best service at all times
Martyn Hamer on behalf of - cavitytrayman.co.uk
