Our new home’s chimney is leaking but the builder has gone out of business
Property Clinic: I’ve been told the bricklayer failed to install a damp tray. What can I do?
Brick chimneys should always have a damp proof ‘tray’. This should be placed within the chimney just at the point where the front face of the chimney passes through the roof surface. Photograph: iStock
Our new dormer bungalow was completed by direct labour in 2016. Since then we have had an issue with water staining in my daughter’s upper floor bedroom. This aligns with an external brick chimney. I have had a friend look at the issue and he says the bricklayer failed to install a damp tray. I did not have the works supervised and I opted out of BCAR. The bricklayer I used has gone out of business. What can I do to solve this unsightly problem?
The opt out you have used brings with it the possibility of non-compliant work in your completed home. As with any ailment, correct diagnosis is the key to formulating a suitable remedy. Your friend has suggested that a damp-proof tray has been omitted in the chimney’s construction.
Brick is porous and a chimney with an open flue is an easy route for water to enter a house. If you imagine a chimney projecting through the roof it has five surfaces exposed to the elements. Four sides and a capping. An open flue with no cowl is like a large straw directing moisture into the inside. All chimneys should therefore have a cowl to prevent direct entry of water through the flue.
Brick chimneys should always have a damp proof “tray”. This should be placed within the chimney just at the point where the front face of the chimney passes through the roof surface. This collects water that penetrates through the chimney and directs it to the external. The absence of a tray will simply allow water to percolate down through the chimney structure and this will eventually show on internal wall surfaces. This can typically be in the form of salts or efflorescence caused by drying out. This should not be confused with interstitial condensation which can occur on chimneys when fireplaces are closed off and not ventilated.
The placing of a tray in a brick chimney is a fundamental necessity. One problem of direct labour projects is that there can be a deficiency in communication between the various tradesmen employed. There can also be an issue with the supply of fundamental but lesser-known items or materials. What can happen where such items are not available on site, and there is no main contractor to go and fetch such items, works progress leaving the item out.
I have seen this happen with cavity wall insulation and seen also where compliant work is interfered with and undone by others. The appointment of an assigned certifier under BCAR would help to eliminate such omissions and non-compliance.
You should have an inspection carried out by a chartered building surveyor to establish in the first instance what the issue is. A tray should be readily visible if it has been installed. If no tray is present the chimney would need to be taken down and rebuilt. The new chimney should have a tray installed.
I have seen some success in the past with clear paint-on damp sealer applied over the brick work but this can seal moisture in and it would need to be re-applied every few years. It may offer a stop gap solution until such time as the chimney is rebuilt.Take advice from a professional and the matter should be diagnosed and resolved without major disruption. – Noel Larkin
Noel Larkin is a chartered building surveyor, Noel Larkin & Associates and member of the Society of Chartered Surveyors Ireland, scsi.ie