I have a flat roof that is adjoined to my neighbour’s house via the hall. I have started to see bubbling on the wall as you enter. What should I do?
It’s understandable to be concerned when you start seeing bubbling or blistering on internal walls, particularly near where your home connects to another property. While the exact cause can’t be confirmed without a site inspection, what you’ve described is likely a symptom of dampness, often caused by water ingress, condensation or sometimes plumbing issues.
Your observation that this is occurring near the junction where your flat roof meets your neighbour’s house is significant. Flat roofs typically have a much shorter life expectancy than slated or tiled pitched roofs. Flat roof abutments to adjoining walls can be a particular weak point if not properly constructed.
There are a few possibilities to consider. These include:
READ MORE
- A failure in the flat roof covering itself, particularly if the roof is covered in traditional bitumen felt or a similar material that has reached the end of its serviceable life. Depending on the specific system used and how well it was installed, these coverings can last as little as 10–15 years.
- A problem at the junction with the neighbouring property, such as failed flashing, poor detailing or deterioration at the upstand or abutment where your roof meets your neighbour’s wall.
- An issue on your neighbour’s side such as a leaking gutter, cracked render or plumbing defect, which may be allowing water to track across or down into the shared wall, bypassing the flat-roof construction.
There are several different types of flat-roof construction. It will be critical that the nature of the structure is properly determined. For example, a key requirement for cold deck roofs is ventilation of the roof structure to prevent condensation moisture build up in the structure, potentially leading to structural issues and leaks.
Given the above, the first and most important step is to engage a chartered building surveyor. Building surveyors are trained to carry out detailed defect inspections and will be able to confirm the nature of the problem, recommend the most appropriate repair options, and advise on any health and safety issues.
It’s important to avoid accessing the flat roof yourself, especially if the structure is timber-framed. Over time, water ingress can cause significant decay, and without understanding the construction type and condition, there’s a real risk of collapse or injury. A professional surveyor will carry out a safe inspection and determine the best approach, which may include internal moisture readings, external assessment and, where necessary, opening-up works.
If the issue does turn out to be with the roof covering or flashing, it’s possible that the materials have simply deteriorated with age. In this case, renewal of the covering and associated weathering details may be required.
If these works are located along a shared wall, the wall would be a party structure as defined in the Land and Conveyancing Law Reform Act 2009. The rights and obligations of adjoining owners is set out in detail in section 43 to 47, including in respect of works carried out to the party structure. The legislation outlines how adjoining owners must co-operate in situations involving repair or access to party structures. Legal advice should be sought if required.
In summary, the bubbling you’re seeing is very likely linked to water ingress and prompt investigation is recommended before the problem worsens. A chartered building surveyor will help you establish the cause, determine safe access, and advise on next steps including repairs, legal responsibilities and co-ordination with your neighbour if required.
Damian King is a chartered building surveyor and a member of the Society of Chartered Surveyors Ireland
Do you have a query? Email propertyquestions@irishtimes.com
This column is a readers’ service. The content of the Property Clinic is provided for general information only. It is not intended as advice on which readers should rely. Professional or specialist advice should be obtained before persons take or refrain from any action on the basis of the content. The Irish Times and it contributors will not be liable for any loss or damage arising from reliance on any content
