What If We Discover Dry Rot or Subsidence in the Party Wall During Excavation?
Stop work in the affected area, photograph and record what you have found, and tell your party wall surveyor straight away. Dry rot or subsidence found in a shared wall is a matter for the surveyors and, probably, an engineer. It can change the scope of the award.
First steps on site
Speed matters. Both problems can worsen if left, and delay in reporting makes cause harder to prove.
- Pause the affected work and make the area safe
- Take dated photographs and notes
- Do not treat, cut out or fill anything on the neighbour's side
- Contact your surveyor, who will contact the neighbour's surveyor
Was it already there?
The schedule of condition is the key document. If the rot or cracking was recorded before you started, it points to a pre-existing defect. If it was not, the surveyors have to work out whether your work caused or aggravated it. An engineer's report may be needed.
Dry rot
Dry rot is a fungal decay in timber that usually comes from long-term dampness. It can spread through masonry to timber on the other side, so a party wall is a route into the neighbour's house. Specialist treatment is likely. Who pays depends on cause. The award will say who carries out the treatment, when, and at whose cost.
Subsidence or movement
Ground movement, failed drains, tree roots or poor earlier work can all be causes. Building work may have not caused it, but excavation can worsen it. Monitoring and temporary support may be needed before work continues. The building owner is liable for damage caused by the work and must make good, but is not liable for a defect that pre-existed.
Changing the award
Where the situation alters the work, the surveyors may need to make a further award, or amend the existing one. Do not rely on informal understandings. Any change to costs, method or programme should be in writing.
Your insurer may need to be told. Read the policy wording and ask them.
Frequently asked questions
Who pays to fix dry rot in the party wall?
It depends on cause and on what the award says. A pre-existing defect is usually the owner's responsibility, not the building owner's.
Can I carry on elsewhere on site?
Possibly, if it is safe and the surveyors agree. Ask before restarting.
Do I have to tell the neighbour?
Yes, through the surveyors. Hiding it will make any dispute worse.
Related guides
- Damage Caused by Party Wall Works: How to Claim Compensation
- What Evidence is Needed to Prove Damage in a Party Wall Claim?
- Schedule of Condition: Why You Need One Before Building
- Security for Expenses: Protecting Against Unfinished Work
Last updated: . This page is general information about the Party Wall etc. Act 1996 (England and Wales). It is not legal advice. Every property and dispute is different, so take advice from a party wall surveyor or a solicitor before you act.