Wall ties and cavity insulation
Cavity insulation is hanging out of a weep hole. Does that mean the wall ties have failed?
No. Fill hanging out of a weep hole means insulation has escaped through a hole that lets water out, which is not a finding that the wall ties have failed. Weep holes are not failed ties, and spilled beads or fibres can block the weep so water sits in the cavity. Seeing fill on the sill is not a boroscope inspection of the ties.
Last reviewed 24 October 2026. Written for buyers in England and Wales unless this answer says otherwise. No named surveyor has signed this page. It is general guidance, not a report on your house, and not legal advice.
What is the fuller explanation?
Weep holes are left open on purpose, often above windows and at the base of a cavity wall. If mineral wool or beads are hanging out of them, the fill has migrated to an opening. The Energy Saving Trust’s cavity advice is about whether a cavity should be filled at all, after the wall is suitable and repairs are done. Escape of fill through a weep is a reason to ask whether this installation is still where it was put, and whether the weep can still drain. It is not a diagnosis of rusty ties. Tie failure is about the metal that holds the two leaves together, and it is judged from cracking, bulging or a proper look inside the cavity.
The home survey has not drilled the wall and has not tested the ties because a weep is messy. Ask the surveyor which elevation and which openings were affected, and whether the weeps are blocked or merely stained. Do not let a contractor replace every tie because fibre is sitting on a window board. Do not let another contractor pump more fill in until someone has said the existing fill, the weeps and the condition of the wall have been looked at properly. A photograph of beads is the start of that conversation, not the end.
What should you ask your surveyor?
- Which weep holes are spilling, and what is coming out?
- Are the weeps blocked, or is the fill only sitting at the mouth?
- Are you reporting the insulation, the ties, or both? Please keep them apart.
What are the typical next steps?
- Do not seal the weep to hide the spill. The hole is there to drain.
- Do not commission new wall ties on the strength of escaped fill alone.
- If the cavity needs to be rechecked, ask a specialist who will look inside, and keep that separate from the home survey.
Costs vary with the building and with who you instruct. Where this page does not cite a published figure, ask the surveyor, a relevant specialist, or your solicitor for a written quote. Do not treat a forum average as the price.
Also asked about this
Is spilled fill the same as slumped insulation?
It is related but not identical. Spillage is fill at a weep. Slump is fill that has dropped inside the cavity. The survey may not have seen the inside.
Can you poke the beads back in?
No. Pushing them back blocks the weep and does not put the cavity right. Leave them until someone competent has advised.