Wall ties and cavity insulation
The weep holes over a window have been pointed up solid. Why is that a cavity-tray question and not a wall-tie failure?
Not a wall-tie failure by itself. Weep holes over a window that have been pointed solid are a cavity-tray and drainage question. Those holes are the outlet for water that a tray should bring out of the wall above the opening. Filling them with mortar closes the outlet. The survey can record the blocked holes. It cannot turn that pointing into proof that the ties have corroded or snapped. Ties are a different mechanism. Treat the solid pointing as drainage until a proper look at the ties says something about 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?
A cavity tray over a window is there to catch water in the cavity and lead it out through the weep holes. If the holes are pointed solid, that path is blocked. You can have a tray problem with healthy ties, and you can have tie trouble with open weeps. One defect does not stand in for the other. Ask the survey to describe the pointing, the tray if it was visible, and any damp at the head of the window.
Do not order tie replacement because the weep holes have been filled. Replacement is a response to ties that have been investigated, not to mortar in a drainage slot. The Energy Saving Trust talks about whether a cavity is suitable to fill, which is again a different job from a blocked outlet. Keep the filled weeps on their own line. If ties worry you for another reason, say what that reason is. Do not borrow it from the pointing.
What should you ask your surveyor?
- Were the weep holes fully pointed, or only partly blocked?
- Did you see a cavity tray, or only the filled outlets?
- Is there any separate sign of tie trouble, apart from this pointing?
What are the typical next steps?
- Describe the filled weep holes as a tray and drainage defect.
- Do not commission tie replacement from the pointing alone.
- Ask for the window head to be read separately from the ties.
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
Can blocked weep holes be ignored if the wall looks straight?
No. A straight wall does not open a blocked outlet. The pointing is still a cavity-tray question, not a tie result for the wall.
Does mortar in the weep holes prove the ties have rusted?
No. Rusted ties are a different mechanism. Filled holes have not measured the ties and do not show they have failed in this wall.