Leasehold
Balcony tiles sound hollow near the door and the covering was not lifted. What membrane under the tiles is unknown?
The membrane under the tiles is unknown, because the covering was not lifted. Hollow sound near the door means the layers there are not bonded solidly to whatever is beneath, or there is a void. It does not show the membrane, its laps or whether it is intact. The survey has recorded the hollow tiles beside the door. It has not lifted them, has not identified a membrane, and has not decided that the balcony is leaking or watertight. Building-safety papers for leaseholders are a separate legal guidance. They are not a view under these tiles.
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?
Balcony coverings hide the waterproofing. A hollow note near the door is a likely place to worry, because the threshold is where water and foot traffic meet, but sound is not sight. Debonded adhesive, a missing bed, or a void over a failed membrane can all knock hollow. The survey cannot pick among them without lifting the covering, and it did not lift it. Guidance on building-safety protections for leaseholders deals with who pays for certain building defects. It does not identify the membrane on this balcony.
Tell the solicitor the tiles sounded hollow and the membrane is unknown, and ask where the balcony sits in the demise and in any building-safety information the block holds. A specialist can lift a tile if the membrane must be seen. Do not tell a lender the waterproofing passed because most of the balcony sounded solid. The part near the door was hollow, and the covering stayed down. The membrane remains unknown.
What should you ask your surveyor?
- How far did the hollow sound extend from the door?
- Did you lift any tile or only tap the covering?
- Are you naming a membrane, or recording that it is unknown?
What are the typical next steps?
- Treat the membrane under the balcony tiles as unknown.
- Keep the hollow sound near the door as a limit, not a diagnosis.
- Ask the solicitor how this balcony sits in the lease and the block's papers.
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
If the rest of the balcony sounds solid, is the membrane proved there?
No. Solid sound is still sound, not a view of the membrane. The covering was not lifted anywhere in this note. Hollow near the door already leaves that area unknown, and the solid areas were not opened either. Sound, solid or hollow, never became a sight of the waterproofing.
Does hollow tile mean a building-safety form has failed?
No. A hollow sound is not a completed form and not a failed one. The survey did not lift the tiles and does not know the membrane. Leaseholder guidance on building safety is a separate document. It is not a reading of this covering.