On a solid wall the decision is the drill and the finish, not a cavity detail. The installer cores the full thickness of brick or stone, sleeves the hole, and makes good the inside plaster and the outside face. There are no cavity ties to specify, because there is no cavity. Survey the thickness and the finish before the quote is fixed. The outdoor unit still needs a lawful spot. An F-gas certified company handles the refrigerant after the hole is a real, weathered opening.
One leaf of brick or stone
Solid brick, stone or flint is one leaf. The core drill has to travel the whole depth, which may be 230 mm and may be far more on stone. Dust, rubble and a wet core are expected. Say the wall is solid, or that you believe it is. Close photos of the inside plaster and the outside face, a wide shot of the wall, and the outdoor spot, plus lime plaster, render or stone if you know it, keep the description honest. Do not describe it as a cavity. If the house is listed, say so in the same note.
A pier, a chimney thickening, or stone over brick
Thickness is not obvious from the street. A pier, a thickening at a chimney, or a stone skin with brick behind changes the drill. The survey should say what it thinks the wall is, and the quote should allow for making that good rather than for a 10 mm neat hole in a new cavity house. Often you can core stone or flint, with the right core and enough time, then a finish that matches. The survey should see the wall. A price copied from a modern brick cavity house will be wrong.
Lime inside and the face outside
Inside, the plaster may be lime. A hard gypsum patch on lime can crack and trap moisture. The quote should name the making good.
- Core through the full solid thickness.
- Sleeve and seal against rain.
- No cavity ties on a wall with no cavity.
- Price the finish you can see, inside and out.
A sleeve that slopes and insulation through the wall
Name the making good: lime or a compatible patch where the wall is lime, a neat plaster repair where it is modern, and decoration only if someone has agreed to paint. Outside, face brick, render, pebbledash or stone each need a different close-up. A foam squirt and a colour that does not match is the complaint that lasts. The sleeve should slope slightly so water cannot run in, and the pipe insulation should be continuous through the wall. A solid wall is cold. Poor insulation on the copper shows up as staining on the plaster you just paid to repair. A hole lets rain in if it is left unsealed. A sleeved hole, weathered to the outside face and insulated through the depth, is the detail the quote should include.
Fixings in masonry, or a stand on the ground
The outdoor bracket has to anchor in solid masonry with fixings suited to that brick or stone, not with plugs chosen for a hollow block. A ground stand avoids a doubtful face. In England, Planning Portal conditions on the outdoor unit are unchanged by the wall being solid. Listed solid-wall houses need consent for the hole as well as for the plant. Pipe length and condensate are ordinary problems made slightly harder because you do not want a second hole. Prefer one core and a gravity drain on that elevation. A pump is for when the gully is elsewhere. As a 2026 illustration, the solid-wall drill and a careful finish often add a few hundred pounds to an otherwise ordinary single-room install in the low thousands including VAT. A stone wall that needs a specialist finish adds more. That is an illustration, not a rate. Cavity ties belong to cavity walls. A solid wall is drilled through and the bracket is fixed into the masonry itself, or the outdoor unit stands on the ground.
When the quote is still talking about cavity ties
A quote that talks about cavity ties, cavity trays or injecting a cavity is describing a different wall. Send it back. Ask for a core drill, a sleeve, and making good of the actual finish, with model codes and the condensate route. Ask the firm to confirm they are not pricing cavity ties. Solid walls do not use cavity wall ties for an air conditioning bracket.
Core buying guides
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Related guides
Sources and further reading
How this guide was prepared
This guide was written by the Local AC Installers Editorial Team. We compare official guidance, legislation and established consumer information, separate general information from project-specific advice, and show publication dates and sources. We do not accept installer accreditation claims at face value.