Air conditioning in a rented flat: what you can fit

A bedroom that is still stifling after midnight can make air conditioning in a rented flat feel like an urgent purchase. The practical choice is not simply between a wall split and a portable machine. You first need to know what the tenancy allows, whether the building has a freeholder, and where an outdoor section could safely sit.

A no-drill system can reduce the permission problem. It does not remove limits on windows, balconies, noise or fire routes. See fixed and portable designs in the split air conditioner comparison. A qualifying purchase can earn us a commission at no extra cost to you. We have not inspected your tenancy or run a lab test.

In short

Get written consent before drilling, changing a window or attaching any part of an air conditioner to a rented home. If permission is unlikely, a hose-connected portable split may be the more workable option, provided its pipe reaches a safe outdoor position and the arrangement does not obstruct an escape route.

What you can fit without permission

A self-contained portable air conditioner is usually less intrusive than a fixed wall split, because you can take it away and it does not need a refrigerant line through the wall. A portable split places the heat-rejecting section outside and connects it with a flexible line. Some products are sold as no-drill designs that pass through a partly open window, door gap or similar opening.

That does not create an automatic right to use one. Your tenancy or occupation contract may restrict equipment outside the flat, and building rules may cover balconies, communal walkways and visible items. A window kit that screws into a frame is an alteration, even when the machine itself is portable. Read the agreement before you spend, and ask the landlord if the wording is unclear.

Fire safety is a firm boundary. A hose or outdoor module must not narrow your only usable escape route, stop a fire door from closing, or sit where somebody could trip. The City of London Corporation's housing improvement pack accepts portable units in its own stock only where they do not obstruct a fire escape, and it refuses permanent air conditioning and drilling through external walls or frames. That is one landlord's policy, not a national rule.

Get written consent before a fixed installation

A wall-mounted split normally needs holes for the pipes, the power connection and the condensate drain, plus a bracket or base for the outdoor condenser. That is more than placing an appliance in a room. Shelter England advises tenants not to start improvements without written agreement, and a letting agent will often have to ask the landlord rather than approve the work.

Write a specific request. Include the indoor and outdoor positions, hole size, drainage, installer details, expected noise, and whether the unit stays when you leave. Ask who pays for maintenance and for making good if it is removed.

Do not book an installer on the strength of a phone call. Keep the signed approval or email with the tenancy documents, and check that any conditions match the quotation. Permission to install does not settle planning control, building rules or refrigerant requirements. The split air conditioner installation guide sets out those separate checks.

If consent is refused, drilling for the summer can leave you liable to remove the system and repair the wall. It can also put a deposit dispute in prospect. A removable arrangement is the safer buying path, but only if it works in the room you actually need to cool.

Leasehold flats can need two approvals

In a leasehold building, the immediate landlord may not control the outside wall, roof or balcony. Those parts are often retained by the freeholder, so agreement in principle may still not authorise the condenser or the pipe route. A tenant's request also has to fit the head lease.

The Leasehold Advisory Service explains that a lease may require the landlord's consent for alterations. Planning permission does not replace consent required by the lease. Permitted by the council is not the same as permitted by the freeholder, and approval from a managing agent may still be subject to formal consent and a fee.

Ask who controls the proposed surface before you choose a product. A unit hung from a balcony wall is harder to justify than one that stands temporarily in a permitted private space. Shared balconies and access decks are poor assumptions, because equipment there can affect neighbours or circulation.

A leaseholder can face tighter alteration controls than a freehold homeowner. If the consent chain looks complicated, compare a fixed system with a movable one before you pay for a survey. The wall split or portable split guide sets out the trade-offs.

Choosing a no-drill system that actually fits

Portable describes movement, not unlimited placement. Measure the route the connecting line must take, not the straight line across the room. One no-drill product in the set states a 1.5 m tube. User reports for another portable split describe a pipe of about 2 m. A short line may work beside a low window and fail where the outdoor section cannot be bracketed to the wall.

Start with four measurements: the clear window or door opening, the sill or balcony depth, the vertical drop, and the full route length. Then check whether the opening can be secured while the unit is in use and closed normally when it is removed. Do not stretch, sharply bend or trap the connecting line to gain a few centimetres. Follow the manufacturer's placement instructions.

The outdoor section needs stable support and a position where condensate will not cause a nuisance. Do not balance it on a narrow sill or hang it from an improvised strap. Reviews can show placement problems. They do not override the manual, your agreement or building policy.

Noise is a consent issue as well as a comfort point. Moving the compressor outdoors can quiet the room and shift sound towards neighbours, including a bedroom window across a courtyard. The top split air conditioner choices can narrow the field. Your permission and measurements decide whether a product is viable.

When heat becomes a housing issue

A landlord is not generally required to supply air conditioning simply because a home is uncomfortable in hot weather. Repairs and improvements are different. Asking for a split system does not turn it into a repair obligation. Serious excess heat should still be recorded, because temperature can be relevant to the condition and safety of housing.

Keep dated indoor temperature readings, note which rooms are affected, and explain measures already tried, such as closing blinds before direct sun and ventilating when the outdoor air is cooler. If heat is affecting your health, seek medical advice and include the practical impact when you report the problem.

Shelter's improvements guidance cited here is for England. Tenancy language and enforcement differ in Wales, Scotland and Northern Ireland, so start with your agreement and advice for your nation. The realistic outcome may be shading or ventilation rather than a landlord-funded wall split. Temperature readings alone are not an order for air conditioning. If you buy a removable unit meanwhile, keep escape routes clear.

A practical permission and buying checklist

Work through the paperwork before you compare cooling capacity. This order stops a good-looking unit becoming a machine you cannot safely or lawfully position.

1. Read the agreement for alterations, walls, windows, balconies, noise and reinstatement. In a leasehold building, identify who controls the outdoor area.
2. Sketch the indoor unit, line, opening, outdoor section, socket and condensate route. Measure the route, not the straight-line distance.
3. Ask in writing whether anything will be drilled, screwed, sealed or left outside, and who must give final approval.
4. Keep fire exits, shared routes and escape windows clear. Do not place an outdoor section where it can fall into a communal area.
5. Confirm pipe length, permitted bends and the gap the line needs. A no-drill claim fails if the window cannot hold that line.
6. If an alteration is approved, record who removes it and who repairs the surfaces. Photograph the area first and keep the consent.

Stop if any approval remains ambiguous. A portable monobloc with an exhaust hose may be noisier indoors than a split, but it can be easier to remove. That trade-off is preferable to a fixed system you cannot install.