Cool the loft office for the hours you work there, not as if it were an empty store. The decision is a vertical piece of wall that can take the indoor unit, a pipe drop that stays inside the height limit, and a condensate route that cannot stain the ceilings below. Survey the slopes, the gable and the consumer unit. An F-gas certified company installs the pair. If the height back to the only lawful outdoor spot fails, this room cannot join the house multi-split.
Calls under the tiles from morning until late afternoon
You are in this room from morning until late afternoon, which is when the roof peaks. The survey counts the slopes, the dormer glass and the kit on the desk. A small study on the gable of an insulated conversion is a modest duty. An uninsulated loft with a south dormer is not. Insulation still matters. The unit does not replace it. Calls need a low fan. Compare that sound figure on the model code, and keep the outdoor unit off the slope above your head if a rear wall lower down is quieter. Anti-vibration mounts matter on a timber loft floor that telegraphs hum into the bedrooms. A low fan on a suitable model is the aim. The outdoor unit on a timber structure above a bedroom can be the louder problem. Place that with the survey, not after the first week of work. Size the working day, the glass and the roof. Say this is a loft office you work in. Photos of the slopes, the gable, the desk, the hatch or stair, and the outdoor elevation at the bottom of the drop, plus the floor level, are the set. Ask for model codes, low-fan sound, and the condensate route past the rooms below.
The drop that breaks a casual multi-split, and water over the ceilings
A loft is the room that breaks casual multi-splits. The drop to a yard condenser, plus a run along the eaves, often exceeds the manufacturer's height or total length. Measure it. If it fails, your choices are a dedicated outdoor unit on a gable that planning allows, or no split in the loft. Do not add a new indoor unit to an old outdoor unit lower down unless that exact combination is listed and the geometry passes. It usually is not a mix-and-match. The loft can join the multi-split in the garden only inside the height and pipe limits. Lofts fail that test more often than bedrooms on the first floor. The survey should measure before you pay for a spare port. If the house multi-split cannot reach the loft, ask for that conclusion in writing. The crew has to get the indoor unit up the loft stair or the hatch. Say which you have. A folding ladder and a tight hatch change the day. In England, a gable outdoor unit is still subject to Planning Portal conditions, and a street-facing gable is the one most likely to be refused. Ask for the height difference against the datasheet.
On the gable or a dormer cheek tall enough for the casing and the service gap is where the indoor unit goes if the walls are sloped. A knee wall that blows at the desk is a poor second. If neither exists, say so and stop. Gable or dormer cheek, with service clearance, is the mounting rule. Condensate must not cross the bedroom ceilings unplanned. Loft offices sometimes sit on a spare way that was already tight for the lights and the sockets. The split wants its own circuit. Someone competent confirms the board. Condensate should fall to a soil stack in a riser you can see, or be pumped on a route with an alarm or a visible check, because a leak here ruins plaster two floors down. As a 2026 illustration, a loft office with a usable gable and a legal drop is often in the low thousands including VAT. A failed height limit that forces a separate outdoor strategy, or a long pumped drain, is the variation to see on the quote before you book the hatch.
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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.