Home / Guides / Other Rooms and Spaces
Mini Split for an ADU
A backyard ADU sits in the same Texas sun as the main house, but it does not share the same air. A mini split gives that small building its own zone so the person living out there sets the temperature without touching the house thermostat.
Along the I-35 corridor from Waco through Austin to New Braunfels, accessory dwelling units show up as backyard cottages, garage conversions, and small studios behind the fence. In summer those rooms heat up fast. Thin walls, a west facing window, and a metal roof can make the space hard to occupy by afternoon, even when the main house feels fine.
Central air is built for the house. Ducts almost never reach a detached unit in a useful way. A long run across a yard leaves the ADU stuck with whatever the living room thermostat is doing. A tenant or a relative should not have to walk inside and change the house setpoint just to sleep.
A single zone mini split puts an indoor head in the ADU and a condenser outside. The occupant controls that room. The house system stays on its own. That split is independent metering of comfort: two buildings, two controllers, and no shared duct across the yard.
The Price on the Card
That is materials and labor for a standard single zone mini split installation. One day every week is the Joker Day at $2,200. Which day it lands on changes week to week, and the current Joker Day is revealed on the home page.
A $400 materials deposit books the date. The balance is due on completion.
Call the crew: (512) 297-7493Independent comfort, not a shared thermostat
The house thermostat does not know the ADU exists. Someone sleeping out back needs a controller in that room. The ADU can hold 70 degrees while the main house runs warmer. A renter does not force the family onto the same number.
A mini split moves heat at the ADU. Refrigerant runs between the outdoor condenser and the indoor head. No supply duct has to cross the yard. The house air handler keeps doing house work instead of trying to serve a building it was never laid out for.
- Separate controller in the ADU
- House system stays off that building
- Occupant sets the zone without walking indoors
One zone for a small footprint
A typical backyard ADU is a studio, a one bedroom, or a garage apartment with a short floor plan. One indoor head is the usual layout when living and sleeping share air. Keep interior doors open if you want that head to serve the whole unit.
If the ADU has a closed bedroom, a loft, or a long narrow layout, say so on the walk through. The crew looks at walls and throw distance. This page is about the common case: one zone, small footprint, one controller.
Sizing starts as a rule of thumb from square footage and sun load. Ceiling height, glass, insulation, and a west wall change the load. A site visit confirms capacity. A BTU number from a chart is not a promise for your building.
Tenant control in a rental or family unit
If the ADU is a rental, the tenant should not message you every time they are hot. They get the remote or wall controller for that zone. They set it when they come home. They drop it at night. You stay out of the middle.
Family use follows the same idea. A parent or an adult child in the backyard unit lives on their own schedule. Morning cooling out back does not mean the main house has to start at dawn.
Do not put the ADU on the house thermostat. Both buildings end up unhappy. A dedicated indoor unit is the clean split.
Texas heat in a backyard dwelling
A small structure gains heat fast. Less mass, more wall and roof relative to the floor, and often more glass than a bedroom in the main house. By late afternoon a west facing ADU can feel like a parked car if nothing is moving heat out.
On a bad afternoon along I-35 it can sit past 110 degrees outside. Inside a backyard unit with no dedicated cooling, it is not a place to work, sleep, or hand to a renter. The mini split pulls heat at the coil and holds a setpoint people live with, often the mid 60s at night through the mid 70s by day.
Humidity rides with the heat. The coil condenses water. That water needs a drain path that does not dump on a walkway or against a fence. Drain routing belongs on the site walk.
Outdoor unit and line set in a tight yard
Backyards on this corridor are often short on spare ground. The condenser needs airflow, a level pad or a wall bracket, and clearance so bins and plants do not choke it. Avoid the hot discharge of the house condenser if another spot exists.
The line set runs from the outdoor unit to the indoor head. On a detached ADU that path may cross a patio, an eave, or a short stretch of yard. Length and lift matter. The crew traces the run before they pick a wall.
The indoor head wants a high wall with a clear shot across the main living space. Do not hide it behind a bunk or a wardrobe. Clear throw is how a single zone covers a small open plan.
Questions People Ask
Can one indoor unit handle a whole backyard ADU?
Most small ADUs are an open studio or a one bedroom that shares air with the living space. One wall mounted head can serve that footprint when air can circulate. If you keep a bedroom door shut all day, that room is not on the same zone. Tell the crew about lofts, glass, and closed rooms so they can judge layout on site.
Will a tenant be able to set their own temperature?
Yes. The indoor unit has its own controller. The tenant sets the ADU without walking into the main house or touching the house thermostat. The house can sit at 75 while the ADU sits at 70. You are not sharing one system across two buildings.
Where does the outdoor unit go in a small backyard?
It needs a pad or bracket, airflow, and a line set path to the ADU wall. In a tight yard that often means a side fence, a back corner, or a wall mount out of the walking path. Do not bury it in plants or stack it on the house condenser. The crew walks the yard and picks a spot that works with the run and the drain.
Does a mini split heat the ADU in winter too?
A heat pump mini split can reverse and move heat into the room in cold weather. A backyard building still loses heat through glass and thin walls. Central Texas winter nights are a different load than a summer afternoon. Talk through winter use on the site visit rather than treating summer sizing as an automatic winter result.
How do you size a mini split for a backyard ADU?
Treat square footage as a starting rule of thumb only. Sun, glass, ceiling height, insulation, and how many people live there change the load. The crew measures the space and confirms capacity on site. A number from a chart is not a promise for your backyard unit. Say whether it is a rental, a guest space, or full time living.
Book the Job
If you have a backyard ADU from Waco down through Austin to New Braunfels and you want that unit on its own zone, call or text the number on this page. Describe the building, how it is used, and whether a tenant will hold the controller. The crew will walk the space and talk through a single zone that belongs to the ADU, not the house.
Call or text the crew at (512) 297-7493. Tell us the room, the size and whether it is insulated, and send a photo of the wall you want the head unit on. Standard days are $2,400, materials and labor. The weekly Joker Day is $2,200, and the home page shows which day it is this week. A $400 materials deposit holds the date and the balance is due when the job is finished.
Call (512) 297-7493