The kitchen is drawn. The ceiling height is set. Then somebody asks where the cooling will go.
Services are the last thing most people think about. They are the first thing to take space. Heating, hot water, ventilation, cooling, power and drainage all need room. By the time a ceiling height is fixed, that room has usually gone.
Here is the order these decisions want to be made in. Most belong in the pre start checklist, not in a conversation on site.
Services need space, and the space gets taken first
Mechanical, electrical and plumbing are the systems that make a home work. They are not an add on. They sit inside the architecture, and they need routes and somewhere to put plant.
Design them before ceilings, floors, cabinetry and layouts are fixed. Reserving plant space during concept work is cheap. Finding it later means losing space or opening up finished work.
Underfloor heating is a floor decision first
Ask whether you can have underfloor heating throughout. The honest answer starts at the floor. Buildup, structural loads, heat output, finishes and control zones all need coordinating.
An existing floor and a new extension may need different solutions. Compare what each room needs, and what each one costs to build. Then choose a system for the whole house.
Ventilation is not air conditioning
These are two different jobs. Ventilation provides air exchange. Cooling controls heat. A comfortable home needs both, particularly once insulation and airtightness improve.
Ask your designer to explain the ventilation strategy on its own. If it only appears inside a cooling conversation, it has not really been designed.
Cooling you cannot see still has to go somewhere
Concealed equipment needs ceiling or joinery space. It also needs duct routes, condensate drainage and maintenance access. External equipment, and any approvals it needs, should be reviewed too.
Noise is the other half of the question. Equipment choice, position, vibration isolation and acoustic treatment all matter. The design should consider bedrooms, neighbours and servicing access.
Agree the visual and acoustic requirements before layouts are final. Quiet operation belongs in the technical brief, not in a complaint afterwards.
Two showers at once is a design question
Premium fittings do not create their own water. The design should assess simultaneous demand and the incoming supply. It should also size the storage or recovery needed.
Choosing the showers before that assessment is how a beautiful bathroom disappoints. Tell the designer how many outlets may run at the same time.
Controls and cabling are a before, not an after
Smart lighting, heating and blinds are easy to want and harder to live with. Define the control functions you actually want. Decide how much complexity you will maintain.
Coordinate wiring, user interfaces, network equipment and manual operation before first fix. Do the same for Wi Fi, data and home working areas. Routes are simple while the walls are open.
Security, CCTV and AV need their scope defined with the electrical and joinery design. Agree who supplies each system. Agree who commissions it and who supports it afterwards.
What nobody should promise you yet
Whether a heat pump suits your home depends on the building. Heat demand, emitters and the power supply all count. So do where the equipment sits and the noise it makes. That needs a system specific assessment, not a rule of thumb.
Existing heating and wiring may be worth keeping. Condition, capacity and fit with the new layout have to be assessed first. Reuse only saves money if the equipment can support the new system.
Extra heating, cooling, cooking or charging loads can change power demand. Water and drainage may need review too. Check network provider requirements and lead times early, not late.
Installed equipment is not a commissioned system. Testing, commissioning and handover records belong in the scope. They are part of how a build actually ends.
One contract and one team means the services are designed with the rooms. They are not squeezed in after them.
Get the comfort decisions made while they are still cheap to make. Fill out the contact form or call 020 7731 6841 and let’s get you booked in for a free call with Nick.
Published 2 October 2026. Written by the NU Projects studio, edited since for house style and accuracy.