First Fix and Second Fix: when does ventilation and central vacuum systems get installed?
What is First Fix?
First fix is the part of the building process where the structural work is done before any plastering takes place. First fix can take place once the foundations and main structure has been finished.
Ventilation in first fix
During first fix,
- Ducting for the heat recovery ventilation system will be installed. Ducting must be installed before concrete slabs are laid, and before partition walls and floors are put in place. By installing the ducting first this makes an easier process throughout, if you’re not sure whether to ventilate a whole house, we still recommend fitting ducting to all rooms, and it means it can be used in the future.
- Allow for the wall vents or roof vents as they can be hard to retrofit later on
- Any required electrical wiring to and from the unit including mains power, controller cables and wiring for the boost switches, if you are fitting a Vent Angel safety device allow for the extra wiring from the smoke alarms
- If a drain is required at the unit allow for a 32mm drainpipe
- Once ducting is installed it is important to place blanking caps on any pipe ends so that no dust or moisture can enter the system.
Central Vacuum in first fix
- Ducting for your Central Vacuum System within the internal walls and floors will need to be installed (before the screed floor is installed and plasterwork is completed)
- For central vacuum units being installed in a detached garage, a 4” trench duct to carry the flexible vacuum pipe must also be installed at this stage.
- Allow for an external vent from the unit for excess air to be dispelled
- Allow for a two-core cable to be daisy chained from inlet valve to inlet valve
- Allow for the kitchen sweep inlet
- Place blanking caps onto any pipe ends.
Other things that happen in the first fix:
Electrics – the bare bones of your electric will be fitted, this would include sockets, switches, and light fittings. A lot of the work and wiring done at this stage will not be seen once your house is finished.
Plumbing – pipes for water supply, water waste and heating pipes will be installed.
Joinery – stud walls, roof struts, door frames and floor joist will be installed. Stairs and door frames will also be fitted during first fix.
What is Second Fix?
Second fix takes please once plastering is finished allowing the electrical and plumbing fittings to be fitted.
Ventilation second fix
During Second fix
- The ventilation unit can be installed
- The main ductwork and external vents connected
- The ceiling plenums can be cut allowing the installation of the air valves
- The electrical connections can be connected
- Water drain can be fitted (if applicable)
- The system can be set up and commissioned
Central vacuum second fix
- Install the vacuum unit onto the wall and connect the ductwork
- Install the inlet valves and kitchen sweep inlet
- Connect the wiring
- Commission the system
Other things that happen in second fix:
Electrics – face plates, light switches, light fittings, plug socket are installed and everything is connected to the main fuse board. All connections should be working and safe at this stage.
Plumbing – All plumbing appliances will be connected, tested, and commissioned. This includes bathroom sanitaryware, radiators and boilers - the aim being when you turn the water on, it doesn't all end up on the floor!
Joinery – finishing touches will be made such as internal doors, architraves, and skirting boards.
All fixtures and fittings are installed throughout second fix. Fixtures and fittings include floors, bathrooms, and kitchens, and then any tiling and decoration will be done at the final stage.