How to build a garden home, step by step

The steps

Who you need

• A designer to prepare drawings that meet the Building Regulations, and a design certifier to certify them.
• An assigned certifier: a competent professional, such as an architect, chartered engineer or chartered building surveyor, who inspects the work at stages and certifies it.
• A competent builder, nominated on the commencement notice. With a modular unit, this may be the supplier.
• A registered electrician, and a plumber for the connections to the main house.

Ask suppliers whether they provide the certifiers and paperwork, or whether you need to appoint them yourself. It affects the price.

The two notices

The planning notification is a condition of the exemption, not an approval. It doesn't confirm your plan meets every Class 3A condition. See notifying your council.

Building Regulations

Unlike a garden room, a garden home must meet the Building Regulations for a dwelling. Council guidance highlights:

• Fire safety: fire resistance of external walls, limits on openings near boundaries, roof covering classification, and interlinked smoke or heat alarms.
• Access: an accessible approach, a level entrance landing and a WC visitors can use.
• Energy, ventilation, drainage and structure, like any new home.
• Modular units: built off-site systems should have NSAI Agrément certification or comply with an Irish Standard. See modular garden homes.

Water, waste and power

Class 3A requires the garden home to connect to the main house's services rather than having its own. Plan the routes early:

• Waste: a connection to the house's drains, with enough fall. Long runs may need a pump. See drainage.
• Water: a supply from the house, sized for a shower and kitchen.
• Power: a cable from the house's fuse board, sized for cooking, heating and hot water. Check the house supply can take it.
• Broadband: lay a duct with the power cable. See electrics.

Before anyone moves in

1. The builder and assigned certifier sign the Certificate of Compliance on Completion.
2. Building Control registers it. Council guidance says the home can't be occupied before then.
3. Get the electrical certificate and keep all the paperwork with your house documents. You'll need it if you sell.
4. Tell your insurer, and register the home for Local Property Tax. See property tax, insurance and mortgages.

How long it takes

Allow time for design and certifiers, at least 14 days of notice before work, the build, and registering the completion certificate. A modular unit can be installed in days once the base and services are ready; a builder-built home takes months. Work relying on Class 3A must be finished by 31 December 2030.