Before winter, a Belgian rental portfolio follows three boiler inspection calendars: gas every two years in Brussels and Flanders, every three years in Wallonia for small boilers, and heating oil every year everywhere. The tenant in principle arranges the inspection, while the landlord supplies and replaces the smoke detectors. Here are the rules region by region, and the schedule to set before October.

Which boiler inspections are mandatory in each region?

All three regions require a periodic inspection of boilers, with frequencies that do not overlap. In Brussels, the Order of 21 June 2018 on the inspection and maintenance of heating systems sets the pace in its Article 2.2.1: at least every two years for gas boilers, every year for liquid or solid fuel. In Wallonia, Article 13 of the Order of 29 January 2009 provides for an annual inspection for solid and liquid fuel. For gas, an inspection is required every three years up to 100 kW of useful rated output, every two years above that. In Flanders, Article 8 of the Order of 8 December 2006 requires annual maintenance for solid fuel, whatever the output. From 20 kW, heating oil is annual and gas comes every two years. The Flemish text allows three months’ leeway between two services.

How do the three regimes compare?

Brussels Wallonia Flanders
Text Order of 21 June 2018, Art. 2.2.1 Order of 29 January 2009, Art. 13 Order of 8 December 2006, Art. 8
Gas At least every 2 years Every 3 years up to 100 kW, every 2 years above Every 2 years, from 20 kW
Heating oil At least every year Every year Every year, from 20 kW
Solid fuel At least every year Every year Every year, any output
Who arranges it The tenant for a gas boiler, if a written lease does not put it on the landlord The user of the installation The user of the appliance
List of tenant repairs Maintenance and periodic inspection borne by the tenant Burner inspection and maintenance entrusted by the tenant to an approved technician Periodic cleaning of the boiler borne by the tenant

Who books and pays the technician?

In principle the tenant, but the rule is not worded the same way everywhere. In Brussels, Article 4.1.1 of the 2018 Order transfers the EPB inspection to the tenant for gas boilers and water heaters. The condition: a written lease that does not explicitly put this task on the landlord. The Brussels Environment page speaks more broadly of “heating installations”. For heating oil, the text provides no such explicit transfer. However, the list of tenant repairs in the Order of 23 November 2017 puts the “cleaning, maintenance, periodic inspection required by the regulations” on the tenant. Replacing defective boiler parts remains with the landlord. For a Brussels agency, the lease clause naming who books the inspection is therefore worth rereading before winter.

In Wallonia, the 2009 Order targets the “user” of the installation, who has the inspections carried out and provides the certificate without delay to the owner who asks for it. Energie Info Wallonie puts it this way: the inspection is borne by the tenant, who calls in the approved technician, pays them and keeps the last two certificates. Annex 7 of the Order of 28 June 2018 on tenant repairs leaves to the landlord the replacement of a boiler or burner that has become unusable and worn out.

In Flanders, the 2006 Order places the obligation on the “gebruiker” (user) of the appliance. The list of minor repairs adopted under the Residential Lease Decree counts periodic cleaning of the boiler among the tenant’s charges. It states that maintenance and cleaning are always for the tenant’s account, and that the list can always be departed from in the tenant’s favour.

What about chimney sweeping?

It is mostly governed by the lists of tenant repairs, often together with boiler maintenance. In Brussels, the periodic EPB inspection includes maintenance of the flue gas exhaust (Article 2.2.2 of the 2018 Order). The 2017 list puts periodic sweeping by a professional on the tenant. It follows the legislation or, failing that, the frequency of use, “and at the very least shortly before leaving the rented premises”. In Wallonia, the body of the 2009 Order sets no specific frequency for sweeping. Annex 7 of 2018 provides for annual maintenance and inspection with sweeping for oil boilers, and annual sweeping for open fireplaces. Unless otherwise agreed, it is borne by the tenant, who gives the certificate to the landlord at each visit. In Flanders, the flue is cleaned before the boiler when this is required, and the tenant repairs list puts periodic sweeping on the tenant.

What rules apply to smoke detectors?

In Brussels, the Order of 28 September 2023 has made detectors mandatory in all dwellings since 1 January 2025. They must comply with standard NBN EN 14604 and must not be of the ionisation type. They need a built-in ten-year battery or a 220 V connection with a backup battery. From four mandatory detectors, they must be interconnected or linked to a centralised system. A landlord who had already installed detectors compliant with the 2004 Order before publication may keep them without interconnection. This period runs until the device is replaced, and at the latest until 1 January 2028. The landlord pays for purchase and installation, and replaces the detector at its expiry date or if it is defective. The tenant notifies the landlord in writing of a flat battery or a malfunction. The landlord may inspect once a year.

In Wallonia, the regulations have been in force since 2004. The Order of 21 October 2004 requires one detector per level containing a living room, two if the level’s usable floor area exceeds 80 m². Detectors must be optical, compliant with standard NBN EN 14604 and guaranteed for five years. Article 4bis of the Walloon Sustainable Housing Code puts purchase, installation and replacement on the owner. The occupant maintains them and reports any malfunction without delay.

In Flanders, smoke detectors are mandatory in all dwellings, including student rooms, on every level, with the CE marking and standard NBN EN 14604. When letting, the landlord must buy and install them. If they choose replaceable batteries, the tenant replaces them in time. Since an Order of 14 October 2022, a detector is also required in every shared-use space.

What schedule should a portfolio follow before October?

  1. Sort the units by region and fuel, with the date of the last inspection.
  2. Ask tenants for the certificates: in Wallonia, the user must provide them without delay to the owner who asks.
  3. Reread the heating clause of Brussels leases: without a written lease, or if the lease puts the inspection on the landlord, it is up to the landlord to act.
  4. Inventory the detectors: installation date, expiry date, replaceable batteries or ten-year battery, interconnection in Brussels.
  5. Plan the end-of-lease sweep in Brussels leases that are ending.

Sweeping and boiler maintenance are also checked at move-out; our article on the digital inventory explains what it is worth as evidence. Flemish kots fall under the detector obligation, as our comparison of the three kot leases recalls. For Walloon oil boilers, see also the Walloon energy roadmap.

How does Seido help organise these visits?

Managing several properties? Seido sends the job to your own heating engineer, on their phone, with no app to install. They accept, propose a slot, and upload their quote and photos. Each document comes back into the unit’s file, timestamped, and you follow up without chasing. See the contractor portal.

Frequently asked questions

Does the tenant have to pay for boiler maintenance?

As a general rule, yes. The three regional lists of tenant repairs put maintenance and periodic inspection on the tenant. In Brussels, the EPB inspection of a gas boiler falls to the tenant if a written lease does not explicitly put it on the landlord. In Wallonia and Flanders, the orders target the user of the installation. Replacing a worn-out or defective boiler remains with the landlord.

How often must a gas boiler be inspected in Wallonia?

Every three years when the useful rated output is 100 kW or less, every two years above that. This is Article 13 of the Order of 29 January 2009. Oil and solid-fuel boilers must be inspected every year. The inspection is carried out by an approved technician, and the tenant keeps the last two certificates.

Who replaces a smoke detector in Brussels?

The landlord. The Order of 28 September 2023 makes them bear purchase and installation, and replacement at the latest on the expiry date indicated by the manufacturer, or earlier if the device is defective. The tenant must notify the landlord in writing of a prematurely flat battery or a malfunction. The Brussels tenant repairs list leaves battery replacement to the tenant where needed.

Is chimney sweeping annual in Wallonia?

The Order of 29 January 2009 sets no specific sweeping frequency in its body text. The 2018 list of tenant repairs provides for sweeping with the annual maintenance of oil boilers, and annual sweeping for open fireplaces. Unless otherwise agreed, it is borne by the tenant, who gives the professional’s certificate to the landlord.

Sources and references

Last updated: September 2026. This article is provided for information purposes only and does not constitute legal advice. For any specific situation, consult a real estate law professional.