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Have you bought the flat next door and want to turn the two into one larger home? Or do you own a four-bedroom flat you would like to divide into two smaller ones to let? Either way, you are changing the make-up of a building under horizontal property, and Portuguese law treats the two operations very differently. Joining and dividing units is governed by article 1422-A of the Civil Code, but also involves planning rules, a deed and registration. In this guide we explain, under the law in force in 2026, when you need the condominium’s consent, which steps to follow and what changed with the revision of the building works regime.
In short
- Joining adjoining units does not need the consent of the other owners (article 1422-A(1)).
- For storerooms and garages, the units do not have to adjoin (paragraph 2).
- Dividing a unit is only possible if the constituting deed allows it or the general meeting approves it with no opposition (paragraph 3).
- The deed is amended by a unilateral act, in a public deed or authenticated private document, and the administrator must be told within 10 days (paragraphs 4 and 5).
- The works needed follow the RJUE, revised by Decree-Law 108/2026, in force since 1 October 2026.
Joining units: when no consent is needed
The rule is in the Civil Code:
«1 – Não carece de autorização dos restantes condóminos a junção, numa só, de duas ou mais fracções do mesmo edifício, desde que estas sejam contíguas.» — Civil Code, article 1422-A(1)
In plain English: you do not need the other owners’ permission to join two or more units of the same building into one, as long as they adjoin. Adjoining units share a boundary, side by side on the same floor or one above the other on consecutive floors. For storerooms and garages, this requirement is waived (paragraph 2): you can join your flat to a garage in the basement, for example.
However, joining units cannot be used to take over common parts. If connecting the units means occupying a landing or a common wall, it is no longer simply joining: it is a change to the common parts, which needs a decision of the general meeting and, possibly, an amendment of the deed with everyone’s agreement (article 1419). Our guide to new horizontal property guidelines covers the wider framework.
Dividing a unit: a stricter rule
Dividing a unit into new independent units increases the number of owners and changes the votes and the sharing of costs. That is why the law only allows it in two situations (article 1422-A(3)):
- When the constituting deed already allows the division.
- When the general meeting approves it with no opposition.
A single vote against is enough to block a division if the deed does not provide for it. Read more about the majorities required at general meetings.
| Operation | Condominium consent | Main requirement | Amendment of the deed |
|---|---|---|---|
| Joining adjoining units | Not needed | Units must adjoin | Unilateral act, public deed or authenticated document |
| Joining with a storeroom or garage | Not needed | No need to adjoin | Unilateral act, public deed or authenticated document |
| Dividing a unit | Deed or meeting with no opposition | Prior authorisation | Unilateral act, public deed or authenticated document |
| Occupying common parts | Meeting and everyone’s agreement | Amendment of the deed | Public deed or authenticated document signed by all |
Step by step
- Check the constituting deed and the land registry certificate for the units.
- Dividing: obtain authorisation in the deed or in a meeting decision with no opposition, recorded in the minutes.
- Works: confirm the planning position with the municipal council (see the next section).
- New permillage: set the relative value of the resulting units. When joining, the permillages are usually added together; when dividing, the original unit’s permillage is split. Read more about permillage.
- Public deed or authenticated private document: the owner who joined or divided the units amends the deed by a unilateral act (paragraph 4).
- Notice to the administrator: within 10 days (paragraph 5).
- Registration: update the land registry, through the registry services, and the tax register.
Works and the municipal council: what changed in 2026
Joining or dividing usually involves works: opening or closing doorways, creating a new entrance, separating water, gas and electricity installations. With the revision of the RJUE (the legal regime for urban development and building) by Decree-Law 108/2026, in force since 1 October 2026, alteration works inside buildings or units are exempt from a licence and prior notification, provided that:
- they do not involve external changes affecting the physical or aesthetic features of the building (heights, façades, roofs or coverings); and
- they do not affect the building’s structural stability or, if they do, are accompanied by a stability design and a statement of responsibility from a qualified technician, lodged with the notice that works are starting.
Even for exempt works, the developer must inform the municipal council up to five days before work begins (article 80-A of the RJUE, as amended). Works that touch the façade also need the general meeting’s authorisation by two-thirds of the building’s value (article 1422(3)). See our guide to building works that need the city council’s authorisation.
When dividing, each new unit must meet the legal requirements for an independent dwelling. Check with the municipal council which documents are needed to amend the horizontal property.
Effect on charges and votes
After joining, the new unit pays charges and votes with the combined permillage. After dividing, each new unit has its own permillage, charge and votes (article 1430). The administrator should update the table of charges once the deed is notified. Works inside the unit must also respect the noise rules: only on working days, from 8 am to 8 pm (article 16 of the General Noise Regulation). See noise in the condominium: what are the rules.
Checklist
- Units adjoin, or the extra unit is a storeroom or garage.
- Authorisation for a division (deed or meeting with no opposition).
- Planning position of the works confirmed with the council and, if needed, a stability design.
- Notice of start of works to the council up to five days in advance.
- Public deed or authenticated document with the new composition and permillage.
- Notice to the administrator within 10 days.
- Land registry and tax register updated.
How Condoroo helps
Condoroo manages more than 600 condominiums, including buildings with more than 300 units, with a team of more than 20 professionals. On the condominium side, we prepare the general meeting when a division is proposed, record the notice of the deed and update the table of permillages, charges and votes.
Joining and dividing units: frequently asked questions
Do I need the condominium's consent to join two flats?
No, if they adjoin (article 1422-A(1) of the Civil Code). You must send the deed to the administrator within 10 days.
Can I join my flat to a garage on another floor?
Yes. For storerooms and garages, the units do not have to adjoin.
Can I divide my flat into two?
Only if the constituting deed allows it or the general meeting approves it with no opposition.
Do works to join units need a council licence?
Interior works with no external impact are exempt from a licence, provided they do not affect stability or have a stability design. Even when exempt, the council must be told up to five days before work starts.
What happens to the permillage after joining units?
The new unit usually has the combined permillage of the units joined, which affects charges and votes.
Who amends the constituting deed?
The owner, by a unilateral act in a public deed or authenticated private document.
This article is for information only and does not replace legal advice on your specific case. Legislation checked on 26 October 2026.
