A Dacorum HMO appeal has succeeded in part after an Inspector confirmed that changing a house in Kings Langley from Class C3 to a six-person Class C4 house in multiple occupation would be lawful, while refusing to certify associated building alterations. The distinction turns on two different permitted development routes and the effect of existing planning conditions.
The decision, issued on 8th October 2026, relates to 1 The Orchard, Kings Langley. Kedgling Developments challenged Dacorum Borough Council’s December 2025 refusal to issue a certificate of lawful proposed use or development for internal layout alterations, two external doors and a change from a dwellinghouse to a six-person HMO.
Inspector J Moss allowed the appeal only for the change of use. She concluded that the proposed door openings could not be established as lawful under Part 1 Class A, taking account of Article 3(4) of the General Permitted Development Order and outstanding evidence about the permissions governing an unfinished rear extension. The internal changes were also excluded from the certificate.
Unsure whether an HMO or alteration is lawful?
Dacorum HMO appeal separates use from building works
The application was made under section 192 of the Town and Country Planning Act 1990, which allows an applicant to seek formal confirmation that proposed development would be lawful if begun at the relevant time. Unlike an application for planning permission, the certificate is determined on lawfulness, not whether the development is desirable in planning terms.
The proposal combined three elements: internal layout changes, insertion of two doors and a change from Class C3 to Class C4. Dacorum refused the certificate as a whole. On appeal, the Inspector identified separate questions for the building works and the change of use.
This distinction is important because a single application description does not necessarily make all its elements legally inseparable. The Inspector ultimately concluded that the Class C4 change of use was genuinely severable from the works. She could therefore issue a partial certificate for the use alone, even though the application had described the measures together.
Why the two proposed doors failed the lawfulness test
The doors were to be inserted into the side elevation of a rear outrigger. The appellant argued that Part 1 Class A of Schedule 2 to the General Permitted Development Order 2015 permitted the external alterations as an improvement or other alteration of a dwellinghouse.
Dacorum pointed to Article 3(4), under which permitted development rights do not authorise works contrary to conditions imposed on relevant planning permissions. The dispute therefore required careful consideration of which permission actually controlled the rear part of the building and whether the applicable conditions had been complied with.
The appellant relied on a 2023 householder permission, reference 23/02402/FHA, and argued that earlier permissions had ceased to govern the site. The Inspector rejected the suggestion that the newer permission necessarily displaced the earlier approvals. She found that the 2023 consent did not appear to authorise the rear outrigger, and that the earlier 2021 permissions remained material.
That conclusion also disposed of the argument based on the Pilkington principle and the Supreme Court’s Hillside judgment. The Inspector did not find the later scheme incompatible with implementation of the earlier permissions in the way advanced by the appellant. One planning permission did not automatically wipe away the conditions governing a separate element of the property.
The Inspector had not been provided with all the earlier permission documents. But the burden of proving lawfulness remained with the appellant. She could not be satisfied that the approved-plans condition relating to the rear outrigger had been discharged, particularly given the apparent state of the unfinished works.
A plans condition does not permanently remove Class A rights
An important qualification in the decision is that compliance with an approved-plans condition may matter as much as the condition’s wording. The Inspector accepted in principle that a requirement to carry out development in accordance with approved plans does not indefinitely prohibit future Class A permitted development once the original scheme has been properly carried out.
However, the evidence suggested that the rear extension had not been completed in accordance with the permissions controlling it. In those circumstances the proposed new doors could still conflict with the underlying condition, so Article 3(4) prevented reliance on Class A.
The practical lesson is not that every approved-plans condition removes all future permitted development rights. Nor is it that later work automatically becomes lawful once an applicant has started building an authorised extension. The approved works, compliance position and precise permission chain must be established before further alterations can safely rely on the GPDO.
For applicants purchasing or modifying a partially completed building, this can create a material due-diligence issue. A lawful use certificate should not be treated as a substitute for checking the planning history, approved drawings and conditions affecting structural or external works.
Class L made the six-person HMO use lawful
The proposed change from Class C3 dwellinghouse to Class C4 HMO was different. Part 3 Class L provides a permitted development route for certain changes between those classes, subject to applicable restrictions. Dacorum itself had indicated that the C3 to C4 change of use would be lawful, notwithstanding its concerns about physical works.
The Inspector saw no reason to depart from that position. The certificate therefore records that a change to a six-person HMO would have been lawful on the application date, 15th October 2025, if carried out then. That does not mean the decision grants planning permission for the two proposed doors or establishes the lawfulness of all physical alterations.
It is also not a ruling that any dwelling can become an HMO regardless of location. Article 4 Directions may remove the relevant Class L right in designated areas and other site-specific restrictions can be decisive. Practitioners must check the direction in force on the relevant date and the actual proposed number of occupiers.
The appeal illustrates why it is useful to separate the planning status of a proposed use from the lawfulness of works intended to accommodate it. Lawful use may be established even when the alteration needed to make that use practicable requires its own planning permission.
The limits of a partial section 192 certificate
The Inspector distinguished section 192, for proposed development, from section 191, which concerns existing uses and operations. The latter provides broader express powers to modify or substitute a description when certifying existing development. A section 192 application is more tightly tied to what was described in the original application.
Even so, where distinct parts of a proposal are genuinely severable, the Inspector concluded it is possible to grant a certificate only for the lawful element. The appeal submissions made clear that the change of use could be separated from the building works, notwithstanding the initial composite description.
The formal decision therefore allowed the appeal for C3 to C4 use only and dismissed it for the internal layout alterations and insertion of two doors. The issued certificate gives the lawful proposed use, its statutory basis and the particular land to which the decision applies.
This is an Inspector’s appeal decision rather than a court judgment. It provides a useful worked example but does not establish binding new law. The outcome also depended on the incomplete permission documents and the evidence the appellant put forward.
Why this matters to homeowners and HMO operators
A development team seeking to maximise a building’s occupation needs to establish three separate matters: whether the use itself is lawful, whether the required physical works have permission, and whether the building can meet applicable licensing and safety obligations. A positive answer to the first question does not answer the others.
For a consultant preparing an application under section 192, separate applications or clearly severable descriptions may sometimes make the certificate issue easier to determine. There is nevertheless no guarantee of a split decision. The actual proposed development and its planning history control the result.
Before relying on an assumed Part 1 right, obtain the full decision notices and approved plans for each permission affecting the relevant part of the building. Check whether the works were implemented in accordance with the approved drawings and whether any express removal of permitted development rights applies.
The primary decision is APP/A1910/X/26/3377958 on Appealbase. The underlying Planning Inspectorate reference is 3377958. For the legal framework see the GPDO Schedule 2 and Planning Practice Guidance on lawful development certificates. For further background see Planning Geek’s HMO guidance and permitted development resources.
0 Comments