Hong Kong Minor Works (小型工程): Class, Contractor and Submission Checklist

The Minor Works Control System (小型工程監管制度), or MWCS, is the Buildings Department’s simplified route for certain small-scale building works. It divides designated minor works into Class I, Class II and Class III according to their nature, scale, complexity and safety risk. Start with the Buildings Department overview, then identify the exact work item before appointing anyone.

Start with the exact work, not the contractor label

A room name such as “kitchen renovation” does not classify the work. Neither does a trade label such as “plumbing” or “window work.” One project can contain several tasks that follow different routes.

Write a separate scope line for each proposed alteration. Record its location, dimensions, material, support or fixing method, and whether it may affect structure, fire-resisting construction, an external wall or drainage. The Buildings Department says classification turns on the substance of the proposed work and directs readers to choose among the exact minor-work items with help from a prescribed professional or registered contractor where needed. See its submission FAQ.

Ask the proposed appointee to state the class, type and item number in writing. That gives you something precise to compare with the official item description and contractor register.

Separate exempt work, minor work and the full approval route

Do not assume that every alteration uses MWCS. The first check is which of these three routes fits each task.

Route	What the official guidance says	Owner’s next check
Exempt household work	The Buildings Department gives plastering, tile laying, and repair or replacement of sanitary fitments as examples that can proceed without prior approval or registered appointments, while still having to comply with relevant building regulations. Domestic alterations FAQ	Confirm that the actual scope stays within the exempt example and does not affect another controlled element.
Designated minor work	An exact item under MWCS follows the simplified route, with appointments and submissions determined by its class. MWCS overview	Record the exact class, type and item, then verify every appointed person against that scope.
Structural work on the full approval route	For work involving structure, such as removal or alteration of a structural wall, beam or column, the Buildings Department says the owner is required to appoint an Authorized Person and Registered Structural Engineer, submit plans, obtain approval and consent, and use a registered contractor. Domestic alterations FAQ	Pause the renovation instruction and obtain project-specific professional advice before work starts.

A wall described as a partition on a quotation may still need checking against approved plans and the building’s actual construction. Classification should come before demolition, not after it.

Use a Class I, II and III responsibility table

This table summarises the current Buildings Department procedure. “PBP” means prescribed building professional, and “PRC” means prescribed registered contractor.

Class	Who must be appointed	Before work	After completion	What the owner should retain
Class I	Prescribed building professionals for design and supervision, plus a PRC for execution. Submission FAQ	MW01 and supporting material at least 7 days before commencement. Procedure	MW02 and completion material within 14 days after completion. Procedure	Appointment details, register results, submitted MW01 and MW02 copies, plans or particulars, photographs and acknowledgement correspondence.
Class II	A PRC to prepare and submit the documents, supervise and carry out the work. Submission FAQ	MW03 and supporting material at least 7 days before commencement. Procedure	MW04 and completion material within 14 days after completion. Procedure	Appointment details, register results, submitted MW03 and MW04 copies, plans or particulars, photographs and acknowledgement correspondence.
Class III	A PRC to prepare and submit the documents, supervise and carry out the work. Submission FAQ	The Class III procedure does not list a pre-work form. Procedure	MW05 with plans or a work description and photographs within 14 days after completion. Procedure	Appointment details, register results, submitted MW05 copy, work description or plans, photographs and acknowledgement correspondence.

Use the table only after an appointee has matched the work to an exact item. It is a submission checklist, not a classification tool.

Find the exact type and item

The three classes describe risk and complexity. Within them, the Buildings Department groups work into eight types: A, Alteration and Addition; B, Repair; C, Signboards; D, Drainage; E, Structures for Amenities; F, Finishes; G, Demolition; and H, Ventilation System inside Building. The official types page also says the contractor’s registration has to correspond to the relevant type or item.

The type is still not the final answer. Ask for the exact item number and compare the proposed dimensions, location, construction and conditions with that item. If the scope changes during quotation or site work, repeat the item check for the changed work.

Put the result into the quotation or appointment document in a compact form:

work description and location;
MWCS class, type and exact item number;
legal name and registration number of each appointee;
who prepares each submission and gives you the final copy.

For a fuller explanation of the roles, use the designer, contractor and registered-specialist guide.

Verify each appointed person in the official register

Ask for the legal name and registration number rather than relying on a shop name or website label. Open the Buildings Department’s Registered Professionals or Contractors search, select the relevant company or individual register, and search the supplied details.

Match the result to the proposed work:

Confirm the displayed legal name and registration number.
Check the class and type, or the exact Class III item, against the written scope.
Check the displayed expiry date against the planned work period.
Save a dated copy or screenshot of the result with the project file.

The register also offers service and district filters, but those are search aids. The Buildings Department states that its lists are available for public inspection and are not government recommendations. Use the register to verify the recorded scope, not to infer workmanship or suitability.

Use a forms and timing table

Agree who prepares each form, who checks the attachments, and when the owner receives a copy. Use the official timing rather than a date supplied from memory.

Stage	Class I	Class II	Class III
Before commencement	MW01 with supporting material at least 7 days before commencement. Procedure	MW03 with supporting material at least 7 days before commencement. Procedure	No pre-work form appears in the Class III procedure. Procedure
After completion	MW02 with completion material within 14 days after completion. Procedure	MW04 with completion material within 14 days after completion. Procedure	MW05 with plans or a work description and photographs within 14 days after completion. Procedure

An acknowledgement is not a compliance approval. The Buildings Department says an acknowledgement letter records receipt after preliminary checking but does not state that the proposed work complies with the Buildings Ordinance. Its FAQ also says an acknowledgement is not required before Class I or Class II work begins under the simplified requirements. Submission FAQ

Retain one project evidence file

Keep one folder that connects the quoted work to the appointed people and the submitted records. A practical index is:

the final work description, drawings and exact MWCS item for each task;
signed appointment or quotation documents naming the PBP or PRC;
dated official-register results for each appointee;
plans, particulars and photographs supplied with the submission;
copies of MW01 or MW03 where applicable;
copies of MW02, MW04 or MW05 after completion;
Buildings Department acknowledgements and related correspondence;
a completion record showing the actual work and completion date.

Check that names and registration numbers are consistent across the forms and attachments. The Buildings Department’s submission FAQ tells submitters to enter the same name and registration number shown in the relevant register.

Use the directory only after defining the work

Once the scope and likely appointed role are clear, the Renovation.hk company directory can help form a shortlist by category and district. A directory category does not prove that a company holds the registration for your exact class, type or item. Complete that check in the Buildings Department register.

Give every shortlisted provider the same itemised scope. The quotation comparison guide shows how to align work descriptions and exclusions, while the renovation cost guide helps organise scope, unit rates, payment milestones and regulated-work evidence. Neither price nor a directory position replaces the official registration check.

Common questions

How many classes are in the Minor Works Control System?

There are three: Class I, Class II and Class III. The Buildings Department classifies them by the nature, scale, complexity and safety risk of the work. MWCS overview

Who handles each class of minor work?

Class I uses prescribed building professionals for design and supervision and a prescribed registered contractor for execution. For Classes II and III, the prescribed registered contractor prepares and submits the documents, supervises and carries out the work. Submission FAQ

Which forms and timing apply to each class?

For Class I, MW01 goes in at least 7 days before commencement and MW02 within 14 days after completion. For Class II, MW03 goes in at least 7 days before commencement and MW04 within 14 days after completion. For Class III, MW05 and its supporting material go in within 14 days after completion. Procedure

Does a Buildings Department acknowledgement mean the work is approved?

No. The Buildings Department says an acknowledgement letter does not state that the proposed minor work complies with the Buildings Ordinance. It should not be treated as a compliance approval or project-specific clearance. Submission FAQ

How do I check a minor works contractor?

Search the official register using the contractor’s legal name or registration number. Match the result’s class and type, or exact Class III item, and its displayed expiry date to the proposed work. The register is for public inspection, not a government recommendation. Buildings Department register

Does a Renovation.hk directory category prove MWCS registration?

No. The directory is a category-and-district shortlist surface. Verify the legal name, registration number and scope separately in the Buildings Department register.

What should I do if a wall may be structural?

Pause the instruction and obtain project-specific professional advice. For removal or alteration of a structural wall, beam or column, the Buildings Department says the owner is required to appoint an Authorized Person and Registered Structural Engineer, submit plans, obtain approval and consent, and use a registered contractor. Domestic alterations FAQ