Bringing a London property up to HMO licensing standard rarely comes down to one figure, since the cost depends on how far the property already is from the standard your borough's scheme requires. A property that only needs fire doors, interlinked alarms and some fire-stopping is a relatively contained job, typically £2,000 to £10,000 depending on the action list. A property needing partition changes to correct undersized rooms, or a new kitchen or bathroom added to meet amenity ratios, costs considerably more once plumbing, electrics and structural work are factored in, often running to £20,000 or more for a full conversion. Licence fees themselves are set and collected by your local council, not by Lian Construction, and vary by borough and scheme, so this guide focuses on the building works cost and points you to your council for the fee itself. Lian Construction carries out the physical works that get a property licence-ready; we don't submit licence applications or make licensing decisions.
HMO compliance cost in London: the full picture
HMO compliance cost splits broadly into three categories, fire safety works, room and amenity reconfiguration, and the documentation and certification a council expects to see, and most properties need some combination of all three rather than just one. Fire doors, interlinked alarms and emergency lighting track the same rates set out in our fire safety compliance cost guide. Where rooms need to be resized or reconfigured to meet minimum floor areas, a standard timber stud partition typically costs £180 to £280 per linear metre, rising to £320 to £480 per linear metre for an HMO fire-rated partition, in line with our partition wall cost guide.
Where an existing property falls short on kitchen or bathroom provision, adding a second shower room into an understairs void or a former store is broadly similar in scope and cost to the mid-range small ensuite figures in our bathroom renovation cost guide, £6,000 to £9,500, though a genuinely new position with no existing waste run nearby can push this towards the top of that range or beyond, depending on how far the waste has to travel to reach the stack. A basic kitchenette built to satisfy an amenity ratio, rather than a full kitchen renovation, typically costs £4,000 to £8,000, covering a worktop, sink, cooker point, storage and mechanical extraction, well below the specification and cost of a full kitchen refit covered in our kitchen renovation cost guide.
HMO stairwell and corridor emergency lighting, 4–6 fittings
£600–£1,100
Timber stud partition, correcting room size (per linear metre)
£180–£280/lm
HMO fire-rated partition (per linear metre)
£320–£480/lm
Adding a doorway within a new partition
£250–£450
Second shower room, built into existing void
£6,000–£9,500
Basic kitchenette to meet amenity ratio (not a full kitchen)
£4,000–£8,000
Fire-safety-only compliance programme, modest action list
£2,000–£5,000
Full HMO conversion, partition, amenity and fire safety works combined
£20,000+
Figures are general London market guidance only, not a fixed Lian Construction quote, and exclude HMO licence fees, which are set and collected by your local council rather than by Lian Construction. Request a free survey for pricing specific to your property.
Licence fees: set by your council, not by Lian Construction
It's worth being direct about this, since it's a common point of confusion: the HMO licence fee itself, whether under a mandatory, additional or selective scheme, is set and collected by your local borough council, not by Lian Construction or any other contractor. Fees vary considerably between London's thirty-two boroughs plus the City, and can change when a scheme is renewed, so a figure quoted for a licence application a few years ago, or in a different borough, shouldn't be assumed to still apply.
We deliberately don't state specific licence fee amounts in this guide, since anything printed here risks being wrong or out of date for a specific borough by the time it's read. Your council's own housing or private rented sector pages are the reliable source for the current fee, and our HMO licence requirements guide sets out how mandatory, additional and selective licensing differ, which is worth reading alongside this cost guide before budgeting for the licence itself.
Fire safety works: the most common starting point
Fire separation is consistently the most common compliance gap councils flag at inspection, missing or degraded fire doors, unsealed penetrations through ceilings and walls, and battery-only alarms that aren't interlinked to the standard most boroughs expect. For a property that's otherwise in reasonable condition and just needs fire doors, alarms and some fire-stopping, this is often the whole of the compliance budget, typically £2,000 to £5,000 for a modest action list.
Our fire safety compliance cost guide breaks these figures down item by item, fire doors, alarms and emergency lighting, and is worth reading alongside this guide where fire safety is the main gap rather than room sizes or amenity provision.
Correcting room sizes: partition costs
Under the national mandatory HMO licence conditions, a bedroom occupied by one person aged 10 or over needs a minimum floor area of 6.51 square metres, two adults sharing a room need 10.22 square metres, and a room used by a single child under 10 needs at least 4.64 square metres. Some boroughs running additional or selective schemes apply their own standards on top of these, occasionally higher, so it's worth checking the specific scheme covering the property rather than treating the national minimum as final, our HMO licence requirements guide covers this in full.
Where a room falls short, the usual fix is either absorbing space from an adjoining boxroom or alcove by moving a partition, or splitting an oversized double room into two compliant singles with a new stud wall. A standard timber stud partition typically costs £180 to £280 per linear metre, and an HMO fire-rated partition, using two layers of plasterboard with staggered joints and mineral wool, typically costs £320 to £480 per linear metre, our partition wall cost guide sets out the full breakdown by partition type.
Adding a kitchen or bathroom to meet amenity ratios
Most councils expect one kitchen for up to five sharing tenants and one bathroom or WC for every four to five occupants, with a minimum number of cooking rings, an oven, a sink and adequate worktop space scaled to occupancy. Where an existing property falls short, the usual fix is adding a facility rather than reducing bedroom count, and a second kitchen or shower room fitted into an understairs void or a former coal store is a common solution in Victorian terraces.
A new shower room built into a void with no existing plumbing is broadly comparable in scope to a mid-range small ensuite, £6,000 to £9,500 per our bathroom renovation cost guide, though the absence of any existing waste run can push cost toward the top of that range. A basic amenity kitchenette, sized to satisfy a licensing ratio rather than serve as a full kitchen-diner, typically costs £4,000 to £8,000, well below the £6,000 to £10,000 starting point for even a budget flat-pack kitchen refit in our kitchen renovation cost guide, reflecting the smaller, simpler scope.
EICR, gas safety and other documentation costs
Beyond fire safety and room standards, councils typically expect a current Electrical Installation Condition Report with no outstanding serious faults, a valid annual Gas Safety Record for any gas appliances, and evidence of portable appliance testing on any landlord-supplied white goods in shared kitchens. Where an EICR flags an old rewirable fuse board, missing RCD protection or unearthed lighting circuits, common in properties that haven't been rewired since an older conversion, we bring in a qualified electrician to remedy those items alongside any partition or fire safety works already underway.
We don't price EICR or gas safety inspections themselves, since these are separate qualified trades' certifications rather than building works, and the cost of any electrical remedial work depends entirely on what the inspection finds. Where we're already opening up walls or ceilings for partition or fire-stopping works, coordinating electrical remedial work in the same visit is usually more efficient than a separate call-out later.
Typical total cost by scenario
A property that's already reasonably close to standard, mains-wired alarms already in place, decent-sized rooms, but a handful of fire doors needing certification, typically sits at the lower end of the overall range, £2,000 to £10,000, since the work is mostly fire safety items rather than structural change.
A property needing genuine reconfiguration, two or three undersized rooms split or resized with new partitions, a second bathroom or kitchen added for amenity ratio, plus the fire safety works most conversions also need, typically runs to £20,000 or more once plumbing, mechanical extraction, electrical work and matching decoration are all accounted for. The gap between these two scenarios is almost entirely about how far the existing property is from the standard, not its overall size.
Timeline for HMO compliance work
A property needing only fire doors, alarms and some fire-stopping can often be costed and scheduled within a matter of weeks once survey and pricing are agreed. Where partition walls need to move or a bathroom or kitchen is being added from scratch, the programme extends considerably once plumbing, electrical first and second fix, plastering and matching decoration are sequenced properly.
Structural changes, removing a load-bearing wall to reconfigure a floor, for example, add both cost and time for building control sign-off, since calculations from a structural engineer and inspection at set stages are needed regardless of how quickly the physical work itself could otherwise be done. We survey the property first and give a realistic programme once the specific scope is confirmed, rather than a generic timeframe based on property size alone.
What Lian Construction does, and what stays with the council or the assessor
We survey a property against the fire safety and room standards that apply, then price and carry out the building works needed to get it licence-ready: fire doors, interlinked alarms, emergency lighting, partition changes to correct undersized rooms, and adding kitchens or bathrooms where amenity ratios fall short. We provide photographs, product certificates and a written specification of completed works, which landlords typically submit alongside a licence application or show an inspecting officer at the first visit.
We don't submit HMO licence applications ourselves, since that involves personal declarations, fit and proper person checks and financial details we're not party to, and we don't set or collect licence fees, which come from the council. We also don't carry out fire risk assessments or decide what a specific council will accept at inspection. What we do is make sure the physical property, once we've finished, actually meets the standard an inspecting officer will check against, our HMO compliance London and fire safety compliance London teams cover this end to end.
Questions
Frequently asked questions
How much does it cost to bring a property up to HMO standard in London?
It depends on how far the property is from standard. A property needing mainly fire doors, alarms and some fire-stopping typically costs £2,000 to £10,000. A property needing partition changes to correct room sizes plus a new kitchen or bathroom for amenity ratio typically runs to £20,000 or more once plumbing, electrics and matching decoration are accounted for.
How much are HMO licence fees?
Licence fees are set and collected by your local borough council, not by Lian Construction, and vary considerably between London's boroughs and by scheme, mandatory, additional or selective. Fees can also change when a scheme is renewed, so it's worth checking your specific council's current published fee directly rather than relying on a general figure.
Does Lian Construction submit our HMO licence application?
No. Licence applications involve personal declarations, fit and proper person checks and financial details we're not party to, and are normally submitted directly by the landlord or their letting agent. We carry out the building works the licence conditions require and provide photographs, certificates and a written specification of completed works that typically get submitted alongside the application.
How much does it cost to fix undersized HMO bedrooms?
A standard timber stud partition, used to absorb space from an adjoining room or split an oversized double into two compliant singles, typically costs £180 to £280 per linear metre, rising to £320 to £480 per linear metre for an HMO fire-rated partition. The overall cost depends on how many rooms need reconfiguring and whether doorways need forming or moving.
How much does adding a second kitchen or bathroom cost?
A second shower room built into an existing void, such as an understairs space or former store, is broadly comparable to a mid-range small ensuite, £6,000 to £9,500. A basic kitchenette sized to meet an amenity ratio, rather than a full kitchen-diner, typically costs £4,000 to £8,000.
Do all HMOs need the same amount of compliance work?
No. Two similarly sized properties can need very different amounts of work depending on when they were last rewired, how the loft and floor voids were left by previous alterations, and whether room sizes already meet the applicable standard. A survey against the specific scheme covering the property is the only reliable way to scope the work.
Can HMO compliance work happen with tenants in place?
In many cases yes, particularly fire doors, alarms and fire-stopping, which we can schedule room by room with notice. More disruptive works, such as major partition changes or adding a new bathroom, are easier to carry out with the room temporarily vacant.
How long does a full HMO conversion take?
A property needing only fire doors, alarms and fire-stopping can often be turned around in a matter of weeks. A full conversion involving new partitions, a new kitchen or bathroom, and any structural work needing building control sign-off takes considerably longer, and we give a realistic programme once the survey confirms the specific scope.
Where can I find the fire safety cost breakdown separately from the wider HMO compliance picture?
Our <a href='/blog/fire-safety-compliance-cost-london'>fire safety compliance cost guide</a> covers fire doors, alarms, emergency lighting and fire-stopping in detail, useful where fire safety is the main gap on a property that already meets room size and amenity standards.
Get a free, no-obligation quote from Lian Construction
Send the site address, photos if available, and a short description of the work. Lian Construction surveys London properties in Kingston upon Thames and across all boroughs, then provides a clear written quote before any work starts.