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Converting to an HMO: Costs Involved

When I was starting out and assessing properties to convert to HMOs, one of my biggest frustrations was not understanding what the likely costs would be of carrying out the work to convert the property to what I wanted it to be.

I often viewed properties that required a quick decision on whether to make an offer, and I was hindered by what was an inability to quickly estimate what the costs would be to turn the property into what I wanted and needed it to be.

To help others who may be in the same position, I have written this blog which gives a ballpark figure for the various things you might need to do. I cannot emphasise enough that it is a ballpark – actual costs will depend on a number of factors, but at least it can give you a broad idea. We always work on high estimates, and then endeavour to get the work done for less, but at least that way we are not left with unpleasant surprises.


So, the first thing to consider is what you want to do, and what you need to do. Let’s look at the things you need to do first, as this is the minimum investment that is required:

Fire doors – as a minimum, the kitchen and each bedroom will require a 30 minutes (FD30) Fire Door.

The cost of the actual door is between £60 to £100 however they also need to be fitted with fire resistant door frames. The total cost per door (including fitting) should be budgeted at between £250 per door.

4 bed HMO: £1250

5 bed HMO: £1500

6 bed HMO: £1750

Smoke/Heat alarms – a heat alarm needs to be installed in the kitchen, and a smoke alarm in each hall and bedroom. The cost for supply and fit for each unit is £150. Always specify that you want wireless alarms interlinked with a lithium battery.

4 bed HMO: £1050

5 bed HMO: £1300

6 bed HMO: £1450


Now, onto the things that you may or not decide to do. How much work you carry out is subjective and will depend on factors such as your tenant profile and the location of your property etc. An HMO aimed at the “working professional” sector may require more investment that perhaps a property designed for LHA tenants.

I have prepared this article on the assumption that you already understand what you need to do to a particular property, and I have broken these costs down into different components.


Prices can vary hugely and its always worth shopping around. In general, I estimate that it takes around one man/day to decorate a room. This includes walls, ceiling and woodwork, but of course it really does vary and depends on how much preparation is required before painting. As a crude average, budget for £300 per bedroom including paint.

Top tips – use neutral colours and keep its simple. Retain extra paint at the property so it’s easy to touch up scuffs. Use wipe resistant paint.


Average pricing (including common areas)

1 bed HMO: £300-400

4 bed HMO: £1800-2500

5 bed HMO: £2500-2750

6 bed HMO: £2750-3000


Re-skim/plaster If your walls are old, you may want to consider a re-skim throughout the property. Or, if there is wallpaper everywhere, you need to budget for skimming as you won’t know what’s underneath. If on the other hand the walls are smooth and in good order, you could get away with just partially re-skimming certain areas. Often the walls will be fine, but if the ceilings have artex/textured ceilings and you may decide to just get these done in which case the price will be less.


1 room: £350-450 (ceiling only £175-250)

4 bed HMO: £2500-3000 (ceilings only £1250-1750)

5 bed HMO: £2750-3250 (ceilings only £1500-2000)

6 bed HMO: £3000-3500 (ceilings only £1750-2250)

Bathrooms and ensuites Every HMO is different. You might want to leave the house as it is, with the existing rooms sharing the existing bathrooms, or you might want to add ensuites to some or all of the bedrooms. I have broken the cost down into two categories – refurbishing an existing bathroom (new sanitary ware, tiling, decorating) and building a brand new ensuite which will include stud walls, plumbing and electrics.


Existing bathroom (full refurbishment): £3000-4000

Building a new ensuite: £4000-5000


Heating and Hot Water

This is a difficult area to qualify as there are so many variables, and it really depends on (a) what is already in place and (b) what you are going to create. I have based the below costings on a new system boiler set up with new boiler and new tank.

Top tip: If there is a decent combi boiler already in the property, you may get away with using this, even if you have four ensuite bedrooms. This should be sufficient as it is not usual for more then two people to us their shower at the same time. Please always take specialist advice.


4 bed HMO: £3000-3500

5 bed HMO: £2500-3500

6 bed HMO: £3000-4000


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The main kitchen suppliers are Howdens, Benchmarx, B&Q, Wicks and Magnet. These suppliers operate on a large mark-up. It’s important to get at least three quotes and negotiate as they will often match or better prices from their competitors.

Top tips: Always ask if carcasses are preassembled or flat-pack. If flat-pack, your fitting costs may be higher so bear this in mind. Consider solid laminate work tops as they are much better quality then standard laminate and half the price of composite or stone work tops.


Average pricing, including fitting

4 bed HMO: £5500-6000

5 bed HMO: £6000-7000

6 bed HMO: £6500-7500



We tend to use laminate throughout. We use insulation to ensure noise does not transfer between floors, however if you are nervous about this, then you can carpet the bedrooms upstairs.

Top Tip: Use hard-wearing carpet with think underlay.  Buy laminate flooring which comes with at least a 15-year guarantee and where the planks are a minimum of 10mm thick.


Average pricing (based on a combination of flooring and carpet)

4 bed HMO: £2000-2500 (supply and fit)

5 bed HMO: £2250-2750 (supply and fit)

6 bed HMO: £2500-3000 (supply and fit)

Building an extension or converting a garage

It may well be that you need to extend a property in order to gain more bedrooms, or that you need to expand common areas such as a kitchen or lounge area. Sometimes, this can be done by converting a garage, however you may also need to build a one or two storey extension. So how much might this cost? Numbers can vary hugely depending on things like location and other factors, but here is a broad indication which include up to plaster finish:

Garage Conversion

Without ensuite: £7500-12,500

With ensuite: £12,500-15,000


Single-storey extension

Ground floor extension costs around £1250-1500 per m2 to plaster finish. In London and surrounding areas, this could be much more. So, a 15 m2 rear ground floor extension would cost between £18,750 and £22,500.


Two-storey extension

As the foundations are already there, and the site is already set up, the cost of building an extra floor is normally around 70% of the cost per m2 of the ground floor. Based on 30 m2 extension (15 m2 ground and 15 m2 first -floor) the cost should be between £31,875 and £38,250 for the whole extension.

Electrical rewire

Always have an appraisal of the electrical set up within a property prior to starting any work. Rewiring is not only expensive, but its very disruptive and so its best to do whilst you are refurbishing rather than finding out you need to do it a few years after you have refurbished, which would likely involve undoing much of your good work to get new wires in.

4 bed HMO: £3000-4000

5 bed HMO: £3500-4500

6 bed HMO: £4000-5000


The above should cover the basic areas you may need to work on. As well as internally, you should also consider the outside. If there is parking space at the front, you may need to allow for gravel or paving if it’s not already there. With the advent of Covid-19, a good garden or outside area is increasingly important to tenants. It’s important to therefore not neglect these areas and invest to make them usable and attractive communal spaces for your tenants. We tend to allocate a budget of between £2000 and £4000 for the outside of the house.


NB: All prices quoted throughout the blog are correct as of August 2020