Empty Rooms, Real Money: What a Void Period Actually Costs During a Refurb

Most people budget the build. Far fewer budget the gap — the weeks between the last tenant handing back the keys and the first new one walking in. That gap has a price tag, and in our experience it's usually bigger than the spreadsheet suggests.

So let's talk about the void properly.

The void isn't a footnote, it's a line item

A void period is a running cost. It ticks along daily, whether the plasterer turns up or not. Every week the place sits empty, you're paying for the mortgage or the rent on it, the council tax, the insurance, the standing charges and a certain amount of security. None of that pauses because the kitchen units are late.

If you're a property manager juggling a small portfolio, this is the number that quietly eats the margin. If you're a homeowner doing a one-off refurb, it's the number that makes you wonder whether the project was worth it at all. Either way, the fix is the same: work out the weekly cost of empty, then treat it as part of the programme.

Council tax: the bit everyone gets wrong

The old idea that an empty property is automatically exempt died years ago. In England, the empty homes premium has been tightening — since April 2024 a property can attract a 100% premium after twelve months empty, rising to 200% after five years and 300% after ten. Wales and Scotland run their own timetables, and some councils are quicker off the mark than others.

There are also genuine discounts for properties that are uninhabitable or undergoing major repair, but they vary wildly from one authority to the next. Some will knock a chunk off for a set period; others won't budge. The only reliable move is to ring the council's revenues team, say plainly what you're doing and for roughly how long, and ask what applies. Get the answer in writing if you can.

One more thing: nobody at the council is watching your property for you. You have to tell them it's empty. Assume silence is billed at full whack.

Insurance: read the small print before the kitchen comes out

This is where people get properly stung. A standard landlord or buildings policy often has a clause about the property being unoccupied for more than thirty or forty-five consecutive days, or undergoing structural works. Breach it and you may find your cover is restricted or gone entirely — usually discovered at the worst possible moment.

What you want is either a vacant property endorsement or a dedicated unoccupied policy. Expect to pay more, and expect conditions attached to it: inspections every week or fortnight, water drained down, gas and electric isolated, all openings secured, alarm maintained and monitored, key holder details logged, no hot works without a permit.

Don't be tempted to just cancel the cover and save the premium. A property stripped back to brick is exactly when you need fire, flood, theft and public liability cover. A leak through a ceiling into the flat below is a four-figure problem you don't want to fund yourself.

Standing charges don't stand still

Small stuff, but it adds up. Gas and electricity standing charges carry on even with nothing running. Water and wastewater charges may still apply depending on metering and whether the supply is live. If you keep broadband on for site wifi, that's another monthly. None of these will sink the project on their own, but over a twelve-week strip-out they're real money — and they're the lines nobody puts in the quote.

Security, and the 'it's empty so nobody's watching' problem

The emptier a building gets, the more interesting it becomes to the wrong people. Copper, boilers, lead, tools, even the odd bit of reclaimed timber. Boarding up, a monitored alarm, decent locks, a site lockup and a key safe are all sensible. So is asking the neighbours to keep half an eye out — a five-minute conversation is cheaper than any CCTV package.

Many insurers will insist on some of this anyway, so check the policy conditions before you decide what to install.

Programme slippage: the expensive half of the story

Here's the bit that really bites. Overruns don't just cost extra labour and materials — they extend the void. Let's put rough numbers on a two-bed terrace in a mid-sized town:

• Mortgage or rent on the property: around £1,000 a month, so roughly £230 a week
• Council tax at band B, no discount: call it £170 a month, £40 a week
• Insurer's vacant property uplift: perhaps £300 over the project, £20 a week
• Standing charges and a bit of site power: £25 a week
• Security and periodic visits: £30 a week

That's around £345 a week before you've counted a penny of lost rent. Add the rent you would have been collecting — say £950 a month, £220 a week — and you're at £565 a week of empty. Six weeks of slippage is nearly £3,400, and that's before the scaffold hire gets extended and the skip gets swapped one more time.

Put like that, a fortnight's delay stops being an inconvenience and starts being a decision.

Building a void budget in half an hour

1. Set a realistic start and finish date, then add 15–20% to the duration. Not the cost — the duration. Builds overrun in time far more often than they overrun in price.
2. Add up the monthly fixed costs, divide by 4.33, and write the weekly number down.
3. Ring the council and ask what happens to the council tax, and when.
4. Ring the insurer and ask what the policy says about unoccupied periods and works.
5. Price the security you actually need, not the fantasy package.
6. Put the weekly figure at the top of every progress meeting agenda.

Where people get caught

The pattern is nearly always the same. The council wasn't told. The insurer wasn't told. The boards went up three weeks after the tools came out. And the programme was written as if the building were the only thing that could go wrong.

A void period that's been priced properly does something useful: it makes the whole project easier to judge. If the numbers only work over fourteen weeks and the build realistically needs twenty, better to know that now than to find out in March.