Red Flags When Viewing a Flat: The Ultimate UK Renter's Checklist

Most flat viewings last 20 minutes. That's not long to spot problems that could cost you thousands, make you ill, or trap you in a miserable tenancy. This checklist covers the physical red flags to look for, the questions to ask before you leave, and the landlord warning signs that are harder to spot than a damp patch but just as damaging.

What should I actually check for damp and mould?

Damp is the UK rental market's worst-kept secret. According to Citizens Advice, 45% of private renters in England are living with damp, mould, or excessive cold. In the private rented sector, 9% of homes have a damp problem, double the national average. Assume it might be there and look properly.

Where to look:

Around window frames and sills, where condensation collects first
The lower sections of external walls, for the tide-mark staining that signals rising damp
Inside wardrobes and behind furniture pushed against outside walls
Bathroom ceilings and behind the toilet
The corners where walls meet ceilings in older buildings

Don't just look. Smell the place. A musty, stale smell in a closed room is a reliable giveaway even when there's nothing visible. Feel the walls in the bedroom and living room, cool, slightly clammy plaster is a warning sign.

If you spot mould and the landlord or agent tries to blame the previous tenants' lifestyle, that's a red flag in itself. Government guidance is clear: damp and mould are not the result of lifestyle choices.

Check the windows too. Misted or cloudy double glazing means the seal has failed. That sounds minor but it means draughts and higher heating bills, and tells you how the landlord maintains the property.

How do I check the boiler and heating?

Ask to turn the heating on. Actually do it, don't just ask if it works. While you're at it:

Look at the boiler flame if it's a gas unit. It should be crisp blue. Yellow or orange means a potential combustion problem.
Listen for banging, gurgling, or whistling from the system.
Turn every radiator on and check they all heat up.
Ask when the boiler was last serviced.

If the property is electric-only heating, that's not automatically a dealbreaker, but you need to know going in. Electric heating is significantly more expensive to run than gas central heating, so factor that into your total monthly cost, not just the rent.

Ask to see the Gas Safety Certificate. Landlords in England are legally required to have a Gas Safe registered engineer inspect the property every 12 months and give you a copy within 28 days of the inspection. Vague excuses about it being "on the way" is a red flag.

Same goes for the Electrical Installation Condition Report (EICR). Landlords must have electrical safety checks done by a qualified electrician every five years. Ask for it.

Check the EPC rating too. By law, rental properties in England must be rated E or above. Anything below that is illegal to let. A band D or E property will cost you noticeably more to heat. From 1 October 2030, all rental properties will need to reach a C rating, worth knowing if you're planning a longer tenancy.

What practical tests should I run during the viewing?

Stop looking around and start testing things. You have 20 minutes, use them.

Run through this list:

Turn on every tap. Check the water pressure in the kitchen, bathroom, and shower. Weak pressure is annoying daily and can signal plumbing issues.
Flush the toilet and watch how fast the cistern refills.
Turn the extractor fan on. Note whether it actually moves air or just makes noise.
Try every window. Does it open, close, and lock properly? A bedroom window that won't open is a fire safety concern, not just an inconvenience.
Check your phone signal in each room.
Look at the sockets. Any scorch marks, loose faceplates, or obvious DIY wiring around the fuse box?
Check smoke alarms are present on every floor. Carbon monoxide alarms are legally required in any room with a fixed combustion appliance, since October 2022.

None of this takes long. Agents expect it from serious tenants.

What layout and livability issues do people miss?

Open-plan layouts look great in photos. In real life, they often mean your kitchen is your living room and the smell of cooking never leaves. Walk through the flat as if you're actually living there, not admiring it.

Specific things worth checking:

Can two people pass each other in the kitchen or hallway without squeezing?
Where does the bed go? If the only wall space is under a sloped ceiling or directly beside the front door, that's your answer.
Is there natural light in the bedroom, or is it a box room with a borrowed window?
Where does the washing machine go? Some flats have no logical place for one.
Is there storage, or will you be living out of your suitcase?

Also ask whether all areas of the property are accessible during the viewing. Some landlords restrict access to certain rooms or the garden, and tenants have discovered only after paying their first month's rent that parts of the property weren't included. If something's locked with no explanation, ask why.

What are the warning signs of a bad landlord or a scam?

A dodgy landlord isn't as obvious as a damp patch. But the signs are there if you know what to look for.

Scam signals to watch for:

Rent that's noticeably below market rate. Action Fraud received 5,000 reports of rental scams in 2024, totalling nearly £9 million. The average victim lost £1,400.
Being asked for a deposit or first month's rent before you've viewed the property in person.
Pressure to transfer money to a personal bank account with no mention of a government-backed deposit protection scheme. That is either a scammer or a landlord breaking the law.
Listings on Facebook or Gumtree where the price seems too good and the contact details don't match any agency you can verify. Scammers copy real listings, swap the contact details, and sometimes even show prospective tenants around an Airbnb they've hired for the day.

Signs of a bad but legitimate landlord:

Slow or unprofessional communication before you've even moved in. It only gets worse after you sign.
A property that's clearly been neglected: peeling paint, broken fittings, appliances that don't work.
Vague or evasive answers to straightforward questions about repairs and responsibilities.
Pressure to sign quickly with no time to read the tenancy agreement properly.

If you're using a letting agent, check they're registered with a recognised redress scheme. It's a legal requirement for letting agents in England to belong to either The Property Ombudsman or the Property Redress Scheme. You can verify this on their websites.

What questions should I ask before I leave?

Don't walk out without knowing these:

What's included in the rent? Council tax, bills, broadband? Get this in writing.
Who handles repairs and how quickly do they respond? Ask for an example.
How long has the property been empty and why did the last tenant leave?
Is the deposit registered with a government-backed protection scheme? The legal schemes in England are the DPS, MyDeposits, and the TDS. The deposit is capped at five weeks' rent for annual rents under £50,000.
Are there any planned rent increases?
What's the notice period on both sides?

On fees: under the Tenant Fees Act 2019, most charges are banned in England. You can only legally be asked to pay rent, a refundable tenancy deposit (max five weeks' rent), and a holding deposit (max one week's rent). Admin fees, referencing fees, and viewing fees are all illegal. If anyone asks for these, walk away.

The short version if you're rushing

Check for damp and mould properly, smell and touch, not just look. Test the boiler, taps, water pressure, and windows. Ask for the gas and electrical safety certificates. Verify the deposit protection scheme. Don't transfer money to anyone before you've viewed in person. And if the rent seems too cheap, ask yourself why before you get excited.

Twenty minutes is enough time to spot most of these. The ones you miss are the ones that'll cost you.