Two apartment blocks can stand side by side, identical in age and construction, and carry liabilities that differ by six figures. The difference is not in the brickwork. It is in the Building Safety Act 2022, which decides who pays for historical safety defects according to the building’s height and the history of each individual lease. For anyone buying blocks or flats within them, the Act is now a core due diligence subject, not a specialist footnote.
Here is the regime as it stands, checked against the legislation on 1 August 2026, and the specific documents to demand before you commit.
The Building Safety Act’s 11-metre line
Section 117 defines a relevant building for the leaseholder protections: at least two dwellings, and either at least 11 metres tall or at least five storeys. Buildings whose freehold is owned by the leaseholders themselves are excluded, on the logic that those leaseholders would only be protected from themselves.
A separate and stricter regime applies from 18 metres or seven storeys, where buildings fall under the Building Safety Regulator with registration and safety case duties. Do not conflate the two thresholds. At 11 metres the cost protections switch on. At 18 metres the operational regime arrives as well, and with it a running compliance cost that belongs in your service charge forecast.
Qualifying leases were fixed in 2022
The protections do not attach to buildings alone. They attach to leases, and section 119 froze the test on 14 February 2022. A qualifying lease is a long lease of a single dwelling in a relevant building where, on that date, the dwelling was the leaseholder’s only or principal home, or the leaseholder owned no more than three UK dwellings in total.
The date matters more than anything that has happened since. Qualifying status was determined once, at that moment, and the lease keeps that status through every later sale. A flat whose 2022 owner lived in it carries protection to every future buyer, including an investor. A flat that sat in a large portfolio on that date is a non-qualifying lease, and it stays one no matter who owns it now.
What a qualifying lease cannot be charged
Schedule 8 of the Act draws the money lines. No service charge at all is payable under a qualifying lease for cladding remediation. For other historical safety defects, contributions are capped: £15,000 in Greater London and £10,000 elsewhere, rising to £50,000 where the lease value is £1m to £2m and £100,000 above that. Leases valued below £325,000 in London or £175,000 elsewhere pay nothing towards those measures, and any permitted contribution can only be collected at one tenth of the cap per year.
Above the leaseholder, the Act stacks liability towards those responsible: landlords connected to the developer, and landlord groups with net worth above a statutory threshold, cannot pass remediation costs down at all. The practical consequence for buyers is that the paperwork establishing where a building sits in this waterfall is itself worth money.
The three dwelling test catches landlords
Read the 2022 test again from an investor’s chair. A leaseholder who did not live in the flat and owned more than three UK dwellings on 14 February 2022 holds a non-qualifying lease, with no Schedule 8 cost protection. A large share of tenanted flats in relevant buildings are therefore unprotected, and the service charge exposure on those leases is uncapped by this part of the Act.
When you buy a tenanted flat in a relevant building, the seller’s 2022 circumstances are your inheritance. Two otherwise identical flats in the same block can be a protected lease and an exposed one, and they should not be priced the same. This is a question to resolve in enquiries, not after completion.
Certificates to demand before you buy
The Act’s secondary legislation created a certificate regime for exactly this problem. A leaseholder deed of certificate records the position that fixes qualifying status, and a landlord’s certificate sets out the landlord’s connections and net worth position in the liability waterfall. Ask for both, along with any fire risk appraisal of external walls and the building’s remediation history and funding position.
Where cladding work is unresolved, ask what scheme is funding it and on what timetable. Government remediation programmes and developer commitments cover many buildings, and a block with funded, scheduled works is a different purchase from a block where nobody has yet accepted responsibility. The difference belongs in your offer price.
A block under 11 metres sits outside it
Most of the smaller blocks we handle sit below 11 metres, and the leaseholder protections simply do not apply there. That cuts both ways. There is no statutory cost regime to inherit, and equally no statutory shield if a safety issue does surface, so the survey and the service charge history carry the weight the certificates carry in taller stock.
Height itself deserves a check rather than an assumption. Eleven metres is roughly four storeys, and marketing floor counts are not measurements. Where a building sits near the line, establish the position from plans or measurement, because every liability question in this guide hangs on it.
What this means for property investors
On any block or flat purchase, run the height question first, then the lease history question. Below 11 metres, buy on survey and service charge evidence. At or above it, demand the deed of certificate, the landlord’s certificate, the external wall appraisal and the remediation funding position, and price non-qualifying leases as carrying uncapped historical defect risk. Do not pay protected-lease money for an unprotected lease, and do not walk away from a well-documented building just because the Act applies to it: a funded, certificated block is often a cleaner buy than an uncertificated short one.
Leasehold structure risk and building safety risk compound each other, so read this alongside our guides to pricing short lease flats and where leasehold reform actually stands. The apartment blocks on our books state title structure and tenure up front.
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