What it is called, by market
One concept, four markets. Where a name means something else locally, the card says so rather than leaving you to find out on site.
United Kingdom
Same word, different thingparty wall
also separating wall, compartment wall, party fence wall, party structure
SEPARATING WALL is the Building Regulations term for the fire and sound performance; PARTY WALL is the legal term under the Party Wall etc. Act 1996. The same wall, two different regimes with different definitions.
Australia
Close, not identicalparty wall
also common wall, separating wall, fire wall
Construction requirements under the NCC as elsewhere, without an equivalent of the English notice-and-award statute.
United Statesyours
Same word, different thingparty wall
also common wall, demising wall, fire wall, fire barrier
DEMISING WALL is the commercial term for the boundary between tenancies. FIRE WALL has a precise code meaning — structurally independent, full height — that a party wall may or may not meet.
Canada
Close, not identicalparty wall
also common wall, demising wall, firewall
As the United States, with the same firewall distinction under the National Building Code.
The governing standard, by market
United Kingdom
Approved Document E / Party Wall etc. Act 1996
Resistance to the passage of sound between dwellings, and the notice, dissent and award procedure for work to a party structure.
United States
IBC 706 / ASTM E90
Fire walls: structural stability, continuity and openings, and laboratory measurement of airborne sound transmission loss.
Calculators for this
Each works in either measurement system, and the terminology on the page follows whichever market you have selected.
Frequently asked questions
- Why does work near a party wall in England need notice?
- Because a statute makes it a process rather than a courtesy, and the process has a timetable that governs when work can start. The Party Wall etc. Act 1996 covers three things: work directly to a party structure — cutting into it, raising it, underpinning it; building a new wall at or astride the boundary; and excavating within defined distances of a neighbour's structure below the level of their foundations. Each requires written notice to the adjoining owner, with a stated period for them to consent or dissent, and dissent means surveyors are appointed and an award is made setting out how the work proceeds and who pays for what. The practical consequences are calendar ones: notice periods run in months, and a loft conversion or a basement that assumed a start date without them is late before it begins. No equivalent statute exists in the other three markets.
- Is a party wall the same as a fire wall?
- Not automatically, and in American code usage the distinction is precise enough to matter. A FIRE WALL in the IBC sense is structurally independent: it is designed so that a collapse on one side does not bring it down, which is what allows the two sides to be treated as separate buildings for code purposes. A party wall may be a fire wall, or it may be a fire BARRIER or a separating wall that achieves a fire resistance period without that independence. British practice frames it differently again, as a compartment wall with a required fire resistance and a requirement for continuity to the underside of the roof covering. The consequence when reading a drawing across markets is that party wall describes ownership, and the fire performance is a separate specification that has to be stated rather than inferred.
- Why is sound the hardest part to get right?
- Because most of it does not go through the wall. A separating wall's laboratory performance assumes sound passing through the wall itself, and in a real building a large share arrives by FLANKING: through the floor that runs continuously under both sides, through a ceiling void that is shared, along a continuous screed, through a service penetration, around the edge of the wall at the external skin. That is why the British regulations test COMPLETED buildings rather than accepting a wall specification, why a wall that measures well in isolation can fail on site, and why remedial work on noise between houses so often has to address the floor rather than the wall everybody is complaining about. A sealed, unpenetrated, structurally isolated junction is usually worth more than extra mass in the wall.