Planning your loft, rear or side extension is exciting—you’re finally turning drawings into space you can live in. If your design encloses on an existing party wall (i.e., you’re building off the full thickness of the shared wall under the Party Wall etc. Act 1996), here’s a smart, low-cost step that saves post-build regrets for both you and your neighbour:
Don’t wait to “hear” the problem—design it out now
When you enclose on a party wall, the new room effectively uses that wall as part of its envelope. Without additional acoustic treatment, everyday sounds (speech, TV, appliances) can transmit through the mass and junctions, especially where new steels, joists, or linings connect. You may only notice it once the room is finished—when it’s expensive and invasive to fix.
The fix is simple: specify acoustic insulation to the area you’re enclosing upon at design stage. That typically means:
- High-density acoustic batts within new studs or ceiling zones abutting the party wall
- Resilient bars or acoustic clips to decouple new linings from structure
- Double-layer acoustic plasterboard (staggered joints) with acoustic sealant to perimeter
- Careful detailing at flanking paths (steel penetrations, joist ends, sockets, pipe chases) so you don’t create sound “bridges”
Result: a calmer, more private room for you—and a quieter life for your neighbour. It’s a fraction of the cost to include now versus remedial works later.
How this sits with the Party Wall Act
- If you’re cutting into the wall for beams, raising/thickening it, or enclosing on a party fence wall, you’ll likely need to serve valid Party Wall Notices.
- If your neighbour dissents, surveyor(s) will agree a Party Wall Award setting out methods (often specifying hand tools at the party wall, hours for noisy works, protection measures).
- Acoustic upgrades are not a legal requirement of the Act, but they’re best practice and demonstrate the “no unnecessary inconvenience” duty in spirit and in fact.
Practical tips for a smoother, quieter build
- Tell your designer now you want an acoustic spec where you enclose on the wall; ask for details on your drawing set so the contractor prices and builds it.
- Position sockets and chases away from the party wall where possible; use acoustic putty pads when you can’t.
- Seal every perimeter (ceiling, floor, abutments) with acoustic mastic—tiny gaps undo big efforts.
- Coordinate steel and joist details to avoid rigid sound paths; ask your engineer about isolation details at supports.
Keep compliance simple (and costs low) with Simple Survey
- Party Wall Notice service: £25 per adjoining ownership (multi-notice bundles discounted)
- Act administration as Agreed Surveyor (single surveyor): typically £300 fixed-fee (depends on complexity and number of notices/owners)
- Two-surveyor route (we act for the Building Owner): fixed-fee proposals from £325 for our side*
We work to keep your neighbour’s surveyor’s hourly fees reasonable and contained.
We’re RICS-qualified building surveyors. We’ll confirm what’s notifiable, serve valid Notices, and (if needed) agree a clear, enforceable Award—while you get on with building a quieter, better room.
Ready to get it right first time?
Email team@simplesurvey.co.uk with your address and plans. We’ll provide a quick compliance check, fixed fees, and a practical acoustic checklist tailored to your enclosure—so you finish with comfort, not complaints.