ARC Party Wall TCB

A compression-fit answer to fire, sound and thermal breaks at timber party-wall junctions

ARC Party-Wall TCB is the vertical barrier your timber-frame build needs wherever a separating wall meets the outer cavity. Each 1.2 m strip contains Euroclass A1 rock-fibre insulation wrapped in a white polythene sleeve for weather protection and site ID. Push-fit it into the external cavity with a 50 mm overlap either side of the party wall and you instantly achieve:

  • 60 minutes fire integrity and 60 minutes insulation, third-party-certified (IFCC 1728) 

  • Lambda 0.037 W/m·K – helps designers achieve the zero-U party-wall detail in SAP 

  • Robust Detail compliance (E-WT 1-4, E-FT 1-6) for acoustic flanking control 

  • Fast, tool-free installation: friction alone holds the sock until the outer leaf closes

Order before 12:00 and spend £200 ex-VAT for free next-working-day delivery. Need a take-off? Call our technical desk on 0118 922 7941.

Pick the right size in seconds

Clear cavityProduct linkDimensions (mm)Pack qty
50 mmPWTCB5055 × 250 × 120012
75 mmPWTCB7580 × 250 × 120010
100 mmPWTCB100105 × 250 × 12008
125 mmPWTCB125130 × 250 × 12006
150 mmPWTCB150155 × 250 × 12006

Need a straight sock with DPC? Check ARC Party-Wall DPC Cavity Socks.
Edge-seal the external side? Use an ARC T-Barrier Masonry.

Installing PW TCB – three quick steps

  1. Trim length so joints land tight against floor slabs or gable returns.

  2. Compress & insert—push the barrier into the external cavity until the sleeve sits flush with the party-wall face; maintain 5 mm compression.

  3. Butt & seal—tight butt joints are fine; gaps > 5 mm get a mineral-wool off-cut or intumescent acrylic bead.

No mechanical fixings, ties or separate DPC are required—the friction fit and 250 mm width keep everything in place.

Compliance snapshot

Regulation / standardPW TCB performance
Approved Document B / BS 999160 min integrity & insulation, IFC third-party certificate IFCC 1728 
Approved Document E (Robust Detail)E-WT 1-4, E-FT 1-6 compliant flanking break
SAP / Part Lλ 0.037 W/m·K – supports zero-U junction
EnvironmentalA+ Green Guide rating; CFC/HCFC-free manufacture 

Frequently asked questions

Is this the same as ARC Cavity Stop Socks?

No. PW TCB is 250 mm wide and designed specifically for the external cavity at a party wall. Standard Cavity Stop Socks sit inside the party wall itself or at separating floors.

Can I use PW TCB horizontally?

Yes—horizontal runs at floor level are fine, provided you keep the 50 mm overlap each side of the party wall.

What if my cavity is outside 50-150 mm?

ARC will manufacture specials up to 150 mm on request—ask the Spechunter team.

Is next-day delivery guaranteed?

Order before noon, hit £200 ex-VAT and check our delivery information for any remote-area surcharges.

Complete your party-wall spec

Spechunter.co.uk – Chasing down specialist construction specifications since 1988. Fact checked and updated on May 2025.

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