ARC Party Wall DPC L-Shape

Close two critical gaps with one push-fit product

When a separating (party) wall hits the external leaf you need to stop fire, smoke, cold bridging and moisture at the junction — in both directions. ARC Party-Wall DPC L-Shape socks make the detail effortless:

• Euroclass A1 mineral-wool core expands to fill both the vertical party cavity and a 250 mm horizontal return across the outer leaf.

• Integral polyethylene DPC sleeve wraps the internal face, blocking capillary moisture and satisfying Approved Document C.

• Tested to EN 1366-4 and third-party approved (IFCC 1728) for up to 4 hours fire integrity / 2 hours insulation at the wall edge.

• Thermal conductivity λ 0 .037 W/m·K helps designers achieve the zero-U party-wall junction in SAP.

Need a take-off or bespoke width? Call the Spechunter technical desk on 0118 922 7941 — we’ll size and schedule the same day.

Choose the right L-shape in seconds

*Links jump straight to the individual bagged sizes on Spechunter.

Need straight or horizontal socks? Switch to ARC Party-Wall DPC Cavity Socks or PW-DPC Horizontal.
Edge seal on the external side? See ARC T-Barrier Masonry.

Installation – three quick steps

1. Measure & cut – trim the 1.2 m lengths so the vertical leg reaches slab-to-slab; keep the horizontal return flush with the outer-leaf face.

2. Compress & insert – squeeze the mineral wool and push the L into the corner until both faces sit tight.

3. Seal joints – butt successive pieces firmly; fill gaps > 5 mm with mineral-wool off-cuts or intumescent acrylic.

No mechanical fixings, ties or separate DPC required.

Compliance snapshot

Frequently asked questions

Why use an L-shape instead of separate vertical & horizontal socks?
One piece guarantees continuity of fire and DPC layers, plus it’s faster to install and eliminates a potential cold bridge at the corner.

Can I bend the horizontal leg up or down?
Only very slightly. For steep steps specify ARC Spandrel Barriers or cut & butt two pieces with intumescent mastic.

Do I need ties through the barrier?
No – the sock is friction-fit. Keep the cavity within ±5 mm of the product size.

Is next-day delivery available?
Yes—order before noon, spend £200 ex-VAT and check our delivery information for remote-area surcharges.

Complete your party-wall package

• Vertical runs – PW-DPC Cavity Socks

• Horizontal floor edges – PW-DPC Horizontal

• External edge seal – T-Barrier Masonry

• Spandrel or roof abutments – ARC Spandrel Barriers

Order today and chase down every last spec with Spechunter’s 35-year envelope know-how. Questions? Contact us or ring 0118 922 7941.

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