ARC Party Wall DPC Cavity Socks

Fire, moisture and heat-loss stopped in one push-fit product

ARC Party-Wall DPC Cavity Socks marry the proven fire-stopping power of Euroclass A1 mineral wool with an integral polyethylene DPC sleeve. Slid vertically up the party-wall junction, the sock expands to fill the void, giving:

• Up to 4 hours fire integrity and 15 minutes insulation to EN 1366-4 (IFC 1728)

• A built-in DPC that blocks interstitial moisture and tackles the cold-bridge at the wall edge

• λ 0.037 W/m·K conductivity – helps achieve the zero U-value credit in SAP calculations 

• Acoustic damping that lifts Robust Detail Part E performance

Order before 12:00 and spend £200 ex-VAT for free next-working-day UK delivery. Call our tech desk on 0118 922 7941 for take-offs or detail check

Size guide – pick & click

*Links jump straight to the pre-bagged sizes on Spechunter.

Need a wider solution? Step up to the ARC T-Barrier Masonry range (up to 300 mm).

Three-step installation

1. Cut to length – socks come in 1.2 m strips; trim so butt-joints land tight to floor slabs or gable returns.

2. Compress & insert – squeeze the mineral wool, push flush with the party-wall face. The red DPC sleeve must remain intact on the room side.

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

No mechanical fixings, ties or separate DPC rolls required.

Compliance snapshot

Frequently asked questions

What’s the difference between PW DPC Socks and standard Party-Wall Cavity Socks?

Standard socks give fire, acoustic and thermal benefits. PW-DPC adds a DPC membrane, so you don’t need a separate damp course at the junction.

Can I use them horizontally?

Yes—PW-DPC strips can run horizontally at compartment floors; for underside slabs many contractors switch to ARC Spandrel Barriers for easier fitting.

Are brackets or ties required?

No. The product is friction-fit; just keep cavity width within ±5 mm of the stated size.

Next-day delivery—any catches?

Order before noon, hit £200 ex-VAT and check our delivery information for Highlands & Islands surcharges.

Complete the junction

• Edge-seal the external cavity: ARC T-Barrier Masonry

• Close window reveals: ARC Eco-Closer

• Need DPC rolls for sills? See our Damp-Proof Course category.

Spechunter.co.uk – chasing down specialist construction specifications since 1988. Fact Checked and Updated May 2025