ARC Party Wall DPC Horizontal

One push-fit strip that blocks fire, smoke and moisture at every separating floor

ARC Party-Wall DPC Horizontal socks slide into the external-wall cavity at the floor edge of a party wall, expanding to create a complete fire, acoustic, thermal and damp break. The core is Euroclass A1 rock-fibre wrapped in a polyethylene DPC sleeve, delivering:

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

• A continuous DPC that stops capillary moisture and satisfies Approved Doc C 

• λ 0.037 W/m·K conductivity—helps designers hit the zero U-value party-wall target

• Flanking-sound damping to boost Part E results

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.

Size selector – pick your sock & add to basket

Need a vertical sock instead? See ARC Party-Wall DPC Cavity Socks.
External edge seal? Step up to an ARC T-Barrier Masonry.

Why you need a horizontal barrier at floor level

• Fire strategy: Approved Document B demands cavity barriers at the junction of a compartment floor and an external wall. The PW-DPC-H range fulfils that in one piece.

• Moisture control: The built-in DPC folds under the screed or timber deck, blocking rising or penetrating damp from the outer leaf.

• Thermal bridge: Closing the air-path and adding mineral-wool insulation keeps Psi-values low for SAP calculations.

• Speed on site: Push-fit installation—no mechanical fixings, no separate DPC roll, no call-backs. Speechunter

How to install (3 quick steps)

1. Trim to length so butt-joints land tight against joists or concrete slabs.

2. Compress & fit—push the sock into the cavity until the red DPC sleeve sits flush with the party-wall face.

3. Seal joints—tight butt joints are usually enough; fill gaps > 5 mm with mineral-wool off-cuts or intumescent acrylic.

Pair with Fire Socks & Barriers for spandrels, soffits and window heads.

Compliance snapshot

Frequently asked questions

Do I need mechanical fixings?
No—the socks are friction-fit provided the cavity width is within ± 5 mm of the product size.

Can these be used in timber-frame construction?
For timber-to-timber junctions switch to ARC TCB Timber Cavity Barriers, which are sized and tested for stud walls.

How many lengths per storey?
Run a continuous strip the full width of the elevation at every separating floor; typically one 1.2 m length per linear metre of wall.

Is next-day delivery guaranteed?
Order before noon, spend £200 ex-VAT and check our delivery information for postcode exceptions.

Still chasing the spec?
Email drawings to Contact Us or ring 0118 922 7941—our 35-year envelope team will size, schedule and quote the same day.

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