ARC T-Barrier Masonry

One-piece protection at every party-wall edge

When a separating wall arrives at the outer leaf you need a barrier that blocks fire, smoke, flanking noise and heat loss—without holding up brickwork. The ARC T-Barrier Masonry (TBM) does exactly that:

  • Euroclass A1 mineral-wool core in a tough white polythene sleeve—weather-safe on site.

  • T-shape gives a 75–150 mm vertical leg inside the party cavity and a 100–150 mm horizontal flange into the external cavity.

  • Up to 4 hours fire integrity / 2 hours insulation (EN 1366-4, IFCC 1727).

  • λ 0.037 W/m·K plus 250 mm overlap meets the zero-U party-wall detail for SAP.

  • No mechanical fixings—compression holds the barrier until the outer leaf is closed.

Spend £200 ex-VAT and order before 12:00 for free next-working-day delivery. Tech questions? Ring 0118 922 7941.

Pick your T-Barrier in seconds

Party-wall leg × External flange (mm)Product linkPack qty*
75 × 100TBM75 1006
75 × 120TBM75 1206
75 × 125TBM75 1256
75 × 150TBM75 1503
100 × 120TBM100 1204
100 × 125TBM100 1254
100 × 150TBM100 1503
125 × 100TBM125 1006
125 × 120TBM125 1206
125 × 125TBM125 1254
125 × 150TBM125 1503
150 × 100TBM150 1006
150 × 120TBM150 1206
150 × 125TBM150 1256
150 × 150TBM150 1503

*Pack quantities vary with width—see each product page for confirmation.
Need wider flanges (up to 300 mm)? Ask our team for specials.

How to install (3-step method)

  1. Trim the 1200 mm length so joints land tight to slabs or gable returns.

  2. Compress & push-fit—the vertical leg slides into the party cavity; the horizontal flange fills the external cavity to the outer leaf face. Maintain 5 mm compression.

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

Pair with ARC Party-Wall Cavity Socks for vertical runs and ARC Spandrel Barriers at the roof line.

Compliance snapshot

RequirementTBM performance
Approved Document B / BS 9991≤ 4 h fire integrity, ≤ 2 h insulation (IFC 1727)
Approved Document CPolythene sleeve forms cavity moisture break
SAP / Part Lλ 0.037 W/m·K; supports zero-U party-wall detail
Approved Document ERock-fibre core reduces flanking sound ≥ 5 dB

Frequently asked questions

Is mechanical fixing ever required?
No—the T-Barrier relies on friction. Keep cavity sizes within ±5 mm of the product to retain the compression.

Can I use TBM in timber-frame construction?
These SKUs are sized for masonry outer leaves. For timber-frame edges specify ARC TCB Timber Barriers.

What about floor junctions?
Use ARC Party-Wall DPC Horizontal or PW-TCB for timber builds.

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

Complete your junction strategy

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

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