Description
One step up from the 110 mm, this length settles a specific case: an 80 mm board on clean new-build masonry, surface-mounted at full 30 mm anchorage. On a retrofit wall carrying old plaster the same box drops to a 60 mm board — both figures from the Klimas selection table, not from a rule of thumb.
Which Board Thicknesses the 120 mm Plug Fits
The LTX 120mm polystyrene fixing plug 200pcs box anchors polystyrene boards up to 80 mm on clean masonry, or 60 mm on a plastered retrofit wall, at 30 mm effective embedment under ETA-16/0509. Every length in the insulation fixing accessories range maps to its own band in that table, and the four cases below are the whole map for this one.
| Wall and mounting method | Board thickness this plug takes |
|---|---|
| New build, surface mount | up to 80 mm (60 mm in aerated concrete) |
| New build, immersed with a cutter | up to 100 mm (80 mm in aerated concrete) |
| Retrofit over 20 mm old plaster, surface mount | up to 60 mm (40 mm in aerated concrete) |
| Retrofit over 20 mm old plaster, immersed with a cutter | up to 80 mm (60 mm in aerated concrete) |
Each row already carries a 10 mm adhesive layer, which is how Klimas builds the table. That makes this the length for 80 mm boards on bare brick or block — the most common domestic specification we ship — while an 80 mm board over 20 mm of old plaster needs either the 140 mm length surface-mounted, or this box installed with a cutter.
Why Specifiers Choose an All-Plastic Pin at This Length
- Point thermal transmittance of 0.001 W/K surface-mounted and 0.000 W/K immersed, so a fixing pattern of several hundred plugs adds almost nothing to the wall's heat loss and the U-value calculation stays clean.
- 0.75 kN characteristic pull-out in concrete C20/25–C50/60 and in solid clay brick at density ≥ 2.00 kg/dm³ — the two strongest substrates in the assessment, and the two most common under UK render systems.
- Five substrate categories, A to E, under ETA-16/0509 to EAD 330196-01-0604, from concrete and solid brick through hollow units and lightweight aggregate concrete to autoclaved aerated concrete, all on one 10 mm bit.
- Polyethylene body with a glass-fibre reinforced polyamide pin, which keeps the pin rigid under hammer blows without running a metal path through the insulation.
- 60 mm collar at 0.50 kN/mm stiffness, moulded with adhesive pockets so the basecoat keys over the head rather than sitting on a smooth disc.
- 200 pieces per box, the same pack Renders World stocks either side of this length, so a mixed-thickness elevation orders in one go.
LTX-10120 Technical Data From the Product Sheet
| Parameter | Value |
|---|---|
| Product code | LTX-10120, 10 x 120 mm |
| Fastener diameter (dk) | 10 mm |
| Collar diameter (Dk) | 60 mm |
| Effective anchorage depth (heff) | 30 mm; 50 mm in aerated concrete |
| Hole depth (h0) | 40 mm; 60 mm in aerated concrete |
| Collar stiffness (S) | 0.50 kN/mm |
| Point thermal transmittance (χ) | 0.001 W/K surface, 0.000 W/K immersed |
| Body / pin material | PE / PA with glass fibre |
| Pull-out, concrete C12/15 | 0.50 kN |
| Pull-out, concrete C20/25–C50/60 | 0.75 kN |
| Pull-out, solid clay brick | 0.75 kN |
| Pull-out, calcium silicate solid brick | 0.60 kN |
| Pull-out, calcium silicate hollow blocks | 0.60 kN |
| Pull-out, perforated brick | 0.60 kN |
| Pull-out, Porotherm 25 | 0.40 kN |
| Pull-out, lightweight concrete blocks | 0.60 kN |
| Pull-out, aerated concrete AAC2 / AAC7 | 0.50 kN / 0.60 kN |
| Partial safety factor (γM) | 2.0, in absence of regulations |
| Assessment | ETA-16/0509 |
| Pack quantity | 200 pcs |
Two of those numbers work together on site. The 0.75 kN is a characteristic value, and the sheet applies γM = 2.0 where no national regulation says otherwise — so a design resistance is half the headline figure, and the plug count comes from the building's own wind-load calculation rather than from the strongest number in the table.
How to Install the 120 mm Plug: Drill, Sleeve, Pin
Identify the substrate first, because both the drilling mode and the embedment follow from it. Boards go up on adhesive, and the plug is a supplementary mechanical fixing whose job is transferring wind suction into the structure behind.
- Match the bit to the plug: 10 mm diameter, and in solid materials a hole at least 10 mm deeper than the 30 mm anchorage.
- Clear the hole: the sheet asks for a back-and-forth stroke at reduced speed, repeated four times, which lifts the dust that would otherwise sit under the expansion zone.
- Drop impact mode on hollow and aerated units: hammering breaks the inner walls of the block, and the pull-out value goes with them.
- Seat the collar flush with the board face, then drive the pin in firm even blows. A pin that is already driven is never struck again — that is how they break.
- Fix where the adhesive is: the installation spot should match an adhesive contact area on the board, which is also where the board is stiffest.
Immersed Mount, and What It Buys
Recessing the head lifts new-build capacity from 80 mm to 100 mm, takes the plastered-retrofit case from 60 mm to 80 mm, and drops χ to 0.000 W/K. The sheet names the two parts for it — a WK-FT plastic cutter for the recess and a KS or KSG polystyrene disc to cap it — and both live in the wider insulation fixing accessories collection rather than on this page.
How to Check Plug Length Against Your Build-Up
Klimas gives a formula rather than a lookup, and it settles any board thickness in one line: Ld = tfix + ttol + heff, where ttol is the adhesive plus any existing plaster and heff is the anchorage depth.
- 80 mm board, new build: 80 + 10 + 30 = 120 mm, which is this box.
- 60 mm board, plastered retrofit: 60 + (10 + 20) + 30 = 120 mm, the same box on a very different wall.
- 80 mm board, plastered retrofit: 80 + 30 + 30 = 140 mm.
For the layout that sits on top of the length decision, the fixing pattern and spacing method works through field and corner zones, and the plug length calculation walkthrough runs this formula against other board schedules. Full-elevation sequencing sits in the EWI fixings installation guide.
Choosing Between the 110, 120 and 140 mm Lengths
Klimas publishes the LTX-10 in ten lengths from 70 mm to 260 mm. Body, collar, pin material and assessment are common to all of them — only the sleeve changes, so the choice is arithmetic rather than performance. The three neighbouring lengths below cover most UK domestic work, shown surface-mounted.
| Length | New-build board | Retrofit board, 20 mm plaster | Pick it when |
|---|---|---|---|
| LTX 110 mm, one step shorter | 70 mm | 50 mm | 70 mm new build, 50 mm retrofit |
| LTX 120 mm (this box) | 80 mm | 60 mm | 80 mm boards on bare masonry |
| LTX 140 mm, one step longer | 100 mm | 80 mm | 80 mm boards over old plaster, 100 mm new build |
One detail worth carrying into a price comparison: the box holds 200 pieces up to the 200 mm length and 100 pieces at 220 mm and above, so a per-plug figure is the only fair way to compare across that break.
How Many Boxes to Order, and What They Cost
The sheet's recommended density for polystyrene is 6 plugs/m² in the field and 8/m² in corner areas up to 15 m above ground, rising to 8 and 10/m² above 15 m — given explicitly as a recommendation that does not replace the thermal insulation design.
- Box coverage: 200 pcs ÷ 6/m² = 33.3 m²; 200 pcs ÷ 8/m² = 25 m². One box covers 25–33 m² depending on zone.
- Per 100 m² of wall: 100 m² × 6–8/m² = 600–800 plugs; ÷ 200 per box = 3–4 boxes, before any allowance for misdrilled holes.
- Price: £30.00 per 200-piece box, in stock, August 2026 — at 6/m² that is £30.00 ÷ 33.3 m² = £0.90/m², and at 8/m² £30.00 ÷ 25 m² = £1.20/m².
Renders World holds the neighbouring lengths in the same 200-piece pack, which matters on a house running one thickness across the main elevations and something thinner at the reveals.
Is the 120 mm Length Right for Your Wall?
- 80 mm boards on bare brick or block: this is the matched length, surface-mounted at full 30 mm embedment on any of the five substrate categories. Graphite-enhanced EPS insulation boards are stocked in that thickness.
- 80 mm boards over 20 mm of existing plaster: either step up to the 140 mm plug, or stay with this box and immerse-mount. Plaster is rarely a flat 20 mm, so measure it before committing a pallet.
- 60 mm boards on a plastered retrofit wall: this length again, which is why one box can serve two quite different build-ups on the same job.
- Plinth and below-DPC zones: the product data sheet covers EPS and XPS while the technical catalogue names EPS only, so for plinth and below-DPC XPS boards confirm the fixing schedule with the system holder before ordering in volume.
- Mineral wool slabs: this sheet's stated application is polystyrene, so mineral wool insulation takes a fixing assessed for wool instead.
LTX 120 mm Plug FAQ: Quantities, Substrates, Limits
How many boxes cover 100 m² of wall?
Three to four. At the sheet's recommended 6–8 plugs/m² below 15 m, 100 m² needs 600–800 plugs and each box holds 200. Corner and edge areas carry the higher density, so an elevation with many openings sits at the top of that range. The final count belongs to the thermal insulation design for the building, which the recommendation explicitly does not replace.
Why this length rather than the 110 mm for an 80 mm board?
Because the plaster decides it. On bare masonry with a 10 mm adhesive bed, 80 + 10 + 30 comes to 120 mm and this is the matched box; the 110 mm length caps at a 70 mm board in that condition. Once 20 mm of old plaster is in the build-up, an 80 mm board needs 140 mm surface-mounted, or this length with a cutter.
Which substrates does it hold in, and how well?
All five categories in ETA-16/0509. Characteristic pull-out runs from 0.75 kN in concrete C20/25 and solid clay brick, through 0.60 kN in calcium silicate, perforated units, lightweight concrete blocks and AAC7, down to 0.50 kN in AAC2 and 0.40 kN in Porotherm 25. Apply the sheet's γM of 2.0 to reach a design value.
What changes on aerated concrete?
Two things get deeper and one gets thinner. Anchorage rises to 50 mm and the hole to 60 mm, while the board this length supports drops to 60 mm on new build or 40 mm over plaster. Drilling stays in rotation-only mode to keep the cell structure that carries the load.
Does it suit mineral wool slabs?
The sheet specifies it for EPS and XPS polystyrene, so wool sits outside its stated application. Mineral wool insulation is fixed with anchors assessed for that material, usually with a wider load-spreading plate to suit the lower slab strength.
How does it compare with a metal-pin plug on thermal bridging?
This plug's own assessed figures are 0.001 W/K surface-mounted and 0.000 W/K immersed, which is about as close to a thermally invisible anchor as an ETICS fixing gets. A metal-pin plug carries its own point transmittance in its own assessment, and that comparison is worth publishing from the metal fixing's document rather than estimating here.
Technical Documentation