Description
The Base Track 93 mm × 2.5 m is an aluminium starter profile sized to receive 90 mm insulation boards — the thickness most often calculated for solid-wall properties where an energy assessor recommends stepping beyond a standard 80 mm build-up. It sits above the damp-proof course and forms the level shelf that carries the first course of insulation around the perimeter.
This profile is part of the insulation fixing accessories range at Renders World and pairs directly with 90 mm graphite EPS boards from the EPS insulation boards collection.
What the 93 mm Base Track Does in a UK EWI System
The 93 mm base track is the aluminium starter profile that carries 90 mm insulation boards in a UK EWI build-up, fixed above the DPC at 300 mm centres to set the perimeter datum. Get the track right and the rest of the wall lines up; get it wrong and every board above it carries the error.
- On the wall — sets the perimeter datum and levels the first course of insulation around every elevation.
- On the system — drains the splash-back zone via an integral drip edge and ventilates residual moisture through a perforated horizontal web.
- On the gauge choice — 0.6 mm suits domestic and low-rise retrofits; the 1 mm heavy-duty 93 mm base track covers taller or more exposed facades at the same 93 mm width.
What Makes the 93 mm Base Track Worth Specifying
- Matched to the 90 mm solid-wall specification — the 93 mm internal channel is sized for 90 mm EPS graphite boards, the thickness most frequently calculated for 9-inch solid brick walls aiming at a U-value in the region of 0.30 W/m²K, subject to calculation.
- Integral drip edge — the formed lower lip projects clear of the wall face, shedding rainwater and splash-back away from the base zone where moisture exposure is at its highest.
- Perforated horizontal web — punched apertures allow trapped construction moisture and minor vapour drive to escape behind the insulation, supporting long-term drying performance.
- Standard 0.6 mm aluminium gauge — light enough for single-person handling, cuts cleanly with tin snips, and resists alkaline basecoat chemistry through the inherent aluminium oxide layer.
- Accurate datum line — fixed at 300 mm centres, each 2.5 m length lays true and gives the first course of boards a level seat that carries through to the render finish.
- Compatible with clip-on mesh profiles — front-edge mesh carriers snap on after the first course is set, integrating cleanly into the basecoat reinforcement layer.
Technical Specifications — 93 mm Base Track Data
| Property | Value |
|---|---|
| Profile width | 93 mm |
| Length per piece | 2,500 mm (2.5 m) |
| Material | Aluminium alloy |
| Gauge | 0.6 mm (standard) |
| Finish | Natural mill aluminium |
| Drip edge | Integral lower lip |
| Ventilation | Perforated horizontal web |
| Recommended fixing centres | 300 mm |
| Suitable insulation thickness | 90 mm boards |
| Pre-installed mesh | No — clip-on profile required |
The 0.6 mm gauge is the right choice for the majority of domestic retrofits. Where a system designer or facade engineer calls for greater rigidity — taller buildings, highly exposed coastal sites, or specifications referencing a thicker-gauge profile — the heavy-duty 1 mm version sits within the same product family and accepts identical 90 mm boards.
How the 93 mm Base Track Installs Above the DPC
For the best result, establish the datum line around the full building perimeter before any track is fixed. A laser level transferred to each elevation, with a chalk reference mark snapped along the run, keeps the line continuous around corners. The track typically sits 150 mm above finished ground level and directly above the existing DPC.
Pre-drill at 300 mm centres with a 6 mm masonry bit, then fix through into the substrate with nylon frame plugs and screws rated for the brickwork or block being anchored. On older solid walls with soft lime mortar, position fixings within the brick faces rather than the joints to maintain consistent pull-out resistance along the full run. Leave a 2–3 mm expansion gap between adjacent lengths so the aluminium can move freely under thermal load.
- External corners — mitre-cut both lengths at 45° to keep the drip edge continuous around the return.
- Internal corners — butt one length cleanly into the adjacent wall face and seal the junction with a compatible flexible sealant.
- Changes in insulation thickness — where the 93 mm profile meets an adjoining 83 mm or 103 mm track, align the rear faces against the wall so the front lip steps forward by the thickness difference, and bridge the step in a single wet pass of basecoat and mesh.
Once the track is set and verified level, apply adhesive to the rear face of each 90 mm board and seat it firmly onto the horizontal shelf. The clip-on mesh profile then attaches to the front lip ahead of the basecoat layer. Full step-by-step procedures for fixing patterns, mechanical anchor placement above the track line, and adhesive coverage rates are covered in the EWI fixings installation guide.
Pro Tips From UK Installers Fitting the 93 mm Base Track
The 93 mm track comes into play on every solid-wall job where the energy assessment pushes past 80 mm. A few site practices make the difference between a clean perimeter and one that has to be reworked once the boards go up.
- Carry the neighbouring profile on site — Victorian terraces can vary in wall thickness between elevations, and an assessor may call 80 mm on the party returns while specifying 90 mm on the front and rear. Having the 83 mm base track on the van alongside the 93 mm means both specifications come off the same datum.
- Lay a dry run before drilling — set every length of track end-to-end along the chalk line first, mark the fix positions through, then pull the lengths back to drill. It catches awkward fix points that fall on movement joints or service penetrations before the masonry bit goes in.
- Mind the expansion gap — 2 mm between lengths reads as a hairline gap on the substrate but absorbs the summer thermal movement that would otherwise bow a continuous run.
- Step up where the assessor calls for 100 mm — exposed gable ends and north-facing walls on the same property may require thicker insulation than the front elevation; the 103 mm base track accommodates that step without disturbing the perimeter datum.
Is the 93 mm Base Track Right for Your Project?
- Ideal for solid-wall retrofits at 90 mm insulation — choose the 93 mm base track when the energy assessment specifies 90 mm graphite EPS on 9-inch solid brick, Victorian terraces, or Edwardian properties targeting a wall U-value in the region of 0.30 W/m²K, subject to calculation.
- For standard 80 mm domestic retrofits — the 83 mm profile for standard 80 mm board work is matched to the UK's most widely specified thickness and suits the majority of cavity-wall over-cladding and general masonry retrofit jobs.
- For deeper retrofits at 100 mm insulation — the 103 mm profile for deeper retrofits at 100 mm boards accepts the next standard thickness, commonly specified on semi-detached gable ends, north-facing walls, and properties pushing toward enhanced thermal performance.
- When a heavier-gauge profile is required at 93 mm — the heavier-gauge 1 mm version at the same 93 mm width covers the same 90 mm boards with greater rigidity for taller facades, exposed sites, or system certifications that call for thicker aluminium at the starter profile.
FAQ — 93 mm Base Track Coverage, Compatibility, Ordering
When does an energy assessor specify 90 mm instead of 80 mm insulation?
The step from 80 mm to 90 mm is most often triggered by the existing wall construction. A solid 9-inch brick wall has a higher baseline U-value than a cavity wall of similar age, so it needs thicker insulation to reach the same target. Where the assessor's calculation shows 80 mm graphite EPS falling just short of the required U-value — typically on exposed elevations or where the brickwork is thinner than expected — adding 10 mm closes the gap without the detailing complexity that comes with a jump to 100 mm or more.
What is the difference between the standard 93 mm track and the 1 mm heavy-duty version?
Both profiles share the same 93 mm internal channel and 2.5 m length, and both accept identical 90 mm insulation boards. The difference is the aluminium gauge. This standard track is pressed from 0.6 mm material, which suits domestic and low-rise commercial work. The 1 mm heavy-duty version provides greater rigidity and higher load capacity, specified on taller facades, highly exposed sites, or where the EWI system designer calls for a thicker-gauge starter profile as part of the system certification.
How many 93 mm tracks does a typical solid-wall retrofit need?
A Victorian mid-terrace usually carries insulation on the front and rear elevations only, with party walls shared with neighbouring properties. The combined linear run across front and rear is commonly 10–14 metres, so five to six lengths cover most mid-terraces with a trimming allowance, plus one spare length for mitre waste at any external corners or bay-window returns. Detached and semi-detached properties scale up accordingly — measure the full perimeter where insulation is to be applied and divide by 2.5.
Does 90 mm insulation affect existing window sills?
Yes. A 90 mm EPS build-up plus basecoat and render finish adds roughly 100–105 mm to the wall depth. On many properties the existing sills will no longer project far enough beyond the new facade line, so over-sill extensions are usually required to maintain a clean drip edge ahead of the finished render. The specific extension depth depends on the original sill projection and the finished render thickness — measure on site before ordering.
What fixings work best when anchoring the 93 mm track to older brickwork?
Standard nylon frame plugs with 6 mm masonry screws perform well in sound Victorian and Edwardian brick. On walls with soft lime mortar joints, place each fixing within the brick face rather than the joint to ensure consistent pull-out resistance. Where the substrate is mixed or unusually friable, step up to a resin-bonded anchor at the affected fix points rather than reducing fix centres across the full run. Detailed anchor selection for the boards above the track is covered in the EWI fixings installation guide.
How well does the aluminium profile hold up over the service life of an EWI system?
Aluminium forms a self-healing oxide layer on the surface that resists alkaline contact from cementitious adhesives and basecoats, as well as long-term moisture exposure at the splash-back zone. In normal UK conditions the profile is expected to perform for the full service life of the surrounding render system. On highly exposed coastal sites where airborne chloride load is high, the 1 mm heavy-duty version provides additional reserve against pitting, though both gauges are made from corrosion-resistant alloy.