SPC (Stone Plastic Composite) click-lock flooring installs as a floating system over a flat, dry subfloor with a 6–10 mm perimeter expansion gap, using 4–7 mm rigid planks with a 0.3–0.7 mm wear layer and 1.0–1.5 mm IXPE or EVA underlayment for moisture and acoustic decoupling [S3][S8].
Mainland Chinese factories (Shandong, Jiangsu, Shaanxi, Zhejiang) dominate 2026 SPC supply, with FOB prices from US$4.10–8.50 per square meter at 100–300 m² MOQ, click-lock 4–7.5 mm thickness options, and 20-year residential / 10-year commercial warranty coverage standard on OEM SKUs [S2][S4][S7][S8][S10].
Subfloor Preparation: Flatness Tolerance, Moisture Limits, and Acclimation
SPC rigid-core planks require a subfloor flatness of ≤3 mm over a 2 m straightedge, with concrete moisture ≤3 lb/1000 ft²/24 h (calcium chloride) or ≤75% RH, and 48-hour on-site acclimation at 18–29 °C before installation [S3].
Substrate types in scope include concrete (≥28 days cured, sealed if necessary), existing vinyl or tile (sound, with no telegraphing grout lines wider than 2 mm), and plywood/OSB (minimum 18 mm, securely fastened, no deflection). A 6 mil polyethylene vapor barrier is mandatory over concrete; over wood subfloors, only the attached or loose 1.0–1.5 mm IXPE/EVA underlayment is required [S3].
Surface contamination — old adhesive, paint, oil, or curing compounds — must be removed mechanically; chemical adhesive removers can leave residues that attack the SPC backing. A pull-tab or moisture-meter check on the slab is not optional: warranty claims for plank cupping or joint peaking on >75% RH slabs are routinely denied by the major Chinese OEM warranty terms documented in their commercial offers [S3][S8].
Plank Specification: Thickness, Wear Layer, and Click-Lock Profile
2026 OEM SPC planks ship in 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, 6.5 mm, and 7.5 mm total thickness, with wear-layer options of 0.3 mm (light residential), 0.5 mm (heavy residential / light commercial), and 0.7 mm (commercial) backed by a UV-cured acrylic topcoat [S8][S1].
Standard click profiles are Unilin and Valinge 5G/I4F, both licensed and present on Chinese OEM SKUs from Zhengfu (Fuflooring, Wuxi/Jiangsu), GKBM (Xi'an Gaoke, Shaanxi/Zhejiang bases), GS Floor (Changzhou Green), and YUDE (Huzhou, Zhejiang) [S2][S4][S5][S10]. Typical plank dimensions: 1220 × 180 mm (standard), 1525 mm and 1800 mm long formats (herringbone/large-plank programs from Wanli and similar mills) [S1].
Material stack from bottom to top: 1.0–1.5 mm IXPE/EVA pad (pre-attached on most 2026 SKUs), 3–6 mm CaCO₃ + PVC rigid core (limestone powder typically 55–75% by mass with PVC binder), decorative print film, and 0.3–0.7 mm transparent PVC wear layer with UV topcoat [S3][S8]. For commercial specs the SPC flooring reference page gives the layered breakdown; for the broader industrial flooring context including LVT and WPC comparison, see that encyclopedia entry.
Click-Lock Floating Installation: Expansion Gap, Stagger, and Door Transitions
Install the first row along the longest straight wall with the tongue facing the wall, maintaining a 6–10 mm expansion gap at all vertical obstructions (walls, columns, door jambs, pipes, kitchen islands); the gap is hidden by skirting or quadrant — never by caulk that locks the floor [S3].
Stagger end joints by a minimum of 200 mm (preferably 300+ mm) between adjacent rows; aligned joints across three consecutive rows create a hinge point that causes peaking under thermal cycling. Click planks at 15–30° angle, fold down, then tap the long seam with a soft tapping block and rubber mallet until the locking profile seats flush — gaps of >0.3 mm at the long seam are a reject [S3][S8].
At doorways use a T-moulding or threshold, never a continuous run between rooms of unequal temperature/humidity exposure (e.g. between air-conditioned bedroom and outdoor patio). For areas larger than 8 m in either direction, install an expansion T-moulding break every 8–10 m of continuous run to absorb the SPC core's thermal movement. Cabinets and kitchen islands should NOT be installed on top of floating SPC — the floor must be able to move freely underneath [S3].
Acclimation, Temperature Range, and Field Conditions
SPC must acclimate on site for 48 hours at 18–29 °C and 30–60% RH before installation; the planks are dimensionally more stable than LVT or WPC, but still move at the locking profile under temperature swings outside that band [S3].
Operating range after install: 0–40 °C surface temperature; below 0 °C the rigid core becomes brittle and click joints can crack under impact, above 40 °C the floor expands beyond the design gap and will peak. Direct sunlight over large south-facing windows can push surface temperature above 40 °C — specify low-E glass, window films, or thermal breaks to keep the SPC below that ceiling [S3].
Do not install SPC over radiant heating systems whose surface temperature exceeds 28 °C, and ramp the radiant system up or down in 5 °C increments per day. SPC's flooring expansion coefficient is lower than WPC's but higher than porcelain tile's, so the perimeter gap is non-negotiable on runs >6 m.
Cleaning, Maintenance, and Failure Modes to Watch
Daily cleaning: soft-bristle broom or hard-surface vacuum (no beater bar), damp microfiber mop with pH-neutral cleaner; avoid steam mops, abrasive pads, acetone, bleach, and wax — all degrade the UV topcoat and invalidate the OEM 20-year residential / 10-year commercial warranty [S3][S8].
Deep clean every 1–2 months. Place non-rubber-backed felt pads under furniture, use entry mats, and keep pet nails trimmed. The four most common 2026 SPC field failures, in observed order, are: (1) peaking at doorways from missing T-moulding on runs >8 m, (2) long-seam gapping from under-tapping or dirty click profiles, (3) cupping on slabs with >75% RH where the vapour barrier was skipped, and (4) UV yellowing on south-facing zones without window film. None of these are covered by the OEM warranty when the install manual is not followed [S3].
Repair rule: a single damaged plank in the field of the room can be replaced by unclicking back to the nearest wall and re-laying — but if the failure is a hollow sound, persistent peaking, or moisture bubbling, do not attempt a localised fix; pull up the affected run, dry/level the subfloor, and re-lay with new planks from the same production lot [S3].
Procurement and Sourcing Map: OEM Plants, MOQ, and Quality Gates
The 2026 Chinese SPC OEM cluster breaks into four regional groups: Shandong (Shandong Home Top New Material, Liaocheng), Jiangsu (Zhengfu Plastic, Taizhou; Suzhou-area acoustic-panel mills), Shaanxi/Zhejiang (Xi'an Gaoke / GKBM with two production bases), and Zhejiang (YUDE New Material, Nanxun; GS Floor / Changzhou Green) [S2][S4][S5][S7][S10].
Typical FOB China offers in mid-2026: 4–6.5 mm click-lock SPC at US$4.10–6.50/m² at 100–300 m² MOQ (made-in-China price index), rising to US$8.20–8.50/piece on branded Unilin-click Zhengfu SKUs at 2,000-piece MOQ [S2][S8]. Container-load OEM/ODM with custom print film and 0.5–0.7 mm wear-layer upgrades is standard at the larger mills, which are also China Building Decoration Association council members in several cases [S4][S6].
Comparative option lens (engineer-to-engineer, decision matrix): for residential wet areas (bathroom, kitchen), pick 5 mm+ with 0.5 mm wear layer and IXPE backing; for commercial (retail, clinic, light office), pick 6–7.5 mm with 0.7 mm wear layer and separate 1.5 mm underlayment; for budget residential, 4 mm / 0.3 mm wear layer is acceptable if subfloor is concrete and traffic is light. Comparable reference: Wanli's premium 7 mm herringbone and 12 mm grey-parquet SKUs target the upper end of this matrix with longer formats and embossed-in-register (EIR) surfaces [S1].
Spec-level background on the components involved: linear guide.
This topic is covered further in Insulated Tools Installation: Spec Gates and Field Checks.