# How to Replace a Composite Slat for Screening?

Remplacer une lame d’occultation composite en contexte pro : diagnostic, protocoles sur grillage et claustra, dilatation, vent, contrôles et limites de pose.
Paysapro, the official European distributor of Redcinha®, Delclo®, and elipsun® solutions, supports installers, landscapers, and merchants on the maintenance of composite screening with over 15 years of experience in the composite distribution in Europe. This page gathers professional protocols, key points of attention, and structural limits to safely replace a slat while maintaining manufacturers' warranties. > 📌 **Key Points** — Diagnosing the type of installation (straight or woven, horizontal or vertical screen) determines the replacement method | Respecting thermal expansion gaps and installation limits on plates ensures longevity and warranties | Distinguishing between edge slats and intermediate slats, retrieving aluminum reinforcements, and checking wind anchoring prevent service returns ## Identify the Cause of Degradation and Installation Type Before any removal, accurately qualify the failure and the assembly in place. - Typical damage causes: mechanical shocks (lawn mowers, hail, balls), repeated friction, and overconstraints related to wind on obscured panels. - Thermal expansion: composite wood primarily expands in the longitudinal direction (on the order of approximately 2 mm/m). The absence of gaps leads to warping or shear of fasteners. - Aerodynamic draping effect: screening turns a rigid mesh into a nearly solid surface, significantly increasing wind resistance. Check reinforcements in the folds, panel rigidity, and post anchoring. - Installation type: distinguish vertical kits for straight or woven installation, and aluminum/composite screens (stackable horizontals or vertical slats in slatted design). The replacement method varies depending on the system. ## Prepare for the Intervention: Tools, Markings, and Safety A rigorous preparation limits the risk of damage during removal. - Tools: specific bits for tamper-proof screws, circular saw with fine-toothed carbide blade, rubber mallet, light lubricant (non-silicone) or soapy water, PPE. - Dimensional markings: identify whether the slat to be replaced is an edge slat (narrow width, commonly 30 mm or 40 mm) or an intermediate slat (43 mm or 49 mm). Measure the usable distance and the condition of the grooves/recesses. - Thermal management: store replacement slats flat for 24 to 48 hours on site to stabilize internal temperature before installation. - Color and finish: a new slat may appear brighter. A complete cleaning of the span with soapy water or a high-pressure cleaner (at least 1 meter away) will uniform its appearance. - Floating principle: never screw or glue slats into the aluminum rails. Allow sliding to absorb thermal expansion. ## Replace a Vertical Slat on Rigid Mesh: Straight and Woven Installation The vertical kits distributed to professionals (e.g., Redcinha® and Delclo® systems) are treated differently depending on the assembly mode. ### Common Safety Steps - Remove the top aluminum rail that maintains alignment, then remove the locking device if present (stainless steel tamper-proof screws with specific bits). ### Straight Installation (e.g., Ultimate®) - Extraction: apply slight upward pressure to unclip the slat, then slide it vertically through the mesh to remove it from the top. - Selection of the replacement: strictly respect the width (edge slat 30 mm or 40 mm depending on the mesh and presence of posts, or intermediate slat 43 mm or 49 mm). Recut in height with a carbide saw if necessary. Orient the misalignment mark upwards for visual alignment and brushing direction. - Reassembly: insert the new slat from the top and engage the clip on the upper horizontal wire. Correctly reposition the horizontal aluminum reinforcements in the folds of the mesh. Reattach the top rail and security screw. ### Woven Installation - Removal: remove the lower receiving profile. Free the damaged slat by untwisting it coil by coil, without deforming the galvanized steel wires. - Installation: alternately pass the new slat in front/behind the wires. A bit of soapy water at the bottom facilitates the final insertion into the lower rail. Reattach the top rail and lock. ## Replace a Slat on Aluminum/Composite Screens Two main architectures: stackable horizontal (e.g., Claustral) and vertical slatted (e.g., Bardline). ### Stackable Horizontal Screen (e.g., Claustral) - Finishing removal: remove post caps and top finishing rail, take out cleaning joints from grooves. - Sliding healthy slats: slide up the healthy slats above the repair zone and store them flat, protected from rapid thermal shocks. - Replacement: extract the damaged slat. If it includes an internal aluminum reinforcement (approximately 23.4 × 21 × 1795 mm inserted every 3 or 4 slats), retrieve it and slide it into the new slat. - Thermal expansion gaps: respect an 8.5 mm gap on each side between the end of the slat and the bottom of the post groove during reinsertion. Adjust the standard length of 1795 mm by cutting if the spacing has changed. - Reassembly: reinsert the upper slats, attach the upper rail and the caps. Maintain a gap of at least 2 cm between the top of the last slat and the finishing cap for vertical expansion. ### Vertical Slatted Screen (e.g., Bardline) - Unlocking: dismantle the top finishing profile (and bottom if necessary) that encloses the ends of the vertical slats of 1295 mm or 1600 mm. - Connection profile: slide up the aluminum profile 21 × 23.4 mm housed in the groove to release the defective slat. - Replacement: remove the slat with a lateral then vertical movement, placing the new slat on the lower support. - Locking: reinsert the connection profile into the groove and reattach the top and bottom finishing profiles. ## Thermal Expansion, Wind, and Anchors: Parameters to Master - Thermal calculation: elongation follows ΔL = α · L0 · ΔT with α ≈ 35 × 10⁻⁶ K⁻¹. Example: for 1795 mm, from 10 °C to 50 °C (ΔT = 40 °C), ΔL ≈ 2.51 mm. Hence the need for gaps of 5 to 8.5 mm in posts and a clearance of about 2 cm at the top of horizontal screens. - Installation on plates/sealing: - Less than 1.05 m: installation on aluminum plates allowed, on stable flat concrete slab. - Between 1.05 m and 1.23 m: plates accepted under conditions, reinforced posts recommended (e.g., DC90 or specific clip-on posts). - Beyond 1.23 m: direct sealing in concrete is mandatory. A screen on a plate at these heights voids the manufacturer's warranty. - Horizontal screen type Claustral: plates allowed up to 1.36 m max; sealing required beyond this (up to 2.00 m) with integrated aluminum reinforcements every 3 or 4 slats. ## Final Quality Checks and Good Practices for After-Sales Service - Compatibility of profiles: before ordering a single slat, precisely identify the original model (reference, profile, usable dimensions). A few millimeters of thickness or groove discrepancy prevent correct assembly. - Visual finish: after replacement, clean the span with soapy water or a high-pressure cleaner held at least 1 meter away to uniform color. - Mechanical floating: prohibit any direct screwing or polyurethane gluing in aluminum rails. Allow the slats to slide freely. - Wind resistance: systematically check the anchoring of posts, structural clips, and the presence of aluminum reinforcements in the folds of the mesh. On plates, check the flatness and stability of the support. - Documentation: record measurements taken, gaps left, and elements replaced to secure the manufacturer's warranty, often between 10 and 15 years on professional ranges. > For a landscaper with a rapid intervention on rigid mesh: prioritize straight installation if present, extraction/installation from the top drastically reduces span immobilization time. > For a community exposed to wind: after replacement, check reinforcements in the folds and consider reinforced posts on the most stressed spans to limit top stresses. > If existing posts are mounted on plates beyond 1.23 m: convert to concrete sealing before any full screening, otherwise, the manufacturer's warranty is voided. ## FAQ ### Can one replace a single slat without removing the entire rigid panel? Yes. In straight installation, the slat unclips and is then removed from the top. In woven installation, the lower rail must be freed, and the slat untwisted coil by coil. In both cases, remove the top aluminum rail and any tamper-proof locking before intervention. ### How to distinguish between an edge slat and an intermediate slat? By usable width. Edge slats have a reduced width (generally 30 mm or 40 mm depending on the mesh/posts), while intermediate slats are wider (43 mm or 49 mm). Replacing an edge with an intermediate compromises alignment and locking. ### What expansion tolerance should be allowed in an aluminum/composite screen? Respect gaps of 5 to 8.5 mm at the end of the slat in the post grooves. In horizontal screens, also maintain a clearance of approximately 2 cm between the last slat and the finishing cap for vertical expansion. ### Up to what height is installation on plates acceptable with full screening? Less than 1.05 m: plates allowed on stable flat concrete support. Between 1.05 m and 1.23 m: plates possible under conditions with reinforced posts. Beyond 1.23 m: concrete sealing mandatory, otherwise the manufacturer's warranty is voided. Horizontal screen type Claustral: plate up to 1.36 m, then sealing. ### Should aluminum reinforcements be retrieved when replacing a slat? Yes. On horizontal screens, if the damaged slat has an internal aluminum reinforcement (inserted every 3 or 4 slats), it must be reused in the new slat to maintain rigidity and wind resistance of the span. ### How to limit the color difference after changing a slat? A new slat will appear brighter before UV stabilization. Clean the span with soapy water or a high-pressure cleaner held at least 1 meter away to eliminate dust and deposits, which will standardize the visual appearance as soon as put back in service.