The Millboard Envello Shadow Line+ Horizontal Siding Installation Guide (PDF) provides complete instructions for installing Millboard’s premium wood-free composite cladding system. This guide covers storage, handling, WRB requirements, drainage and ventilation, furring strips, corner profiles, starter trims, fastening, board cutting, window and door details, and long-term maintenance.
The document begins with an overview of Millboard’s construction and performance (pages 4–5), highlighting its wood-free composite core, hand-molded grain texture, UV-stable surface, closed-cell structure, and ASTM E84 fire rating. Storage and handling rules on page 7 emphasize keeping boards stacked flat, carrying boards on edge with two people, and acclimating material for at least 72 hours prior to installation.
Pre-installation tools and PPE (page 8) include a miter saw or jigsaw, level, carpenter tools, stainless fasteners, a N99 mask, and safety glasses. Cutting recommendations on page 9 note that Envello cuts with standard wood tools and should be cut face-up for the cleanest finish. Touch-up coating is required for any visible cut edges.
Wall preparation guidelines (pages 16–18) detail the need for a compliant WRB, proper flashing, and drainage behind the boards. For higher-exposure areas or vertical installations, the guide recommends rainscreen drainage mats or pressure-treated furring strips set at 16–24″ on center. Diagrams on pages 17–18 show typical WRB assemblies and required airflow gaps.
Installation begins with corner profiles (pages 19–20), starter trims (page 21), and the first course of boards. Fasteners are installed through the tongue at a slight angle, using stainless screws or approved siding nails. A uniform 1/4″ shadow gap is maintained using Millboard Multi-Spacers. Page 22 outlines when face-fastening or colored-head screws are needed around windows, soffits, and cut-down boards.
Window and door details (pages 24–25) show proper 1/4″ uncaulked gaps at heads, flashing requirements, and options for using Enhanced Grain or fascia trim boards. Page 26 covers transitions to stucco using casing beads, caulk joints, and step-flashings.
Maintenance guidance (page 27) recommends once- or twice-yearly cleaning, avoiding cement dust, and using a fan-tip pressure washer below 2000 PSI.
Download the full Millboard Envello Shadow Line+ Horizontal Siding Installation Guide (PDF) for complete diagrams and installation requirements. If you need help planning a Millboard siding project, your TimberTown team is always here to help.
Download Resource
