Current Calculation details List of components Surface area: Number of m2 of your decking Board width Our boards come in 2 widths, 138mm and 180mm. 138 mm 180 mm 138 & 180 mm Type of installation Depending on the type of floor, choose the right type of installation. Installation on plots Laying on a concrete floor REVERSIL aluminium joist or solid wood (laid on studs) Type of joist 3.6m REVERSIL aluminium joist 3m solid wood joist Composite or solid wood joist Type of joist : 3m wood composite joist 4m wood composite joist Leave this field blank