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Cladding & Exterior

Cladding & Exterior
Calculators

Accurate material quantities for every external wall finish. From timber weatherboard and brick slips to render board, EWI, soffit, and pebbledash - calculate what you need before you order and avoid costly under-runs or over-ordering.

7 Free Calculators
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Waste Allowance Included
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Why Accurate Cladding Calculations Matter

External cladding and wall finishes are among the most visible elements of any building. Getting the quantities right before ordering saves money, avoids scheduling delays, and ensures consistent appearance across the whole elevation - particularly important with materials like timber where different batches can vary in colour.

Our cladding calculators account for the face width of boards, shadow gaps and overlaps, window and door openings to deduct, wastage from cutting around features, and the fixing requirements for each system - giving you a complete and accurate material list.

Whether you are a main contractor specifying materials for a new build, a builder quoting for a re-clad, or a homeowner improving kerb appeal, these tools help you order with confidence.

Key Factors in Cladding Calculations

  • Face width vs board widthFeatheredge and shiplap boards have a face width that is less than the board width due to overlaps. Always calculate based on face width coverage, not the nominal board size.
  • Deduct openings carefullyDoors and windows reduce the cladding area, but boards still need to be cut around reveals. A good rule of thumb is to deduct only 50-75% of the opening area to account for waste.
  • Fixings add up quicklyEach board course requires fixing points, and on large areas the number of nails, screws, or clips becomes significant. Include these in your material list and cost estimate.
  • Battens and counterbattensMost cladding systems require a batten and counterbarren framework behind the board. Calculate batten quantities separately - they are often as costly as the cladding itself.
  • EWI thickness affects revealsExternal wall insulation adds thickness to the wall. This must be factored into window and door reveal extensions and can require bespoke trims and fixings at significant extra cost.

Cladding & Exterior Calculators

Select a calculator below to get instant material quantities for your external wall project.

Weatherboard Calculator

Calculate the number of weatherboard lengths required for horizontal cladding on timber frame or masonry walls. Enter the wall area, board face width, board length, and waste allowance. Supports fibre cement, uPVC, and timber weatherboard profiles. Also estimates the number of lengths, linear metres, and fixing quantities.

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Timber Cladding Calculator

Estimate featheredge, shiplap, tongue and groove, or square-edged timber cladding quantities for external walls. Specify the cladding profile, face width, wall area, and fixing centres. Returns total linear metres, number of boards, and batten requirements. Covers both vertical and horizontal laying directions.

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Render Board / Cement Board

Calculate cement board or render board sheet quantities for external wall substrates, rain screen backing, or direct render applications. Enter wall area, board size, and cutting waste. Returns number of sheets, screws, washers, and jointing tape lengths. Suitable for Aquapanel, Hardiebacker, and similar products.

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Brick Slip Calculator

Estimate brick slip quantities, adhesive, and pointing mortar for thin brick veneer systems on external and internal walls. Enter the wall area, slip face size, and joint width. Returns total number of slips, adhesive coverage in kg, and pointing mortar volumes. Supports standard, metric, and continental slip formats.

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Soffit & Fascia Calculator

Calculate soffit board, fascia board, and barge board lengths and quantities for eaves finishing. Enter the perimeter of the roof overhang, fascia height, and soffit width. Returns linear metres of each component, number of standard lengths, and an estimate of joints and fixings. Covers uPVC, timber, and fibre cement systems.

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External Wall Insulation (EWI)

Estimate EWI board quantities, adhesive, fixings, reinforcing mesh, and basecoat for external wall insulation systems. Enter wall area and board size. Returns total boards, adhesive bags, mechanical fixings, mesh rolls, and basecoat volume. Suitable for EPS, mineral wool, and phenolic EWI board systems.

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Pebbledash / Roughcast Calculator

Calculate pebbledash aggregate and render quantities for traditional roughcast external wall finishes. Enter the wall area and specify the scratch coat, float coat, and pebble application method. Returns render volumes in m3 and kg, aggregate weight in kg or tonnes, and optional bag quantities for ready-mixed products.

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