Replace facade cladding – board-on-board — step by step

How facade cladding comes together

You replace facade cladding when the paint flakes off, when the boards have gone grey and split, or when you find soft, rotten timber down by the ground and around the windows. It's also your chance to get everything right behind the cladding: a new wind membrane, a proper ventilation gap and sound battens. Vertical board-on-board cladding is simple in principle — wide base boards are fixed to the battens with a few centimetres between them, and narrower cover boards are screwed or nailed over the joints. The movement in the timber is absorbed in the gap, water runs straight down the vertical boards and air can travel freely behind the cladding. Here we walk through the whole job, from stripping the old cladding to end-grain priming, undercoat and final topcoat.

1. 01

   Plan, measure and check the conditions

   Measure the facade area (height × width minus windows and doors) and work out the material per side. Find out whether the house has conservation requirements or a local plan that controls colour and cladding type — contact your local building authority if you're unsure. Photograph the facade before you start so you can easily recreate trim, corner boards and flashing details.

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   Pro tip:

   Before you start removing the cladding, do a quick check of the timber's condition. Use a screwdriver or knife and gently press the tip into the cladding board, especially at the bottom where the panel is most exposed to moisture. If the tool goes into the wood easily or the wood feels soft and crumbles, it may be a sign of rot and the board should be replaced.

   Note: This is a quick check that can indicate the condition of the cladding. If you suspect extensive rot, the underlying structure, ventilation gap, battens and wind membrane should also be checked before the new cladding is fitted.

   💡Tip: Do one facade side at a time. That way the house is never exposed for more than a few days and you have time to cover up before rain.
2. 02

   Strip the old cladding carefully

   Start at the top and work down. Remove trim, corner boards and flashings first and label them if you plan to reuse them. Lever the cladding off against a block of wood so you don't damage the framing, and pull out any remaining nails straight away so nobody steps on them. Sort the timber — rotten wood goes to recycling.

   💡Tip: Have a tarpaulin and a skip or bulk bag ready from the start. Stripped cladding takes up more space than you'd think.
3. 03

   Check the framing, sill plate and rot

   With the cladding off you see the truth. Probe the studs, the sill plate and the window corners with an awl — soft timber means rot. Replace all damaged studs and sill sections before you go on, and look for dark moisture streaks that show where water got in. Check that window sill flashings slope outwards and that no water is being led into the wall.

   💡Tip: If there's extensive rot in the sill plate or load-bearing framing, get a builder or structural engineer in before you close the wall up.
4. 04

   Fit a new wind membrane

   Staple up the wind membrane or fit wind boards over the whole frame. Work from the bottom up with at least 10 cm overlap so water is always led outwards, and tape the joints. Fold the membrane into the window and door reveals and seal it against the frames.

   💡Tip: The wind membrane must shed water but stay vapour-permeable — never use plastic sheeting on the outside.
5. 05

   Fix the battens and create the ventilation gap

   Fit vertical battens in line with the studs first, normally at 600 mm centres. For vertical board-on-board you need cross battens: horizontal battens at 600 mm centres on top of the vertical ones — those are what the cladding is nailed to. The dimension is up to you, e.g. 22 × 45, 25 × 45 or 34 × 45 mm, as long as you get at least a 22–25 mm ventilation gap behind the cladding. The battens don't need to be pressure-treated; untreated spruce works fine behind a ventilated facade. Use a long level to check that every batten sits in the same plane.

   💡Tip: Fit insect mesh at the bottom of the gap. The gap must be open both at the bottom and up at the roof, or the facade will never dry out.
6. 06

   Prime all end grain and undercoat

   Cut the boards to length and dip or brush every cut end in end-grain primer — end grain absorbs water 10–20 times faster than the face, and that's where rot almost always starts. Then prime bare cladding all round, including the back, before fitting. Factory-primed cladding only needs the end-grain treatment.

   💡Tip: Keep a tin of primer and a brush at the saw horse. Then it actually gets done at every cut, rather than 'later'.
7. 07

   Fit the base boards

   Start in a corner with a plumbed string line. Get the first base board perfectly vertical — the whole facade follows it. Nail or screw once per batten, in the middle of the board, so the timber can move. Leave 20–40 mm between the base boards depending on the width of the cover board, and keep at least 20–30 cm of clear distance between the bottom of the cladding and the ground.

   💡Tip: Cut a spacer block to the width of the gap and use it all the way — far faster and more even than measuring every time.
8. 08

   Fit the cover boards over the joints

   Centre the cover board over the gap so it overlaps each base board by at least 20 mm. Nail through the middle of the cover board, into the gap between the base boards — never through two boards at once, or the cladding will split as the timber moves. Check plumb every fifth board.

   💡Tip: The bottom edge of the base board should sit slightly below the cover board so water drips off clear of the wall.
9. 09

   Deal with windows, doors, corners and flashing

   Fit trim around windows and doors so the cladding stops against the trim, not the other way round. Fit window sill flashings with at least 14 degrees of outward slope and a drip edge in front of the cladding. Corner boards cover the corners and protect the end grain. Use a flexible sealant between metal and timber — but never seal the ventilation gap at the bottom.

   💡Tip: Flashing always goes on the outside of the cladding below it, never behind it. Water must be able to run out, not get trapped.
10. 10

    Prime and apply two finished coats

    Paint when the timber is dry (below 16 % moisture content), in the shade and at 10–25 degrees. Prime all bare surfaces, let them dry as the tin says, then apply two finished coats of opaque paint or Falu red paint. Be extra thorough in the gaps, on the edges of the cover boards and on all end grain.

    💡Tip: Never paint in direct sun — the paint skins over too quickly and lets go after a couple of years.
11. 11

    Final check and tidy up

    Walk the whole side: is the ventilation gap open at the bottom and up at the roof, is the insect mesh in place, do all flashings slope outwards, is every end-grain surface painted, and is the distance to the ground at least 20–30 cm? Clear away nails, refit downpipes and lights, and take a photo of the finished result.