How to fix exterior weatherboards?

[AstridT]

 

Is there anything I can do to even up these rough edged timber planks on the outside of our house? We want to repaint but can’t afford to replace at the moment

[JDE]

Suggest you use a product like Pollyfilla exterior timber should be able to get a tub from Bunnings.

1. Ensure surfaces are clean and dry and remove any rotted timber and fix split timber firmly before filling. Priming is not necessary. 
2. Apply Polyfilla Exterior Timber firmly using your filling blade. Scrape off any excess to save time sanding. Allow to dry for 2-3 hrs in thin 2-3mm applications depending on humidity. For deeper jobs apply in 10mm layers, allowing each layer to dry completely before applying the rest.
3. Sand back to a smooth, even surface and paint with a quality exterior water or oil-based paint, or stain and clear varnish.
4. For a smoother finish allow filler to dry, sand back and apply another very thin coat of filler. Allow this to dry then sand lightly with fine (>300 grit) sandpaper before painting or varnishing.
5. Protect from rain until painted over and for best results apply undercoat before applying exterior top coat.

Instructions are from their site

[JacobZ]

Hi @AstridT,

Thank you for your question about fixing up some deteriorated weatherboards at your home.

@JDE's advice is excellent and is more or less what I would recommend.

Start by sanding back the damaged areas to determine if any rotting timber needs to be removed or treated. If you find rotted timber, remove the worst affected sections and use Earl's Wood Hardener to treat the rest.

Once any rotted timber has been removed, sanded and treated, use a filler product such as Poly Exterior Timber Filler or Builders Bog to imitate the shape of the weatherboards.

You can apply and shape your filler with a 100mm Sharp Edge Paint Scraper. Once your filler has dried, use a Trojan 120 Grit Angled Sanding Sponge to sand the filler to prepare for painting.

Let me know what you think and if you have any further questions, please don't hesitate to ask.

Jacob