How to paint and protect a pergola?

[ramonrodriguez]

Bought house with suspected untreated pergola, I am painting it asap to stop rot, house is brand new. Can you tell me if the products bought and process is correct to protect it? 

I have sanded, primed with Dulux 1 step prep and 2x coats of cabots exterior deck paint - this has all been done to decking and pergola. 

See below photos prior to the above work :

  

See report from building inspector and photos. 

Main Building

Pergola

Timber - exposed to weather

The beams of the pergola that has been built appear to be laminated veneer lumber

(LVL) and it is unclear whether it has been treated for external use. Veneer lumber has a tendency to move and the veneer come apart when exposed to weather.

External timbers that are frequently exposed to harsh weather conditions require adequate protection in order to maintain their condition. Where timbers have not been painted or treated adequately, general deterioration is likely to occur at an accelerated rate.

If left unattended, replacement of these timbers is likely to be necessary in the short-term future. Adequate treatment of these timbers is required as soon as possible by a painting contractor or general handyman.

[MitchellMc]

Welcome to the Bunnings Workshop community @ramonrodriguez. It's wonderful to have you join us, and many thanks for your question about protecting timber.
 

You’ve made great progress on painting your pergola. This is indeed a sufficient approach to provide protection against rot and weather damage. However, since the pergola is already assembled, you wouldn’t have been able to paint the surfaces that are not exposed, particularly the joints where water could potentially accumulate.

Even with the paint, water can still creep down into those joint areas and start the decay process over time. It might be worth considering sealing the gaps at the top of the pergola where the joints are to prevent water from running down into them. You can then paint over this sealant.

Please let me know if you have any questions.

Mitchell
 

[ramonrodriguez]

Thanks very much. Do you have a suggested filler?

[MitchellMc]

I've added a link above, and Selleys 410g Paintable Sealant Paint Over White would be suitable, @ramonrodriguez.

Mitchell

[ramonrodriguez]

Thanks very much mate- I need the tool to apply that right? Is there anything that doesn’t require it like standard filler? Or would you suggest this type? Also any other cheaper ones? Quality is my priority though for sure and something easy to apply. Maybe the applicator is important to get into small cracks? 

cheers!!

[MitchellMc]

You'll need a caulking gun to apply the sealant @ramonrodriguez. It comes with a thin nozzle to get into gaps, but I'd just apply it along the gaps and then with a gloved finger, run over the bead of sealant so it pushes into the gap and bound with either side of it, creating a weatherproof seal.

You'll probably only need one or two containers, and since it's a paintable version, I'd go with it.

Mitchell