Bitumen or clear coat for the substructure?

[mvs]

It's time to renovate the 15-year-old wooden deck.

The substructure (45x90mm beams) needs to be replaced, and now the question is whether I should best brush the tops of the pressure-treated beams (which the decking is mounted on) with bitumen or clear lacquer.

Hornbach recommended bitumen (after priming), but what really speaks against using a clear lacquer for outdoor use? It feels like clear lacquer would be an easier and at least equally good solution. And if I understand correctly, no priming is needed for clear lacquer.

What do you think?

 

[Matti_75]

There is special tape for the purpose.

 

[z_bumbi]

Clear coat sits on the surface and as soon as moisture gets underneath, it comes off. Biltum penetrates the wood and provides a "zone" even below the surface.
But is it necessary to treat pressure-treated wood?

 

[mvs]

There is special tape for that purpose

Yes, I saw it - Bitumen tape. It's really expensive. Hornbach recommended that I use Bitumen paint instead because there are large areas and painting penetrates better. Much cheaper too.

 

[mvs]

Clear coat sits on the surface and as soon as moisture gets underneath it, it comes off. Biltum penetrates the wood and provides a "zone" even under the surface.
But is it necessary to treat pressure-treated wood?

Good to know about the varnish. Thanks. Yes, here's a picture of the old pressure-treated wood that I unfortunately didn't brush with bitumen before:

 

[Matti_75]

This one is not so expensive
Verktygsvaruhuset

 

[mvs]

This one is not so expensive
Verktygsvaruhuset


[bild]

Ok, so you mean that Bitumen tape is better than brushed bitumen? Any special reason?

 

[mvs]

Clear varnish sits on the surface, and as soon as moisture gets underneath, it comes off. Biltum penetrates the wood and creates a "zone" even below the surface. But is it necessary to treat pressure-treated wood?

Came to think of something. There is boat varnish that should be suitable for moisture. Could that be an alternative?

 

[Oldboy]

Roslagsmahogny