Posts for the terrace - have I completely messed up?

[kniv]

I saw now that the posts available at the building supply store were classified as NTR-B. Wouldn't you prefer AB?

Both AB and B are above ground, so no difference. B is usually used for finished carpentry with pine while AB is for paneling, boards, battens, decking, etc. A would have been preferable as it is most common for posts, but since you are using it above ground, it's a bit overkill anyway.

It looks like you have a recessed floor joist? Since no screw beams rest on the carrier beam in the previous picture.

 

[kniv]

I have primed with indstriprimer, like Caparols Unigrund or Biltemas snickerigrund. This grips the wood really well. It's held for 25 years on the oldest pressure-treated woodwork I've painted. Probably stronger impregnation back then, but the principle is the same. What you paint on the primer matters less. Choose the same type of paint as for the house.
The pressure-treated laminated posts are already dried out and should be paintable directly. Wipe them down with a solvent, like white spirit or T-sprit first. There might be "greasy" residues on them.

Overall, acrylic paint, which is often used on houses, is hardly preferable for posts where you paint all four sides. And if you still want to paint a post on all four sides with acrylic paint, snickerifärg should be chosen.

 

[Amrich]

Both AB and B are above ground, so no difference. B is typically used for finished carpentry of pine while AB is for paneling, boards, battens, decking, etc. A would have been preferable as it is most common for posts, but since you're using it above ground, it's a bit overkill anyway.

Looks like you have a recessed floor structure? Since no screw battens rest on the support beam in the previous picture.

Yes, that's correct, the floor joists are at the same level as the front support beam. Built by previous owners and looks okay.

Does it really not matter if I choose B or AB? The image below is from the wood guide, which made me a bit unsure. Is it just the surface of NTR B that is impregnated? In my case, it's the end grain at the bottom of the post that will be the most exposed.

Strange that there are glulam posts in A and AB but not in A when it's recommended for posts?

 

[fribygg]

Color type?

Linolja, linoljefärg, tjära or roslags mahogny are probably the only known surface treatments that help against rot. I suggest half-oiling with balsamterpentin and linolja now and three thin layers of linoljefärg in the spring when the humidity is low.

 

[DennisCA]

But what time frames are we talking about? People have been building with regular timber for ages, both in good and bad ways. It doesn't become unusable by rotting within just a year directly.......

It can vary greatly; my parents have a patio that is over 30 years old, not treated, and it's low down. But it has its own roof. Nothing there has rotted.

 

[DennisCA]

I personally wouldn't want to start redoing things at this stage... I would keep going and deal with the consequences later, which could be decades in the future... I would try to get linolja down there at the bottom so it can soak into the end grain. I might also try to get tar in there.

It might be easier to do something with the roof overhang, for example, if it doesn't already have one, install a gutter and downspout which makes the overhang larger and diverts water more effectively.

 

[Amrich]

Thank you

Personally, I wouldn't want to start redoing things at this stage.... I would just go ahead and deal with the issue later, which could be decades in the future... I would try to get some linolja down there at the bottom so it can soak into the end grain. I might also try to get some tjära there.

It might be easier to do something with the roof overhang, like if it doesn't already have one, install a gutter and downspout which will make the overhang larger and lead water away more effectively.

Thanks for the advice!

I'm prepared to redo it as long as I know what the "best" solution is. I thought I was in the clear when I found pressure-treated glulam posts, but when they turned out to be only NTR B, I became unsure of how much better that would actually be compared to what I have now.

The roof overhang is quite substantial at the moment, but the front end of the deck is facing the direction from which the wind blows, so it probably gets wet about 50cm onto the deck with each shower right now without it blowing particularly hard.

 

[Amrich]

I thought I would follow up on how this story ended.

I found a solution that was acceptable in terms of economy, effort, and results:

I loosened the screws at the bottom of the posts, jacked them up with a jack, and placed shims under the post both against the plinth and the beam. This should prevent the end grain from standing in water and help it dry out faster.

I already had the shims, so the cost was 0 kronor, and it was very quickly resolved. Hopefully, I've extended the lifespan of my posts somewhat with this solution.

Thanks for all the advice in the thread, even though I eventually chose my own alternative.

 

[Leif i Skåne]

Perfect! That's what I wrote in post #6
My entire patio construction and conservatory are built on 10mm plastic spacers.

 

[Amrich]

Perfect! That's what I wrote in post #6.
My entire patio construction and conservatory stand on 10mm plastic washers.

Yes, apologies, credit where credit is due! It was probably your suggestion that settled in the back of my mind and matured for a while. Thank you for your help 😄

 

[sblixten]

Well done! Don't forget to paint - there should be no bare wooden surfaces where the post will be exposed to moisture.

 

[fribygg]

Don't forget to paint - no bare wood surfaces should be where the post will be exposed to moisture.

I don't share that opinion, I believe that bare (or linseed oiled) wood surfaces hold up better than posts painted all around with Beckers window paint.

Overall, acrylic paint, which is often used for houses, is hardly preferable on posts where you paint all four sides. And if you're going to paint a post on all four sides with acrylic paint, you should choose carpentry paint.

Water-dilutable alkyd, which is likely the question in this case, is hardly the best if you're going to paint a post on all sides.

 

[Workingclasshero]

Well done!
/W

 

[sblixten]

I do not share that opinion, I believe that clean (or linseed oiled) wooden surfaces hold up better than posts painted all around with Beckers window paint.

Do you mean that you should not paint the circled areas below, but instead make more such marks?

 

[Leif i Skåne]

Good job!
Don't forget to paint - no bare wood surfaces should be where the post will be exposed to moisture. A bare end grain on a pallet block dries the end grain several decimeters up.

No!
Those who have access to compressed air, try blowing through one end of freshly cut firewood when it's fresh and wet, it bubbles at the other end.

At the sawmill, the freshly cut wood is dried by cooking it in steam up to 120° temp, and the water in the wood squirts out of the end grain. There are many cubic meters of liquid from a wood dryer!