Protect end grain on posts on plinth?

[Skumpe]

Hello Byggahus!

I will be installing posts of this type https://www.byggmax.se/95x95-impregnerad-stolpe-grön-p08795095
(impregnated wood 95x95)

On concrete piers with a "fork," such as these: https://www.byggmax.se/betongplint-p0352#1225=55338

The posts will be cut to approximately 1.5 meters in length.

If I place the post in the "fork" so that the distance from the end grain to the concrete is 5-10 cm, do I need to protect the end grain in any way? I have read that if you place the end grain on concrete, there should be protection in between. But my question is if any kind of treatment or protection is needed if the end grain is suspended in the air?

 

[myrstack]

With distance, you'll manage, but given how end grain absorbs, I usually over-recommend letting the end grain sit in suitable oil for a while. Whether the hole pattern on the pedestal iron can handle the distance you have in mind is another matter, but they should at least withstand a few centimeters so that you get the lower attachment between the wood and the pedestal a bit in from the end grain.

 

[Skumpe]

With distance, you manage, but given how end grain usually absorbs, I recommend overdoing it by placing the end grain in suitable oil for a while. Whether the hole pattern on the foundation iron can handle the distance you have in mind is another matter, but they should at least manage a few centimeters so you get the lower fastening between the wood and foundation a bit in from the end grain

How do I avoid the post getting discolored by the oil if I place it in oil? Should it stand in 2 mm of oil or something? Otherwise, there will likely be a line on the post where the oil level was?

 

[myrstack]

How do I avoid the post becoming discolored by the oil if I place it in oil? Should I let it stand in 2 mm of oil or something? Otherwise, there will likely be a line on the post where the oil level has been?

Normally, you oil the entire post in addition to allowing the end grain to absorb a little extra, and that coating on the surface with oil should normally remove any color shifts.

 

[Skumpe]

Normally, you oil the entire post in addition to letting the end grain soak in a little extra, and that application on the surface with oil should usually remove any color variations

That is a very strange viewpoint. It says almost everywhere when reading various guides and the like that pressure-treated wood does not need to be treated, is protected against rot for 20 years, and if you are going to treat it, you should wait a year so it dries properly first.

However, it also states that if you place the posts on a plinth with contact against concrete, you should protect the end grain.

My question is whether this applies if the end grain is hanging in the air as well. I don't think oiling the entire recently impregnated post is the correct procedure.

 

[klaskarlsson]

Hello Byggahus!

I will be installing posts of this type [link]
(impregnated wood 95x95)

On concrete footings with "fork", like these: [link]

The posts will be cut to approximately 1.5-meter length.

If I place the post in the "fork" so that the distance from the end grain to the concrete is 5-10 cm, do I need to protect the end grain in any way? I've read that if you place the end grain on concrete, there should be protection in between. But my question is if some kind of treatment or protection is needed if the end grain is hanging in the air?

If it's hanging in the air, you probably don't need to protect it.
But for a little extra stability, perhaps it's better to let it rest on the concrete (with a sill gasket in between)?

 

[Lulaua]

NTR/A can be in contact with the ground. Do nothing, leave a few cm down towards the plinth if you are worried.

 

[Skumpe]

If it hangs in the air, you shouldn't need to protect it. But for a little extra stability, maybe it's better to let it rest on the concrete (with syllpapp in between)?

Yes, that's how it's usually done, but I was just wondering if some protection was needed for the end wood if you don't do that and instead let the end wood hang in the air. Thanks for the answer!

 

[Skumpe]

NTR/A can be in contact with the ground. Do nothing, leave a few cm down to the plinth if you're worried.

I agree that this is what is said and written everywhere. But it also says everywhere that if you place the post on concrete, there should be paper in between. So it's contradictory.

 

[klaskarlsson]

I agree that's what is said and written everywhere. But it also says everywhere that if you place the post on concrete there should be paper in between. So it is contradictory.

Even if it "can" be in contact, it holds better if you minimize the risk of the end grain absorbing water.
It will surely last for quite a while without paper too, but in many cases the time may be shortened by several years.

 

[Skumpe]

Even if it "can" be in contact, it holds better if you minimize the risk of end grain absorbing water. It will probably last a good while without tar paper too, but in many cases, the time may be shortened by several years.

Yes, exactly. You do wonder how long it can actually last with tar paper if without tar paper it is guaranteed to resist rot for 20 years.

 

[klaskarlsson]

Exactly. You do wonder how long it can really last with the paper if without it the wood is guaranteed to resist rot for 20 years.

Then the question is what that guarantee is worth?
You need to make sure to save the guarantee certificate and receipt, and then only the material affected is replaced, not the labor.

As usual with construction, you can often "get by with less," but standards are set to cover all cases.

By the way, note that if you cut the post, you must treat the end:
"Processing
If cutting, drilling, or other minor processing is unavoidable, the processed surfaces should be treated with a suitable wood preservative, such as wood protection oil in qualification class 3. The classification according to the NTR system is lost if other processing is done, such as splitting or other longitudinal processing like planing and profiling."

https://traskydd.com/bestandigt-tra/rotskyddsgaranti/
https://www.valbotra.se/wp-content/uploads/2020/05/Garantisedel-NTR-A-Valbo-Trä.pdf

 

[Villa1949]

I placed 1 cm plastic spacers under the posts that I set on the footings.

 

[Skumpe]

[

I put 1 cm plastic spacers under the posts that I placed on the plinths

Can you link to the type of plastic spacers you mean?
What's the benefit compared to some cardboard?

 

[Viktor.J]

Swedish wood etc. recommend that all cut surfaces be treated with penetrating oil. What do they mean by that? I've used half oil (50/50 raw linseed oil/balsam turpentine) just to use something, but it changes the color of the decking.