What sort of posts are needed to hold up a very lightweight screen

[gavinabrown]

I have a very lightweight privacy screen that I need to put up. It's probably only about 5kg. I need to put two posts in the ground to hold it up. I wonder if the 90 x 42 treated pine pieces would do the job, given that it is so light, or should I still stick to the 90 x 90 posts?

It needs 1.8m above ground, so typically you'd need at least 600mm depth for the hole. But given the lightweight requirement, could I get away with a bit less?

Cheers.

[Skew ChiDAMN!!]

While you may be able to get away with 90x42's as uprights, I definitely would not skimp on the depth of foundations.

The screen may be lightweight but it's still inherently a "sail" that will catch the wind.

Are you sure you only need two posts? That's a narrow screen...

One alternative you could try is to use 1m@90x90 in the ground, bolting the TP studs to the sides with pairs of coach-bolts, much like a flagpole. This'd make maintenance of the screen easier in that you could remove the top bolt from each joint so the assembly would hinge around the lower bolt and fold down into easy reach.

[Chesand]

As Skew said, do not skimp on depth. I put up two metal screens using 70 x 35 with a bit more than 600mm in the ground, and concreted, and they are quite sound. They are decorative with patterns cut in so the wind has somewhere to go.
If using ordinary treated pine it is recommended to paint the base of the posts with bitumen paint to retard rotting.

[gavinabrown]

While you may be able to get away with 90x42's as uprights, I definitely would not skimp on the depth of foundations.

The screen may be lightweight but it's still inherently a "sail" that will catch the wind.

Are you sure you only need two posts? That's a narrow screen...

One alternative you could try is to use 1m@90x90 in the ground, bolting the TP studs to the sides with pairs of coach-bolts, much like a flagpole. This'd make maintenance of the screen easier in that you could remove the top bolt from each joint so the assembly would hinge around the lower bolt and fold down into easy reach.

Yes, it's a very narrow screen - it only has to hide a wheelie bin. Privacy screen is actually not the correct word for it.
I doubt that it would be a sail as it it has plenty of gaps - the wind would just pass right through it.

I didn't really get your final suggestion. I don't know what you mean by TP studs.

Yes, I was thinking about the 90 x 90 in the ground

[gavinabrown]

As Skew said, do not skimp on depth. I put up two metal screens using 70 x 35 with a bit more than 600mm in the ground, and concreted, and they are quite sound. They are decorative with patterns cut in so the wind has somewhere to go.
If using ordinary treated pine it is recommended to paint the base of the posts with bitumen paint to retard rotting.

Sounds like your screen is like mine - decorative with patterns cut into the wind. So 70 x 35 will do on one side, but I may go for 70 x 45 just in case - the other side is actually a colourbond fence so I can just connect the second post onto that.

Cheers.

[Skew ChiDAMN!!]

I didn't really get your final suggestion. I don't know what you mean by TP studs.

Yes, I was thinking about the 90 x 90 in the ground

Sorry, builders cant. TP = treated pine. By studs I mean lengths of (70-90)x(35-45)

If you sink a couple of, say, 1.2m lengths of 90x90 posts 600mm into the ground, you could bolt the studs to the sides in such a way it folds down for easy maintenance.