Plastic wedges under floor joists

[ZipLock]

I am leveling a floor on an uneven concrete surface and plan to use plastic wedges as shown in the link below between the floor and the joist.

http://www.biltema.se/sv/Bygg/Fastelement/Ovrigt/Plastkil-194743/

I plan to use the yellow wedge, which is 25 mm at the thickest part. I have read different instructions on how they should be installed and need some clarity before I start.

Should they be installed "two stacked from opposite directions" or "two side by side from opposite directions" or is one sufficient? Are the hooks enough for them to stay in place, or do I need to drive a screw through the joist and into the wedge/wedges?

 

[pelle242]

Isn't the idea that the hooks should lock into each other? Then you should have two in each other from opposite directions. Then I'm wondering if you shouldn't drive a screw through the wedges and down into the concrete floor. All solutions like Nivelll, granab and ghia fasten their spacers to the substrate, and it seems to me that you are trying to do the same thing....

 

[titanium]

This is how I did it. The wedges that I did not drill through were simply skew-nailed to keep them in place.

 

[Peter2400]

You might be able to use pallningsbrickor, feels a bit more stable if the dimensions match.
http://www.biltema.se/sv/Bygg/Fastelement/Ovrigt/Mellanlagg-194748/