raised-bed Weed barrier under or over dirt in raised beds?

[newbiepepperguy]

Pretty much just the question in the title. I want to keep weeds under control, but I also don't want to mess up the potential for root development. The weed barrier I'm looking at is supposed it be good for drainage, so that's not a concern. The beds are 1 foot deep. Here's the link:
 
https://www.amazon.com/Dewitt-50-Foot-12-Year-Barrier-12YR450/dp/B0016AJC1Q/ref=cm_cr_arp_d_product_top?ie=UTF8
 
Should that go over or under the dirt? Or both, so that it warms the soil, too? Any help is much appreciated.

 

[juanitos]

over

 

[D3monic]

I had under as it was too much sod to cut. After a year I just dug down and cut out hole through weed mat.

 

[nzchili]

yea you dont want it underneath..that would hinder the roots growing down and into the earth below (if the plants ever got large enough)

 

[solid7]

No weed barrier in the bottom of the raised bed.

 

[Spicytigger]

put mulch on top to hold it down and keep moisture in.

 

[cone9]

Over and I use landscape staples to hold it down - no weeding is such a joy!