Questions regarding raised beds

[Plot70]

There is very little in this world that can stop couch grass roots apart from digging them out and cooking them in full sunlight for a few weeks.
I even found a dandelion root where a couch grass root had stabbed right through it.
Plastic membranes stand little chance.
It will depend on the species of plant the roots come from.

[gardengrace]

i personally like raised beds since they set encourage
defined walk ways.

[mrsbusy]

I prefer raised beds without sides.
I started out very enthusiastic about raised beds and put in 5 wooden boxes on my allotment. I find nettles and bindweed brambles etc creep in up the sides and are difficult to extract. The sides of the beds get very dry and harbour lots of slugs and co.
The sides are also getting pushed out and some have started to rot.
I now make raised beds without a physical 'box' but put a few logs or posts round to start it off. Charles Dowding is worth following for no sides raised beds.

[Plot70]

I use clods of grass with the roots outwards and neat manure against the tops.
Over the summer the sun bakes the root side and any growth inside can be stopped by adding a small amount urine between the soil and the wall.
The urine burns the unwanted growth and by the time it gets to the crop it is sufficiently diluted to be useful.

[Stan79]

Timber raised beds. As has been mentioned above, the edges of the beds can dry out quite quickly and the wood will rot from the ground up and from cut ends first so... make sure you have plastic between ground and timber and line the inside of the timbers with plastic too. Treating the cut end of the timbers with a preservative will help rotting and because you have plastic between timber and compost you can be confident of the preservative not getting into the compost/soil. The plastic also helps keep the moisture in around the edges of the beds as the wood isn't wicking the moisture out of the soil in summer.