Waterproofing inside of wooden raised beds

[GasEngineer]

Renewing my raised beds for this year as the wood has rotted away got me thinking about waterproofing the inside face of the new timbers.

The weed suppressant type material is porous so that would be no good; plastic would just trap any water that gets between the plastic and the timber (and also perhaps wick it up by capillary). Although the wood is pressure treated I suppose I could paint it with some kind of waterproofing product on the inside.

Any ideas welcome please - or is it not worth it?

[OutInTheShed]

I'd say it's worth putting a barrier between what you're trying to grow and the biocides in the timber, more so if you might eat any produce?

Thick polythene such as DPC sheet is a normal choice.

[Mazinbrum]

Sika Black Jack.

[paulwirral]

OutInTheShed said:

I'd say it's worth putting a barrier between what you're trying to grow and the biocides in the timber, more so if you might eat any produce?

Thick polythene such as DPC sheet is a normal choice.

That’s what I used

[Harpoon]

We built two new beds and rebuilt an old one last summer. I got a big roll of DPM from Screwfix and cut it with a Stanley knife using a long length of timber as a straight edge. I left a little lip at the bottom so didn't have to worry about an exact height and soil wouldn't get behind it. Then just stapled along the top and anywhere sections overlapped.

https://www.screwfix.com/p/damplas-damp-proof-memb...

[drmotorsport]

I doubt it's worth it. I made a raised vegetable patch bordered with sleepers and lined with DPM, the sleepers still rotted in less that 10 years.

[GasEngineer]

Thanks for all the tips - much appreciated.

[sherman]

You could paint it with bitumen paint.

[paulwirral]

Maybe to late but it’s worth knocking a few galvanised nails in the bottom sleepers and standing them on bricks to stop the bottoms rotting out

[48k]

Painting with bitumen paint is the best solution. Any kind of liner will always trap moisture against the wood however tightly you seal it / staple it.

I would also highly recommend integrating some hose pipe in the beds (buryable hose pipe that loops through from bed to bed) which you can then t-off to provide irrigation on a per-bed basis. Watering then becomes a simple matter of clipping on a hose pipe. Much less hassle then standing there every evening watering beds by hand.