Raised Beds

[i_am_fubar]

I folks,

I'm going to be building some raised beds and am looking for suitable timber. I want these to be chunky beds, so avoiding 19mm thick timber if possible. At first I purchased a couple of lengths of this stuff:

http://www.wickes.co.uk/Treated-Regular-KD-C16/invt/166360

But the 'pressure treatment' seems to only go in a few mm. I'm therefore guessing it wouldn't last as long as this sort of timber:

http://www.wickes.co.uk/Sawn-Treated-Softwood/invt/107070

Next quesion is. How would either decking boards or decking joists compare? :

http://www.wickes.co.uk/Deck-Board/invt/101000
http://www.wickes.co.uk/Deck-Joist/invt/101318

Would these hold up to being continually in contact with soil?

Natrually, I understand that none of these will last forever, I just don't want to have to re-build it all in 2 years.

Cheers guys.

Sam.

 

[raebhoop]

I've used B&Q decking boards just over two quid each..I figure good for about 5 years

 

[uzziel49]

I built a couple of raised beds last year using decking board, painted them inside and out with fence paint and lined the sides with DPC membrane. Should last a few years I reckon.

 

[i_am_fubar]

>.< I forgot the membrane. I've built two sides on the raised beds into the top of 30cm high timber retaining walls and I just have the soil piled up agianst them.

Aw crud, I guess I'm digging it back out when I'm back from holiday :/

 

[Thermo]

you dont want a dpc memebrane. it will hold moisture against the boards and speed up the rotting.

 

[i_am_fubar]

Ah, thank goodness... Still, I imagine a weed suppressant would be good to stop any stray roots getting through.

What sorta life expectancy should I get from tantalised timber if fully buried?

 

[uzziel49]

you dont want a dpc memebrane. it will hold moisture against the boards and speed up the rotting.

You know, I wondered about that too, but every "how-to" I read last year said that you should line the raised bed with DPC membrane. Well, they've lasted 1 year, we'll see how much further they go