A Softwood garden structures and their treatments question

[davic]

I am intending to make some garden structures such as archways, benches and defiantly a planter. out of softwood as I have some kicking around and and too skint/tight to buy hardwood. I just cant afford it.

It it is treated properly will it last a good while? Some of it is going to be for climbing rose and I'd hate the structure to crumble just as the plant gets established

Also with a softwood planter/raised bed, would contact with the soil just rot out the wood in no time? What sort of wood treatments would be best and what sort of lifespan would be reasonable please?

All help appreciated

 

[AndyT]

You could be lucky but random softwood will not be naturally durable. Preservative treatment will help but is just a way of buying a few extra years.
If you do want to build an arch or plant support, don't just bury the wood in the ground - that is the surest way to make it rot. Instead, buy or scrounge some Metpost fence supports or something equivalent so that the bottoms of your uprights are up off the soil.
Oak fence posts only cost a few quid and could make a cheaper job in the long run.

 

[davic]

Thanks for the quick reply. I went into a superstore yesterday and was amazed at the amount of treatments. It was bit daunting; would unspecified/leading brand clear wood preserver do the trick?

I was thinking about decking oil as it sounds like its heavier duty and wondered how this would work with a planter. Would you get five years out of it possibly?

 

[AndyT]

I don't think any of them will come with a promise to make your wood last for x years. A lot will depend on whether it stays permanently damp or not. Softwood fixed vertically and off the ground (as in a fence) can last quite well - but use it for raised beds in a damp spot and you should expect it to rot out in only a couple of years. Your planter might last longer if it has a liner - though that might make it worse!

 

[davic]

Yep, all good stuff! I was just wondering what type would be the best for the this type of usage. Just get the cheapest and hope for the best maybe?

 

[Eric The Viking]

Two things work:

Creosote -- proper creosote. find a tall tin or a piece of pipe you can seal, put some pebbles or coarse gravel in the bottom (so the liquid can circulate and stand the end of the post in it. Fill as far up as you can with creosote and leave for as long as you dare (weeks, preferably). It helps if the post is as dry as possible to start off with. Ideally, it wants to be immersed to at least 6" above the ground level. Paint the rest of the post in creosote in the usual way.

It hasn't actually been completely withdrawn. Thanks to EU directive you can't buy it retail, but it's still avaliable to fencing contractors and can be got through farm suppliers (I think). Leastways, that's how I came to have some And before someone goes on about it being nasty stuff, there's no proof it's a carcinogen, only heresay (read the WIkipedia entry), and it was even sprayed on Saharan sands for a while to stimulate plant growth to stabilise the dunes.

Bitumen paint ("Synthaprufe"). Stand the post in it, in the same way as for Creosote, but you probably only need to leave it overnight. Dampness in the wood doesn't matter as the stuff is water-based. Let the post dry thoroughly before use (it's brown when wet, dries to black, but skins over quickly (still liquid underneath). Synthaprufe bonds well to concrete. Our back garden gate posts are done that way, getting on for five or six years with no signs of rot, even though they're in a spot that gets drenched in the winter. The above ground part was Creosoted properly.

Also softwood usually rots first via the end grain. If you can design the whatever so that the end grain can't get soaked, or that it sheds easily, the whatever will last a lot longer. I've started to use Flashband as a capping for posts, as it's cheap and easy to apply, looks fairly neat and lasts ages (you can tack the edges down). It also gets used hereabouts for nestbox roofs, and the Blue **** are delighted, apparently. Our oldest nestbox is just softwood, and it's about 14 years old with no real signs of decay (and you can't creosote nestboxes!).

E.

(PS: insert rude comment about the EU here.)

 

[beech1948]

Can recommend the Synthaproof approach.

I have 12 6"x6"x12' posts in 12m pergola.

Dried the posts first ( 2 months), then covered with 2 layers of Synthaproof upto about 9 " above ground level, then created a boot from thick plastic sheet hot welded together also 9" above ground. Has lasted very well and no rot visible.

Al

 

[nev]

I too have just been asked to build a pergola type erection. Is there an affordable alternative to timber yard softwood?

 

[Spindle]

Hi

Try and get Larch, sawmills tend to turn it into fence posts up here, arguably the most resilient softwood.

Regards Mick

 

[Random Orbital Bob]

did someone say Larch?.......the mighty Larch....we sing...sing...ooooooh Im a lumberjack...

I'll get me coat!