The Brew Cabin

Hi,
I'm extending a driveway "spur" some 12metres along
the front of my house.
At the end of the extension I plan to install a "pergola"
which will really be a car-port in disguise!
It would be folly to install a sub-base, then pavers, then
have to mess these up to install the posts for the pergola, so is
there a "best" order for this job?
Any advice on ensuring the maximum life for the
wooden posts:
do I wrap them in polythene before encasing them
in concrete,
do I install further drainage beneath the end of the
post to avoid water pooling?

I want to leave sufficient soil near the base of each
pergola to permit me to grow a climber plant from the
ground (I don't want to put the climber in a pot: too
much work to remember to water the damn things! :-)

Any help appreciated; thanks in advance

Mungo

Hi Mungo,

the usual order of construction would be to build the pergola first, or at least get the uprights in position before doing the paving, and then you can piece-in around them as required.

As for the wooden posts, well, you must use properly treated timbers, and, now that the EU has more or less banned CCA, that means Tanalith or similar. They can be concreted in directly, but I know some contractors believe that wrapping the end of the post in polythene, or a damp proof membrane such as visqueen, protects it from the alkalinity of the concrete, but I've not seen any genuine data to back up that theory.

The best way to avoid water pooling is to lay the paving with adequate falls. Remember, though, that once the paving is settled in, it is pretty much water-tight. The usual figure quoted is that 98% of surface water will run-off, with only 2% penetrating the pavement, which, for planter pockets, means they risk being parched or starved of air, so make each pocket at least 300mm square and be prepared to chuck a bucket of water at them in the dry weather of summer. Failing that, it might be worth connecting up a micro-irrifgation system, especially if you're planning on big, thirsty climbers such as honeysuckle or wisteria.