making a pergola / arbor

[danlightbulb]

Hi all,

The arbors / pergola's / arches in the sheds are around 2.4m tall. How much of this (on the legs) gets buried in the ground or do they stand free?

I am thinking of building my own, and was going to use sawn treated timber as follows:

4 Legs 47x100x2400 (would of liked to use 100mm square posts but they are double the price...
2 cross beams 47x75x2000
7 roof beams 47x75x1000.
Trellis panels made of 19x32 (40x1800 lengths).

All this coming in at about £60.

Ending up with a structure 2.4m high, 2m wide and 1m deep with trellis to sides and rear.Then will put a bench in it.

Best way of securing it to the ground / does it need securing at all?

Cheers

 

[JohnD]

wooden legs buried in the ground will rot, so IMO a good way to do it is to concrete-in concrete spurs (these are sold in fence post places and range from 4' upwards). they have a couple of bolt-holes in them so you can bolt your wooden structure to them with the ends clear of the ground. if you like, you can paint the concrete to blend in with the woodwork.

this will give support and prevent it blowing away.

as it is a rectangular structure without solid sides it will be less prone to wind than a fence.

if the loading is very light and you want to take them out later, you can pack them in earth and beat it down well, but this will not be so strong and depends on a cohesive soil

btw metposts are rubbish.

btw2 I think square posts will look better, you can get 75x75 fence posts to suit. If you put 100x100 at the end where people walk in, it will look more impressive.

 

[danlightbulb]

Thanks JohnD.

I like your idea about using larger posts for the front legs only.


Cheers
Dan

 

[Thermo]

hmmm concrete spurs screwed to an arbour. that will look nice john!

go with 100 x 100 posts, looks better and will last a lot longer (youll still get many years use out of them, despite what john says, hes got shares in a precast concrete firm!)

best to concrete the posts into the ground, 12-18 inches will be more than enough

 

[JohnD]

pay no attention to Thermo, he makes a living out of replacing rotted-off fenceposts and he's saving up for a new helicopter

 

[Deluks]

Agreed on the square posts, if money is a problem then you'll get away with minimum 75mm fence posts, if you can track these down at longer lengths then you'll get more in the ground without it being too low. You can just sink them in holes packed tight with gravel if you can get a decent length in.

Shop around, DIY sheds such as wickes and homebase etc will be at least a third, and up to twice the price of a proper timber merchant. (The timber guys will also have round posts at 100 or 125mm thick, these will look the mutts nutts but will cost more still )

 

[big-all]

assuming there is no more than a few plants hanging from the frame then i think 3x2 will be fine although i personaly would go for 4x2" for the longer run[2m]

i would also go for posts as the timber and treatment is completly different

posts are a much denser wood and the treatment is more sutable for continual standing in water

if you have kids or plan to put a roof on the structure you will need to beef it up quite a bit more