Building a pergola

[Terry Pinnell]

I want to build a pergola, over a patio, supporting an existing large, mature, straggling rose tree (which i suppose I'm going to have to attack savagely at some stage). I'm no skilled carpenter so I'd like to go for one of those kits, with interlocking beams. However, the widest pergola I've found in kit form is about 3 metres wide. So to achieve that I would be forced to mount the 4 corners on the patio itself, rather than in the surrounding earth, as the latter would require beams of over 4 metres.

Now, the patio is of the brick variety. Just one layer of brick, I think on sand, or maybe it was on a thin layer of concrete. So my question is, if I use those Metpost things, (the bolt-down type rather the spike type), will that be secure enough? As I see it, there should be a net *downward* force, with all that weight, so I'm assuming all should be well?

BTW, do those Metpost come with bolts suitable for screwing into bricks?

Any advice offered will be much appreciated.

[Andy Dingley]

Have one custom-made. Talk to the right people (timber framers are _cheap_ !) and what they save by having cheaper sources for timber can save you enough to pay for much of the extra cost.

If you're around Bristol, talk to

[Terry Pinnell]

enough. Anyone know of a suitable firm a little closer to East Grinstead (6 miles SE of Gatwick) than Bristol?

[Owain]

I think I would be inclined to carefully lift a few bricks, dig a hole and concrete in the posts, then relay the bricks around the post.

Owain

[Set Square]

My sentiments exactly - but you beat me to it! You can hire a (manual) post-hole digger which digs neat holes about 8" in diameter. Then use a bag of gate-post concrete in each hole. Insert, centre and level each post, pour and ram in the *dry* concrete mix, and pour the prescribed amount of water onto it. Job done - apart from supporting the post in the upright position until the (quick setting) concrete has set.

[Tim Lamb]

In message , Set Square writes

Umm. No matter how well the timber is preserved, setting in concrete is a recipe for a short life.

I have secured my pergola uprights by slotting the bottoms and bolting in a galvanized bracket which can then be secured with a rag bolt to the concrete. The timber is not in contact with the soil and can dry out after rain. Standing the cut end in a bucket of preservative is wise:-)

regards

[usenet]

... but it makes the fence look a bit odd! :-)

[Sue Begg]

LOL My thought was how do you fasten the bucket without the preservative leaking out :-))

[Set Square]

Well, I have some tanalised (sp?) fence posts which I set in concrete over

20 years ago - and they're still going strong!

[Andy Dingley]

First of all, you don't know this. Concrete also makes it difficult to check the timbers for rot, so they could already be short stumps at the top, sitting over a pile of mush. You may never know until one windy night, the whole lot goes.

Secondly, the "concrete causes rot" argument depends a lot on water tables. If it's dry locally and they're not mounted low down, then they may survive pretty well.

[Set Square]

Well, I can't be absolutely sure - but I'm *pretty* sure they're ok. It is a post and rail fence with 8' posts set 2' into the original ground, and with the level then built up (on the side of a bank) so the fence is only 4' high relative to the new ground level. If the posts had rotted, that lot would surely have gone for a burton long ago.

[Tim Lamb]

That new creosote uses a fungicide discarded by agriculture years back. Doesn't inspire much confidence. It also smells like a corporation toilet.

regards

>

[Tim Lamb]

In message , Set Square writes

I am truly amazed:-) Not an issue with a self supporting pergola but the concrete provides a sharp edge which encourages fracturing in weakened timber. I'm not conversant with current legislation on permitted timber treatments but those relying on any form of bitumen seem to have been withdrawn.

Treated fencing posts supplied for agriculture have a life of less than ten years unless the part in contact with the soil is re-treated before use. (usually by standing in a barrel of real creosote).

regards

[David]

In article , Tim Lamb writes

This is not true Tim, it depends on the ground conditions and also whether you re-treat the timber before concreting in.