Privacy screening

[PeterW]

Western Red Cedar can be pruned into a really nice cone or pinnacle but needs doing annually - the trick is to take the tip leaders out as it will develop 5 or 6 main branches that will form the cone. RHS is always a good source of guidance. Here

 

Easier if there are two of you - one standing back and giving direction, and Mrs JSH up the ladder with the secateurs ....

[Jeremy Harris]

Thanks @PeterW, that's pretty much what the chap at the tree nursery said, I was just a bit cautious when I read how high these can grow, plus having had a nasty experience with Leylandii!

[Ferdinand]

Seems to be a quite good selection, @JSHarris.

 

Big hollies are beautiful My comment would be to be sure that you have the correct mix of holly trees to get berrys, should you want them.

 

I like the thing about Western Red Cedars that they can have boats made from them by carving planks out of the living tree, due to the self-preservative nature of the wood. Your future purchasers will be able to continue your boat-building tradition if they wait long enough and let the tree go.

Ferdinand

Edited October 31, 2017 by Ferdinand

[Jeremy Harris]

Now I've got over the flu I'm back on this, it being tree planting season!

 

I've spent many hours looking through tree supplier catalogues and ringing around to find what's available, and have also been put off from planting a red cedar by several people locally, on the grounds that it will need a fair bit of maintenance to keep it at the right size and shape, and there seem to be a fair few tales of the lack of expertise in trimming these that have led to disasters.

 

One major problem has been both finding a supplier that has big holly trees in stock and at an affordable price.  The costs are eye-watering for the few places that have large specimens, it looks as if demand has outstripped supply over the past year or two, and because hollies only grow slowly it will be a couple of years before most of the tree nurseries have larger specimens available.

 

The tree place we looked at last summer doesn't have the most efficient office, as we went back there in late October to both finalise the order (asking them to give us a price including delivery) and look at the trees we'd selected (from this post: https://forum.buildhub.org.uk/topic/2850-privacy-screening/?do=findComment&comment=63532

).

 

They finally got back to me on Friday, after much pestering, and they can't get hold of large holly trees either.  Another problem that's come up is the steepness of the bank where we need to plant these.   These photos illustrate what it was like before I cut back all the weeds etc - it's now basically a muddy bank with a few hedging plants at the bottom:

 

 

The main screening trees need to go where the red oval is.

 

 

This is the view up from the lane.  Essentially we need to screen the small window at the rear of my car, the gable around the centre of my car and the kitchen window at the front of my car.  The bank is pretty steep and gets steeper towards the front of my car, which looks like being a problem.

 

 

This view shows just how tight we are for space at this end.  There is about 1.2m between the two fences at the end of the upper fence, and the screening tree for the kitchen window needs to be just behind that first upper fence post.

 

The solution I've come up with involves some engineering.  When I built the stone box for the air pump and the platform for the grey salt container (just visible by the drive at the left of the first photo above), I was faced with having to build on to a steep (around 40 deg) slope on clay.  The method I came up with to make a stable foundation was to bore a couple of holes with a post borer, poor some wet concrete in, then hammer in some galvanised 4" diameter tubes, leaving them sticking up and filling them with concrete.  I have loads of this tubing left, and as this piling solution worked well, I'm planning to do much the same along the edge of the drive, just on the bank side of the upper fence.  I can't easily do this at the bottom, as our services trench runs along there, so I couldn't go very deep without risking hitting a power cable or phone duct.

 

The idea I've had is to put in a deep row of piles at the top, with the tops about level with the drive (so around 200mm poking above ground level).  Each of these will have a horizontal hole and be bolted to big galvanised steel angles, one that runs down the slope, the other that runs horizontally out to a vertical angle that is driven down a bit into the ground about 800mm away from the upper fence (so clear of the services run at the bottom)  I have some 5m lengths of 4 x 2 galvanised channel, so the plan is to put one of these along the base, bolted to the vertical angles.  I'll then bolt some sturdy treated timber to all this ironwork that's hanging off the piles at the top, to create a 5m long by 800mm wide planter, in effect. 

 

The advantages of doing all this seem worthwhile, as I can knock this up quickly, using mainly stuff that I have lying around and that would otherwise probably end up as scrap.  The piles will also stiffen up the area around the upper fence, I think.   I can then plant the three really important trees a fair bit higher, as they will be pretty much at drive level.  This makes a very significant difference to their price, and makes planting a great deal easier, as we can fill that planter up with really good soil around each tree with much smaller holes needed dug into the bank itself.  It also leaves a narrow gap at the bottom where I can re-plant some more mature hedging to fill in where a lot of it died off.

 

There's no problem where we want to plant the other trees along this front area, they can just be planted in the wider, less steep, part of the bank.

 

The question I have relates to substitutes for the big holly trees.  We're still going for a smaller holly, Ilex Nellie R Stevens around 2m high, pot grown, in front of where my car is, but just on the top of the bank,  along with probably an Acer at the top of the bark covered area (that's not yet finalised).  This area now gets full sun from around mid-morning through to sunset, as the house faces 20 deg W of due South.  As it gets so hot and sunny in this area, we've been thinking about planting olive trees as the primary screening trees, in place of holly.  They are a lot cheaper than holly in large sizes, tend to have a wider spreading canopy that would be better suited to what we're after and like sunny spots.  The planter will be pretty well-drained too, as I can chuck some gravel in the bottom and make sure all the clay is dug out to drain down the slope.

 

The question for the tree experts here is, would olive trees be a good choice in this location?

 

I can buy 4m high pot grown olive trees that look pretty good for around 1/4 the price, or less, than holly, so that is tending to influence my decision making just a bit!

 

 

 

 

 

[Ferdinand]

Western Red Cedars (which may not be the exact one you are thinking about) go woooooossshhhhhh like  a Roman Candle, and nearly as quickly. Ours did, anyway.

 

I'll leave the detailed species comment for @PeterW.

 

I like the sound of the engineering - in 500 years they will think it was an unfinished mini-Motte-and-Bailey castle. 

 

Edited February 4, 2018 by Ferdinand

[Jeremy Harris]

5 minutes ago, Ferdinand said:

Western Red Cedars (which may not be the exact one you are thinking about) go woooooossshhhhhh like  a Roman Candle, and nearly as quickly.

 

 

Yes, this is the advice I've been getting from lots of people.  It is possible to keep them in check, but it needs a fair bit of regular trimming by someone who's competent.  The latter seems to be a bit of a local issue, I've been warned!

 

I've spent much of this afternoon reading up on olive trees and looking at what's available, and although they wouldn't have been suitable for direct planting in the clay bank, it looks like they might do quite well in the raised planters that I've sketched up, as I can put a layer of gravel at the bottom and being on a steep slope the soil in them should drain very well.  The fact that the big hedge opposite has come down actually helps a lot, as means anything in the spot will get full sun for a lot of the time, plus the areas around our house seems to be a warm microclimate anyway, with air temperatures that are generally a bit higher than the surrounding area.

[Gone West]

We have an olive tree, pot grown though. As long as the soil is well drained and you are not in a particularly bad frost hollow or windy spot they should be fine. The sunnier the better.

[Jeremy Harris]

1 minute ago, PeterStarck said:

We have an olive tree, pot grown though. As long as the soil is well drained and you are not in a particularly bad frost hollow or windy spot they should be fine. The sunnier the better.

 

 

Thanks Peter, that helps to confirm what I've read so far.  We're very well sheltered, right at the bottom of a deep valley, facing more or less South, with a stream running along the side of the lane that helps to keep the air temperature up in very cold weather, I think, as the stream rises from springs only a short distance away, so tends to always be around 5 to 6 deg C, even in very cold weather.

 

We can get a bit of wind funnelling down the valley from the West, but we are planting more trees on the windward side of the place where we wish to put the olive trees, so I think they should be pretty well sheltered.

[Ferdinand]

I think the last couple of winters should tell you whether you are also a frost-pocket, @JSHarris.

 

Get those vines in and you can have "vinum & oleum" (to quote one of the Roman poets I vaguely recall reading at school).

 

Get a walnut tree in now, and you can have walnuts by about your 100th birthday!

[Jeremy Harris]

2 minutes ago, Ferdinand said:

I think the last couple of winters should tell you whether you are also a frost-pocket, @JSHarris.

 

Yes, we've rarely seen sub-zero temperatures, and then only down to about -2 deg C.  At our old house we've seen -4 deg C to -6 deg C a few mornings this winter, so the new house is in a bit warmer location.  From what I've been reading the frost tolerance of olive trees seems variable.  Some sites say -7 deg C is OK, some say they are OK down to -15 deg C.  Probably academic, as I doubt we'd see temperatures as low as -7 deg C anyway.

 

 

2 minutes ago, Ferdinand said:

Get a walnut tree in now, and you can have walnuts by about your 100th birthday!

 

A bit like the Greek proverb:

 

“A society grows great when old men plant trees whose shade they know they shall never sit in.”

[Ferdinand]

And you get to compete with the squirrels.

 

Need to do some admin now ... boo.

[PeterW]

Olives will be ok once established as they can cope with down to -10c as long as it’s only a short spell. Young bushes struggle, a decent tree that is 6-8cm should be fine. 

 

The best ones in the UK are varietals such as Olea europaea Leccino and Maurino if you want to actually get olives. Leccino is a sterile olive so needs a pollinator and Maurino will do both pollinate and be self fertile. 

 

If you want something faster growing and don’t mind a bit of pruning then the Spanish olive or Olea Eu. Picual will suit you fine. They also take plenty of abuse too - something to bear in mind if you have someone who doesn’t know what it is to prune it ..!! 

[Jeremy Harris]

Thanks for that Peter, especially the tip about the species.  We're not fussed about getting fruit, if we do it would be a bonus.  The main reason for looking at olive trees (apart from price!) is that the taller specimens with a clear trunk fit our need to screen at high level well.  The fact that they develop a spreading canopy is also useful, as a wider area of screening would improve the overall outlook in that direction a lot, yet the trees are likely to stay low enough to not hide the view of the hill on the other side of the valley.

[Jeremy Harris]

Right, I've been clambering around on what's turned into a very slippery clay bank, building a large'ish planter to raise the level and allow me to put in some better soil in which to plant the trees.  Roughly in the centre of this there is a deep hole that used to hold a power pole, which I'm going to fill with rubble in the hope that it will provide a natural soakway to make sure that water doesn't collect in this thing (the gault clay underneath is virtually completely water impermeable).  There are also some old railway sleepers that were driven down vertically, presumably to help support the power pole, and I'm just going to leave them, as they are around 600mm below where the soil surface will be:

 

 

 

I could do with a bit more advice though.  This is what I've built so far, using 8 x 2 treated C24 timbers, bolted with M10 bolts to some metal beams driven around 1m down into the ground.  I've also driven metal beams into the top, again going down about 1m, to help stabilise the bank and also hold the thing in place.  These are left over bits of aircraft alloy, a bit stronger than mild steel, and very corrosion resistant (it's the same stuff they may aluminium boats from).  In this application it should be fine, as although it's more flexible than steel (much lower Young's Modulus) I'm using it mainly to take shear or tensile loads, so bending isn't an issue.  This is what the part built thing looks like, I've yet to fit the ends properly and the other cross ties that hold the top in (not that it seems to need it; it's pretty solid as it is - it doesn't lean and isn't bent, that's just the camera distortion):

 

 

The question is, should I line the inside of the timber with some heavy duty membrane or not?  I have some DPM lying around, and could easily line the inside with this, folded over and stapled just below the soil line at the top, with a drainage gap at the bottom (I can fold the DPM under the boards at the bottom).  My thinking is that a lining like this will help to keep the timber dry, but I'm also a bit concerned that it might make things worse, but allowing damp to be trapped between the membrane and the timber.

 

Any thoughts?

 

 

 

[Construction Channel]

I would line it. It’ll help keep the bugs away from the timber as well. 

[Jeremy Harris]

Thanks, I'd not thought about bugs, but there are probably bugs in soil that eat timber, given half a chance.

[PeterW]

If you do DPM line it then it means you can treat the timber with a preservative without any fear of the trees being affected. 600mm DPM is ideal for this job. 

[Oz07]

Me and a cousin built some raised beds for our grandad. I'd never heard of dpm lining till we did it for him. I can't see it being that effective. Surely the timber is still damp regardless?! The bugs is a good point but in reality how long are we expecting these structures to last and how many extra days/weeks/months/years will a bit of dpm make?! The treatment angle is another good point. 

 

Just begrudgingly do it like I did and atleast you can say I told you so in 20 years!

[Cpd]

I think lining it will be a good idea, i would think the wood will last longer as it will have more chance to dry out. I got a whole load of c24 8x2 for free as it had fallen of the back of the stack and had been on the wet ground under an overgrown hedge, its still usable for garden work but i was shocked at how quickly some had deteriorated... i guess its just not designed to be left under a wet hedge !  So any level if protection would be a good idea. You could fold the dpm over the top and put a length  of sarking on top to protect it from the elements and uv, that way your not going to get soil between the plastic and the wood and this will help to prolong its life, did this on a sheds turf roof and it worked really well. 

[Onoff]

Line it I would. I've seen people use slaters felt before on the basis it's quite oily. 

[Hecateh]

20 minutes ago, Cpd said:

I think lining it will be a good idea, i would think the wood will last longer as it will have more chance to dry out. I got a whole load of c24 8x2 for free as it had fallen of the back of the stack 

................................ a what?         LOL that's a new one 

[Jeremy Harris]

Thanks everyone, looks like I will be lining it tomorrow!  I also have some offcuts of the plastic slates we used on the roof, so I may see if I can fit a mini roof along the top, trapping the DPM.

 

@Hecateh

 

C24 is a timber strength and quality grade, important when using timber like this for rafters or joists.

8 x 2 = 8" x 2" = 220mm x 45mm regularised timber, again the standard size is important for things like rafters and joists, where you need consistent dimensions.

 

The planter I've made uses this size and grade of timber.

[Ferdinand]

I would line the retaining wood, but fold over the top to prevent moisture running down the back. I assume you will be stopping the lining a  little above the bottom of the retaining planks.

 

I have usually just used a staple gun to attach.

 

On drainage, I would also line the gap at the base of the retaining planks with half bricks or gravel or similar .. like crocks at the bottom of a plant pot. Just  to make sure that water has a rapid escape route ... depending slightly on the nature of the soil you use.

 

With this type of structure eg for a raised patio I also sometimes knock round fence posts in on the outside say 100mm rounds and screw back through into the planks using timbascrews of 125mm. THat would tie in the design as rustic like your fence, and also gives the opportunity for a parapet should one be needed by using longer posts. I do that to prevent bulging should the soil become heavy with water. If such posts rot after say a decade it is a work of minutes to add a couple of new ones, and cut the old ones off at the base, removing the screws.

 

Your cross braces may be adequate however.

 

Do you plan to colour the planters to match the house?

 

Ferdinand

 

 

 

Edited February 9, 2018 by Ferdinand

[Onoff]

Definitely "cap" the top edge of the top board. Angle, strip, plastic trunking / trunking lid, inverted mini guttering,  tile offcuts as you say. Some even bevel / double bevel the top. As an aside I've before capped wood fence posts with the aluminium from heavy duty foil take-away containers!

 

Back to "long" edges, on my curved top wooden gate I temporarily put plastic trunking over the cut ends. (The gate will eventually have a rolled, galvanised steel, spiked feature). For now it's disguised in black duct tape.

 

 

 

(That's my versions of "temporarily", "eventually" and "for now").

 

 

Edited February 9, 2018 by Onoff

[Hecateh]

9 hours ago, JSHarris said:

C24 is a timber strength and quality grade, important when using timber like this for rafters or joists.

8 x 2 = 8" x 2" = 220mm x 45mm regularised timber, again the standard size is important for things like rafters and joists, where you need consistent dimensions.

 I meant fallen off the back of a ....................  The norm being a lorry.