I have a recently-erected six-foot high garden fence consisting of plastic
posts and panels, not dissimilar to this:

http://hantsanddorsetgardening.co.uk/plastic-fencing/

Alongside this fence I'd like to build a raised bed, some thirty inches
high. The front face could be attractive walling and the infill rubble and
stones topped with earth. I'm reluctant to use the fence itself as a rear
wall (and would it, in any case, resist the outward pressure of the infill?)
but it seems somewhat over the top to build, say, a block wall right up
against it. I've wondered about a rear wall of some suitable coated or
protected sheet material (OSB maybe?) braced to the front wall, but I'd
welcome any other suggestions.

Many thanks.

On Sun, 03 Jun 2018 11:35:34 +0100, Bert Coules wrote:

I have a recently-erected six-foot high garden fence consisting of
plastic posts and panels, not dissimilar to this:

http://hantsanddorsetgardening.co.uk/plastic-fencing/

Alongside this fence I'd like to build a raised bed, some thirty inches
high. The front face could be attractive walling and the infill rubble
and stones topped with earth. I'm reluctant to use the fence itself as
a rear wall (and would it, in any case, resist the outward pressure of
the infill?)
but it seems somewhat over the top to build, say, a block wall right up
against it. I've wondered about a rear wall of some suitable coated or
protected sheet material (OSB maybe?) braced to the front wall, but I'd
welcome any other suggestions.

Many thanks.

Not OSB for starters. It rots over time, as do most wood boards when
constantly wet/damp.

Just been out with a tape measure to check my visualisation and 30" is
pretty high - just over 3 standard blocks.

I would guess that in the long run a block wall would be sensible and
probably cheaper than using sleepers.

I read the plastic fencing site with interest and didn't see a direct
comparison with concrete posts. Therefore I cannot judge how robust the
plastic posts are. However we have concrete posts, concrete gravel boards
and wood panels.

For a couple of panels we have replaced the panels with concrete gravel
boards and these would certainly be strong enough to act as a rear wall
for a raised bed.

I can post a photo if this would help.

Cheers


Dave R

--
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On 03/06/2018 11:55, David wrote:
On Sun, 03 Jun 2018 11:35:34 +0100, Bert Coules wrote:

I have a recently-erected six-foot high garden fence consisting of
plastic posts and panels, not dissimilar to this:

http://hantsanddorsetgardening.co.uk/plastic-fencing/

Alongside this fence I'd like to build a raised bed, some thirty inches
high. The front face could be attractive walling and the infill rubble
and stones topped with earth. I'm reluctant to use the fence itself as
a rear wall (and would it, in any case, resist the outward pressure of
the infill?)
but it seems somewhat over the top to build, say, a block wall right up
against it. I've wondered about a rear wall of some suitable coated or
protected sheet material (OSB maybe?) braced to the front wall, but I'd
welcome any other suggestions.

Many thanks.

Not OSB for starters. It rots over time, as do most wood boards when
constantly wet/damp.

Just been out with a tape measure to check my visualisation and 30" is
pretty high - just over 3 standard blocks.

I would guess that in the long run a block wall would be sensible and
probably cheaper than using sleepers.

A 30 inch block retaining wall ought to have decent foundations. If you
build the whole thing out of sleepers, you can fasten the ends to the
sides, and use the tensile strength of the timber to keep it together.

David, thanks for that. Concrete gravel posts are a neat idea (and would
look better than blocks too, as the visible upper part of the rear wall) but
how would you suggest I install them? Or would simply resting them against
the fence posts one above the other be enough, letting the infill hold them
in place? Then the question of the outward pressure would arise, wouldn't
it?

The posts are well sunk into the ground and concreted in place. I'm
confident that they would hold against the pressure from say, an eighteen
inch bed, but I'm not sure about twice that height. Or is the bulk of the
pressure downwards rather than sideways?

I hadn't thought of sleepers, so thanks for the idea.

I've known treated OSB have a decent life outdoors but admittedly I've never
used it in a situation where one side of it was effectively buried in stone
and soil. Perhaps if I covered it with roofing felt?

GB wrote:

If you build the whole thing out of sleepers,
you can fasten the ends to the sides, and
use the tensile strength of the timber to
keep it together.

Nice idea. Thanks.

On 03/06/18 11:55, David wrote:
On Sun, 03 Jun 2018 11:35:34 +0100, Bert Coules wrote:

I have a recently-erected six-foot high garden fence consisting of
plastic posts and panels, not dissimilar to this:

http://hantsanddorsetgardening.co.uk/plastic-fencing/

Alongside this fence I'd like to build a raised bed, some thirty inches
high. The front face could be attractive walling and the infill rubble
and stones topped with earth. I'm reluctant to use the fence itself as
a rear wall (and would it, in any case, resist the outward pressure of
the infill?)
but it seems somewhat over the top to build, say, a block wall right up
against it. I've wondered about a rear wall of some suitable coated or
protected sheet material (OSB maybe?) braced to the front wall, but I'd
welcome any other suggestions.

Many thanks.

Not OSB for starters. It rots over time, as do most wood boards when
constantly wet/damp.

Just been out with a tape measure to check my visualisation and 30" is
pretty high - just over 3 standard blocks.

I would guess that in the long run a block wall would be sensible and
probably cheaper than using sleepers.

get some concrete gravel boards and use those.

I read the plastic fencing site with interest and didn't see a direct
comparison with concrete posts. Therefore I cannot judge how robust the
plastic posts are. However we have concrete posts, concrete gravel boards
and wood panels.

For a couple of panels we have replaced the panels with concrete gravel
boards and these would certainly be strong enough to act as a rear wall
for a raised bed.

I can post a photo if this would help.

Cheers


Dave R



--
If I had all the money I've spent on drink...
...I'd spend it on drink.

Sir Henry (at Rawlinson's End)

On Sun, 3 Jun 2018 12:07:38 +0100, "Bert Coules"
wrote:

David, thanks for that. Concrete gravel posts are a neat idea (and would
look better than blocks too, as the visible upper part of the rear wall) but
how would you suggest I install them? Or would simply resting them against
the fence posts one above the other be enough, letting the infill hold them
in place? Then the question of the outward pressure would arise, wouldn't
it?


Re gravel boards - use concrete posts, then you will know that you are
not putting any stresses on the fence. Get a longer one and cut it in
half if the shortest is too long for you.

Peter, a fence-beside-the-fence. I can see that would work, yes. Thanks.

900 X 600 concrete paving flags on their ends would give you 150mm buried in a decent concrete footing below the fence base leaving approx. 30" above ground level. Some bolt holes drilled on the seams would let you use some bolts with wide washers either side to hold them in line higher up.

Richard

On Sun, 03 Jun 2018 12:07:38 +0100, Bert Coules wrote:

David, thanks for that. Concrete gravel posts are a neat idea (and
would look better than blocks too, as the visible upper part of the rear
wall) but how would you suggest I install them? Or would simply resting
them against the fence posts one above the other be enough, letting the
infill hold them in place? Then the question of the outward pressure
would arise, wouldn't it?

The posts are well sunk into the ground and concreted in place. I'm
confident that they would hold against the pressure from say, an
eighteen inch bed, but I'm not sure about twice that height. Or is the
bulk of the pressure downwards rather than sideways?

I hadn't thought of sleepers, so thanks for the idea.

I've known treated OSB have a decent life outdoors but admittedly I've
never used it in a situation where one side of it was effectively buried
in stone and soil. Perhaps if I covered it with roofing felt?

The gravel boards fit in place of the fence panels.

You know that when you fit a fence panel between concrete (or in your case
plastic) fence posts with slots?
The first thing you usually do is slide a gravel board down inside the
slots to keep the fence panel off the ground, and then slide the fence
panel down the slots to sit on top of the gravel boards.

What we did was slide down a gravel board between the slots. Then another
one. Then another one.

So it was gravel boards all the way down.

I will post a photo!

Cheers



Dave R


--
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On 03/06/2018 11:35, Bert Coules wrote:
I have a recently-erected six-foot high garden fence consisting of
plastic posts and panels, not dissimilar to this:

http://hantsanddorsetgardening.co.uk/plastic-fencing/

Alongside this fence I'd like to build a raised bed, some thirty inches
high. The front face could be attractive walling and the infill rubble
and stones topped with earth. I'm reluctant to use the fence itself as
a rear wall (and would it, in any case, resist the outward pressure of
the infill?)

Can't see a plastic fence taking that amount of side load.

but it seems somewhat over the top to build, say, a block
wall right up against it.

Dense concrete blocks are cheap and would do the job fairly quickly. As
others have said, gravel boards or sleepers would also do the job.

I've wondered about a rear wall of some
suitable coated or protected sheet material (OSB maybe?) braced to the
front wall, but I'd welcome any other suggestions.

Any sheet material (iven if it would last - which is doubtful) would
need lots of support from something else like posts etc.



--
Cheers,

John.

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Thanks, John. Clearly, something substantial is needed.

Tricky Dicky wrote:

900 X 600 concrete paving flags on their ends
would give you 150mm buried in a decent
concrete footing below the fence base leaving
approx. 30" above ground level.

That's a very clean and neat solution, though the weight would make them
tricky to manoeuvre working alone.

On 03/06/2018 12:20, Bert Coules wrote:
GB wrote:

If you build the whole thing out of sleepers, you can fasten the ends
to the sides, and
use the tensile strength of the timber to
keep it together.

Nice idea.Â* Thanks.


The main disadvantages are a) cost and b) they are bloody heavy to move
around.

GB wrote:

...and b) they are bloody heavy to move around.

Yes indeed. And concrete gravel boards and 3 x 2 ft slabs aren't exactly
lightweight. And I'll be working alone.

On Sun, 03 Jun 2018 14:20:20 +0100, Bert Coules wrote:

Tricky Dicky wrote:

900 X 600 concrete paving flags on their ends would give you 150mm
buried in a decent concrete footing below the fence base leaving
approx. 30" above ground level.

That's a very clean and neat solution, though the weight would make them
tricky to manoeuvre working alone.

I was considering something like this.

https://www.hss.com/hire/p/500kg-engine-crane-folding

When I had mine done I had the services of two hairy arsed builders.

Lifting them into place with just me and herself would be dangerous.

Cheers


Dave R



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David wrote:

I was considering something like this.
https://www.hss.com/hire/p/500kg-engine-crane-folding

I didn't know small portable hoists like that could be had. Thanks.

The only problem with that particular hoist is the wheels which are no more than castors and will only move on fairly smooth surfaces. You can get versions with extended stabilisers that pivot round which means you can site your material in one area and swing it round into the required position.

To be honest something like a sack trolley is probably your best bet for manoeuvring sleepers, concrete flags or gravel boards.

Richard

On Sun, 03 Jun 2018 11:56:46 -0700, Tricky Dicky wrote:

The only problem with that particular hoist is the wheels which are no
more than castors and will only move on fairly smooth surfaces. You can
get versions with extended stabilisers that pivot round which means you
can site your material in one area and swing it round into the required
position.

To be honest something like a sack trolley is probably your best bet for
manoeuvring sleepers, concrete flags or gravel boards.

Richard

The problem with gravel boards is that you have to raise them above the
top of the fence posts to get them into the vertical slots.

Lifting them above head height is not trivial.


Cheers


Dave R


--
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Thanks, Richard.

David I have never seen any fencer lift a gravel board up to head height. The normal procedure in erecting slotted concrete posts and fencing is to position your first post then insert gravel boards and/or fence panel prop as required and then positioning the next post along against the gravel board or panel. I did once see a fence made entirely of posts and concrete panels 2m high but that was constructed by three workers and a FLT.

I got the impression Bert was considering simply to rest gravel boards against his existing slotted posts?

Richard

Richard wrote:

I got the impression Bert was considering simply
to rest gravel boards against his existing slotted posts?

That was certainly my idea, laying them horizontally and relying on the
infill to hold them in place. But it's been suggested that the plastic
posts, however rigid and however far sunk and well secured into the ground,
probably wouldn't be able to take the sideways pressure of the infill.

On Sunday, June 3, 2018 at 9:23:01 PM UTC+1, Bert Coules wrote:
Richard wrote:

I got the impression Bert was considering simply
to rest gravel boards against his existing slotted posts?

That was certainly my idea, laying them horizontally and relying on the
infill to hold them in place. But it's been suggested that the plastic
posts, however rigid and however far sunk and well secured into the ground,
probably wouldn't be able to take the sideways pressure of the infill.

Depends on the infill. Clay will give you side pressure but compost/loam shouldn't. I'd use my old chum, vermiculite, mixed with the soil. This keeps it light and airy, and a hell of a lot easier to work.

Stuart Noble wrote:

Depends on the infill...

I do have a sizeable quantity of hardcore-type rocks and rubble which I was
hoping to use at the lowest level, topping that with smaller stones and
coarser earth and a top layer of better quality soil. Wouldn't that put the
majority of the sideways pressure against the bottom foot or so of the fence
posts, where presumably they're at the point of their strongest resistance
to movement?

I'd use my old chum, vermiculite, mixed with the soil.
This keeps it light and airy, and a hell of a lot easier to work.

Thanks for that, and I could do it for the upper two-thirds, say. But this
is a good opportunity to get rid of that hardcore if it would be feasible to
use it.

On 03/06/2018 17:30, Bert Coules wrote:
GB wrote:

...and b) they are bloody heavy to move around.

Yes indeed.Â* And concrete gravel boards and 3 x 2 ft slabs aren't
exactly lightweight.Â* And I'll be working alone.


It's not worth killing yourself over. Maybe you'd be better off with
some lighter weight wood. It won't last as long and will need more
support, but you can do it single handed. Line the wood with DPM so it
lasts longer?

GB wrote:

It's not worth killing yourself over.

I agree wholeheartedly.

Maybe you'd be better off with some lighter weight wood...
Line the wood with DPM so it lasts longer?

I was thinking of plastic tarp or roofing felt. This was my original idea.
I can live with the need for extra bracing, and I've found wood (suitably
treated and/or clad) to be surprisingly resilient outdoors.

Thanks for the thoughts.

On Monday, June 4, 2018 at 11:03:42 AM UTC+1, Bert Coules wrote:
Stuart Noble wrote:

Depends on the infill...

I do have a sizeable quantity of hardcore-type rocks and rubble which I was
hoping to use at the lowest level, topping that with smaller stones and
coarser earth and a top layer of better quality soil.

If you avoid clay, I don't think you'll have a problem, especially with the rubble at the base (and obviously drainage holes along the bottom). Treat it as a container i.e. mainly compost/loam,
I use 1 part vermiculite to 6 parts compost. Not cheap but worth every penny

On Monday, June 4, 2018 at 11:37:14 AM UTC+1, Bert Coules wrote:
GB wrote:

It's not worth killing yourself over.

I agree wholeheartedly.

Maybe you'd be better off with some lighter weight wood...
Line the wood with DPM so it lasts longer?

I was thinking of plastic tarp or roofing felt. This was my original idea.
I can live with the need for extra bracing, and I've found wood (suitably
treated and/or clad) to be surprisingly resilient outdoors.

Thanks for the thoughts.

You might consider cement board, expensive though

On Sun, 3 Jun 2018 11:35:34 +0100, "Bert Coules"
wrote:

I have a recently-erected six-foot high garden fence consisting of plastic
posts and panels, not dissimilar to this:

http://hantsanddorsetgardening.co.uk/plastic-fencing/

Alongside this fence I'd like to build a raised bed, some thirty inches
high. The front face could be attractive walling and the infill rubble and
stones topped with earth. I'm reluctant to use the fence itself as a rear
wall (and would it, in any case, resist the outward pressure of the infill?)
but it seems somewhat over the top to build, say, a block wall right up
against it. I've wondered about a rear wall of some suitable coated or
protected sheet material (OSB maybe?) braced to the front wall, but I'd
welcome any other suggestions.

Many thanks.

I built myself two raised beds about ten years ago out of "sleepers".
Kneee high and about 6ft x 9ft. Then I built two more only 4ft
"narrow" with one 10ft long and the other 6ft based on experience.

I use mine for veg. The reach to get at things in the 6ft wide beds
isn't doable even with my reach AND I have to kneel to achieve maximum
reach (I'm just over 6ft). If I was starting from scratch I'd build
to about waist high and possibly higher and then adopt a no dig
policy.

There are some recycled material kits available. This one
https://britishrecycledplastic.co.uk...c-raised-beds/ is
recycled plastic but there's another one I can't find at the moment
which, if memory serves, looks nicer.

Don't forget to research soil. You DON'T want anything containing
clay. Also think where the load is going to be dumped whilst you
move it to the bed. It's quite easy to block your car in, for
instance (I remembered just in time!).

Stuart Noble wrote:

You might consider cement board...

I've never used it for anything, indoors or out so I'm really not familiar
with it at all: I'll investigate, thanks.

...expensive though.

Well wood isn't exactly cheap (though for this I could probably use
secondhand/well-weathered if I can find some).

Thanks, Stuart.

Graham Harrison wrote:

There are some recycled material kits available.

Yes, I've seen those, and also similar material in plank form. Rot-proof of
course, which is a big bonus, but also considerably pricier than wood if I
recall correctly.

Thanks for the soil tip, and also for this:

It's quite easy to block your car in, for
instance (I remembered just in time!).

I'll bear that in mind.