Building a retaining wall close to trees
rtreter
I'm planning to have a retaining wall built to hold back a 1 metre height
difference between two gardens, It will be built from blocks mortared
togther. I guess the concrete footings will extend about 1 metre below the
surface of the "low" garden. There are some trees within 30 cm of the
planned location of the wall, their trunk diameters range between about 5cm
and 20cm. I don't want to kill or substantially harm the trees.
The builder I'm getting a quote from says he will put lintels into the wall
and footings so that roots larger than about 1cm in diameter don't have to
be cut. Is this a sensible approach, for the trees and/or the wall?
Thanks
rtreter
news:4bc8accb$0$26316$bed6...@gradwell.net...
®óñ© © ²°¹°
wrote:
Sorry, I can make no sense of this at all.
I doubt that 1 metre of footings will be put in below the surface of
the bottom level.
And are you seriously saying that the wall footings will be within 12
inches of an unspecified number of trees and that the builder is going
to accommodate all of the tree roots larger than 1/3 of an inch, not
cut them and allow room for their future growth?
I am boggled. Are you using a builder or a conjuror?
He is suggesting building a wall within 12 inches of trees, some of
which have trunk diameters of 8 inches, without cutting or disturbing
their roots.
Why bother with such an impractical project. I would stick in a
graded slope and live with it.
--
(¯`·. ®óñ© © ²°¹° .·´¯)
Tim Watts
wibbled:
If a wall is required, I would consider a curved wall - that's one that
leans over and into the earth mound - see a few ancient ones round here,
all of one brick thick and they've survived. However, won't work with
modern building methods (ie hard cement). If doing such a wall, I'd lay
the first course onto earth about 1 brick under the surface direct to
dirt and use clay or lime mortar for joining them. They work by the
physics of a graded slope but you can get away with a someone sharper
slope as the bricks reduce the tendency of the earth to wash down with
rain and the weight of the bricks works to balance the pressure of the
earth. Think dry stone wall on a sideways lean.
These sort of walls typically hold back 2-2.5 ft of earth bank quite
happily for decades - dunno if that is sufficient for the OP.
Then accept that as the trees grow, the wall moves and bits of it may
need adjusting and re-bedding.
The modern version of the same line of thought are these:
http://www.dme.co.za/sites/site1/images/Brick_Simulation/RWBD.jpg
Got them at the local kiddy nursery - simple, effective and laid "dry".
Made of concrete and can be planted with ground cover plants like heather
and creepy things to make them look good. In the local case, I think
(without a tape measure to hand) they are holding back a bank about 3-4'
high at an angle of about 15 degrees off vertical. Work by interlocking
and dead weight (once filled with earth). Again, the trees may move them
and it won't matter too much. When/if it matters, disassemble and re bed
the damaged section to accommodate the tree. Building next to trees
requires the "earthquake" mentality - either stupidly strong (hoover dam
strong) otherwise the tree will prevail eventually - or make it flexible
and accept Nature.
Cheers
Tim
--
Tim Watts
Managers, politicians and environmentalists: Nature's carbon buffer.
aquachimp
If you have roots which vary in diametre from 5cm to 20cm, and the
builder 'accomodates' say, a 8cm root, will the 'accommodation'
suffice when it gets to, oooh, say, 27cm?
So, I'll presume what the builder is hoping to be able to do is to
create pillars of concrete on to which to rest the lintels; After all,
I would think that there would be no point in putting concrete under a
root. So, essentially, the wall would be built on a bridge of lintels?
Sure would benefit drainage and therefore lessen the pressure on the
wall to some extent.
And I'll assume that the idea will be to have, say 4 lintels abreast
and in staggered formation: (like as in laying grass turfs) in order
to limit the potential of the cracks which would most likely occur if
they weren't laid thus.
A lot of trouble, and expense for a 1m high retaining wall. Why not go
for a drystone wall?
And whilst I think of it, I've seen this done (albeit only around 70cm
high) with stkaes driven into the ground, leaning towards the bank of
earth and wooden slates nailed inbetween.
rtreter
news:98960955-8e9c-4480...@z7g2000yqb.googlegroups.com...
Thanks for the comments.
I think the wall needs to be a fairly substantial one, because there are
buildings about 4 metres away on the high side.
The height difference is currently retained by a wooden fence with 4" posts,
but it is starting to lean over.
Does anyone have any comments on replacing the existing wooden fence with a
fence using 5" concrete posts set in concrete, with concrete gravel boards
to retain the soil. I think this is known as a "Berlin Wall" in the building
trade. Hopefully it would be possible to position the posts so that they
don't interfere with too many roots (there are only 4 trees along the 9
metre fence).
I think I'm going to get an engineer in to advise, but the idea of using
concrete fence posts and gravel boards appeals to me initially.
Donwill
saw your contribution.
Cheers
Don
aquachimp
> "aquachimp" <aquach...@aquachimp.freeserve.co.uk> wrote in message
>
> news:98960955-8e9c-4480...@z7g2000yqb.googlegroups.com...
> On Apr 16, 8:29 pm, "rtreter" <df...@invalid.invalid> wrote:
>
>
>
> > Hello -
>
> > I'm planning to have a retaining wall built to hold back a 1 metre height
> > difference between two gardens, It will be built from blocks mortared
> > togther. I guess the concrete footings will extend about 1 metre below the
> > surface of the "low" garden. There are some trees within 30 cm of the
> > planned location of the wall, their trunk diameters range between about
> 5cm
> > and 20cm. I don't want to kill or substantially harm the trees.
>
> > The builder I'm getting a quote from says he will put lintels into the
> wall
> > and footings so that roots larger than about 1cm in diameter don't have to
> > be cut. Is this a sensible approach, for the trees and/or the wall?
>
> > Thanks
>
> builder 'accommodates' say, a 8cm root, will the 'accommodation'
> suffice when it gets to, oooh, say, 27cm?
>
> So, I'll presume what the builder is hoping to be able to do is to
> create pillars of concrete on to which to rest the lintels; After all,
> I would think that there would be no point in putting concrete under a
> root. So, essentially, the wall would be built on a bridge of lintels?
> Sure would benefit drainage and therefore lessen the pressure on the
> wall to some extent.
>
> And I'll assume that the idea will be to have, say 4 lintels abreast
> and in staggered formation: (like as in laying grass turfs) in order
> to limit the potential of the cracks which would most likely occur if
> they weren't laid thus.
>
> A lot of trouble, and expense for a 1m high retaining wall. Why not go
> for a drystone wall?
> And whilst I think of it, I've seen this done (albeit only around 70cm
> earth and wooden slates nailed in-between.
>
> Thanks for the comments.
> I think the wall needs to be a fairly substantial one, because there are
> buildings about 4 metres away on the high side.
Shouldn't they be able to stand on their own feet, as it were, or do
they not have foundations?
> The height difference is currently retained by a wooden fence with 4" posts,
> but it is starting to lean over.
>
> Does anyone have any comments on replacing the existing wooden fence with a
> fence using 5" concrete posts set in concrete, with concrete gravel boards
> to retain the soil. I think this is known as a "Berlin Wall" in the building
> trade.
http://www.eco-foundations.co.uk/king_post_walls.html
As for concrete gravel boards;;; You'd be better trying it with kerb
stones; concrete gravel boards tend to first bulge (and they break
easily) and eventually sort of have that ruptured look, with their
rusting internal mesh for all to see.
Cicero
> "aquachimp" <aqua...@aquachimp.freeserve.co.uk> wrote in message
> news:98960955-8e9c-4480...@z7g2000yqb.googlegroups.com...
> On Apr 16, 8:29 pm, "rtreter" <df...@invalid.invalid> wrote:
>> Hello -
>>
<snipped>
>
> Does anyone have any comments on replacing the existing wooden fence with
> a fence using 5" concrete posts set in concrete, with concrete gravel
> boards to retain the soil. I think this is known as a "Berlin Wall" in the
> building trade. Hopefully it would be possible to position the posts so
> that they don't interfere with too many roots (there are only 4 trees
> along the 9 metre fence).
>
> I think I'm going to get an engineer in to advise, but the idea of using
> concrete fence posts and gravel boards appeals to me initially.
================================================
If you go deep enough with the concrete posts (30" or more below ground
level) and have the first gravel board just partly below ground level you
should be OK. The spacing of the posts will allow the tree roots to find
their own path through. Try to get a good spread of concrete along the
line of the wall at the base of each post-hole to provide some resistance
to the pressure of the earth at the top of the wall.
Cic.
--
=================================================
Using Ubuntu Linux
Windows shown the door
=================================================
mark
"rtreter" <df...@invalid.invalid> wrote in message
news:4bc8accb$0$26316$bed6...@gradwell.net...
Plan B:
Just build a wall to do the job. Prune roots that are in the way.
Plant a couple of trees elsewhere as a form of 'guilt offset'.
mark,
Dave Hill
>
> - Show quoted text -
Sorry but if you have buildings that require a wall that substantial
then I would get rid of the trees, to have them within 4 m of the
buildings is much to close for comfort,
The .rule of thumb that I was taught was never have a tree closer to a
building than the eventual height of the tree.
David Hill
Chris J Dixon
>As for concrete gravel boards;;; You'd be better trying it with kerb
>stones; concrete gravel boards tend to first bulge (and they break
>easily) and eventually sort of have that ruptured look, with their
>rusting internal mesh for all to see.
>
This shot doesn't quite show the full nature of the upheaval, but
here is one panel that is giving up the fight. The pavement has
recently been resurfaced, but is already beginning to bulge
again.
Chris
--
Chris J Dixon Nottingham UK
ch...@cdixon.me.uk
Have dancing shoes, will ceilidh.
aquachimp
> aquachimp wrote:
> >As for concrete gravel boards;;; You'd be better trying it with kerb
> >stones; concrete gravel boards tend to first bulge (and they break
> >easily) and eventually sort of have that ruptured look, with their
> >rusting internal mesh for all to see.
>
> This shot doesn't quite show the full nature of the upheaval, but
> here is one panel that is giving up the fight. The pavement has
> recently been resurfaced, but is already beginning to bulge
> again.
>
>
Even a kerb stone would be undone in that situation I think. What I
thought the OP referred to was gravel boards all the way up.
dennis@home
"aquachimp" <aqua...@aquachimp.freeserve.co.uk> wrote in message
news:42215beb-35e9-49d5...@k41g2000yqf.googlegroups.com...
> Even a kerb stone would be undone in that situation I think. What I
> thought the OP referred to was gravel boards all the way up.
I have seen a retaining wall made from concrete fence panels three high.
It broke in several places within a couple of months.
The last time I saw it they had inserted extra concrete posts in the centre
of each panel, AFAIK they are still holding it back after a few years.