Stone walls including dry stone walls stacked
stone and random Rubble walls have been around for hundreds of years and today we're looking
at a technique which is basically dry stone wall but using a clay mortar, and this is
a technique that's also been around for hundreds of years. They make a great feature in the garden and
can be used as low retaining walls. The wall that we're looking at being built
today is a dry stone wall with some clay from the site used in the joins, and this is a
traditional method of construction. This is a low retaining wall and the stone
is from the site so it's making do with available materials. The wall that you're looking at now has been
in place for over 10 years and this type of wall can last for hundreds of years if it's
properly constructed, so let's take a look at how to build a stone wall. It starts with site excavation taking the
topsoil away until you get to the subsoil which contains good amounts of clay. The materials that we're using are Stone,
Clay and Screenings to fill in behind the wall. The screenings improve drainage as well as
stability. The wall is battered back at around 9 degrees
the amount of batter could be as much as 15 degrees on a taller wall. A line of flexible conduit is used as a guide
for the base while a string line is used as a guide for the top the base layer needs to
be strong and the working principle is Big Stones surrounded by Smaller Stones . Rocks
are spread out and sometimes put into sizes to make selection easier, the irregular shaped
rocks are used behind the wall for extra stability. The face of the rock that you choose is important
in this case being flat, choosing stones that are the right size and shape is essential
it's also important where you place the stones when you're putting one on top of the other,
and here we'll get Ross to explain a little about the processes and techniques used and
talks about Stretcher Bond. The next Rock we would lay would go over that
Gap that's that's called a Stretcher Bond so that's your Perp and you go on like that
the same principle as applies with a rock wall you'll notice that there's no line consistent
perpendicular line at all they're all broken. You have always got a rock, there's a perp
there perp here they always sort of conscious to that . Got a bit of a line there doesn't
matter too small , broken hear so these two you break it there yep where and you've got
to be consistent with that, if you don't it looks wrong and it is wrong. It's a weak spot they always have the Stretcher
Bond. On freestanding dry stone walls they have
what they call through Stones stones that go from one side right through to the other
so from the face of the wall back into the excavation behind. The same principle is used here on the retaining
wall a long rock that goes right through the wall into the excavation, how many and how
far depends on the height of the wall. This is an example of a through Stone, yeah
and that would go back back into the wall depending on the size of the rock half meter
or so? At least half a meter all the ones that are
poking out this one here I mean the it looks small it's actually big so the bulk of the
rock is back into the wall, okay and that gives it strength and stability because this
is reasonably oh yep and you've also used the Terracotta feature old broken pot anything
masonry I've thrown in there's bits of concrete this is an old slab of concrete which actually
goes back again. So you can really use your imagination you
can old handmade bricks to get what you want and then if we put it in the full picture
we've got layers and layers and uh it works really well .
So yeah I'm just looking for one that'll go in here now could be something like that but
then I need some Smalls in here to pack it out, but what I'm also trying to do whatever
Rock I put in I wanted to sort of reflect that angle I don't want it sort of going off
on the weird angle so you're always trying to get something that looks like it belongs
, yeah and takes up the space. See I can do that that works all right I've
covered that perpendicular there, I'm sitting over the top of that one so I'm looking at
one little poke in there yeah so I pretty much set that up there, it's gonna be a bit
like that I get my clay prepared earlier and I think it was like that Thats Pretty good
I make sure that i have the rock supported at the back, get the rock poke it in, so it's
not going to collapse. As you go the crushed rock and filler stones
are placed behind the wall and firmed in for more support. Then when all that's dry I get a wire brush
and clean it all up I guess the mud gives you a bit of room to
move too. A little bit but not a lot. I want Rock touching Rock, and I want the
rock supported with the stone yeah so it's not going to twist at all we've got the height So that's just taking out the first lot of excess yeah adjust it and then
at the back we've got some stones crushed rock, so its well supported. Get some more rock,
Ordinary Rock that's you can't use anywhere else and after that Clay is dried
or just lost more of its moisture because it's wetter now than it'll ever be
yeah you get a wire brush and just clean the face, it's the moisture you can get through
the rock, yeah through the soil then you don't need you haven't got that pressure of water
built the hydrostatic pressure building up behind the wall no the wall can breathe and
quite often the wall will actually be cool and moist I guess yeah hence the Moss and
what have you, but uh a concrete and cement mortared wall will lock in moisture behind
it , Which means you've got to have , weep holes and a drainage system behind the wall
otherwise the pressure builds up and uh and all cement will crack, eventually, we'll crack
eventually cement just cracks yeah but it locks in moisture that's why there's all these
troubles and all the uh conservation you know the conservation jobs in the UK we're in the
60s and 70s they started, you know doing a cement mortar on their buildings yep and that's
locked in the moisture created all those damp issues because the walls can't breathe. Subscribe to the YouTube channel for regular
updates on a whole range of garden plants landscaping ideas and as always good luck
with your gardening.
