Tuesday, 3 September 2013

Dry Stone Walling

Out of the many jobs I've done over the years my favourite has always been dry stone walling. This is the means of building a boundary wall using rough stone without the use of mortar to bind the stone together. There's the satisfaction of putting something together that isn't obvious how it's done and that fits in to its surroundings. I've done walling since I was a child helping my dad repair walls on the farm filling in the hearth or heart of the wall while he handled the stones that probably weighed as much as I did at that age.

Building of the garden wall back in 2006
Dry stone walls are particularly prevalent in the upland areas of northern Britain and two main types can be distinguished: those built from stone recovered during ground clearance and those built by contract wallers either following the enclosure act or renovating much older walls. The dry stone wallers association estimate that it would cost around £3bn to repair all the walls to the top stock-proof standards, current labour prices are around £30 per metre. Walls provide both stock-proof boundaries as well as shelter to animals in poor weather, walls on the high fells aren't completely solid and the gaps allow wind to pass through so that snow doesn't drift next to the wall and burying animals sheltering there.

In 2006 I'd cut down a line of leylandii and built a wall on the side of the garden next to the lane. The wall on the other side of the garden was slowly deteriorating, partly as a result of cows picking apples from our fruit trees! After confirming with the farmer that he wasn't planning on putting stock in the field for a few weeks I set to work.

Starting to pull down the old wall. It's in a sorry state really.

The pile of stones always looks as if it's too much.

As a rough guide, you can reckon on one tonne of stone per running metre of wall and I'd about twenty five metres to sort out. Day one involved pulling down the old wall making sure that the cams or top stones were kept to one side. Some walls have dressed stones for cams but most field walls simply have large stones of a similar size and shape to do the job of protecting the top of the wall. The section of wall changed direction and went across slopes of different angles so I began with the main length of about sixteen metres. Shifting sixteen tonnes of stone is quite hard work and I was definitely tired by the end of the day.

Getting the footings in and then up to the first line of throughs.

Most of day two was getting the wall footings sorted out - no point in rebuilding a wall if the foundations are all wrong. Some of the footings were in good shape but a lot had slipped meaning that they needed pulling out and the earth digging away to get to firm ground. Fortunately this didn't take all day and I was able to begin building the first few metres.

The wall is now up to the level of the first set of throughs. Although this one doesn't go all the way "through" it was too good to not use. It actually is the roof of a rabbit smoot.

The two end guide towers are now up. The batter or lean can be seen on the upper tower.

The construction of a dry stone wall is in some ways very similar to that of a brick or block cavity wall. From the foundations two towers or skins of bricks/blocks/stone are built and then tied together at regular intervals. For brick walls you use brick-ties which these days are also used to support cavity insulation whereas for stone walls you use throughs: these are large flat stones that span the full width or more of the wall. Depending on the height of the wall there may be two or even three courses of throughs, this wall had two courses. The height of a wall is measured to the base of the cams and typically is four feet. The width of the wall at the base is half that of the height whilst the width at the top would be around 12 -15 inches. This means that, unlike a brick wall, the sides of the wall lean inwards, this is known as the batter and can indicate several things.

A wall can be built with equal batter on both sides or with one face almost vertical and the other with the majority of the batter. In this instance the vertical side is the face and usually indicates that the wall is the responsibility of whoever owns the land on that side of the wall. However if a wall goes across a slope then the face will always be on the uphill side as earth creep will naturally try and push the wall downhill - think of the cross section of a water dam. Often the batter is provided naturally by the stone itself, when stone is broken it doesn't break at right-angles but actually has a slight lean to the face, this means that a stone has a right and a wrong way up when placed in a wall, get it wrong and the profile of the wall looks like a saw tooth, get it right and the profile of the stone fits in with the batter.

This run of wall went straight up the slope plus I wasn't sure who had responsibility for it so I went for equal batter on both sides. I couldn't use the pieces of wall to either end as guides as they were just as dilapidated as what I'd taken down so my plan was to build a small section of wall at either end of the run then stretch a line between these and fill in the middle part to that level, put on the throughs then build the end sections to the height of the next row of throughs and repeat, finally building to the finished wall height.

At the height of the second row of throughs.

Finally at cam height. The run of wall to the right was later re-built as well.

Once I'd got to cam height on the main run of the wall I then pulled down the section at the lower end of the run. This both kinked through two slight bends and was partly on a flatter section of ground so needed a bit closer attention than would a straight run. I'd decided not to repair the final few metres down to the field gate as it wasn't bounding our garden - I might do it later if it nags me - so the last bit of this part of the wall was slightly rough in that it hand to match in to a wall that might be getting pulled down. Then it was on to the cams.

As well as being the final set of stones that bind the wall together, cams can help in stock proofing a wall. When jumping a wall, sheep actually run their feet up the stonework so a set of cams that overhangs the wall interrupts this movement and forces the sheep backwards. Thus a relatively low wall with overhung cams can be more stock-proof than a high wall with flush cams. One style of walling around here (West Yorkshire) has small cams resting on a layer of large throughs that overhang each side of the wall by three inches or so thus providing this protection.

Most of the wall is now complete.

Just the last bit to do and tie in to the wall running along the bottom of the neighbour's garden.

Amazingly I'd actually managed to keep enough stone back for cams for the length of wall I'd done so far. Phew! Then it was just the final few metres at the top of the run to patch in to the wall between our garden and that of our neighbours (actually this needs rebuilding as well). Finally it was done, ten days' work for roughly twenty five metres of wall with eight days of actual construction, not the fastest bit of walling but the fruit trees you can see in the photos meant that I was working from one side for most of the time. Unusually I actually had some stone left over, normally I run out and have to pilfer stone from wherever. I reckon that the new wall is just under an inch lower than the previous wall. Still, if I rebuild the bit next to the gate I can use it there.

So, as promised, that was something completely different.

1 comment:

  1. Building a boundary wall using rough stone without the use of mortar is the best idea and also it looks great. wonderful post related to dry stone walling.