Rebuilding a Collapsed Section: A Step-by-Step Approach

Every dry stone waller eventually faces the same job: a section of wall has collapsed, and it needs to be rebuilt. It might be a few metres, it might be twenty. The principles are the same, and if you take your time and work methodically, you can produce a repair that blends into the wall and will stand for decades. Here is how I approach it.

Before you touch anything, look at the wall around the collapse. Note the height, the stone type, the way the coping is set, and whether the wall leans. Take a few photographs. These will be your reference when you are rebuilding, and they will stop you from accidentally building something that looks out of place.

Then strip out the collapsed section properly. Do not just pick up the fallen stones and start stacking. Remove the loose stones, then take down the wall back to sound work on both sides of the gap. You want to rebuild onto firm, stable wall, not onto a section that is about to fall as well. As you strip out, sort the stone. Keep the coping stones separate, keep the larger face stones separate, and put the small hearting — the filler stones that go in the middle of the wall — in its own pile. This sorting will save you hours later.

Building the New Section

Start at the base. If the foundation stones are still in place and sound, build on them. If not, dig out a shallow foundation trench and set new base stones, larger than the stones above, bedded into the ground. A wall is only as good as its base.

Build up in courses, keeping the wall the same height and thickness as the original. Place each stone so it sits firmly, with its longest face into the wall. Avoid stacking stones directly on top of each other in a vertical line — this creates a weak seam. Instead, bridge the joints below, so each stone spans the gap between two stones beneath it. This is the fundamental rule of dry stone walling, and it is what gives the wall its strength.

As you build, fill the centre of the wall with hearting. This is not optional. Hearting locks the face stones in place and stops them from moving. Use small stones that fit tightly, and tap them in with the handle of your hammer or a small mallet. A wall built without hearting will bulge and fail.

Keep checking your line and your batter — the slight inward lean of the wall from base to top. A dry stone wall should be wider at the bottom than the top. This is what makes it stable. Use a line and pins, or a straight edge, to check as you go.

Finishing with the Coping

When you reach the top, the coping is the last job and the most visible. Match the style of the existing wall. If the original coping is on-edge, set your stones on edge, leaning slightly outward and locked by a second row behind. If it is flat, lay your coverband stones across the top, overlapping carefully and keeping them level with the neighbouring wall.

At the joins between your new work and the old wall, take extra care. This is where repairs most often fail. Make sure your new stones interlock with the old ones rather than butting up against them, and do not leave a straight vertical joint. Step the join so the two sections knit together.

Finally, clean up. Put surplus stone where it will not be seen, and leave the site tidy. A good repair should look like it has always been there. If someone walking past cannot tell where your work starts and ends, you have done the job properly.