Repointing flint and brick walls in Iwerne Minster

Pointing a flint panel. Tap a suspect panel first: a hollow note, or mortar crumbling out between your fingers, means the bedding has gone and is usually where penetrating damp starts. A flint wall is not laid to a course. The stones are bedded into a thick mortar and it is the mortar that holds the wall together, so the joints are irregular in both width and depth and the material between the flints is doing structural work rather than filling a gap. That changes the method completely, and it rules out a disc cutter or angle grinder: a straight kerf through work that was never straight loosens a stone before it cleans a joint. You cannot rake to twice the joint width, because on flint that measure means nothing and the depth you would reach takes the bedding out from under the stones and loosens more than it fixes. We judge the depth stone by stone, take out only what is genuinely perished, and leave anything sound alone. Loose flints come out and go back properly bedded, and the galleting, the small chips pressed into the joint, goes back where the original had it, because it is not decoration: it stops a wide joint slumping while it cures.

The mix for flint, and why it is coarser. Joints between flints run wide and irregular where a brick bed joint runs at a consistent ten millimetres. A fine mortar filling a wide joint shrinks as it dries and cracks away from the stone either side, which is the commonest fault we see on flintwork that has been pointed by somebody used to brick. So the mix for a flint panel carries a coarser, well graded sharp sand, sometimes with a little chalk or brick dust to match the original, and it goes in in more than one pass rather than being buttered on in a single thickness. The finish sits back slightly from the face of the stones rather than being smeared flush across them, which is what makes a flint wall read as flint from the lane instead of looking rendered.

Brick dressings, quoins and lacing courses. The brickwork framing the flint is ordinary coursed work and it rakes and points normally, but it wants a different mix from the panel beside it, matched to the brick rather than to the stone. On banded flint and brick the two run through the same elevation in alternating bands, so both mortars are on the wall at once and the joint where they meet has to be handled cleanly. It is slower than pointing a plain brick wall and it is the part that shows from the road.

Undoing a cement repoint. This is the most common job in the village. A solid wall is breathable by design, and hard cement stops water leaving through the joint, so it leaves through the flint or the brick face instead and the first hard frost takes the face off. Flint fails worse than brick does when this happens, because a flint has nothing to lose off its surface: instead of spalling a face, it lets go of the wall entirely. Taking cement out of a flint joint without disturbing the stones is careful, slow work, and it is the reason a proper price for it looks nothing like a price for brick pointing.

Stacks, copings and gate piers. Stacks up here are exposed on every side and normally fail first, wanting repointing above the flashing, perished brick cut out and the flaunching renewed around the pots. The flint and brick walls along the lanes and driveways fail from the top down: once the coping lets water into the core the joints in the panel below go, and then the wall bows. Getting a coping rebedded and the top courses pointed is the cheap end of that story.

No rate per square metre: the area tells you almost nothing until somebody has looked at what the joints are like. A trial panel settles colour and weathering first, because a Victorian flint wall and its later brick repairs rarely take the same mix.

Getting to it. A flint boundary wall you can work off the ground, a village semi with a brick gable and a detached house with a stack on the ridge are three different set ups before a joint is opened. The work at height rules are why the scaffold is a priced line rather than something absorbed into a rate.

The joints decide it, not the wall. How deep the joints have to come back, and whether the faces have already spalled, sets the hours far more than the area does.

Matching is the part that shows. Too strong a mix is the classic mistake, and one hard frost takes the face off soft brick. Lime is right on most pre-1919 walls here.

Comparing quotes? Ask how deep the joints are raked and by hand or by disc, what the mix is and whether it has been matched, and whether the scaffold is in the price. Two quotes for the same job are usually two different jobs.

Most quotes for repointing in this village are written as though the wall were brick, and that is the single most useful thing to watch for. Flint and brick sit in the same elevation on a great many buildings around the Iwerne valley, and they are two different jobs measured in the same square metre. Brick pointing is fast and predictable: consistent joints, a known depth, one mix. Flint pointing is slow, the depth has to be judged stone by stone, the mix is coarser and goes in in more than one pass, and there is nothing to stop a careless rake from loosening a face of stones that then has to be rebedded before anything can be pointed at all.

So if you are comparing prices, ask each one to split the flint from the brick and give the mix for each separately. A quote that shows one rate across the whole elevation is either going to be repriced once the work starts or is going to treat your flintwork the way it treats brickwork, and the second is worse than the first. It is also worth asking what happens to loose stones, because rebedding is part of the job on flint and not a variation. We separate the two on every quote here, and we make up sample panels on both, left a few days before you judge them, because lime lightens a great deal as it dries.

We cover Iwerne Minster, Iwerne Courtney, Fontmell Magna and the DT11 villages along the valley towards Blandford Forum, under Dorset Council. You are dealing with Bournemouth Roofing & Building, the trading name of Bournemouth Roofing & Building Ltd, registered in England and Wales, company number 15471719, which you can look up in a minute. Thomas Hannen's business, and he is the one who comes out to price the job, not a salesman. A verified customer's 10 out of 10 on Checkatrade. The visit and the written quote are both free.