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DIY in France: How to point a barn

So how did you learn to point a barn? My neighbours looked impressed and wide eyed as they spotted me up the local farmer’s ladder, balanced on a timber decking, tapping away at the crumbling stone jointing.

But pointing a barn is not so very technical and needs no special courses or experience – just patience and thoroughness and the right mortar mix.

After the initial preparation stage [see below], the ideal time to point is in the morning before the heat of the midday. Do not point when frosty, and if it rains you will need to cover the pointing.  The mortar takes about three to five hours to harden enough to brush and finish, so best not to commence new pointing too late in the afternoon, or you will be finishing with the owls for company.

Preparation – cleaning

When I started pointing my barn, the first exploration of the stonework sent lizards and spiders scurrying away.  Sets of little wide eyes in the crevices blinked, bags were packed and homes evacuated.

Loose stones revealed holes stuffed with straw and twigs, cosy spaces for baby birds to be born and safe for the local moggy, a large tabby cat who had evidently grown very fat on country mice and sparrows.

Health and safety in mind, I donned a bike helmet, jeans, jumper, gloves, safety boots, glasses and breathing mask.

Repairing walls

Walls are usually repaired in two stages – jointing then pointing. Jointing is the first fill for deeper holes and crevices with pointing being the final fill to surface and sometimes decorative.  or the barn, being a delicate creature, and not wishing to dislodge too much stone, joints will be raked out only to a maximum 3 cms and the jointing and pointing can be done in one go. Very large gaps should be repaired with stone first, rather than stuffing in lots of mortar. Clean out the gap, find a stone that fits tight and may need to be slightly tapped into place, then mortar in place, leaving the edge to be pointed up with the remaining wall.

The walls appeared sound, but evidently stayed up due to weight, as the jointing was now sand and a slight prod with a chisel sent it pouring out like the sand user to close an Egyptian tomb. Gingerly, loose jointing was carefully removed and everything else, left as found. Taking a small chisel and hammer, every joint was cleaned back 1-3cms and loose jointing removed. The aim being to leave a small ledge on each stone to accommodate the mortar, to help it stay put and not fall out.

Standing back after six hours of chipping, left the stones neatly isolated and mortar free and ready for washing down. First a soft bristle brush was used to clean out the loose dust and particles, and then with a garden sprayer, working from top to bottom the joints were washed out, making sure the stone surfaces well wetted and free of dust and to give the stones their first clean. The water will help suction, the sticking of the mortar to the stones and bond better. Before pointing another spray of water will be done and maybe during the process. Any dry areas will not stick and later will weaken the walls as they will let in rain.

When neighbours see the walls all chipped out, they seem worried they might collapse, but to be honest they won’t, well not for a few months, but I wouldn’t risk a winter, with storms, high winds and frost. But a week or two if you want a break will be fine.

Tools and mortar mix

Now for jointing/pointing – we need tools and the secret ingredient – lime mortar.

  • Buckets
  • Gloves and safety glasses. Lime burns the skin.  Ideally thin, waterproof.  I have cotton backed rubber ones. Goggles especially when mixing as the lime is very powdery and a breathing mask too. Once the mortar is mixed you can dispense with the mask.
  • A large rubber tray for mixing small batches of mortar.
  • A spade to mix the mortar, small trowels to point with, a mortar board to put the mortar on and carry to the joint to be filled, damp clothes, a garden sprayer to damp the wall prior to pointing and a “Frenchman”, a slim pointing tool that I find great for pushing mortar into the joints when finishing.
  • A soft wire brush for final work.

The mortar mix for pointing a French barn

Internet forums are crammed fall of the same questions that often go unanswered.  What do I point my French barn with? What ratio of sand and lime? Should I use cement?

Now here is the mix that satisfies most barn pointing works. You should read around the subject. Point some trial patches and check what your local building pointing shades are.

Do not add cement. It weakens the mortar. Lime is strong, flexible, and breathable. Cement makes the mix brittle, and only in exceptional circumstances, i.e. walls exposed to harsh weather conditions, use in a ratio of one cement to three lime minimum. But not for your average French country barn. If you have to add cement – a good Portland cement – Optimat Multi Usage is fine – II/B-LL 32.5 R.

I recommend hydraulic lime from “Saint-Astier” – Chaux Pure Blance LC – NHL3.5. It’s soft and makes a creamy mortar. Calcia Renocal produces a slightly too softer mortar and Lafarge Tradifarge is not so elastic/workable.  The Saint Astier gives a pliable mix with enough time to work into the joints and finish.

The sand is fine and has good water retention. I use Sable type 0/1.

Sand shades:

Sable blanc – white; Sable Roux – red/ochre; Sable Casse – beige; Sable Riviere – grey

How to mix lime mortar

A 35kg bag of lime is the equivalent to 5 x 10 litre buckets. The mix is 1:3, being 1 parts lime [chaux] to 3 parts sand [sable].  The bag will therefore need 15 x 10 litre buckets of sand.  But you won’t mix this amount all in one go. So here is a quick matrix:

1 bucket of lime with 3 buckets of sand
2 buckets of lime with 6 buckets of sand
3 buckets of lime with 9 buckets of sand etc

For smaller amounts, I use an old large baked bean can and measure 1:3 with that.

Thoroughly mix the lime and sand together to ensure consistency in the mix, then you can add water.

Mix a little water at a time till you have a quite thick mixture that you can take a piece and roll into a ball in your hand and it doesn’t collapse. It should be sticky and easily placed into the joints without falling out. It should be easy to smooth round the stones and not pull out as you use your trowel to fill and poke mortar deep into open recesses.

Re-wet your wall area about 5 minutes before working. When you start, more mortar does end up on the floor than on the wall. Master masonry takes practice, but the barn you point will take ages and you will be brilliant in the end.  It’ s fine to scoop up some mortar in your hand, and throw it hard at the wall. This method is good to get in deep crevices and holes, the mortar stays put and you reach parts you couldn’t with the trowel. It’s about filling the gaps and whatever works, you can use. Don’t fuss about with smoothing just yet. Get the mortar in, the more you put in the more it helps stick the next piece. Work with urgency and if the stones dry, spritz with a little water.

Once the joints are filled, take the trowel and smooth the joints ensuring they touch all the stone faces and there are no gaps. The Frenchman tool is good to give a final press on the mortar to ensure firmly in place. A quick smooth with your finger in a glove will save you hours of hard wire brushing later. Leave the mortar to cure for around three to five hours, but I check every hour to ensure it doesn’t dry to quick if the weather is hot. I set an alarm clock as I have been known to forget and then it’s a panic to get a good finish, if at all.

Once the mortar is firm to touch but has a slightly crumb service when rubbed, you are ready to wire brush. The brushing should be dusty. If mortar sticks to the brush, it’s too wet. Leave for longer.

Wire brushing cleans the lime off the stone faces, ensures the mortar tight to the stones and leaves the mortar free of small particles and the part I like, brush marks, a bit of texture.

Once complete, leave well alone. It will take a few weeks to cure and become strong and durable. The neighbourhood will give you copious praise, local car drivers will slow down to admire your progress and you would have given another old crumbling building a new long lease of life.

by Judi Castille, a photographer and entrepreneur who lives in south west France.

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