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Pointing with lime mortar ~ Part 3 = Technique

Category: Starter for 10 February 24th, 2011 by mbc




Lime Pointing Tips

Here’s my take on how to go about pointing with a lime based mortar – others may have differing guidelines – this is very much my take.

This post is this third in the series.

In the first instalment, I covered the tools of the (pointing) trade.

The second instalment was about lime mortar and how to go about making it.

Now in part three I’ll address – pointing technique

Technique

Firstly the old mortar joints will need cleaning out. If the old mortar is really rotten or dirty then a pressure washer can be used initially to clean down the masonry and blast out any really lose rotten mortar.

With a hand pick work back the mortar to give a repointable joint. When repointing over old mortar, a joint of around 25mm / 1 inch depth will allow a good packing in of fresh mortar that will be able to carbonate externally and remain stable over time. Too deep a treatment and the deepest mortar, deep in the joint and away from the air will remain too moist and too flexible and potentially be unstable. For deep joints point in ‘shifts’ of 25mm or so at a time, allow the mortar to go-off between applications. If you can’t get down to the ideal 25mm joint don’t worry too much, I’ve pointed plenty of shallower joints that are still sound after several years.

Some advisors on the subject talk about the need for a squared internal surface to point up against (in contrast to a rounded one). Whilst probably ideal, this is time consuming to achieve and so unless you’re lucky enough to have abundant time for your pointing project I wouldn’t worry too much about it. Square the corners if you can, but don’t fret about it if you can’t.

If the existing mortar is sound, then I leave it in place – if it ain’t broke

Before applying new mortar, damp down the wall before pointing. Use a bristled brush and a bucket of water. Personally, I favour a ‘flick’ technique – water in bucket – dip brush and flick! Get right into the joints that you’re repointing. The warmer the day the keener you’ll need to be. On a generally damp, cold, dismal day (not that we get many of those in Wales!) your damping down will likely be minimal.

It’s best to point a wall top-down – that way you can damp down the wall without damaging or washing out previously pointed joints lower down the wall.

So, to work…
Load your small pointing hawk with a trowel full of mortar, then using your trowel of choice (either a ‘normal’ pointing trowel or a smaller ‘trowel and square tool’ as I discussed in part 1) take up a sliver of mortar on the back-face of the trowel appropriate to the size and shape of the joint you are pointing and push the mortar into the joint. Use the trowel to work the mortar fully into the joint and tidy up any that doesn’t go where you want it to.

After pointing a length of joint or a discrete area of wall then go back over your work, tidying and smoothing along the length of joints to get a consistent finish.

…and repeat…

Where you have wide and / or deep joints it’s important to use pinning stones to reduce the width / depth of the joints and so reduce the amount of mortar you need which in turn will reduce the time needed for setting and carbonation of the joint.

For very narrow or very shallow joints do what you can. Sometimes you’ll need to pack the mortar into a very narrow joint – place a blob of mortar on the joint and repeatedly press the mortar into the joint, hopefully filling it slowly. I’ve been known to build up very shallow joints to stand proud of the masonry surface, although this is more of a cosmetic affectation than a practical necessity.

Cleaning up
I must admit to being a bit lax when it comes to finishing the joints. Ideally, after around 24 hours you will tidy up your pointing. At this stage the surface of the mortar will be hard with softer mortar underneath. A brush with stiff bristles (but not too stiff as you’ll just end up ruining your good work of the day before) can be used to tidy up the joints, remove excess ‘tags’ of mortar and mortar that is misplaced on the masonary.

When to point
You can point for most of the year in the UK (except perhaps in the far north), I tend to ‘retire’ over the Winter – Novemberish to Marchish. Keep an eye on the five day forecast when pointing and have a tarpaulin or sacking ready to cover over any pointing should a sharp shower unexpectedly arrive. Don’t let rain anywhere near your freshly pointed joints. Beyond that, fill your pointing boots…

If you enjoyed that post, then read these...

Lime Pointing ~ Summer 2008
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Building Progress ~ November 2010

Category: Barn Conversion Journal December 15th, 2010 by mbc

At last I’ve broken the strangle-hold that pointing has had on me! I’ve also gone back to being late making my monthly updates to the website (this one for November being written on the 15th of December) – swings & roundabouts I guess…

I’ve retired from pointing for 2010, probably in truth falling just a little bit short of the finishing line in relation to my original goals for the year. I have about a square metre to point at the top of the back wall and the gable end (6 or 8 square metres) to finish. We had a major (for Carmarthenshire) deluge of snow on the day that I intended to finish the back wall and the cold weather has put me off ever since.

Beyond pointing I’ve been busy in the bathroom, finishing the floor, mosaic tiling and boxing-in. As previously reported, we started some work on landscaping the garden, first with a digger and I then started to level the patio area by hand with a pick & shovel and plan to lay flag stones on sand in the area shortly. I’ve also started to build a small ‘hut’ around the external tap that stands rather proudly at the front of the barn. My ‘tap hut’ is another victim of the weather as it’s been too cold to play work with my new concrete mixer to mix up the mortar and aggregate mix I need to finish the ‘hut’.

I’ve also got a satellite dish to install, but that’s a job for December and all those Christmas repeats on TV…

If you enjoyed that post, then read these...

Lime Pointing ~ Summer 2008
last weekend's raking out In what seems to be an annual event, I've restarted repointing the exterior of the barn.

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Building Progress ~ September 2009
Straight in this month, no excuses and no delay.

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Slack
Sorry, I've been very slack in updating the site over the last few weeks - very busy at work (my proper job) at the moment with a system implementation.

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Building Progress ~ October 2010

Category: Barn Conversion Journal November 3rd, 2010 by mbc

Seems like I’ve been repointing for ever and ever…

Back in August I said…

I’m not sure that I’ll hit my end of September goal, but if I need a few more days in October then so-be-it. It’ll be a lovely feeling to get it finished and move onto something else (the to-be back garden is top of the list if the weather holds).

I’ve not managed to complete all the repointing by the end of September, or even by the end of Octoberbut it will be done by the end of November

Whilst it is not ideal to be lime pointing at this time of year, it’s not yet turned too cold – it’s still usually 10C+ during the day and no real frosts at night. Anyway, I think damp weather is far more lime mortar friendly than dry, sunny weather – and I really need to get this done, so I’ll soldier on.

I just have the top of both the back wall and the gable end to finish. I’m using a ladder to reach the top of the walls which is fine, a bit hard on the feet but otherwise more comfortable that standing on top of a step ladder as I have been. I’ve switched work to the back wall, that I’ve estimated as 8 or so hours work. Hopefully I’ll get that done this weekend (if fireworks allow!). As I’ve already said – We’ll see…

Beyond pointing I’ve very little to report – the final small section of the concrete path has been finished, so once the pointing is done, I think we’re ready for completion. I’ve also tinkered around with the edging of the oak flooring on the landing; I need some more wood of the correct thickness to make a neat job of it.

If you enjoyed that post, then read these...

Building Progress ~ September 2008
As Autumn (and an end to lime pointing) approaches things have come on at the barn.

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Building Progress ~ April 2009
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Building Progress ~ July 2010
Let's get in early this month.

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Lime pointing ~ before pictures

Category: Barn Conversion Journal October 21st, 2010 by mbc

As much time as I’ve spent on pointing and all the ancillary activities such as moaning, evangelising and generally bumping-my-gums about pointing, I’ve just realised, I’ve not posted a great deal of evidence related to my actually doing any pointing.

To address this, I thought a range of before photographs, showing the walls of the barn in various states before being repointed was in order, to be followed by some evidential after photographs.

From Barn Conversion 2007

This picture from 2007 gives a view of the barn from the southerly end up and across the front toward the kitchen. No repointing, no lime washing, no new window openings, no new window frames or doors and no paths. The unadulterated version of the barn as we bought it.

The southern gable end had been repointed sometime in the previous few years.

From Pointing

Unfortunately, despite originally thinking that the pointing was good and sound having been recently repointed with what we thought was a lime based mortar, the repointing had actually been done with a cement based mortar that had cracked over time and so let in a lot of water. That end of the building catches the worst of the weather as it blows in along the valley and so is exposed to plenty of rain year round. So much water had worked it way in and dribbled down inside the wall that we had stalactites in our walls.

Repointing that wall would have been very difficult as the concrete mortar was very hard and virtually impossible to hack out by hand and the use of any machine was bound to lead to damage to the stonework. But something had to be done as the mortar was as leaky as a sponge. The solution we arrived at was to limewash it – a solution I’m pleased with for its practicality, attractiveness (well I find it attractive) and for the fact that it cut down the amount of repointing I needed to do.

From Pointing

I’ve left the other small patches of concrete mortar sprinkled around the other walls of the barn as they are – they’re sound and too hard to bother removing for purely cosmetic reasons.

The mortar in the long front wall that stretches away from the closest corner in the photo up toward the barn doors was the most rotten of all. In places it had rotted out or dissolved completely with lime loving plants growing out from the crevices.

From Barn Conversion 2007

This picture, again from 2007 shows the kitchen end of the barn, not long after the chickens had been evicted from their former home (they where relocated elsewhere on the farm, but apparently used to still come back to visit). You can see how rotten the mortar is in the lower left hand corner of the barn. The north facing gable end, in shade here, is the last I started work on. The original mortar on this wall was softer than on the other walls, I think partially due to the lack of sunshine ‘curing’ the mortar over the years. It gets very little sunlight, just some weak rays at the end of the day. I also get the feeling that as the least visible wall of the barn the original pointing hadn’t been done with as much care and attention to materials and technique as the other walls.

From Pointing
From Pointing

These pictures are more recent and show the walls at the rear of the barn having been prepared for pointing by hacking out old mortar. As you can see there were some very deep holes to fill.

From Pointing

Finally, a picture from 2007 of my first fledgling and somewhat messy attempts at pointing. Unfortunately I chose the most often seen portion of the barn walls that is passed by whenever entering or leaving the barn.

If you enjoyed that post, then read these...

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Inspired to analyse the composition of my mortar, I improvised and placed a lump of mortar that I'd levered out of my wall in the strongest acid I could lay...

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Whilst not wanting to become a lime-pointing-bore (I bet there aren't too many of those in the world) I feel another update is in order.

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I'm not sure that the barn resembles any kind of bird's nest, but I do appreciate Roger Deakin's words on the beauty to be found in the ordinary.

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Building Progress ~ September 2010

Category: Barn Conversion Journal October 4th, 2010 by mbc

Seems like I’ve been repointing for ever…

Back in August I said…

I’m not sure that I’ll hit my end of September goal, but if I need a few more days in October then so-be-it. It’ll be a lovely feeling to get it finished and move onto something else (the to-be back garden is top of the list if the weather holds).

As predicted, I’ve not managed to complete all the repointing by the end of September, HOWEVER, I have completed the front wall — Horray! Photo’s to follow soon as I’ve not yet seen it properly dried out and therefore not had the opportunity to photograph it. Just the back and the gable end to finish in October (maybe more than a few days but I’ll get there). I think simply using a ladder to reach the top of the walls should be okay. I had considered needing scaffolding of some description, but the small amount of work I needed to use the ladder for at the front was fine – even more comfortable than my usual position at the top of a step ladder.

I did manage to drag myself away from the wall for an hour or so the other weekend and ventured into the wood to discover much to my disappointment that many of the trees I planted earlier in the year have died. I think a post-mortem is called for, although I suspect that not enough sunlight was reaching them.

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Whilst the interiors of this barn conversion in Austria are a little too coldly architectural for my liking, I love this external wall.

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