Re-pointing garden wall...HELP!

[jungle_jim01]

Hi, I hope someone out there can give me some advice. I've recently moved into an old sandstone property in North Yorkshire. The previous owner must have had the house and garden wall repointed at some point....but unfortunately they used Cement!! argh!...which has obviously caused a few problems! Anyway...after weeks of researching about Lime Mortars and pointing i've decided to go for it and poractice on the garden wall. The garden wall has obviously been neglected over the years and has the odd weed growing out....i've been really careful to chisel out the cement using a combination of hand tools.. Most of it is pretty loose and has just been shoved in quite superficially. My problem is that behind the cement there's sections with quite a lot of earth, worms, bugs etc...great for the wildlife enthusiast but not so good to practice my pointing and repair the wall. I've cleaned out a couple of sections to repoint but i'm not too sure what to do about the deep holes (up to 12cm in some places). And certainly can't remove all the loose stuff in the back....should i just shove in the lime mortar and build it up over a few days?

Also...the top of the wall is made up triangular sandstone blocks with deep and wide cement mortar between the blocks...again this is all weak and i'm worried that by removing all the cement and loose material i'll completely remove the mortar in the vertical joints between these capping stones, again leaving a massive hole to fill.

Thanks in advance for anyone who can provide some advice.

 

[johnandrew]

Hi Jim

I don't really have any good advice but have nothing better to do so thought I would share a few thoughts.

I did a weekend course at St Ives estate in Bingley (West Yorks) where we worked on repointing a big random coursed sandstone wall with big holes containing dirt and other crud. Not much sign of the rubble infill remained. The chap in charge just decided we should try to fill the gaps with pinnings, sometimes quite large ones, until we have something to work the mortar into/onto.

I have also been thinking about repointing our large (10 feet) sandstone wall that borders our garden. There is very little sign of mortar between the stones and I haven't yet decided whether it was originally mortared. And just to complicate matters further we may have bats living in/using the wall.

In case you are interested the YHTA (part of the NHTG) is running a course on Lime and the Building Stones of Yorkshire in conjunction with York University.
http://cmsmigrate.york.ac.uk/archaeology/research/current-projects/nhta/short-courses/lime-stone/

 

[jungle_jim01]

Thanks John. I've actually been looking at that course...looks interesting.

I was wondering about putting some pinnings in...think i'll look for some tomorrow. Just out of interest...when you were on the course, repointing the wall, how much was raked out? Did they rake out sections or just go for it all?

Thanks again

 

[johnandrew]

Jim

The wall at St Ives was very large - probably about 12 feet tall and 30 metres* long strething around three sides of a garden area.There was a small group of us and we each focussed on a small area about 1 sq. metre. We cut/raked out and pointed that area over the weekend. I would probably do the same as long as I could be pretty sure of maintaining a consistent finish.


* Apologies for mixing my units.

 

[MurrayPrice]

Hi,

I think your on the right track, with the larger joints try to use small stones to fill along with mortar. Insure you use some kind of sheeting or hesien to protect the wall from the elements and insure you keep it damp. Wet the joints prior to pointing too. Have you though of the lime you are going to use NHL 2 3.5 or 5. If the stone is soft possibly a 2 or a 3.5 would be better suited.

 

[OddJob]

If it's an original drystone wall I can't help as I have no experience there whatsoever.
If it's a mortared wall I'm not keen on pinnings if you're talking about the epoxy bonded steel ties.

Don't attack it all in one go,do a square yard or so at a time(sorry,I can't speak metric)
Use wooden wedges to support loose stones and after raking out as much as you can wash out with a high pressure hose or pressure washer,you may have to do it more than once to get all the debris out.
12cm,4 3/4" isn't that deep,not deep enough to warrant grouting so using a fairly long flat jointing iron push it in as deep as you can then shove right to the back with a stick,build it up in layers.
Once you've consolidated one section you can move on to the next before you finally finish and repoint but consolidate from the bottom up and repoint from the top down.
The capping stones it sounds like you may have to remove and re-bed.
Chances are you'll just find huge voids between each behind the cement.
Beneath most likely will be more earth and debris.
Clean it out,I've even used an industrial hoover to do this and pack mortar and infill into the voids.
You can use a slurry lime grout but I prefer to pack good mortar and infill.
The capping stones are quite important and offer a lot of protection to the wall so I'd make sure you do that pretty well.
Andy

 

[jungle_jim01]

Thanks for all the advice. I'd been wondering about bottom vs top first so thats really useful. The pinnings i referred to are small pebbles bedded into the larger spaces...i think 'pinnings' is the right terminology.

As for the mortar i've been in touch with a local restoration company who have recommended an NHL 3.5 which is matched to the original mortar used in this area.

I'm a newbie to all this so really appreciate all the advice.

 

[jungle_jim01]

Oddjob...what do you mean by "not deep enough for grouting"? Further exploration has uncovered 2 large crevasses...approx 25cm deep and big enough to reach in and clench my fist...do i need to adopt a different method?

Thanks for your help

 

[jungle_jim01]

Just read about using different mixes of lime/aggregate depending upon the repair. Does anyone if know if NHL3.5 will be ok for the repairs described above or do i need a stronger mix?

Thanks

 

[vicky whitworth]

Hi Jungle Jim, we had a similar situation albeit internally. Our cottage is built of very rough random rubble with the stone a mix of sizes, shapes and composition. We had the cement render taken off the inside walls downstairs and then needed the bare rubble stone made ready for replastering in lime. The walls sound much like yours - 'mortared' in earth, dust, with huge gaps and voids. Stones just fell out all over the place. Our builder was great. He just said you have to do the best you can. Shove stones back in, fill the voids with pinnings, shove in the mortar. He did sections about a metre square at a time building out the mortar in one go (rather than in layers). It looked pretty rough but we didn't need to then re-point in neatly as it was being plastered over. I think what I'm saying is it looks a nightmare job but maybe it isn't so bad once you get started. Good luck.

 

[worms]

Further exploration has uncovered 2 large crevasses...approx 25cm deep and big enough to reach in and clench my fist...

I left a couple of these unfilled in my wall (at about 6ft above ground level) since the blue tits like them as nesting sites. Just narrow the entrance hole to about an inch in diameter and shape the entrance so that there is a small lip to stop the babies falling out!

looks a nightmare job but maybe it isn't so bad once you get started

Its actually very therapeutic!

 

[chuckey]

Have a pile of cleaned and broken stones in a bucket at your side. Use them to prop stones back into the proper place with the face of the stone wedge behind the pointing depth. Depending how broken the wall is, you can use a crow bar to wangle a large stone, such as a through, back in place (slowly and carefully!!), using you new mortar and stones to hold it.
You can't have too many pointing irons of different widths and a few which have got a radius on them (sort of like a spoon with the sides cut of). Two other tools which are useful are a straightened out SS wall tie with a little 1/2" 90 degree bend at one end, this is for hooking out loose bits of mortar, caterpillars, small pots of gold etc. The other tool I use a lot is a 1" wide X 1/4" thick stiff polypropylene brush for removing debris and finishing the mortar's surface. I got my one in Carreforrs (Sp.?) in Calais.
Frank

 

[OddJob]

Oddjob...what do you mean by "not deep enough for grouting"? Further exploration has uncovered 2 large crevasses...approx 25cm deep and big enough to reach in and clench my fist...do i need to adopt a different method?

Thanks for your help

25cm is plenty deep enough for grouting,you said 12cm :shock:
Grouting and pointing are too different things,for grouting deep voids in stone and I admit I've only done this once though it was quite a large job,a slurry of NHL 3.5,silica sand and casein was gravity fed into the wall.
Most of what I do stone wise is Kentish rag or sandstone so the pinnings I use are mostly small sharp stone shards and bits of slate.
I'm with chuckey on the jointing irons,I've got more than a dozen in various sizes,the narrowest being only about 3mm wide and made from an old table knife.
I use a couple of hoof picks from a tack shop for pulling out debris.
For finishing the joints I use a stiff churn brush.
I'd say you'd be okay with NHL 3.5 on sandstone,I'm using NHL 5 on rag at the moment but that would be too hard for sandstone.
Good luck

 

[jungle_jim01]

Thanks for the detailed advice. I've got a collection of stones for pinnings but they're mostly quite hard similar to granite pebbles. I'm wondering if there's a reason that you go for slate?...do they need to be soft?

 

[worms]

I don't think it matters what you use as pinnings (although I guess rougher stones might bond better to the mortar) but slate is very handy to slide into deep flat joints and for building in layers to get a tight fill. I've also used bits to bridge wider gaps to support other pinnings and mortar, but the purists might frown on this.

In some styles of pointing, bits of slate are deliberately left visible in the pointing as a feature of the wall.

 

[OddJob]

Basically what worms said,hard rough stones for your pinnings are good,I use slate and broken tile to tightly pack out flat joints and tighten up mainly brickwork.