Top of the Wall

[Sue Wilkinson]

As some of you will have realised from previous posts, I've had to rebuild a substantial section of garden wall this year. I was a bit daunted at the start, but I have just one and a half courses left to go!!! I've been unable to decide what to put on the top. I don't want a mortar cap. I'd like verticle standing stones, but don't have enough stone and can't afford to buy more really. But I do have a lot of smaller bits of stone. So I'm thinking that if I build up the middle of the wall a bit higher than the last course I could simple mortar the smaller stones lying flat to form a stone and mortar cap at the top.

I've been using cheap hydrated lime for the wall with some of Mike Wye's pozzolan because it is afterall only the garden wall, and its fine, but I don't think that will do for the top which will get the full force of the rain and wind. What mortar mix would you recommend for this more exposed section?

Sue
PS I've had many comments from villagers and passers by as I've done this work. Mostly helpful and moral boosting. With one exception, a man I've never seen before stopped his car, got out and watched for a bit on my first day at trying to put it back together, and said after a while that he'd built miles of the stuff and if I kept going like that it would fall down! I see no reason why he should be right, so I ignored him and carried on. Yesterday a cyclist I've never seen before puffed past (its a steep hill for a bike) and said as he went "that's a nice bit of brick laying". OK, he should have said stone not brick, but I was still very chuffed. It looks a lot better than I ever thought it would and I've been able to build it round a tree trunk which contributed to the collapse in the first place.

 

[Penners]

Hi Sue

If I've understood your plans correctly, I think that a domed mortar capping with an inlay of smaller stones flat along the top of the dome might look rather nice. Just as a thought, why don't you just try a couple of feet of it, and see what you think?

Other than that, I'm not sure what you could do with these remaining small bits of stone. If you were to do vertical "cock and hen" you would need alternate small and large slabs, so I guess that's not possible within budget?

Congratulations on your venture. Do post a picture when you've finished.

David

 

[Gervase]

Well done!
I'd be tempted to use the same stuff with a pozzolan for the cap. I know that the books say to use NHL3.5, but that means spending anbother £7 on a bag of Castle. And, to be honest, the people who built the wall in the first place probably wouldn't have had access to bags of NHL 3.5 (or even best blue lias) - they would have used the same stuff throughout, which would have been a largely fat lime (with some impurities giving it very feebly hydraulic qualities).
Just like a mix of hydrate and pozzolan really!
As for the decorative element, as Penners said, a cock'n'hen top would look authentic, but you could also bed large stones flat if they cleave nicely. What used to be on the rest of the wall?

 

[biffvernon]

I've just done the ridge of a pantiled outbuilding with hydrated lime - straight out of the bag, mixed 1:4ish with dirty sand. Maybe I'm trying to prove a point but I'll tell you how it fares in a couple of years or decades!

Where's this wall, Sue? We need a topping out party

 

[Gervase]

y'know Biff, I've a feeling that reprobates like us will soon be forming the Provisional Wing of the Limies. or, at the very least, some sort of breakaway faction.
it does amaze me to hear folk go on about the precise nature of the lime needed for a particulr job when one thinks of what was (or wasn't) available in the past.
Which reminds me - watch this space for news in the next few months of the reincarnation of perhaps the best all-round lime of all. It seems that the way is being paved for the re-release of an NHL1 by at least one of the UK's major lime producers, which will be a perfect match for maybe 90 per cent of the lme that built London and the south east, and most of that used in other major cities as well.
It's based on the grey chalk limes that were once made in a great swathe along the Thames valley and in the south east, particularly in Dorking.

 

[Sue Wilkinson]

Thanks Gervase, Biff and Penners, I'm glad you said that about carrying on with the same mix. I mean it looks fine and seems OK, I just thought I'd be shouted at for not doing something stronger. Its cheap and cheerful, which is what I needed.

Topping out party, that would finish it quickly, especially as I have to run the top over much more of the adjoining wall as well as the repair. I hope I can get it finished before the bad weather. Much of the adjoining wall needs repointing too. I keep forgetting to go and get a load of plastic sheeting. I've not enough to do the longer top. I do feel it has been an achievement. I'm pleased with it. Not sure I'd dare risk a photo in case you all thought it was rubbish though.

The original top of the wall was a concrete cap, much broken up and missing. Obviously there would have been something different earlier on, but no evidence of what. The wall is much older than the cap. I have a big worry coming soon about a different stretch, about 18 feet of wall further down has obviously fallen over at some point and been rebuilt with hard cement. It is now tipping outwards as a solid piece. If it falls on anything it will do serious damage. I won't be able to reuse the stone as its one big lump. Any ideas how I could buttress this to stop it falling?

Sue

 

[NT]

Is this random stone? If so I would have thought you could break the big lump apart and use what you can get from it, tho there will be wastage. Buttressing can be done with a pier, a thing I cant remember the name of (triangular section of stonework), iron poles, or for temp support only, woodwork.


NT

 

[biffvernon]

Buttressing can be done with a pier, a thing I cant remember the name of (triangular section of stonework),

Buttress perhaps?