Advice needed on repointing.

[Gervase]

You can buy 50-metre rolls of hessian for about £45 from places like Ty Mawr and Mike Wye. You just wrap and staple it around some 2x1 battening and then either screw it to the soffits or a front kicker board on the scaffold. It only has to stay in place for a week or so, unless you're expecting the temperature to plummet well below freezing.

 

[vannie]

Oh god,
I am now getting worried this is all starting to sound way too complicated, does my house HAVE to be swathed in hessian if we repoint using lime ? I think that would be the last straw for my husband regardless of the advantages.

Vanessa.

 

[Andrew Bodenham]

any recomendations for a good dust mask? the ones we bought were cheap, and worse than useless as you got so steamed up. a tshirt, tied cowboy style was better, but very uncomfortable

The best disposable dust masks I've used are the three-panel design made by 3M (Screwfix quote 11366). They fit really well and seal around the nose properly, so specs don't mist up. Not the cheapest, but in my opinion the best. Sometimes I wear these all day long if I'm working for clients who have cats, as I'm really allergic to them.
The cats, that is.

 

[michael]

Looking at the photos above, it seems like Gervase has been spending his winter nights in front of the sewing machine joining 8ft x 4ft Hessian sheets together. Was he a sail maker in his past life perhaps?

 

[borischarlton]

Vannie
Please do not get put off using lime, It is the product that you need to use. I feel that there is so much info flying around you could get lost!! Also in my opinion it is not all correct. I belive that you are in Southampton, if correct you have a fantastic resource just up the road in Winchester http://www.thelimecentre.co.uk I have been on their lime course and although they have given me some very conflicting advise to that I have read on here,they are the experts and it has always worked out well for me. It really doesn't have to complicated just understood.
Good Luck
Rob

 

[borischarlton]

Just looked and they have a course on 1 November
Rob

 

[Nemesis]

Does all the expertise lie at the Lime Centre in Winchester?

Possibly not!

Plenty of lime courses around, although of course many are held by those with products to sell, so be aware that not everything they say could be untainted by that.

http://www.buildinglimesforum.org.uk/courses.htm


The SPAB runs lime courses too.
http://www.spab.org.uk/

Mike Wye produces a DVD which is possibly worth watching.

Jane Schofield's little book on lime is worth reading.

Lime in Building - A Practical Guide
Written by Jane Schofield
Price £4
Available from: Jane Schofield,
Black Dog Press, Lewdon Farm, Black Dog, Crediton,
Devon EX17 4QQ, UK.
Tel: 01884 861181 and 861196
E-mail: jane@blackdog.ukf.net

(see also books part of this site, and SPAB publications)

I appreciate that some are sniffy about using bagged hydrate to make your own non-hydraulic putty, but many are becoming more convinced, especially where budget is a consideration and any other sort of lime is in short supply.

Also - I suspect that Gervase was rendering, not pointing, behind the hessian. That's a different issue.

Pointing is usually done in small amounts. It can be useful to cover with hessian, especially if there is danger of too rapid drying or frost, but not totally compulsory.

Never use something though simply because it's the easiest to use - use it because it's the best choice for the building. Mostly, for pointing, that's non-hydraulic. A pozzolan can be added, but it may not be necessary.

There are contractors who use lime, but use hydraulic, simply because as far as they are concerned it's easier, works more like cement.

In the long run, it's not their building, they are there to make money, and many if questioned I suspect couldn't really tell you why they think it better. Unless they are prepared to discuss the issues and the pros and cons (and I know Gervase uses hydraulic at times, but I am sure he could explain why) then be wary.

 

[borischarlton]

I really feel that, if I posted that the world was round you would try to say its flat!!

I was just giving my personal experience of their advise and how it had worked for me. Also, if Vannie goes ahead and uses lime then it is local to her.
Rob

 

[Flyfisher]

I really feel that, if I posted that the world was round you would try to say its flat!!

There's no argument that it's flat, beyond that promulgated by a few contrarians of course :wink:

 

[Nemesis]

I was just trying to be even handed, not a contrarian! (Me???) Maybe the alcohol levels are still high and I wasn't my usual charming and diplomatic self. Sorry, wasn't trying to be rude. Just wind me up on the topic of lime and off I go...

But all places have their own ideas, and it's worth bearing that in mind. Not all tradespeople are as caring about your house as you are.

http://www.alaska.net/~clund/e_djublonskopf/Flatearthsociety.htm


There you go.

Tom are you there? Tom? Tom???

 

[Gervase]

It was pointing, but it was at the end of October, when the elements were a little iffy and the temperature was threatening to drop faster than Sue Lawley's drawers.
Nevertheless, the nice thing about using lime is that - within reason - it's remarkably tolerant stuff. Thus, although every practitioner will have his or her own favoured techniques, provided you stick to a few basics, you won't go far wrong. As an example, look at the thread on lime plaster with chalk. Most courses would say 'don't do it!', yet lime and chalk have been used in Sussex, Hampshire and Kent for centuries for plastering with no problems.
As for hydraulic lime; I use it when I'm up against the clock and there are big voids to fill, or if I'm reconstituting stonework where there has already been a lot of cement used to bind stuff together, or for rendering or pointing on severely expose or damp areas. Given a choice I'd use fat lime every time. It is the most breathable form of lime and the most tolerant of movement - and also the easiest to work with. And for plastering I'd never use hydraulic lime.
Sometimes, however, when putting right the wrongs of others or trying to work within limited time-frames, there is no choice - but even then it's best to use the weakest mix possible; go for an NHL2 or NHL3.5 rather than and NHL5.

 

[Nemesis]

Sue L?????

Do kissntell....

 

[Gervase]

I'm the soul of discretion. Wild horses wouldn't get me to say why her underpinnings were compared to a yo-yo after a studio mike was inadvertently left live... :wink:

 

[Nemesis]

Would a tame one?

 

[michael]

If the only advice for Vannie is to use sand and hydrated lime with Hessian protection for her repointing rather than Hydraulic NHL2 like me, then is it absolutely necessary for her to use slaked lime putty? On the odd bits of “internal” repointing that I’ve done, I’ve simply made a 3:1 mix of sharp sand and builders merchant Hydrated lime (white powder) straight from the bag without slaking and this has given pretty good results. It mixed up well with no lumpy bits, went on well, looks pretty good and is holding up in its “indoor” application. I’ve heard that Lime putty gives a smoother finish, mixes up better etc.etc but like I said my powdered mix seems to have done the job quite adequately. Slaking your own lime putty can be a bit troublesome, messy and long winded and you really need a good practical outside work area where your patio and Rhododendrons won’t get messed up and if you go for the ready bagged putty option, then this can be a bit expensive. I can understand it if you’re looking for the perfect lime rendered wall but is it absolutely necessary to use the putty version of hydrated lime for repointing?
Lastly, be honest. How long dose the Hessian sacking have to stay up for? We all know that lime can stay relatively soft to the fingernail test for several months and will take years to fully carbonate. Even the “internal” Lime and horsehair plastering which I had done in Feb/March, I was told to leave alone until at least the summer. If you’re dealing with the outside elements as well then surely it will need to be protected for some considerable time?

 

[Nemesis]

Mixing bagged (non-hydraulic) hydrated lime into a putty to mix with aggregate isn't slaking lime.

Not sure really you have got to grips with all this.

 

[MdB]

limestone + heat = quick lime

quick lime + lots of water = lime putty (+ lots of heat and steam) ~ looks like cream cheese
quick lime + just the right amount of water = lime hydrate (+ lots of heat and steam) ~ dry powder

The above two operations are both called slaking and is not something to be done outside the factory due to the dangers involved.

lime hydrate + water = lime putty (no heat generated) ~ looks like cream cheese

lime putty + sand = lime mortar

lime hydrate + sand + water = lime mortar

Above processes are safe as no heat is generated but a mask should be used when dealing with the lime hydrate. Water proof gloves should be used with all the above unless you want the top layer of your skin falling off a few days later.

(I think I've got all that right - corrections please)

 

[NT]

> is it absolutely necessary to use the putty version of hydrated lime for repointing?

not in the slightest. Bagged lime plus water contains exactly the same things, and works fine.


NT

 

[MdB]

> is it absolutely necessary to use the putty version of hydrated lime for repointing?

not in the slightest. Bagged lime plus water contains exactly the same things, and works fine.

I agree with NT but putty does have the advantage that it will keep for ages (forever??) and doesn't go off in the bag. Some also say that the plasticising properties of putty are better than hydrate as the water has had time to soak into all the particles. I'm not sure I believe this myself though I do convert the hydrate to putty as my house is a bit damp and I don't think it would store well.

Putty + sand removes the problem of hydrate blowing about (you don't want it in your lungs) and it also removes the problem of judging the correct amount of water to add (as your not adding any).

 

[michael]

Ok MdB. I think you are saying that adding Builders merchant Lime Hydrate into a bath of water will form a lime putty but this is not the same as bags of readymade slaked lime putty from specialist suppliers as theirs is made from quicklime and water?( a relatively dangerous process)

Do they have different properties and advantages in their usage? One is certainly more expensive than the other.

I understand from the other comments that the only advantage of making putty from builders merchant hydrate rather than using the hydrate powder directly is that it doesn’t blow around and it keeps better.

And what about the Hessian? How long dose it have to stay up before the lime can withstand the elements on its own two feet? As I said Lime can stay soft to the fingernail scratch for a long time but perhaps the more expensive "quikelime" lime putty(only to be made by proffessionals) goes harder quicker?