Anyone got any hints?

I've an old (~100 years) stone-build house (sandstone? - not completely
sure) which may or may not need repointing. And I'm not sure whether it
should be lime, cement, or a lime-and-cement mortar that needs to be
used.

Period property websites, and lime sellers insist that it has to be
lime, or the building won't breath, become damp, and the stonework will
crack.

The pointing man says the stone is hard enough. Cement mortar is fine -
that's what he always uses - and it doesn't matter when you're doing
'sunken' pointing rather than the old-style 'raised' pointing. (Can't
remember the proper terms he used..)

I'm not sure who to believe. Has anyone got any experience?

In article ,
AJ writes:
Anyone got any hints?

I've an old (~100 years) stone-build house (sandstone? - not completely
sure) which may or may not need repointing. And I'm not sure whether it

Why do you think it may require repointing?

should be lime, cement, or a lime-and-cement mortar that needs to be
used.

Period property websites, and lime sellers insist that it has to be
lime, or the building won't breath, become damp, and the stonework will
crack.

The pointing man says the stone is hard enough. Cement mortar is fine -
that's what he always uses - and it doesn't matter when you're doing
'sunken' pointing rather than the old-style 'raised' pointing. (Can't
remember the proper terms he used..)

I'm not sure who to believe. Has anyone got any experience?

You need to find a builder who is knowlegable dealing with
buildings of your type/age. If it really is sandstone and
originally built with lime mortar, I would be very concerned
about his suggestion to use cement based mortar. Most likely
he has no knowlege of old buildings or experence of lime
mortars.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 8 Feb, 12:15, AJ wrote:

Period property websites, and lime sellers insist that it has to be
lime, or the building won't breath, become damp,

Lime _renders_ are important (especially for "harling" in Scotland),
but lime _mortars_ make zilch difference to any "breathability".
They're too little surface, too thick in section.

If it is a lime mortar, stick with lime. This is for mechanical
reasons though, not permeability.

AJ says...
Anyone got any hints?

I've an old (~100 years) stone-build house (sandstone? - not completely
sure) which may or may not need repointing. And I'm not sure whether it
should be lime, cement, or a lime-and-cement mortar that needs to be
used.

Period property websites, and lime sellers insist that it has to be
lime, or the building won't breath, become damp, and the stonework will
crack.

The pointing man says the stone is hard enough. Cement mortar is fine -
that's what he always uses - and it doesn't matter when you're doing
'sunken' pointing rather than the old-style 'raised' pointing. (Can't
remember the proper terms he used..)

I'm not sure who to believe. Has anyone got any experience?


We've got an old stone house (~ 200 years or more) with
lime mortar between the stones and clay / cob / rubble
infill between the inner and outer walls. When I looked
into the repointing issue I too was told not to use cement
based mortar. Looking at part of our house bears this out
as the previous owner had pointed a small section using
cement and the stone work around the mortar has blown. As I
understand it moisture becomes trapped in the wall because
cement mortar cannot breath. In cold weather this moisture
freezes and blows the stone.

The purists say you should use slaked lime mortar, not the
CaOH stuff sold in bags because it has partly gone off
absorbing CO2 from the atmosphere. However, slaking your
own lime from CaO is a tad over the top for me. Someone
else recommended using hydraulic lime (grade 3.5) and I've
been using that for pointing. It seems to work well. The
main problem is the colour. It is very pale so I needed to
add cement dye to match the colour of the ancient aged
mortar.
--
David in Normandy

I agree with the previous posters about it being the type of stone
that matters. Soft sandstone or limestone will def require lime
mortar, harder stones may not.

AIUI the problem with cement mortars is that they may block moisture
wicking away from particularly wet areas of stonework. It's not their
action in releasing moisture directly back to the atmosphere that's so
important as not preventing moisture migration from wetter to drier
areas and allowing the larger surface to do its work.

I've made up my own lime putty from builders lime, and given a
sufficiently long soaking period has been successful. However I'm more
likely to use a commercial lime putty in future.

Hydraulic lime usage seems more common in France - certainly it seemed
commonly available in builders merchants in Southern Brittany - though
the local building stone was granite.

I've also successfully used cement dyes in lime mortars.

On 8 Feb, 12:15, AJ wrote:
Anyone got any hints?

I've an old (~100 years) stone-build house (sandstone? - not completely
sure) which may or may not need repointing. And I'm not sure whether it
should be lime, cement, or a lime-and-cement mortar that needs to be
used.

Period property websites, and lime sellers insist that it has to be
lime, or the building won't breath, become damp, and the stonework will
crack.

The pointing man says the stone is hard enough. Cement mortar is fine -
that's what he always uses - and it doesn't matter when you're doing
'sunken' pointing rather than the old-style 'raised' pointing. (Can't
remember the proper terms he used..)

I'm not sure who to believe. Has anyone got any experience?

Dear AJ
The other posts are quite right. I recommend a lime putty as opposed
to the bagged lime for reasons given.
Advice generally is to be found in "Mortars, Plasters and Renders in
Conservation" by Prof John Ashurst obtainable from the SPAB but I am
told that some of his mixes he no longer recommends
You cannot go far wrong with 3 to 1 sand lime
Ignore your builder as clearly he has not a clue and go an find
someone who has worked with lime ie knows the origin of the expression
"knock up" appertaining to mortar.
chris

The message
from contains these words:

On 8 Feb, 12:15, AJ wrote:
Anyone got any hints?

I've an old (~100 years) stone-build house (sandstone? - not completely
sure) which may or may not need repointing. And I'm not sure whether it
should be lime, cement, or a lime-and-cement mortar that needs to be
used.

Period property websites, and lime sellers insist that it has to be
lime, or the building won't breath, become damp, and the stonework will
crack.

The pointing man says the stone is hard enough. Cement mortar is fine -
that's what he always uses - and it doesn't matter when you're doing
'sunken' pointing rather than the old-style 'raised' pointing. (Can't
remember the proper terms he used..)

I'm not sure who to believe. Has anyone got any experience?

Dear AJ
The other posts are quite right. I recommend a lime putty as opposed
to the bagged lime for reasons given.
Advice generally is to be found in "Mortars, Plasters and Renders in
Conservation" by Prof John Ashurst obtainable from the SPAB but I am
told that some of his mixes he no longer recommends
You cannot go far wrong with 3 to 1 sand lime
Ignore your builder as clearly he has not a clue and go an find
someone who has worked with lime ie knows the origin of the expression
"knock up" appertaining to mortar.
chris


A mixture of lime putty and hydraulic lime will give both a good initial
set and maximum strength. That's the latest recommendations from the
historic building preservation people. Source? One of my sons is an
apprentice traditional stone mason with a firm specialising in
conservation work.

Appin says...
The message
from contains these words:

On 8 Feb, 12:15, AJ wrote:
Anyone got any hints?

I've an old (~100 years) stone-build house (sandstone? - not completely
sure) which may or may not need repointing. And I'm not sure whether it
should be lime, cement, or a lime-and-cement mortar that needs to be
used.

Period property websites, and lime sellers insist that it has to be
lime, or the building won't breath, become damp, and the stonework will
crack.

The pointing man says the stone is hard enough. Cement mortar is fine -
that's what he always uses - and it doesn't matter when you're doing
'sunken' pointing rather than the old-style 'raised' pointing. (Can't
remember the proper terms he used..)

I'm not sure who to believe. Has anyone got any experience?

Dear AJ
The other posts are quite right. I recommend a lime putty as opposed
to the bagged lime for reasons given.
Advice generally is to be found in "Mortars, Plasters and Renders in
Conservation" by Prof John Ashurst obtainable from the SPAB but I am
told that some of his mixes he no longer recommends
You cannot go far wrong with 3 to 1 sand lime
Ignore your builder as clearly he has not a clue and go an find
someone who has worked with lime ie knows the origin of the expression
"knock up" appertaining to mortar.
chris


A mixture of lime putty and hydraulic lime will give both a good initial
set and maximum strength. That's the latest recommendations from the
historic building preservation people. Source? One of my sons is an
apprentice traditional stone mason with a firm specialising in
conservation work.

For some time "experts" were recommending mixing a small
amount of cement with the lime putty as it makes the mortar
set quicker. However I've since read somewhere that this
leads to "microcrystaline cracks" forming which weaken the
mortar.

It seems like this topic is an ongoing issue with
recommendations changing all the time. I do like the
hydraulic lime to work with though as this does "set"
fairly quickly. I still haven't been able to source any
lime putty, but it is possible to buy CaO here and make
your own but it seems like lots of extra work for unknown
benefits.
--
David in Normandy.
The "Reply to" email address is valid BUT you must include
the password FROG on the subject line or emails are
automatically deleted.

It's definitely sounding that lime+sand is the mix to expect them to
use..

Does anyone know of a suitable craftsman they could recommend around the
Oldham/Manchester area.??

In article ,
says...
Anyone got any hints?

I've an old (~100 years) stone-build house (sandstone? - not completely
sure) which may or may not need repointing. And I'm not sure whether it
should be lime, cement, or a lime-and-cement mortar that needs to be
used.

Period property websites, and lime sellers insist that it has to be
lime, or the building won't breath, become damp, and the stonework will
crack.

The pointing man says the stone is hard enough. Cement mortar is fine -
that's what he always uses - and it doesn't matter when you're doing
'sunken' pointing rather than the old-style 'raised' pointing. (Can't
remember the proper terms he used..)

I'm not sure who to believe. Has anyone got any experience?

AJ wrote:
Anyone got any hints?

I've an old (~100 years) stone-build house (sandstone? - not completely
sure) which may or may not need repointing. And I'm not sure whether it
should be lime, cement, or a lime-and-cement mortar that needs to be
used.

Period property websites, and lime sellers insist that it has to be
lime, or the building won't breath, become damp, and the stonework will
crack.

Most of them have no real understanding of teh physics chemistry and
mechanics of buildings. Like most builders in gact.



The pointing man says the stone is hard enough. Cement mortar is fine -
that's what he always uses - and it doesn't matter when you're doing
'sunken' pointing rather than the old-style 'raised' pointing. (Can't
remember the proper terms he used..)

I'm not sure who to believe. Has anyone got any experience?

Not direct with stone, but the issues with l,ime versus portland are the
portland is string, brittle and relatively impervious, whereas lime is
wek, never truly sets hard, and is fully porous.

Where teh myths come from are that if there is damp inisde, the lime
lets it out. Where the structure is rickety and foundations are poor,
the lime will adjust. Whereas portland wont, and you end up cracking
your fine crumbly tudor bricks etc.

Otherwise limes a crap material IMHO.

Id the foundations are good, and the stone is tough, and there is no
evidence of movement, it doesn't matter except aesthetically: I managed
to make the brickwork LOOK old by using a 1:1:4 (very roughly) mix of
white cement, hydrated lime and sand.

If the stone is clunch, or maybe soft limestone or sandstone, then you
may benefit from using a lime mix. Especially if the foundations are not
that good. Otherwise really don't worry. If the stone itself is
imepervious, the mortar isn't going to let it breathe anyway, and if its
strong enough, the cement wont break it if movement happens.

There needs ti be a balane between 'museum restoration' and plain
refurbishment of old, and not really that distinguished properties.

If todays 'period' crew had been around in the 16th and 17th century all
those wonderful timber farmed houses that were infilled with - gasp -
'modern brick', and which have as a result survived when many others
perished, wouldn't have been around for them to drool over today.

The message
from David in Normandy contains these words:



For some time "experts" were recommending mixing a small
amount of cement with the lime putty as it makes the mortar
set quicker. However I've since read somewhere that this
leads to "microcrystaline cracks" forming which weaken the
mortar.

It seems like this topic is an ongoing issue with
recommendations changing all the time.

That is indeed so.

On 2008-02-08 14:36:09 +0000, David in Normandy said:

We've got an old stone house (~ 200 years or more) with
lime mortar between the stones and clay / cob / rubble
infill between the inner and outer walls. When I looked
into the repointing issue I too was told not to use cement
based mortar. Looking at part of our house bears this out
as the previous owner had pointed a small section using
cement and the stone work around the mortar has blown. As I
understand it moisture becomes trapped in the wall because
cement mortar cannot breath. In cold weather this moisture
freezes and blows the stone.

The purists say you should use slaked lime mortar, not the
CaOH stuff sold in bags because it has partly gone off
absorbing CO2 from the atmosphere. However, slaking your
own lime from CaO is a tad over the top for me. Someone
else recommended using hydraulic lime (grade 3.5) and I've
been using that for pointing. It seems to work well. The
main problem is the colour. It is very pale so I needed to
add cement dye to match the colour of the ancient aged
mortar.

Do they sell this in Brico Depot?

I went into one last weekend in Alencon - not impressed - mostly
stacked up with tat.

I asked for some specific electrical fittings. Gallic shrug.

OTOH, I did get a good lunch in Domfront.

AJ wrote:

Anyone got any hints?

I've an old (~100 years)

That's not old, it's not even out of puberty yet.

stone-build house (sandstone? - not completely
sure) which may or may not need repointing. And I'm not sure whether it
should be lime, cement, or a lime-and-cement mortar that needs to be
used.

Period property websites, and lime sellers insist that it has to be
lime, or the building won't breath, become damp, and the stonework will
crack.

They are right.

The pointing man says the stone is hard enough.

He's an idiot.

Cement mortar is fine - that's what he always uses - and it doesn't matter
when you're doing 'sunken' pointing rather than the old-style 'raised'
pointing. (Can't remember the proper terms he used..)

Strap pointing, I suspect. It's vile and ugly and causes stone to
deteriorate even faster.

I'm not sure who to believe. Has anyone got any experience?

Not the "pointing man", find someone else.

Andy Hall says...
The
main problem is the colour. It is very pale so I needed to
add cement dye to match the colour of the ancient aged
mortar.

Do they sell this in Brico Depot?

I went into one last weekend in Alencon - not impressed - mostly
stacked up with tat.

I asked for some specific electrical fittings. Gallic shrug.

OTOH, I did get a good lunch in Domfront.


BricoMarche sells cement dye in around 10 different
colours.
--
David in Normandy.

To e-mail you MUST include the password FROG on the
subject line or emails are automatically deleted.

Steve Firth wrote:
AJ wrote:

Anyone got any hints?

I've an old (~100 years)

That's not old, it's not even out of puberty yet.

stone-build house (sandstone? - not completely
sure) which may or may not need repointing. And I'm not sure whether it
should be lime, cement, or a lime-and-cement mortar that needs to be
used.

Period property websites, and lime sellers insist that it has to be
lime, or the building won't breath, become damp, and the stonework will
crack.

They are right.

The pointing man says the stone is hard enough.

He's an idiot.

Cement mortar is fine - that's what he always uses - and it doesn't matter
when you're doing 'sunken' pointing rather than the old-style 'raised'
pointing. (Can't remember the proper terms he used..)

Strap pointing, I suspect. It's vile and ugly and causes stone to
deteriorate even faster.

I'm not sure who to believe. Has anyone got any experience?

Not the "pointing man", find someone else.

The question that is never addressed is to what extent the addition of
pozzolans to make a hydraulic lime modify its basic properties. If it
sets in a reasonable time, I don't see how it retains its self-healing
properties

The message
from Stuart Noble contains these words:



The question that is never addressed is to what extent the addition of
pozzolans to make a hydraulic lime modify its basic properties. If it
sets in a reasonable time, I don't see how it retains its self-healing
properties

Which is why the mix must have lime putty. An initial set of some sort
is desirable within a reasonable timeframe to keep the pointing in
place, but the ability to soften when moistened and heal again on drying
is vital.

Appin wrote:
The message
from Stuart Noble contains these words:



The question that is never addressed is to what extent the addition of
pozzolans to make a hydraulic lime modify its basic properties. If it
sets in a reasonable time, I don't see how it retains its self-healing
properties

Which is why the mix must have lime putty. An initial set of some sort
is desirable within a reasonable timeframe to keep the pointing in
place, but the ability to soften when moistened and heal again on drying
is vital.

Yawn. I guess thats why the world and his dog moved to Portland cement
once it was available.

I bet you cure your own leather in urine and dog****e too.

AJ wrote:

Anyone got any hints?

I've an old (~100 years) stone-build house (sandstone? - not completely
sure) which may or may not need repointing. And I'm not sure whether it
should be lime, cement, or a lime-and-cement mortar that needs to be
used.

Period property websites, and lime sellers insist that it has to be
lime, or the building won't breath, become damp, and the stonework will
crack.

The pointing man says the stone is hard enough. Cement mortar is fine -
that's what he always uses - and it doesn't matter when you're doing
'sunken' pointing rather than the old-style 'raised' pointing. (Can't
remember the proper terms he used..)

I'm not sure who to believe. Has anyone got any experience?

Yes, but experience isnt what you need here. Either will work, so
experience wont tell you much. Best thing to do is look at the
writings of the researchers and orgs that use their work (eg SPAB),,
and to a lesser extent sites that discuss and explain it (eg
http://periodpropertyshop.co.uk/phpB...wforum.php?f=1 )

The short answer is use lime because:

1. Cement mortar frequently pulls the edges of the stone away
when it finally gives up, in 20 years or more time. Theres a fair bit
of such cement damage about.

2. Lime wicks and evaporates water from the wall, whereas with
cement the evaporation will mostly occur from the stone faces,
causing salt damage in time. Mortar otoh is expendable.

3. Minor building movement, which is common in old builds, will
crack the soft lime, which is expendable. With cement OTOH the
stone breaks, which is not good. 2ndly cracked lime can self heal
on exposure to CO2 in the air, whereas cement can't.

The downsides of lime a
1. very slow setting. dont add cement.
2. vulnerable to frost when setting: avoid exterior lime work this
time of year
3. Overly sandy mixes are prone to rising damp, but there is no
reason to use a bad mix of course. 1:2.5 - 3 is fine.
4. Bagged lime is fine if its not old and wrongly stored. Cement
and lime can both go off, but lime looks exactly the same when it
has, whereas with cement its obvious.

And yes, theres plenty of BS about. 'Cement has no problems'
and 'you need putty' are the main variants. Just read the experts,
eg the leaflets at SPAB, or the research papers if you want
unnecessary depth.


Oh, ribbon pointing: it causes water splash onto the stone and
reduces run-off. Consequently it makes the stone more vulnerable
to freeze-thaw damage. Its also totally out of character. Its not
recommended for any type of period property.


NT

The message
from The Natural Philosopher contains these words:

Appin wrote:
The message
from Stuart Noble contains these words:



The question that is never addressed is to what extent the addition of
pozzolans to make a hydraulic lime modify its basic properties. If it
sets in a reasonable time, I don't see how it retains its self-healing
properties

Which is why the mix must have lime putty. An initial set of some sort
is desirable within a reasonable timeframe to keep the pointing in
place, but the ability to soften when moistened and heal again on drying
is vital.

Yawn. I guess thats why the world and his dog moved to Portland cement
once it was available.

Portland cement is in many ways easier to use and is of generally
consistent quality.

I bet you cure your own leather in urine and dog****e too.

Not actually.

But on one of our very large buildings there is only one are where there
is efflorescence on the interior plaster. And that's the one area
where on the outisde the cement pointing of recent years has not been
replaced by lime.