We have an old timberframed house which was completely renovated 40
years ago.

The side walls are rendered, and the end walls are brick.

I have a problem with the rendering on one corner in that the fillet
between the rendering and the brickwork has come away. See:

http://i36.tinypic.com/n5pqps.jpg and

http://i33.tinypic.com/23vj96q.jpg

My friendly neighbourhood jobbing builder pointed the crack with lime
mortar, but it pretty much all fell out over the winter.

The rendering is about an inch thick, and the piece adjacent to the
crack does sound hollow on tapping, but in spite of that seems quite
stable and unlikely to fall down for a while yet - I can't get any
movement when I try and pull it away from the wall. On the other
hand, I can't help wondering if it is imperceptible movement that
meant the lime mortat fell off, or if it was a bodged up job!

How would you tackle this? I presume lime mortar is the right thing
to use - if so, what proportions? I know PVA is used in these
situations - does one it paint onto the rendering/brickwork. If so,
does one let it dry before applying the mortar, and/or does one mix it
in with the mortar? Presumably it is important to wet throughly
before applying mortar even if PVA has been applied. Should I try and
filll the crack with anything else before applying mortar, and if so,
what. Is there any other kind of mortar that is more flexible and
more likely to stay put?

Sorry for all the questions, but this is not (yet) an area of
expertise I have developed yet!

TIA

Keith

Keefiedee wrote:
We have an old timberframed house which was completely renovated 40
years ago.

The side walls are rendered, and the end walls are brick.

I have a problem with the rendering on one corner in that the fillet
between the rendering and the brickwork has come away. See:

http://i36.tinypic.com/n5pqps.jpg and

http://i33.tinypic.com/23vj96q.jpg

My friendly neighbourhood jobbing builder pointed the crack with lime
mortar, but it pretty much all fell out over the winter.

The rendering is about an inch thick, and the piece adjacent to the
crack does sound hollow on tapping, but in spite of that seems quite
stable and unlikely to fall down for a while yet - I can't get any
movement when I try and pull it away from the wall. On the other
hand, I can't help wondering if it is imperceptible movement that
meant the lime mortat fell off, or if it was a bodged up job!

How would you tackle this? I presume lime mortar is the right thing
to use - if so, what proportions? I know PVA is used in these
situations - does one it paint onto the rendering/brickwork. If so,
does one let it dry before applying the mortar, and/or does one mix it
in with the mortar? Presumably it is important to wet throughly
before applying mortar even if PVA has been applied. Should I try and
filll the crack with anything else before applying mortar, and if so,
what. Is there any other kind of mortar that is more flexible and
more likely to stay put?

Sorry for all the questions, but this is not (yet) an area of
expertise I have developed yet!

TIA

Keith
I reckon you will always get movement there and any form of rigid filler
lime or not, will fall out in time with seasonal movement. Maybe you
could inject a high modulus silicone in there and rub some sand into the
surface before it cures. With this as a key you might just get masonry
paint to stick to it and give a reasonable texture.

Bob

On Aug 14, 2:03*pm, Bob Minchin
wrote:
Keefiedee wrote:
We have an old timberframed house which was completely renovated 40
years ago.

The side walls are rendered, and the end walls are brick.

I have a problem with the rendering on one corner in that the fillet
between the rendering and the brickwork has come away. *See:

http://i36.tinypic.com/n5pqps.jpgand

http://i33.tinypic.com/23vj96q.jpg

My friendly neighbourhood jobbing builder pointed the crack with lime
mortar, but it pretty much all fell out over the winter.

The rendering is about an inch thick, and the piece adjacent to the
crack does sound hollow on tapping, but in spite of that seems quite
stable and unlikely to fall down for a while yet - I can't get any
movement when I try and pull it away from the wall. *On the other
hand, I can't help wondering if it is imperceptible movement that
meant the lime mortat fell off, or if it was a bodged up job!

How would you tackle this? *I presume lime mortar is the right thing
to use - if so, what proportions? *I know PVA is used in these
situations - does one it paint onto the rendering/brickwork. *If so,
does one let it dry before applying the mortar, and/or does one mix it
in with the mortar? *Presumably it is important to wet throughly
before applying mortar even if PVA has been applied. *Should I try and
filll the crack with anything else before applying mortar, and if so,
what. *Is there any other kind of mortar that is more flexible and
more likely to stay put?

Sorry for all the questions, but this is not (yet) an area of
expertise I have developed yet!

TIA

Keith

I reckon you will always get movement there and any form of rigid filler
lime or not, will fall out in time with seasonal movement. Maybe you
could inject a high modulus silicone in there and rub some sand into the
surface before it cures. With this as a key you might just get masonry
paint to stick to it and give a reasonable texture.

Bob

"High modulus silicone" - such as? Link please if possible.

It is not just a question of filling though - there is a need to
create a smooth rounded end to the rendering where it meets the
brickwork - you will see from the photos that the rendering hasn't
come away at the edge all the way down - at the top the is just a
crack between the rendering and the brickwork, while lower down the
whole edge of the rendering has come away.

Keith

On 14 Aug, 13:46, Keefiedee wrote:
We have an old timberframed house which was completely renovated 40
years ago.

The side walls are rendered, and the end walls are brick.

I have a problem with the rendering on one corner in that the fillet
between the rendering and the brickwork has come away. See:

http://i36.tinypic.com/n5pqps.jpgand

http://i33.tinypic.com/23vj96q.jpg

My friendly neighbourhood jobbing builder pointed the crack with lime
mortar, but it pretty much all fell out over the winter.

The rendering is about an inch thick, and the piece adjacent to the
crack does sound hollow on tapping, but in spite of that seems quite
stable and unlikely to fall down for a while yet - I can't get any
movement when I try and pull it away from the wall. On the other
hand, I can't help wondering if it is imperceptible movement that
meant the lime mortat fell off, or if it was a bodged up job!

How would you tackle this? I presume lime mortar is the right thing
to use - if so, what proportions? I know PVA is used in these
situations - does one it paint onto the rendering/brickwork. If so,
does one let it dry before applying the mortar, and/or does one mix it
in with the mortar? Presumably it is important to wet throughly
before applying mortar even if PVA has been applied. Should I try and
filll the crack with anything else before applying mortar, and if so,
what. Is there any other kind of mortar that is more flexible and
more likely to stay put?

Sorry for all the questions, but this is not (yet) an area of
expertise I have developed yet!

TIA

Keith

I'd look at trying to make a "movement joint" here so that it can move
without cracking and falling out. ISTR polysulphide sealants used in
these circumstances?? you'd need to tidy the render edge and leave a
gap say 10/15mm into which you squirt the sealant which then (when set
etc) stretches to accomodate the (hopefully seasonal) movement that
there appears to be going on in the wall..

Cheers
Jim K

On 14 Aug, 14:36, Keefiedee wrote:
On Aug 14, 2:03 pm, Bob Minchin



wrote:
Keefiedee wrote:
We have an old timberframed house which was completely renovated 40
years ago.

The side walls are rendered, and the end walls are brick.

I have a problem with the rendering on one corner in that the fillet
between the rendering and the brickwork has come away. See:

http://i36.tinypic.com/n5pqps.jpgand

http://i33.tinypic.com/23vj96q.jpg

My friendly neighbourhood jobbing builder pointed the crack with lime
mortar, but it pretty much all fell out over the winter.

The rendering is about an inch thick, and the piece adjacent to the
crack does sound hollow on tapping, but in spite of that seems quite
stable and unlikely to fall down for a while yet - I can't get any
movement when I try and pull it away from the wall. On the other
hand, I can't help wondering if it is imperceptible movement that
meant the lime mortat fell off, or if it was a bodged up job!

How would you tackle this? I presume lime mortar is the right thing
to use - if so, what proportions? I know PVA is used in these
situations - does one it paint onto the rendering/brickwork. If so,
does one let it dry before applying the mortar, and/or does one mix it
in with the mortar? Presumably it is important to wet throughly
before applying mortar even if PVA has been applied. Should I try and
filll the crack with anything else before applying mortar, and if so,
what. Is there any other kind of mortar that is more flexible and
more likely to stay put?

Sorry for all the questions, but this is not (yet) an area of
expertise I have developed yet!

TIA

Keith

I reckon you will always get movement there and any form of rigid filler
lime or not, will fall out in time with seasonal movement. Maybe you
could inject a high modulus silicone in there and rub some sand into the
surface before it cures. With this as a key you might just get masonry
paint to stick to it and give a reasonable texture.

Bob

"High modulus silicone" - such as? Link please if possible.

go to google.co.uk

put the words in the box, click the search button - simples....

Jim K

Yes - I can see a "movement joint" is exactly what is required.

Any tips on how to create that? My immediate thought is to fix a thin
(5 to 10 mm) piece of wood to the brickwork and then build the render
up onto that. But how to stop the render sticking to it so it can be
removed to leave the required gap?

Is "high modulus sealant" the same as "ISTR polysulphide sealant"?
Found the former on google, but not much of a result with the latter!

Keith

On Aug 14, 4:10*pm, Keefiedee wrote:
Yes - I can see a "movement joint" is exactly what is required.

Any tips on how to create that? *My immediate thought is to fix a thin
(5 to 10 mm) piece of wood to the brickwork and then build the render
up onto that. *But how to stop the render sticking to it so it can be
removed to leave the required gap?

Is "high modulus sealant" the same as "ISTR polysulphide sealant"?
Found the former on google, but not much of a result with the latter!

Keith

Actually, on looking at it again, the gap is not that thick at all.

What I think I might just need to do is to angle grind the render that
has come away to a straight line, then put some sort of tape on the
brickwork to stop the render sticking to it, replace the render over
the tape without getting it on the brickwork, and when all complete
fill the edge between render and brickwork with hign modulus sealant.
Would gaffer tape do? Would it actually matter if the render actually
stuck to the tape - presumably gaffer tape would accommodate a small
amount of movement?

Further thoughts please - does this make sense to those with more
experience than myself?.

Keith

On 14 Aug, 16:10, Keefiedee wrote:
Yes - I can see a "movement joint" is exactly what is required.

Any tips on how to create that? My immediate thought is to fix a thin
(5 to 10 mm) piece of wood to the brickwork and then build the render
up onto that. But how to stop the render sticking to it so it can be
removed to leave the required gap?

Is "high modulus sealant" the same as "ISTR polysulphide sealant"?
Found the former on google, but not much of a result with the latter!

Keith

the ISTR is "I seem to recall" so just put the other 2 words in and
voila....

Jim K

On Sat, 14 Aug 2010 05:46:14 -0700 (PDT), Keefiedee wrote:

How would you tackle this?

Trim back all the fillet, carefully as you say the render is blown.
It will fall off at some point, hit it a bit hard and it might fall
of now...

Then repoint with a fairly strong cement mix, 4:1 sand:cement. Might
be tempeted to use some sharp sand in the mix (1:1 sharp:building or
1:2 sharp:building) to give a bit of texture by brushing the surface
with water when almost set.

Lime mortar is "flexable" but not like a silicone is "flexable". Lime
mortarstill cracks but then self heals. I wouldn't use a silicone
sealant for the job.

--
Cheers
Dave.

Sorry, I meant how do I go about creating a movement joint?

Keith

On 15 Aug, 17:07, Keefiedee wrote:
Sorry, I meant how do I go about creating a movement joint?

Keith

http://www.google.co.uk/search?q=how...movement+joint

(can you see the evolving self-help based pattern here?;)

Jim K

On Aug 15, 5:32*pm, Jim K wrote:
On 15 Aug, 17:07, Keefiedee wrote:

Sorry, I meant how do I go about creating a movement joint?

Keith

http://www.google.co.uk/search?q=how...movement+joint

Jim, have you actually done the search you suggest? All I can find is
advice about movement, or expansion, joints in paving etc., i.e in a
horizontal surface, which is quite different to the difficulty I have
here which is trying to create a vertical rendering edge that cannot
be allowed to adhere to the underlying brickwork because of movement,
yet needs to be watertight. It was your very helpful suggestion that
I need to create a Wmovement jointW - but in my inexperience I do not
know how to create an edge to the render in thin air, as it were, and
keep it from adhering to the brickwork underneath. I was wondering
whether I needed to build up the render edge using ? expanded metal
lath ? with gaffer tape on the back to stop the mortar adhering, but I
felt that seems a bit Heath-Robinson-ish and assumed there might be a
better way which someone might be able to suggest.

(can you see the evolving self-help based pattern here?;)

I'm not sure I appreciate this rather patronising comment. I, perhaps
mistakenly, thought this newsgroup was a place where the experienced
were happy to help and guide the inexperienced. It has certainly been
very helpful for me in answering questions in the past that I could
perhaps have googled, but googling doesn't allow one to find someone
who has had a similar problem and found a good way of dealing with it.

Keith

On Aug 15, 5:32*pm, Jim K wrote:
On 15 Aug, 17:07, Keefiedee wrote:

Sorry, I meant how do I go about creating a movement joint?

Keith

http://www.google.co.uk/search?q=how...movement+joint

Jim, have you actually done the search you suggest? All I can find is
advice about movement, or expansion, joints in paving etc., i.e in a
horizontal surface, which is quite different to the difficulty I have
here which is trying to create a vertical rendering edge that cannot
be allowed to adhere to the underlying brickwork because of movement,
yet needs to be watertight. It was your very helpful suggestion that
I need to create a Wmovement jointW - but in my inexperience I do not
know how to create an edge to the render in thin air, as it were, and
keep it from adhering to the brickwork underneath. I was wondering
whether I needed to build up the render edge using ? expanded metal
lath ? with gaffer tape on the back to stop the mortar adhering, but I
felt that seems a bit Heath-Robinson-ish and assumed there might be a
better way which someone might be able to suggest.

(can you see the evolving self-help based pattern here?;)

I'm not sure I appreciate this rather patronising comment. I, perhaps
mistakenly, thought this newsgroup was a place where the experienced
were happy to help and guide the inexperienced. It has certainly been
very helpful for me in answering questions in the past that I could
perhaps have googled, but googling doesn't allow one to find someone
who has had a similar problem and found a good way of dealing with it.

Keith

On Aug 15, 5:32*pm, Jim K wrote:
On 15 Aug, 17:07, Keefiedee wrote:

Sorry, I meant how do I go about creating a movement joint?

Keith

http://www.google.co.uk/search?q=how...movement+joint

Jim, have you actually done the search you suggest? All I can find is
advice about movement, or expansion, joints in paving etc., i.e in a
horizontal surface, which is quite different to the difficulty I have
here which is trying to create a vertical rendering edge that cannot
be allowed to adhere to the underlying brickwork because of movement,
yet needs to be watertight. It was your very helpful suggestion that
I need to create a Wmovement jointW - but in my inexperience I do not
know how to create an edge to the render in thin air, as it were, and
keep it from adhering to the brickwork underneath. I was wondering
whether I needed to build up the render edge using ? expanded metal
lath ? with gaffer tape on the back to stop the mortar adhering, but I
felt that seems a bit Heath-Robinson-ish and assumed there might be a
better way which someone might be able to suggest.

(can you see the evolving self-help based pattern here?;)

I'm not sure I appreciate this rather patronising comment. I, perhaps
mistakenly, thought this newsgroup was a place where the experienced
were happy to help and guide the inexperienced. It has certainly been
very helpful for me in answering questions in the past that I could
perhaps have googled, but googling doesn't allow one to find someone
who has had a similar problem and found a good way of dealing with it.

Keith

On Aug 15, 8:55 pm, Keefiedee wrote:
On Aug 15, 5:32 pm, Jim K wrote:

Jim, have you actually done the search you suggest? All I can find is
advice about movement, or expansion, joints in paving etc., i.e in a
horizontal surface,

snip

first page of results 9th link down....your call

(can you see the evolving self-help based pattern here?;)

I'm not sure I appreciate this rather patronising comment.

??so??

I, perhaps
mistakenly, thought this newsgroup was a place where the experienced
were happy to help and guide the inexperienced. It has certainly been
very helpful for me in answering questions in the past that I could
perhaps have googled, but googling doesn't allow one to find someone
who has had a similar problem and found a good way of dealing with it.

Speaking for myself I am more than happy to contribute to person(s)
quests for information if I beleive I have thoughts/experience that
*may* be of use.
However what is rather soul-destroying is occasional posters who
appear (as you appear) to be unwilling to actually put *some of their
own* time and effort into helping themselves, rather than just sitting
back expecting an *instant solution* to drop in their lap - gratis.

You request help and guidance - and that is what I have offered along
with a mechanism for gleaning information *yourself*. If after
investigating for *yourself* there are still mysteries - posting back
here, I am sure, wll bring positive responses along with discussions
as necessary.

"You get out what you put in" is an adage that summarises this
resource in my mind - YMMV...

Jim K

On 15/08/2010 20:55, Keefiedee wrote:
On Aug 15, 5:32 pm, Jim wrote:
On 15 Aug, 17:07, wrote:

Sorry, I meant how do I go about creating a movement joint?

Keith

http://www.google.co.uk/search?q=how...movement+joint

Jim, have you actually done the search you suggest? All I can find is
advice about movement, or expansion, joints in paving etc., i.e in a
horizontal surface, which is quite different to the difficulty I have
here which is trying to create a vertical rendering edge that cannot
be allowed to adhere to the underlying brickwork because of movement,
yet needs to be watertight. It was your very helpful suggestion that
I need to create a Wmovement jointW - but in my inexperience I do not
know how to create an edge to the render in thin air, as it were, and
keep it from adhering to the brickwork underneath. I was wondering
whether I needed to build up the render edge using ? expanded metal
lath ? with gaffer tape on the back to stop the mortar adhering, but I
felt that seems a bit Heath-Robinson-ish and assumed there might be a
better way which someone might be able to suggest.

(can you see the evolving self-help based pattern here?;)

I'm not sure I appreciate this rather patronising comment. I, perhaps
mistakenly, thought this newsgroup was a place where the experienced
were happy to help and guide the inexperienced. It has certainly been
very helpful for me in answering questions in the past that I could
perhaps have googled, but googling doesn't allow one to find someone
who has had a similar problem and found a good way of dealing with it.

Keith

I'd get myself a bag of B&Q gen purpose mortar. Mix that with a 4 water/
1 pva mixture to a stiff cake consistency, and fill the gap. It's
probably just the usual live render issue where it didn't stick to the
brickwork from day 1. This can result in a chicken and egg situation
where it's the water getting in that causes the movement, so you have to
think in terms of stopping it rather than accommodating it. FWIW I have
done this kind of thing several times. Don't make it more complicated
than it needs to be :-)