Hello All,

We are having difficulty laying flagstones evenly because these flagstones
are a natural, limestone product and the thickness varies by up to 3mm.
We are using a builder who is very good in many respects but, maybe, not an
expert in this area.

The flagstones are part of a heated/warmed floor, and they need to be laid
on flexible adhesive. Our builder knows about varying the amount of adhesive
to allow for variations in thickness. I feel that the height variation
should be within about 1 - 2 mm. Do you think that this is reasonable ?

We are using a wider grout, about 15mm. to make the height variation less
obvious.

Has anyone any views/experience on this ?

All comments welcome.

John N.

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John Nolan wrote:
Hello All,

We are having difficulty laying flagstones evenly because these
flagstones are a natural, limestone product and the thickness varies
by up to 3mm.
We are using a builder who is very good in many respects but, maybe,
not an expert in this area.

The flagstones are part of a heated/warmed floor, and they need to be
laid on flexible adhesive. Our builder knows about varying the amount
of adhesive to allow for variations in thickness. I feel that the
height variation should be within about 1 - 2 mm. Do you think that
this is reasonable ?

Not at all reasonable, even if the flags were exactly uniform.


We are using a wider grout, about 15mm. to make the height variation
less obvious.

Has anyone any views/experience on this ?

All comments welcome.

John N.

if the thicknesses vary by 3mm, it's impossible to get them to within 1 -
2mm.

What do you mean by 'flexible adhesive'? - are you using flags as floor
tiles? - if you are, and they are indeed natural stone, I would imagine that
they would look better naturally uneven than unnaturally perfectly flat.

--
Phil L
RSRL Tipster Of The Year 2008

"Phil L" wrote in message
. ..
John Nolan wrote:
Hello All,

We are having difficulty laying flagstones evenly because these
flagstones are a natural, limestone product and the thickness
varies
by up to 3mm.
We are using a builder who is very good in many respects but,
maybe,
not an expert in this area.

The flagstones are part of a heated/warmed floor, and they need to
be
laid on flexible adhesive. Our builder knows about varying the
amount
of adhesive to allow for variations in thickness. I feel that the
height variation should be within about 1 - 2 mm. Do you think
that
this is reasonable ?

Not at all reasonable, even if the flags were exactly uniform.


We are using a wider grout, about 15mm. to make the height
variation
less obvious.

Has anyone any views/experience on this ?

All comments welcome.

John N.

if the thicknesses vary by 3mm, it's impossible to get them to
within 1 -
2mm.

What do you mean by 'flexible adhesive'? - are you using flags as
floor
tiles? - if you are, and they are indeed natural stone, I would
imagine that
they would look better naturally uneven than unnaturally perfectly
flat.

--
Phil L
RSRL Tipster Of The Year 2008



Ah but they won't be able to push the tea trolley over them without
spilling the tea G

AWEM

On Mar 1, 5:43*pm, "Phil L" wrote:
John Nolan wrote:
Hello All,

We are having difficulty laying flagstones evenly because these
flagstones are a natural, limestone product and the thickness varies
by up to 3mm.
We are using a builder who is very good in many respects but, maybe,
not an expert in this area.

The flagstones are part of a heated/warmed floor, and they need to be
laid on flexible adhesive. Our builder knows about varying the amount
of adhesive to allow for variations in thickness. I feel that the
height variation should be within about 1 - 2 mm. Do you think that
this is reasonable ?

Not at all reasonable, even if the flags were exactly uniform.



We are using a wider grout, about 15mm. to make the height variation
less obvious.

Has anyone any views/experience on this ?

All comments welcome.

John N.

if the thicknesses vary by 3mm, it's impossible to get them to within 1 -
2mm.

Why? You just need more adhesive under the thinner ones.


What do you mean by 'flexible adhesive'? - are you using flags as floor
tiles? - if you are, and they are indeed natural stone, I would imagine that
they would look better naturally uneven than unnaturally perfectly flat.

It rather depends on the surface finish of the flags. If they go up
and down by 10mm (as the ones in our last house did), it doesn't make
sense to fuss about the height of one edge. If they are riven slate
and smooth to .1mm, it's rather a different story.

Martin Bonner wrote:
On Mar 1, 5:43 pm, "Phil L" wrote:
John Nolan wrote:
Hello All,

We are having difficulty laying flagstones evenly because these
flagstones are a natural, limestone product and the thickness varies
by up to 3mm.
We are using a builder who is very good in many respects but, maybe,
not an expert in this area.

The flagstones are part of a heated/warmed floor, and they need to
be laid on flexible adhesive. Our builder knows about varying the
amount of adhesive to allow for variations in thickness. I feel
that the height variation should be within about 1 - 2 mm. Do you
think that this is reasonable ?

Not at all reasonable, even if the flags were exactly uniform.



We are using a wider grout, about 15mm. to make the height variation
less obvious.

Has anyone any views/experience on this ?

All comments welcome.

John N.

if the thicknesses vary by 3mm, it's impossible to get them to
within 1 - 2mm.

Why? You just need more adhesive under the thinner ones.


I see, so if you lay ten flags and then find one that is thicker than all
those already down, how much adhesive do you put under it to get it lower?




--
Phil L
RSRL Tipster Of The Year 2008

Phil L wrote:

Martin Bonner wrote:
On Mar 1, 5:43 pm, "Phil L" wrote:

if the thicknesses vary by 3mm, it's impossible to get them to
within 1 - 2mm.

Why? You just need more adhesive under the thinner ones.

I see, so if you lay ten flags and then find one that is thicker than all
those already down, how much adhesive do you put under it to get it lower?

You dont. It is too late then.
You sort them out into the varying thicknesses before work starts, then
put the thickest ones down first, then, in theory, it is possible to get
them level.
If the OP's builder hasnt done that, or allowed a suitably thick bed of
cement to lay them, then they will never be level. If I was the OP, I'd
insist that they were taken up and got level.
Alan.
--
To reply by e-mail, change the ' + ' to 'plus'.

"John Nolan" wrote in message
.uk...
Hello All,

We are having difficulty laying flagstones evenly because these flagstones
are a natural, limestone product and the thickness varies by up to 3mm.
We are using a builder who is very good in many respects but, maybe, not
an
expert in this area.

The flagstones are part of a heated/warmed floor, and they need to be laid
on flexible adhesive. Our builder knows about varying the amount of
adhesive
to allow for variations in thickness. I feel that the height variation
should be within about 1 - 2 mm. Do you think that this is reasonable ?

We are using a wider grout, about 15mm. to make the height variation less
obvious.

Has anyone any views/experience on this ?

All comments welcome.

John N.

--

Get shut of the builder or have someone else fit the tiles. It is possible
to fit them perfectly level using what you describe.
You do not need to leave 15mm for a gap or have the floor uneven.

In article ,
John Nolan wrote:

[..]
The flagstones are part of a heated/warmed floor, and they need to be laid
on flexible adhesive. Our builder knows about varying the amount of adhesive
to allow for variations in thickness. I feel that the height variation
should be within about 1 - 2 mm. Do you think that this is reasonable ?

We are using a wider grout, about 15mm. to make the height variation less
obvious.

Has anyone any views/experience on this ?

All comments welcome.

I think that Dave Symes ..'Grumpy Dave'(?).. may have
some real knowledge in this area. He may be around in
the argonet groups somewhere, eg a.a.voyager or a.a.misc
- but he's also seems to be around a lot in zfc-chat..

You could try to raise him there as well, John. I'm
sure he would have some helpful comments.. )

Bill ZFC

--
Adoption InterLink UK with -=- http://www.billsimpson.com/
Domain Host Orpheus Internet -=- http://www.orpheusinternet.co.uk/

On Sun, 01 Mar 2009 17:27:43 GMT
John Nolan wrote:

Hello All,

We are having difficulty laying flagstones evenly because these flagstones
are a natural, limestone product and the thickness varies by up to 3mm.
We are using a builder who is very good in many respects but, maybe, not an
expert in this area.

The flagstones are part of a heated/warmed floor, and they need to be laid
on flexible adhesive. Our builder knows about varying the amount of adhesive
to allow for variations in thickness. I feel that the height variation
should be within about 1 - 2 mm. Do you think that this is reasonable ?

We are using a wider grout, about 15mm. to make the height variation less
obvious.

Has anyone any views/experience on this ?

All comments welcome.

John N.


I recently laid my own traverine floor. The stones arrived smooth on
one face (top) and varying in thickness only very little (+-1mm). I
too had to use a flexible adhesive, as they were going onto the screed
of a UFH.

The key is the flatness of the screed. It may look flat, but in fact
undulate over quite long distances. This means that tiles in the
bottom of the dips might be 3mm lower that those on the crests. I wish
that I had put down self-leveling, but I didn't. It meant that I had
to fill the dips with very expensive adhesive, and sometimes put in
little wooden pegs to stop the tiles sinking before the adhesive set.
It was quite fiddly.

In the end it isn't perfect (2mm in some places), but as my first
(last?) attempt I'm content. However if I had paid someone, I would
expect better than I managed.

R.

Hello Bill, Dave, Phil, Alan and TheOldFellow,
(from various NGs)

Many thanks for your responses. Sorry I didn't say it before.

I was given a tip that someone, with potentially useful information, might
lurking on some other NGs as above. if you are coming in on this thread, for
the first time, and want to know what has gone on before, I can fill you in
Yes, I did have some DIY feedback. But, basically, it didn't add to what we
knew already.

I hope that I'm not breaking any netiquette rules by writing a piece, for
anyone that is interested, that brings together my own experiences, for what
they are worth, and those of other contributors.

Basically, you have to find the thickest flag, lay that, and then build up
the adhesive under thinner ones, to get the same level.

That might seem obvious. But it is not so easy to do when the sticky labels
with the thickness measurement keep coming off and you are laying a special
pattern of flags of different sizes. The thickest flag may not be the first
to be laid !!

If, as we have, your flags are different sizes in plan, as well as
thickness, then it is a bit more complicated. I would suggest that the
pattern is laid out, sufficient to include the thickest flagstone. If, from
experience, you know how thin the thinnest layer of adhesive can be, then
you put spacers under the thickest flagstone to mimick the thickness (or
thinness) of that layer of adhesive. You then lay the thinner
flagstones level with that thickest one. Then, when its turn comes take
up the thickest one and lay it properly.

This all may seem obvious, when I've explained it, but wisdom in hindsite is
a wonderful thing !

TheOldFellow - uk.d-i-y - said he used little wooden pegs to stop the tiles
sinking before the adhesive set. Yes, I had thought the same sort of thing.
If I had been laying them myself, I might have used small pieces of
slate of different thincknesses for the spacers. Of which we have an
abundance.

We didn't have the problems of a slightly undulating screed surface.
If the wavelength of undulations were sufficiently long horizontally and
sufficiently small vertically, I would not have thought it would matter.
As for difference in height of adjacent flags, I have felt an error of up
to 2 mm. was reasonable. Our builder suggested a wider grout, about 15 mm.
to "mask" this. But, with different sizes of flags, this brings other
problems of different grout widths - see below - unless you cut each flag to
suit !!

So, we are on a learning curve, but are getting there. We have lost some
flags in the process :-( There are other costs, like thicker layers of
adhesive being needed. We averaged 3 sq.m. per 20 kg. bag, when we were
advised that the spread should be 5 - 6 sq.m. per 20 kg. bag.

Another cost is the amount of grout required and flag cutting. Most of the
flags, except the smallest, have been cut to fit assuming zero grout
thickness. With different flag sizes this causes problems. It is impossible
to get a constant grout width without cutting every flag. This takes
considerably longer. So there are extra time costs, as well. For us, it
is probably a "one-off", in a lifetime. We have about 200 - 250
flagstones to lay to get half way !


Our flags have nominal sizes in mm of 300 x 300, 600 x 300, 600 x 600 and
600 x 900. Obviously, these last, being much heavier, were much more
difficult and also much more expensive if you get it wrong.

Finally, because we wanted coloured grout - brown - we have had to go to a
company called Mapei as Bal seem not to make it anymore. We were warned by
the Mapei suppliers that we should use white adhesive as the colour of
ordinary grey could come through our slightly porous marble flags. Our
builder, who normally uses Evostik cement based, polymer modified adhesive
was sure that this would not happen with our flags, particularly as they are
about 23 mm. thick. But, doubt having been sown in our minds, we felt we had
no choice but not to take the risk. After all, we do not have the choice to
get it wrong. The Mapei adhesive is much more expensive.

No one seems to be quite sure about this point of discoloration. Some felt
it could happen with thin travertine, others felt the problem was sometimes
translucency. I even managed to extract an informal and free opinion from
the Building Research Establishment. They felt that it could happen !!

For both adhesive and grout for UFH, you need flexible material. We are
using Mapei Kerqquick white with liquied Latex Plus, for the adhesive
and Ultracolour grout.

John N.


--
From Glorious Gloucestershire, near Lydney, using :------------
_ _________________________________________
/ \._._ |_ _ _ /' Orpheus Internet Services
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Traditionally they were laid on soft sand, which has enough clay in it
to set stiffish. Or very weak dry mortar i.e.sand plus a bit of lime.
Quite easy then to get them perfectly flat. Wet mortar no good as it
moves about, or they sink, etc.