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  #1   Report Post  
Andy Hall
 
Posts: n/a
Default How soon can I tile a new concrete floor?

On 17 Aug 2003 04:05:15 -0700, (Jon Weaver)
wrote:

My conservatory gets finished this week, and I wanted to lay some
floor tiles ASAP.

I was under the impression that I could do this straight away, but I
have just read the 'Topps Tiles' brochure which says that a new
concrete floor should be left 6 weeks.

However, its not quite as black and white as that as the base of the
conservatory is a 'raft', so the floor (Slab) was laid at the same
time as the footings.

This part was finished exactly one month ago today and considering the
heat that we have had over the past few weeks, I would guess that its
dry by now.

Once the plastic has gone on, the builder is coming back to lay approx
80mm of screed onto of the concrete that he laid a month ago.

How quickly can I lay ceramic tiles onto this 'screed' layer? I would
understand leaving it for a few weeks if laying laminate, but didn't
think that tiles would be a problem.


I had a very similar scenario of timescales and was told to leave the
screed for 3 weeks before laying tiles. This was done and it has
been fine.


I was hoping to start as soon as next weekend but should I wait a
while?


Yes. One thing that you may well find useful is to wash over the
floor with a 1:5 solution of PVA adhesive to water. This will
provide a light seal and stop the release of dust.


If I need to wait, is there anything that I can do to speed up the
'drying' process (i.e a de-humidifier)?


It isn't a drying issue, but a chemical curing one. The screed
should be allowed to do that naturally.



If I should wait, but choose not too. What are the implications of
this?


The tiles may well lift.

You should wait......



..andy

To email, substitute .nospam with .gl
  #2   Report Post  
Christian McArdle
 
Posts: n/a
Default How soon can I tile a new concrete floor?

Once the plastic has gone on, the builder is coming back to lay approx
80mm of screed onto of the concrete that he laid a month ago.


Is there any insulation in this floor? There should be large chunks of
Jablite or similar going down, as well as the plastic sheet (DPM). Although
not compulsory in many conservatories, it should still be done for your own
comfort.

If I need to wait, is there anything that I can do to speed up the
'drying' process (i.e a de-humidifier)?



Concrete doesn't "dry". It sets. It actually needs water to set properly.
Removing the water by overdrying will actually slow down the setting process
(sometimes so much that it never completes) and damage the floor.

Basically, you should wait the recommended time scales. How does the phrase
go? Bodge in haste, repent as leisure. Or something like that. ;-)

Your floor will take much longer to complete if you disturb it too soon,
cause gaping cracks and need the whole lot ripping up again.

Christian.


  #3   Report Post  
Jon Weaver
 
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Default How soon can I tile a new concrete floor?

"Christian McArdle" wrote in message .net...
Once the plastic has gone on, the builder is coming back to lay approx
80mm of screed onto of the concrete that he laid a month ago.


Is there any insulation in this floor? There should be large chunks of
Jablite or similar going down, as well as the plastic sheet (DPM). Although
not compulsory in many conservatories, it should still be done for your own
comfort.


There is going to be a DPM, but I must admit, I don't think that the
builder will be putting any insulation down! How thick would a layer
of Jablite be? Its not too late for me to get some myself and insist
on it being put under the screed.

Where would the insulation layer go, ontop, or under the DPM?



Basically, you should wait the recommended time scales. How does the phrase
go? Bodge in haste, repent as leisure. Or something like that. ;-)


I think that you are right.. However, I spoke to the 'tiler' who lives
opposite, and he said "nahh.. I have been tiling for 20 years and I
always lay straight onto the concrete.. As long as you give it a few
days to set, you will be fine".. This is the same attitude as my
builder who is doing the floor work for me. However, this is directly
against the advice that I seem to be getting from EVERYONE, including
the supplier of my tiles and manufacturer of the 'adhesive' (Dunlop)
who quotes 6 weeks for concrete and 3 weeks for screed!

Its amazing what 'tradesmen' get up to, and people questioned why I
wanted to keep an eye on my builder, to make sure he did things
correctly!

As always, a huge thanks for your advice

Jon
  #4   Report Post  
Christian McArdle
 
Posts: n/a
Default How soon can I tile a new concrete floor?

Where would the insulation layer go, ontop, or under the DPM?

AIUI, on top of the DPM. Someone more knowledgable than me will suggest the
exact ordering and thicknesses. However, I suspect 50mm of Jablite would
make a real difference, and 30mm of screed might work on top to make the
original thickness.

Christian.


  #5   Report Post  
The Natural Philosopher
 
Posts: n/a
Default How soon can I tile a new concrete floor?

Christian McArdle wrote:

Where would the insulation layer go, ontop, or under the DPM?


AIUI, on top of the DPM. Someone more knowledgable than me will suggest the
exact ordering and thicknesses. However, I suspect 50mm of Jablite would
make a real difference, and 30mm of screed might work on top to make the
original thickness.

Christian.




Actually it makes sod all difference where the DPM goes. Above or below
the insulation. I asked teh architecet, and he just shrugged.

I put mine ABOVE for the imple practical reason that it wouldnt get
puntured on teh rather rough surface underneath - the insulation is very
good as covering sharp lumps

50mm blue/pink foam is excellent. 75mm is even better. At LEAST 75mm
screed, and more if you can fit it in.




  #6   Report Post  
Jon Weaver
 
Posts: n/a
Default How soon can I tile a new concrete floor?

The Natural Philosopher wrote in message ...
Christian McArdle wrote:

Where would the insulation layer go, ontop, or under the DPM?


AIUI, on top of the DPM. Someone more knowledgable than me will suggest the
exact ordering and thicknesses. However, I suspect 50mm of Jablite would
make a real difference, and 30mm of screed might work on top to make the
original thickness.

Christian.




Actually it makes sod all difference where the DPM goes. Above or below
the insulation. I asked teh architecet, and he just shrugged.

I put mine ABOVE for the imple practical reason that it wouldnt get
puntured on teh rather rough surface underneath - the insulation is very
good as covering sharp lumps

50mm blue/pink foam is excellent. 75mm is even better. At LEAST 75mm
screed, and more if you can fit it in.


My problem is that the current 'slab' height means that it will be
impossible to raise the floor by any more than 100mm.. So, If I have
to add 50mm of insulation and 75mm of screed, the only physically way
possible would be to lower the slab by 25mm, and as you will imagine,
this impossible.

A colleague of mine (who is building his own house) has suggested that
I go for 50mm of insulation and 50mm of screed, but use a steel mesh
to re-enforce the screed.

My other option of course is to forget ever having asked the question,
and go along with the plan WITHOUT insulation.

If I can get away with 50mm of each and a steel mesh, I might be
tempted to get the bits that I need and ask the builder to do this
when he lays the screed at the weekend.
  #7   Report Post  
Christian McArdle
 
Posts: n/a
Default How soon can I tile a new concrete floor?

My problem is that the current 'slab' height means that it will
be impossible to raise the floor by any more than 100mm.. So,
If I have to add 50mm of insulation and 75mm of screed, the only
physically way possible would be to lower the slab by 25mm, and
as you will imagine, this impossible.


Well, 25mm of insulation would be infinitely better than none. That would
allow 75mm of screed.

Christian.


  #8   Report Post  
The Natural Philosopher
 
Posts: n/a
Default How soon can I tile a new concrete floor?

Jon Weaver wrote:

The Natural Philosopher wrote in message ...

Christian McArdle wrote:


Where would the insulation layer go, ontop, or under the DPM?


AIUI, on top of the DPM. Someone more knowledgable than me will suggest the
exact ordering and thicknesses. However, I suspect 50mm of Jablite would
make a real difference, and 30mm of screed might work on top to make the
original thickness.

Christian.




Actually it makes sod all difference where the DPM goes. Above or below
the insulation. I asked teh architecet, and he just shrugged.

I put mine ABOVE for the imple practical reason that it wouldnt get
puntured on teh rather rough surface underneath - the insulation is very
good as covering sharp lumps

50mm blue/pink foam is excellent. 75mm is even better. At LEAST 75mm
screed, and more if you can fit it in.


My problem is that the current 'slab' height means that it will be
impossible to raise the floor by any more than 100mm.. So, If I have
to add 50mm of insulation and 75mm of screed, the only physically way
possible would be to lower the slab by 25mm, and as you will imagine,
this impossible.

A colleague of mine (who is building his own house) has suggested that
I go for 50mm of insulation and 50mm of screed, but use a steel mesh
to re-enforce the screed.



Mmm. Actually for reason I'll explain, I'd use chicken wire.

The problem with thin scred over insulation, is that heavy pinted object
- chair leg etc - over a small area could compress the insulation and
crack teh screed. So you want a lot of local reniforcement rather than
overall reinforcement. Chicken wire or the sort of mesh that used to
render over on walls etc would I think be better able to do this.

Try and use the insulation if you can. If you slate or laminate the
floor afterwards that will also help load spereading.





My other option of course is to forget ever having asked the question,
and go along with the plan WITHOUT insulation.

If I can get away with 50mm of each and a steel mesh, I might be
tempted to get the bits that I need and ask the builder to do this
when he lays the screed at the weekend.



  #9   Report Post  
Jon Weaver
 
Posts: n/a
Default How soon can I tile a new concrete floor?

The Natural Philosopher wrote in message ...
Jon Weaver wrote:

Where would the insulation layer go, ontop, or under the DPM?


AIUI, on top of the DPM. Someone more knowledgable than me will suggest the
exact ordering and thicknesses. However, I suspect 50mm of Jablite would
make a real difference, and 30mm of screed might work on top to make the
original thickness.

Christian.




Actually it makes sod all difference where the DPM goes. Above or below
the insulation. I asked teh architecet, and he just shrugged.

I put mine ABOVE for the imple practical reason that it wouldnt get
puntured on teh rather rough surface underneath - the insulation is very
good as covering sharp lumps

50mm blue/pink foam is excellent. 75mm is even better. At LEAST 75mm
screed, and more if you can fit it in.


This whole issue of insulation re-opens a can of worms already
discussed in the following thread:

http://groups.google.com/groups?hl=e...ogle.com#link1

Basically, the problem here was that I was planning to install my ring
main into the cavity, which contained insulation.

It seems that 2.5mm cable surrounded by insulation is not able to
carry the current required for a 32A ring main.

The solution to this was to simply no add the insulation into the
cavity.

However, in order to get the cable from the cavity, to a suitable
point behind a socket to gain access to the existing ring, I have run
the cables under the dwarf wall and along the slab for around 8-10".
This is protected by some metal capping and I intended to lay the DPC
and screed directly on top.

However, if I am now going to be adding some insulation, then I will
be back to square one, as the Electrical regs state that an 2.5mm
cable surrounded in insluation is not suitable for a 32A ring main.

I can't seem to win here!.

Can anyone comment on this? Bearing in mind that the lengh of the
inslated cable is less than 10", is it really a concern? I guess that
a consideration is that the insluation won't be 'surrounding' the
cable, instead it will simply be on top... A crude cross section of
the installation is as follows:

----------------
Ceramic Tiles
----------------
Adhesive
----------------

Screed

----------------

Insulation

----------------
++++++++++++++++ DPC
~~~~~~~~~~~~~~~~ Metal Capping
================ 2.5mm Cables (Layed side by side)
----------------


Concrete


----------------


Why not lay them in the screed then?


Good point.. I suppose I could, however, I have already installed the
metal capping.. It would mean ripping it all up and messinging about
with it, whilst the builder is trying to work.

Thinking about it, I don't think that it would do any harm, to leave
the cable un-covered.. The area in question would only be 100x400mm
and I don't really think that this would affect the efficiency of the
insulation.
  #10   Report Post  
Martin Angove
 
Posts: n/a
Default How soon can I tile a new concrete floor?

In message ,
The Natural Philosopher wrote:

Jon Weaver wrote:



Can anyone comment on this? Bearing in mind that the lengh of the
inslated cable is less than 10", is it really a concern? I guess that
a consideration is that the insluation won't be 'surrounding' the
cable, instead it will simply be on top... A crude cross section of
the installation is as follows:

----------------
Ceramic Tiles
----------------
Adhesive
----------------

Screed

----------------

Insulation

----------------
++++++++++++++++ DPC
~~~~~~~~~~~~~~~~ Metal Capping
================ 2.5mm Cables (Layed side by side)
----------------


Concrete


----------------


Why not lay them in the screed then?


According to table 3A in the On Site Guide, PVC cable is "unsuitable for
embedding directly in concrete".

However, I will re-state my previous advice. In the situation described
above, 2.5mm cable *is* suitable for carrying the current of a 32A ring
main. It may be "covered" with insulation, but it is "in contact with a
[thermally] conductive surface on one side" (method 15) and is therefore
capable of carrying up to 21A (table 6F, OSG). There *may* be a grouping
issue, but I don't think so over this short distance with FTE.

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Don't fight technology, live with it: http://www.livtech.co.uk/
.... Visa, Visa, Viso - I shopped, I shopped, I ran out of cash.


  #11   Report Post  
The Natural Philosopher
 
Posts: n/a
Default How soon can I tile a new concrete floor?

Jon Weaver wrote:

"Christian McArdle" wrote in message .net...

My problem is that the current 'slab' height means that it will
be impossible to raise the floor by any more than 100mm.. So,
If I have to add 50mm of insulation and 75mm of screed, the only
physically way possible would be to lower the slab by 25mm, and
as you will imagine, this impossible.

Well, 25mm of insulation would be infinitely better than none. That would
allow 75mm of screed.

Christian.


Interesting.. I just spoke to my local(ish) supplier of insulation and
they can supply 40mm boards.. This will give me 60mm of screed, and if
I follow the next posters advise of using chicken wire as re-enforcing
material, its should give me a base which is still strong enough.

With regards to installation, is it as simple as cutting it to shape
and placing it on the floor (ontop of the DPC) before they lay the
screed? Should it go right upto the wall, or should I leave a gap??

I was surprised how much the insulation costs though (16+vat for
1.2x24m boards).. I will make some enquiries over the next few days.



Make sure you are gettng polystrne foam - blue or pink generally - not
Cleotex. That price sounds about right for a 5 pack of 4x2 shhets.

Just slap it down, and you may, if its a huge area, want to lay some up
the sides of the screed as well to allow for expansion, but it shouldn't
be necessary on normal installations.




Thanks for your advice, I will see what I can find before the builder
returns on Saturday.

Jon



  #12   Report Post  
Jon Weaver
 
Posts: n/a
Default How soon can I tile a new concrete floor?

Well, 25mm of insulation would be infinitely better than none. That would
allow 75mm of screed.

Christian.


Interesting.. I just spoke to my local(ish) supplier of insulation and
they can supply 40mm boards.. This will give me 60mm of screed, and if
I follow the next posters advise of using chicken wire as re-enforcing
material, its should give me a base which is still strong enough.

With regards to installation, is it as simple as cutting it to shape
and placing it on the floor (ontop of the DPC) before they lay the
screed? Should it go right upto the wall, or should I leave a gap??

I was surprised how much the insulation costs though (16+vat for
1.2x24m boards).. I will make some enquiries over the next few days.



Make sure you are gettng polystrne foam - blue or pink generally - not
Cleotex. That price sounds about right for a 5 pack of 4x2 shhets.

Just slap it down, and you may, if its a huge area, want to lay some up
the sides of the screed as well to allow for expansion, but it shouldn't
be necessary on normal installations.

What I was quoted for was 40mm 'Polyurathane'. They quoted me 16+vat
for a 1.2 x 2.4 Mtr sheet, which seemed excessive.

However, I am starting to think that this might be a bad idea.. One
thing which has bothered me from the start of this discussion is
strength.. A 50mm sand/cement screed ontop a soft (foam) base, doesn't
sound like it will have much local strength. I am worried that a few
months down the road, the screed could end up cracking, and it will
all be ruined.. Even if I added some re-enforcement in the screed, its
fact is that its on a soft, flexible foam base which worries me.

I guess that I should have got the insulation put it weeks ago, when
the slab was being laid, but its too late to worry about that now.

I am not sure how much difference the lack of insulation will make,
but for peace of mind, I am thinking that it might be better to have a
cold but solid floor then a slightly warmer, but weaker one!
  #13   Report Post  
Martin Angove
 
Posts: n/a
Default How soon can I tile a new concrete floor?

In message ,
(Jon Weaver) wrote:

Martin Angove wrote in message ...
In message ,
The Natural Philosopher wrote:

Jon Weaver wrote:



Can anyone comment on this? Bearing in mind that the lengh of the
inslated cable is less than 10", is it really a concern? I guess that
a consideration is that the insluation won't be 'surrounding' the
cable, instead it will simply be on top... A crude cross section of
the installation is as follows:

----------------
Ceramic Tiles
----------------
Adhesive
----------------

Screed

----------------

Insulation

----------------
++++++++++++++++ DPC
~~~~~~~~~~~~~~~~ Metal Capping
================ 2.5mm Cables (Layed side by side)
----------------


Concrete


----------------


Why not lay them in the screed then?


According to table 3A in the On Site Guide, PVC cable is "unsuitable for
embedding directly in concrete".


Oh no.. It never stops... However, I am not actually 'embedding
directly in concerete' though.. I have layed the cable on solid
concerete and put metal caping over the top to protect it. The capping
is nailed down and sealed with silicon for good measure.. Once the
screed is poured, it won't actually be in contact with the cable,
because the metal capping will form a 'channel' in the screed.. Its
not 100% watertight, so I guess, during the pour, some amount of
water/sand/cement will get under the capping, but the cable will not
end up 'encased' as such.

Do you think that this is a problem? If it is, its not to late to take
it up and bring it along the wall, instead of the floor.


Didn't realise you'd already decided not to lay it under the insulation
:-)

I'd say that what you describe sounds fair enough. Let us know in ten
years if it fails ;-)

Hwyl!

M.

--
Martin Angove:
http://www.tridwr.demon.co.uk/
Don't fight technology, live with it: http://www.livtech.co.uk/
.... Don't use a big word where a diminutive one will suffice.
  #14   Report Post  
Rick Hughes
 
Posts: n/a
Default How soon can I tile a new concrete floor?


"Jon Weaver" wrote in message
om...
"Christian McArdle" wrote in message

.net...
Once the plastic has gone on, the builder is coming back to lay approx
80mm of screed onto of the concrete that he laid a month ago.


Is there any insulation in this floor? There should be large chunks of
Jablite or similar going down, as well as the plastic sheet (DPM).

Although
not compulsory in many conservatories, it should still be done for your

own
comfort.


There is going to be a DPM, but I must admit, I don't think that the
builder will be putting any insulation down! How thick would a layer
of Jablite be? Its not too late for me to get some myself and insist
on it being put under the screed.

Where would the insulation layer go, ontop, or under the DPM?



Basically, you should wait the recommended time scales. How does the

phrase
go? Bodge in haste, repent as leisure. Or something like that. ;-)


I think that you are right.. However, I spoke to the 'tiler' who lives
opposite, and he said "nahh.. I have been tiling for 20 years and I
always lay straight onto the concrete.. As long as you give it a few
days to set, you will be fine".. This is the same attitude as my
builder who is doing the floor work for me. However, this is directly
against the advice that I seem to be getting from EVERYONE, including
the supplier of my tiles and manufacturer of the 'adhesive' (Dunlop)
who quotes 6 weeks for concrete and 3 weeks for screed!

Its amazing what 'tradesmen' get up to, and people questioned why I
wanted to keep an eye on my builder, to make sure he did things
correctly!

As always, a huge thanks for your advice

Jon



Jon,
first off you don't want it to dry straight away. Screed sets by
chemical reaction not by drying out ... screed can be walked on after 24Hrs
..... give it a soaking with a fine spray (or watering can) and cover with
plastic sheet.
Re-soak if it looks likes it's drying out .... keep doing this for first 3
days.

After which no more water .... then let it 'dry out' , it will take around a
week per 1" of thickness.

Your better half advises you are tiling on floor - then 3 weeks can be
shortened, to 2 weeks ... slight moisture will not be a problem, but would
be a big no-no if laying wooden flooring.

If it were me - I would still leave it 3 weeks.

Rick


  #15   Report Post  
Rick Hughes
 
Posts: n/a
Default How soon can I tile a new concrete floor?


"The Natural Philosopher" wrote in message
...
Jon Weaver wrote:

"Christian McArdle" wrote in message

.net...

My problem is that the current 'slab' height means that it will
be impossible to raise the floor by any more than 100mm.. So,
If I have to add 50mm of insulation and 75mm of screed, the only
physically way possible would be to lower the slab by 25mm, and
as you will imagine, this impossible.

Well, 25mm of insulation would be infinitely better than none. That

would
allow 75mm of screed.

Christian.


Interesting.. I just spoke to my local(ish) supplier of insulation and
they can supply 40mm boards.. This will give me 60mm of screed, and if
I follow the next posters advise of using chicken wire as re-enforcing
material, its should give me a base which is still strong enough.

With regards to installation, is it as simple as cutting it to shape
and placing it on the floor (ontop of the DPC) before they lay the
screed? Should it go right upto the wall, or should I leave a gap??

I was surprised how much the insulation costs though (16+vat for
1.2x24m boards).. I will make some enquiries over the next few days.



Make sure you are gettng polystrne foam - blue or pink generally - not
Cleotex. That price sounds about right for a 5 pack of 4x2 shhets.



Not correct ..... you want floor grade polyuretane not polystyrene ... it
has about twice the insulant value of polystyrene.

Jon has limited depth - and therfore to get max insulation with minium depth
he should most defionietly go for Poyurethane.

I buy mine from Seconds & Co. http://www.secondsandco.co.uk/

Recently bought 140 m2 of 50mm polyurethane ... and 124m2 of foil faced
100mm polyurethane. Most of what they supplied was Kingspan product.


Just slap it down, and you may, if its a huge area, want to lay some up
the sides of the screed as well to allow for expansion,


Vertical insulation is important if heating the floor - but if no floor
heating agree you can leave it out - and on your size slab it is not really
needed for expansion.


Rick




  #16   Report Post  
Rick Hughes
 
Posts: n/a
Default How soon can I tile a new concrete floor?

so I guess, during the pour, some amount of
water/sand/cement will get under the capping, but the cable will not
end up 'encased' as such.

Do you think that this is a problem? If it is, its not to late to take
it up and bring it along the wall, instead of the floor.




The screed will be laid semi-dry ... not a poured liquid, so leave it as you
have it.

Rick


  #17   Report Post  
The Natural Philosopher
 
Posts: n/a
Default How soon can I tile a new concrete floor?

Jon Weaver wrote:

Well, 25mm of insulation would be infinitely better than none. That would
allow 75mm of screed.

Christian.


Interesting.. I just spoke to my local(ish) supplier of insulation and
they can supply 40mm boards.. This will give me 60mm of screed, and if
I follow the next posters advise of using chicken wire as re-enforcing
material, its should give me a base which is still strong enough.

With regards to installation, is it as simple as cutting it to shape
and placing it on the floor (ontop of the DPC) before they lay the
screed? Should it go right upto the wall, or should I leave a gap??

I was surprised how much the insulation costs though (16+vat for
1.2x24m boards).. I will make some enquiries over the next few days.


Make sure you are gettng polystrne foam - blue or pink generally - not
Cleotex. That price sounds about right for a 5 pack of 4x2 shhets.

Just slap it down, and you may, if its a huge area, want to lay some up
the sides of the screed as well to allow for expansion, but it shouldn't
be necessary on normal installations.


What I was quoted for was 40mm 'Polyurathane'. They quoted me 16+vat
for a 1.2 x 2.4 Mtr sheet, which seemed excessive.



Sounds like they are trying to sell you polyisocyanurate - Celotex.

The best value for money for screeds is blue or pink polystyrene. Its
hugely more dnes than teh whites tuff and is rally very strong - won't
compress as long as you wire the screed.




However, I am starting to think that this might be a bad idea.. One
thing which has bothered me from the start of this discussion is
strength.. A 50mm sand/cement screed ontop a soft (foam) base, doesn't
sound like it will have much local strength. I am worried that a few
months down the road, the screed could end up cracking, and it will
all be ruined.. Even if I added some re-enforcement in the screed, its
fact is that its on a soft, flexible foam base which worries me.



It may well crack a little as it shrinks anyway. I poured gallons of
thinned PVA down my cracks and they all shrank and glueed themsleves
back togeher. It wasnpt the fom so much as inconsistent mixes in teh
screed and doing it a little at a time.



I guess that I should have got the insulation put it weeks ago, when
the slab was being laid, but its too late to worry about that now.

I am not sure how much difference the lack of insulation will make,
but for peace of mind, I am thinking that it might be better to have a
cold but solid floor then a slightly warmer, but weaker one!


Put in teh insulation. Its gione with 75mm screed, Hobenets.



  #18   Report Post  
Jon Weaver
 
Posts: n/a
Default How soon can I tile a new concrete floor?

Jon,
first off you don't want it to dry straight away. Screed sets by
chemical reaction not by drying out ... screed can be walked on after 24Hrs
.... give it a soaking with a fine spray (or watering can) and cover with
plastic sheet.
Re-soak if it looks likes it's drying out .... keep doing this for first 3
days.

After which no more water .... then let it 'dry out' , it will take around a
week per 1" of thickness.

Your better half advises you are tiling on floor - then 3 weeks can be
shortened, to 2 weeks ... slight moisture will not be a problem, but would
be a big no-no if laying wooden flooring.

If it were me - I would still leave it 3 weeks.


Cheers Rick.. I think I will be leaving it for a few weeks, but
probably won't have the patience for 3 weeks (or the capacity for a
daily ear bending from Helen )

I am glad that I can walk on it after 24 hours, as I have loads of
things I need to do (specifically the electrics) and want to get
started on SOMETHING. This whole project has takens 3 times longer
than I planned, mainly due to the planning permission that I found I
needed at the start. I am now just anxious to get busy on the things
that I can do. The builders have taken weeks to do things that should
have taken days. They were ment to be coming on Saturday to 'finish
off', but now its been postponed (again) to Monday.. But the end is in
sight and hopefully, this time next week, I will be able to get
going...

Thanks for the advice from everyone.. All the best

Jon
  #19   Report Post  
Jan Wysocki
 
Posts: n/a
Default How soon can I tile a new concrete floor?

Jon Weaver wrote:

My conservatory gets finished this week, and I wanted to lay some
floor tiles ASAP.

I was under the impression that I could do this straight away, but I
have just read the 'Topps Tiles' brochure which says that a new
concrete floor should be left 6 weeks.

[snip]

I'm jumping in a bit late, but here goes.
Topps' advice presumably applies if you use tile adhesive, but why are you
using tile adhesive? Mortar is a bit fiddly on vertical surfaces but is a
doddle on horizontal surfaces. If you tile with mortar, then a. you
want the
concrete to be damp and b. you should also soak the tiles in water
If the base concrete has been set a long time, you need to spray
it with PVA before tiling with mortar to get a satisfactory bond, but
you're actually about to get a new screed which would be ideal for
tiling after a day.

In theory you could just float mortar onto the floor and bed the tiles
in it*,
but the usual (traditional) advice is to 'butter' the individual tiles.
I guess that this minimises air bubbles under the tiles.

* Well that's not really any different to just bedding the tiles into the
fresh screed. Somebody on this ng must have tried that?

Pros: mortar is a LOT cheaper than 'tile adhesive'
Cons: you may need a jack hammer if you ever want to remove the tiles!

How quickly can I lay ceramic tiles onto this 'screed' layer? I would
understand leaving it for a few weeks if laying laminate, but didn't
think that tiles would be a problem.

I was hoping to start as soon as next weekend but should I wait a
while?

If I need to wait, is there anything that I can do to speed up the
'drying' process (i.e a de-humidifier)?

If I should wait, but choose not too. What are the implications of
this?

Any info would be appreciated

Jon

  #20   Report Post  
Mark Evans
 
Posts: n/a
Default How soon can I tile a new concrete floor?

Christian McArdle wrote:

Concrete doesn't "dry". It sets. It actually needs water to set properly.
Removing the water by overdrying will actually slow down the setting process
(sometimes so much that it never completes) and damage the floor.


Hence there are circumstances where it is advisable to "water" new
concrete. e.g. using a sprinkler on a concrete drive in hot weather.
(after it has initially set hard enough not to wash away of course.)

One early form of cement was known as "hydrolic lime" because it would
set underwater.
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