Hi folks I want to waterproof some cement at the base of a greenhouse
how would I go about this?
There was a small gap between slabs and the aluminium base of a
greenhouse I filled this gap with a 6:1 sand:cement mix now whenever it
rains hard a small pool of water forms at the base and this water seaps
through the S+C mix. I was thinking of painting it (the mortar), what
kind of paint/mastic is recommended and is it easy enough to apply? The
water used to lie for a while as I had "pointed" the gaps between the
slabs but have now drilled holes in this "pointing" (neatly, it doesn't
look as horrendous as it sounds) to allow water to drain away .
I fully realise that greenhouses are NOT wind and water tight
(although for most purposes...)but there is more influx than desirable
(although this influx is not major I would still like to stop it).

soup wrote:
Hi folks I want to waterproof some cement at the base of a greenhouse
how would I go about this?
There was a small gap between slabs and the aluminium base of a
greenhouse I filled this gap with a 6:1 sand:cement mix now whenever it
rains hard a small pool of water forms at the base and this water seaps
through the S+C mix. I was thinking of painting it (the mortar), what
kind of paint/mastic is recommended and is it easy enough to apply? The
water used to lie for a while as I had "pointed" the gaps between the
slabs but have now drilled holes in this "pointing" (neatly, it doesn't
look as horrendous as it sounds) to allow water to drain away .
I fully realise that greenhouses are NOT wind and water tight
(although for most purposes...)but there is more influx than desirable
(although this influx is not major I would still like to stop it).

Soak the mortar with PVA. This isn't water PROOF but its sufficiently
pore filling to pretty much stop the water soaking through..

The Natural Philosopher wrote:
soup wrote:
Hi folks I want to waterproof some cement at the base of a greenhouse
how would I go about this?
There was a small gap between slabs and the aluminium base of a
greenhouse I filled this gap with a 6:1 sand:cement mix now whenever
it rains hard a small pool of water forms at the base and this water
seaps through the S+C mix. I was thinking of painting it (the mortar),
what kind of paint/mastic is recommended and is it easy enough to
apply? The water used to lie for a while as I had "pointed" the gaps
between the slabs but have now drilled holes in this "pointing"
(neatly, it doesn't look as horrendous as it sounds) to allow water
to drain away .
I fully realise that greenhouses are NOT wind and water tight
(although for most purposes...)but there is more influx than desirable
(although this influx is not major I would still like to stop it).

Soak the mortar with PVA. This isn't water PROOF but its sufficiently
pore filling to pretty much stop the water soaking through..

Why not just use a proprietary cement waterproofer? I think this is
probably some kind of surfactant that packs the particles closer together

Stuart Noble wrote:
The Natural Philosopher wrote:
soup wrote:
Hi folks I want to waterproof some cement at the base of a greenhouse
how would I go about this?
There was a small gap between slabs and the aluminium base of a
greenhouse I filled this gap with a 6:1 sand:cement mix now whenever
it rains hard a small pool of water forms at the base and this water
seaps through the S+C mix. I was thinking of painting it (the
mortar), what kind of paint/mastic is recommended and is it easy
enough to apply? The water used to lie for a while as I had "pointed"
the gaps between the slabs but have now drilled holes in this
"pointing" (neatly, it doesn't look as horrendous as it sounds) to
allow water to drain away .
I fully realise that greenhouses are NOT wind and water tight
(although for most purposes...)but there is more influx than
desirable (although this influx is not major I would still like to
stop it).

Soak the mortar with PVA. This isn't water PROOF but its sufficiently
pore filling to pretty much stop the water soaking through..

Why not just use a proprietary cement waterproofer? I think this is
probably some kind of surfactant that packs the particles closer together
AKA 'PVA' :-)

On 12 Dec, 19:14, soup wrote:
Hi folks I want to waterproof some cement at the base of a greenhouse
how would I go about this?
There was a small gap between slabs and the aluminium base of a
greenhouse I filled this gap with a 6:1 sand:cement mix now whenever it
rains hard a small pool of water forms at the base and this water seaps
through the S+C mix. I was thinking of painting it (the mortar), what
kind of paint/mastic is recommended and is it easy enough to apply? The
water used to lie for a while as I had "pointed" the gaps between the
slabs but have now drilled holes in this "pointing" (neatly, it doesn't
look as horrendous as it sounds) to allow water to drain away .
I fully realise that greenhouses are NOT wind and water tight
(although for most purposes...)but there is more influx than desirable
(although this influx is not major I would still like to stop it).

Dear soup
Either rake out the mortar and fill it with the proper mix i.e. 3:1
sand: cement incorporating a pore blocker such as SIKA No 1 or a
hydrophobic chemical "waterproofer" such as the Feb or Cementone
brands ideally with SBR in mix and on surfaces
or
paint on what you have with SBR
PVA may well re-emuslify in an external environment
chris

On Thu, 13 Dec 2007 15:24:54 +0000, The Natural Philosopher
wrote:

... Stuart Noble wrote:
... The Natural Philosopher wrote:
... soup wrote:
... Hi folks I want to waterproof some cement at the base of a greenhouse
... how would I go about this?
... There was a small gap between slabs and the aluminium base of a
... greenhouse I filled this gap with a 6:1 sand:cement mix now whenever
... it rains hard a small pool of water forms at the base and this water
... seaps through the S+C mix. I was thinking of painting it (the
... mortar), what kind of paint/mastic is recommended and is it easy
... enough to apply? The water used to lie for a while as I had "pointed"
... the gaps between the slabs but have now drilled holes in this
... "pointing" (neatly, it doesn't look as horrendous as it sounds) to
... allow water to drain away .
... I fully realise that greenhouses are NOT wind and water tight
... (although for most purposes...)but there is more influx than
... desirable (although this influx is not major I would still like to
... stop it).
...
... Soak the mortar with PVA. This isn't water PROOF but its sufficiently
... pore filling to pretty much stop the water soaking through..
...
... Why not just use a proprietary cement waterproofer? I think this is
... probably some kind of surfactant that packs the particles closer together
... AKA 'PVA' :-)


But PVA can re-emulsify, can it not?
Therefore perhaps slowly but surly letting water back into the render.

Mike P

Mike P wrote:
On Thu, 13 Dec 2007 15:24:54 +0000, The Natural Philosopher
wrote:

.. Stuart Noble wrote:
.. The Natural Philosopher wrote:
.. soup wrote:
.. Hi folks I want to waterproof some cement at the base of a greenhouse
.. how would I go about this?
.. There was a small gap between slabs and the aluminium base of a
.. greenhouse I filled this gap with a 6:1 sand:cement mix now whenever
.. it rains hard a small pool of water forms at the base and this water
.. seaps through the S+C mix. I was thinking of painting it (the
.. mortar), what kind of paint/mastic is recommended and is it easy
.. enough to apply? The water used to lie for a while as I had "pointed"
.. the gaps between the slabs but have now drilled holes in this
.. "pointing" (neatly, it doesn't look as horrendous as it sounds) to
.. allow water to drain away .
.. I fully realise that greenhouses are NOT wind and water tight
.. (although for most purposes...)but there is more influx than
.. desirable (although this influx is not major I would still like to
.. stop it).
..
.. Soak the mortar with PVA. This isn't water PROOF but its sufficiently
.. pore filling to pretty much stop the water soaking through..
..
.. Why not just use a proprietary cement waterproofer? I think this is
.. probably some kind of surfactant that packs the particles closer together
.. AKA 'PVA' :-)


But PVA can re-emulsify, can it not?
Therefore perhaps slowly but surly letting water back into the render.


It does a bit, but it still occupies the pores..




Mike P

The Natural Philosopher wrote:
Stuart Noble wrote:
The Natural Philosopher wrote:
soup wrote:
Hi folks I want to waterproof some cement at the base of a
greenhouse how would I go about this?
There was a small gap between slabs and the aluminium base of a
greenhouse I filled this gap with a 6:1 sand:cement mix now whenever
it rains hard a small pool of water forms at the base and this
water seaps through the S+C mix. I was thinking of painting it (the
mortar), what kind of paint/mastic is recommended and is it easy
enough to apply? The water used to lie for a while as I had
"pointed" the gaps between the slabs but have now drilled holes in
this "pointing" (neatly, it doesn't look as horrendous as it
sounds) to allow water to drain away .
I fully realise that greenhouses are NOT wind and water tight
(although for most purposes...)but there is more influx than
desirable (although this influx is not major I would still like to
stop it).

Soak the mortar with PVA. This isn't water PROOF but its sufficiently
pore filling to pretty much stop the water soaking through..

Why not just use a proprietary cement waterproofer? I think this is
probably some kind of surfactant that packs the particles closer together
AKA 'PVA' :-)

I don't think so. Last one I used was the same consistency as a
plasticiser (which isn't PVA either :-) )
A drop of washing up liquid reduces the amount of water you need to make
it workable by a huge amount, so I guess that would produce a denser,
and therefore a more water resistant, mortar.
SBR is certainly miles better than PVA but it doesn't incorporate itself
into the mortar that well

In article ,
Stuart Noble writes:
The Natural Philosopher wrote:
Stuart Noble wrote:
Why not just use a proprietary cement waterproofer? I think this is
probably some kind of surfactant that packs the particles closer together
AKA 'PVA' :-)

I don't think so. Last one I used was the same consistency as a
plasticiser (which isn't PVA either :-) )
A drop of washing up liquid reduces the amount of water you need to make
it workable by a huge amount, so I guess that would produce a denser,
and therefore a more water resistant, mortar.

I don't think so -- washing up liquid is a wetting agent (surfactant)
and often salt.

The waterproofing agents have the opposite effect, causing water to
be repelled from the internal surfaces in the mortar. You can buy
combined plasticiser and waterproofer for mortar from a builders
merchant (and on occasion from Wickes and B&Q too). These will
prevent moisture wicking through mortar, but probably won't prevent
moisture under pressure from penetrating.

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

Andrew Gabriel wrote:
In article ,
Stuart Noble writes:
The Natural Philosopher wrote:
Stuart Noble wrote:
Why not just use a proprietary cement waterproofer? I think this is
probably some kind of surfactant that packs the particles closer together
AKA 'PVA' :-)
I don't think so. Last one I used was the same consistency as a
plasticiser (which isn't PVA either :-) )
A drop of washing up liquid reduces the amount of water you need to make
it workable by a huge amount, so I guess that would produce a denser,
and therefore a more water resistant, mortar.

I don't think so -- washing up liquid is a wetting agent (surfactant)
and often salt.

Cement plasticisers are also wetting agents (often lignosulphonates).
Supposedly they reduce the voids between the particles.


The waterproofing agents have the opposite effect, causing water to
be repelled from the internal surfaces in the mortar. You can buy
combined plasticiser and waterproofer for mortar from a builders
merchant (and on occasion from Wickes and B&Q too). These will
prevent moisture wicking through mortar, but probably won't prevent
moisture under pressure from penetrating.