Hi,

Took some old vinyl flooring up at the bungalow, and, not surprisingly[1],
there were large patched of black mould.

[1] The floor is known to be (by digging a holes): 4" concrete on earth, no
DPM, and 1.5-2" sand/cement screed. Vinyl laid direct on screed.

Finally, I have made up my mind what flooring to lay:

Bedrooms: 15-20mm Marmox tilebacker board[2] glued to screed, then floating
wood floor on top.

Other rooms: 20-30mm Marmox board, glued down, then ceramic/stone/similar
tiles glued with flexible adhesive to Marmox.

[2] Marmox is a closed cell waterproof foam, with both faces finished in
polymer+cement impregnated fibreglass mat

http://www.marmox.co.uk/products_board.asp

Now, the Marmox board will act as a damp barrier (except the joints) and I
would glue it down with cementous tile adhesive which isn;t bothered by
damp.

So, the question: Do you reckon I would be better off applying a liquid DPM
to the screed before sticking this down, or not?

And if so - which one? Most of them (eg Synthaprufe or Aquaseal random)
look like they are basically bitmen based - in which case would I be
weakening the bond to the Marmox board? Would blinding with sand help?

Or - are there any other products that sink in to the surface of the screed?
In the USA, there seems to be some references to a polyuretha/ene DPM -
which soaks in - but I can't find anything like that here.

Builders' Merchants round here have loads of Thompson products - but they
all seem to be aimed at driveway block sealing, brickwork sealing and
suchlike...

Cheers and TIA

Tim

PS - I decoded against the floorheater.co.uk UFH panels. Marmox is stonger,
more rigid and I don't have to worry about wasting money to warm the worms.
20-30mm of Marmox will add to the comfort of the floor, and is a guaranteed
energy efficiency measure (how much, I don;t know, but at least it's better
than now).

Tim S wrote:
Hi,

Took some old vinyl flooring up at the bungalow, and, not surprisingly[1],
there were large patched of black mould.

[1] The floor is known to be (by digging a holes): 4" concrete on earth, no
DPM, and 1.5-2" sand/cement screed. Vinyl laid direct on screed.

Finally, I have made up my mind what flooring to lay:

Bedrooms: 15-20mm Marmox tilebacker board[2] glued to screed, then floating
wood floor on top.

Other rooms: 20-30mm Marmox board, glued down, then ceramic/stone/similar
tiles glued with flexible adhesive to Marmox.

[2] Marmox is a closed cell waterproof foam, with both faces finished in
polymer+cement impregnated fibreglass mat

http://www.marmox.co.uk/products_board.asp

Now, the Marmox board will act as a damp barrier (except the joints) and I
would glue it down with cementous tile adhesive which isn;t bothered by
damp.

So, the question: Do you reckon I would be better off applying a liquid DPM
to the screed before sticking this down, or not?

And if so - which one? Most of them (eg Synthaprufe or Aquaseal random)
look like they are basically bitmen based - in which case would I be
weakening the bond to the Marmox board? Would blinding with sand help?

Or - are there any other products that sink in to the surface of the screed?
In the USA, there seems to be some references to a polyuretha/ene DPM -
which soaks in - but I can't find anything like that here.

Builders' Merchants round here have loads of Thompson products - but they
all seem to be aimed at driveway block sealing, brickwork sealing and
suchlike...

Cheers and TIA

Tim

PS - I decoded against the floorheater.co.uk UFH panels. Marmox is stonger,
more rigid and I don't have to worry about wasting money to warm the worms.
20-30mm of Marmox will add to the comfort of the floor, and is a guaranteed
energy efficiency measure (how much, I don;t know, but at least it's better
than now).

Youre putting down a vapour barrier - why would you want two. The one
issue I see is picking a glue for under the marmox that will be ok
permanently damp.


NT

coughed up some electrons that declared:


Youre putting down a vapour barrier - why would you want two.

Belt and braces? I don't know - I was considering the joints, small as they
are.

Truth be told, having read up on laying engineered wood - I might just as
well put polythene DPM over the top under the wood - that costs practically
nothing and does no harm, on the offchance that any vapour does leak
through.

The one
issue I see is picking a glue for under the marmox that will be ok
permanently damp.

That's OK - had it on good authority that plain old cement based tile
adhesive (the grey sort you mix from powder) will be fine, damp.

Cheers

Tim

Tim S wrote:
coughed up some electrons that declared:


Youre putting down a vapour barrier - why would you want two.

Belt and braces? I don't know - I was considering the joints, small as they
are.

Truth be told, having read up on laying engineered wood - I might just as
well put polythene DPM over the top under the wood - that costs practically
nothing and does no harm, on the offchance that any vapour does leak
through.

The one
issue I see is picking a glue for under the marmox that will be ok
permanently damp.

That's OK - had it on good authority that plain old cement based tile
adhesive (the grey sort you mix from powder) will be fine, damp.

Cheers

Tim

The marmox should prevent condensation, which may have been the original
problem

Stuart Noble coughed up some electrons that declared:

Tim S wrote:
coughed up some electrons that declared:


Youre putting down a vapour barrier - why would you want two.

Belt and braces? I don't know - I was considering the joints, small as
they are.

Truth be told, having read up on laying engineered wood - I might just as
well put polythene DPM over the top under the wood - that costs
practically nothing and does no harm, on the offchance that any vapour
does leak through.

The one
issue I see is picking a glue for under the marmox that will be ok
permanently damp.

That's OK - had it on good authority that plain old cement based tile
adhesive (the grey sort you mix from powder) will be fine, damp.

Cheers

Tim

The marmox should prevent condensation, which may have been the original
problem


I hadn't thought of it that way - but that room was never heated much and
the floor never gets higher than 15C - the earth base temperature under the
slab is around 8-10C by quick and dirty measurement. The floor covering has
been down a good 10 years too.

It's not like the slab is actually soaking wet - so it seems that it's more
a case of vapour coming through, getting trapped and presumably liquifying
as you suggest.

Yep - all things said and done, Marmox (or an identical product - there are
a few) is clearly the best thing for this house, with the least risk of
going wrong.

Thanks!

Tim

Tim S wrote:
Stuart Noble coughed up some electrons that declared:

Tim S wrote:
coughed up some electrons that declared:


Youre putting down a vapour barrier - why would you want two.
Belt and braces? I don't know - I was considering the joints, small as
they are.

Truth be told, having read up on laying engineered wood - I might just as
well put polythene DPM over the top under the wood - that costs
practically nothing and does no harm, on the offchance that any vapour
does leak through.

The one
issue I see is picking a glue for under the marmox that will be ok
permanently damp.
That's OK - had it on good authority that plain old cement based tile
adhesive (the grey sort you mix from powder) will be fine, damp.

Cheers

Tim
The marmox should prevent condensation, which may have been the original
problem


I hadn't thought of it that way - but that room was never heated much and
the floor never gets higher than 15C - the earth base temperature under the
slab is around 8-10C by quick and dirty measurement. The floor covering has
been down a good 10 years too.

It's not like the slab is actually soaking wet - so it seems that it's more
a case of vapour coming through, getting trapped and presumably liquifying
as you suggest.

Yep - all things said and done, Marmox (or an identical product - there are
a few) is clearly the best thing for this house, with the least risk of
going wrong.

Thanks!

Tim

I have a tiled solid floor, and you can see by the darker colour on the
grout lines in certain places that there is always a degree of
condensation in the winter.

Tim S wrote:
coughed up some electrons that declared:


Youre putting down a vapour barrier - why would you want two.

Belt and braces? I don't know - I was considering the joints, small as they
are.

a VB is already belt n braces. Lots of floors are ok without one, as
long as you dont put an impermeable cover on top.


Truth be told, having read up on laying engineered wood - I might just as
well put polythene DPM over the top under the wood - that costs practically
nothing and does no harm, on the offchance that any vapour does leak
through.

yes, but you cant glue it, and it doesnt last well.


The one
issue I see is picking a glue for under the marmox that will be ok
permanently damp.

That's OK - had it on good authority that plain old cement based tile
adhesive (the grey sort you mix from powder) will be fine, damp.

I wish. Bitumen works. Cement can too.


NT

coughed up some electrons that declared:


That's OK - had it on good authority that plain old cement based tile
adhesive (the grey sort you mix from powder) will be fine, damp.

I wish. Bitumen works. Cement can too.


Sorry, don't follow - are you saying I should bitumen the board down?

In the meantime, I phoned Marmox. They said the failsafe solution is to plug
and screw the board down then tape the joints and screws and this would be
guaranteed to give a DPM as well as an insulating layer.

They said they didn't have anything against using adhesive, but it would be
up to an adhesive manufacturer to advise on suitability. I'll ring Mapei
now and see what they say...

Cheers

Tim

Tim S coughed up some electrons that declared:


They said they didn't have anything against using adhesive, but it would
be up to an adhesive manufacturer to advise on suitability. I'll ring
Mapei now and see what they say...

And the answer was: Keraquick. They said there were no guarantees as to
whether the hydrostatic pressure would destroy the bond in X decades, but
he reckoned that Kerquick was the most likely to succeed, being cementous
and having extra polymers.

Cheers

Tim

Tim S wrote:
Tim S coughed up some electrons that declared:


They said they didn't have anything against using adhesive, but it would
be up to an adhesive manufacturer to advise on suitability. I'll ring
Mapei now and see what they say...

And the answer was: Keraquick. They said there were no guarantees as to
whether the hydrostatic pressure would destroy the bond in X decades, but
he reckoned that Kerquick was the most likely to succeed, being cementous
and having extra polymers.

Cheers

Tim

What does it cost compared to a can of bitumen roofing adhesive?


NT

coughed up some electrons that declared:

Tim S wrote:
Tim S coughed up some electrons that declared:


They said they didn't have anything against using adhesive, but it
would be up to an adhesive manufacturer to advise on suitability. I'll
ring Mapei now and see what they say...

And the answer was: Keraquick. They said there were no guarantees as to
whether the hydrostatic pressure would destroy the bond in X decades, but
he reckoned that Kerquick was the most likely to succeed, being cementous
and having extra polymers.

Cheers

Tim

What does it cost compared to a can of bitumen roofing adhesive?


Nothing horrendous - it's not a latex mix, though it can be made into one by
buying a horrendously expensive admix.

I don't think felt adhesive would have enough gap filling abilities; Marmox
is very rigid and even my good floors have a couple of mm variation.

Cheers

Tim

Tim S wrote:
coughed up some electrons that declared:
Tim S wrote:
Tim S coughed up some electrons that declared:

They said they didn't have anything against using adhesive, but it
would be up to an adhesive manufacturer to advise on suitability. I'll
ring Mapei now and see what they say...

And the answer was: Keraquick. They said there were no guarantees as to
whether the hydrostatic pressure would destroy the bond in X decades, but
he reckoned that Kerquick was the most likely to succeed, being cementous
and having extra polymers.

Cheers

Tim

What does it cost compared to a can of bitumen roofing adhesive?


Nothing horrendous - it's not a latex mix, though it can be made into one by
buying a horrendously expensive admix.

I don't think felt adhesive would have enough gap filling abilities; Marmox
is very rigid and even my good floors have a couple of mm variation.

Cheers

Tim

Bitumen felt adhesive fills bigger gaps than that easily. But it
sounds like either would work ok - I cant help but think someone wants
your money though, just a gut feeling Bitumen also gives you a 2nd
dpm, fwliw.


NT