Consider the patch of concrete floor shown at

http://www.cogsci.ed.ac.uk/~richard/concretefloor.jpg

It's on the ground floor (which is below ground level at the front)
of a Victorian house. The dark brown and blue patches are bits of
underlay rubber that have stuck to the floor.

Am I right in thinking that the thin rubbery surface on most of the
floor is intended to seal against damp? And that its absence in
places would explain a patch of mould on the carpet? It was under
a chest of drawers.

The exposed parts don't *feel* damp.

-- Richard

Richard Tobin wrote:
Consider the patch of concrete floor shown at

http://www.cogsci.ed.ac.uk/~richard/concretefloor.jpg

It's on the ground floor (which is below ground level at the front)
of a Victorian house. The dark brown and blue patches are bits of
underlay rubber that have stuck to the floor.

Am I right in thinking that the thin rubbery surface on most of the
floor is intended to seal against damp? And that its absence in
places would explain a patch of mould on the carpet? It was under
a chest of drawers.

The exposed parts don't *feel* damp.

-- Richard

you can check if there is any damp by putting down a sheet of newspaper
and then polythene on top. weight it down and leave for a few days. if
the floor is dry, the paper will stay crisp. if it is limp or wet then
you don't have adequate damp proofing.

On Thursday 24 October 2013 14:53 Richard Tobin wrote in uk.d-i-y:

Consider the patch of concrete floor shown at

http://www.cogsci.ed.ac.uk/~richard/concretefloor.jpg

It's on the ground floor (which is below ground level at the front)
of a Victorian house. The dark brown and blue patches are bits of
underlay rubber that have stuck to the floor.

Am I right in thinking that the thin rubbery surface on most of the
floor is intended to seal against damp? And that its absence in
places would explain a patch of mould on the carpet? It was under
a chest of drawers.

No - I think that was solvent adhesive used at some point to stick vinyl or
lino down. I had the same.

The exposed parts don't *feel* damp.

That's a poor metric - take a 50cm square sheet of plastic, ideally clear
and tape it down over the test area.

Leave for 2-3 days - damp will be very obvious as condensation underside the
plastic.

What covering are you planning on laying?

-- Richard
--
Tim Watts Personal Blog: http://squiddy.blog.dionic.net/

http://www.sensorly.com/ Crowd mapping of 2G/3G/4G mobile signal coverage

Richard Tobin wrote:
Consider the patch of concrete floor shown at

http://www.cogsci.ed.ac.uk/~richard/concretefloor.jpg

It's on the ground floor (which is below ground level at the front)
of a Victorian house. The dark brown and blue patches are bits of
underlay rubber that have stuck to the floor.

Am I right in thinking that the thin rubbery surface on most of the
floor is intended to seal against damp? And that its absence in
places would explain a patch of mould on the carpet? It was under
a chest of drawers.


The floor does appear to be damp judging by the rust on the carpet gripper
nails about 2/3rds across from the left of the picture.
Also, you still have cement skirtings, which tells me that this floor isn't
new concrete but probably a thin screed, probably over quarry tiles, if it
had been new, the skirtings would have been removed while taking up the old
floor and the chances are it would have minimum a damp proof membrane and
possibly insulation, as it is is has neither.

If it's all damp I would expect ALL the gripperod spikes etc to be rusty thanks to the underlay etc trapping moisture & leaving the only exit via the gripperods...

Are those skirtings "cement" ??

Jim K

In article ,
Phil L wrote:

The floor does appear to be damp judging by the rust on the carpet gripper
nails about 2/3rds across from the left of the picture.

There certainly seems to be some amount of damp - elsewhere on the
lower floor paint has peeled off the cement skirting, and where a board
was left leaning against a wall for months the surface (I think it's
painted wallpaper) has come loose.

Also, you still have cement skirtings, which tells me that this floor isn't
new concrete but probably a thin screed, probably over quarry tiles

That seems very likely.

The question is, what to do? The dampness has not been enough to
cause any mould before, at least in the last 15 years. Should I just
turn up the heating and try to improve ventilation?

Do you agree with the other poster that the rubbery coating is old
glue rather than a seal?

-- Richard

Richard Tobin wrote:
In article ,
Phil L wrote:

The floor does appear to be damp judging by the rust on the carpet
gripper nails about 2/3rds across from the left of the picture.

There certainly seems to be some amount of damp - elsewhere on the
lower floor paint has peeled off the cement skirting, and where a
board was left leaning against a wall for months the surface (I think
it's painted wallpaper) has come loose.

Also, you still have cement skirtings, which tells me that this
floor isn't new concrete but probably a thin screed, probably over
quarry tiles

That seems very likely.

The question is, what to do? The dampness has not been enough to
cause any mould before, at least in the last 15 years. Should I just
turn up the heating and try to improve ventilation?

Do you agree with the other poster that the rubbery coating is old
glue rather than a seal?

It's highly likely that the coating is some kind of adhesive and not any
attempt at sealing the concrete.
The chances are, it's a small amount of moisture coming up from the floor,
and if you can live with it, then leave it as it is, you may want to raise
the chest of drawers up on blocks so as to allow air flow, which I'm
assuming is already the case with the other furniture in this room? - Sofas
etc usually have an inch or two gap underneath and this is sufficient to
allow moisture (damp) to evapourate naturally.
If it's something you can't put up with, it could get a bit expensive, and
so it boils down to how much you want to spend - in an ideal world where
money was no object, the floor would be excavated to 200mm deep, 100mm of
kingspan insulation and 100mm of concrete, along with a plastic DPM, but
that's the dearest option, you could put a floating floor in there,
insulation boards with floorboards over the top, but it would mean a step up
into the room and you'd lose the skirtings and a few inches off the height
of the door, the third option is to have it asphalted over, which is about
10mm of hot bitumen laid over the entire room, this is completely damp
proof, but has no insulation properties, or, as I said earlier, you can live
with it as it is, and if it's not causing any serious problems, this would
be my preferred course of action on account of me being a tightfisted old
sod, but it's your house and it's up to you.

Jim K wrote:
If it's all damp I would expect ALL the gripperod spikes etc to be
rusty thanks to the underlay etc trapping moisture & leaving the only
exit via the gripperods...

Damp works in mysterious ways


Are those skirtings "cement" ??

Yes, often known as granolithic skirtings, the Victorians did use cement
occasionally and this was one of it's rare uses, the only other i know of
was to point the joints in underground salt glazed drainage pipes.

As a youngster starting off in the building trade, I asked why they put
cement skirtings on and was told it was to combat against cockroach
infestation, but whether this was true or not I don't know, there was
certainly no shortage of timber or labour judging by the amount of lathe and
plaster used back then, so it can only be assumed that it was an expensive
job compared to using timber skirtings, cement being very costly at the time

In article ,
Phil L wrote:

as I said earlier, you can live
with it as it is, and if it's not causing any serious problems, this would
be my preferred course of action on account of me being a tightfisted old
sod, but it's your house and it's up to you.

I think it's my preferred course too...

Thanks to you and all the others who commented.

-- Richard

On Fri, 25 Oct 2013 14:40:00 +0100, Phil L wrote:
If it's something you can't put up with, it could get a bit expensive,
and so it boils down to how much you want to spend - in an ideal world
where money was no object, the floor would be excavated to 200mm deep,
100mm of kingspan insulation and 100mm of concrete, along with a plastic
DPM, but that's the dearest option, you could put a floating floor in
there, insulation boards with floorboards over the top, but it would
mean a step up into the room and you'd lose the skirtings and a few
inches off the height of the door, the third option is to have it
asphalted over, which is about 10mm of hot bitumen laid over the entire
room, this is completely damp proof, but has no insulation properties,
or, as I said earlier, you can live with it as it is, and if it's not
causing any serious problems, this would be my preferred course of
action on account of me being a tightfisted old sod, but it's your house
and it's up to you.

I'm not sure if the stuff sold as garage floor paint has sealing
properties - I'd expect that it would, simply because there are surely
lots of garages out there with concrete floors that aren't insulated and
have no DPM.

There's also the latex basement wall paint which is designed to seal
cracks, but IME it's crap even on walls, so I don't know how well it
would work on a floor (with some sort of carpeting or whatnot over the
top to reduce damage, obviously).

Oh, they do epoxy garage floor covering stuff this side of the Pond, too
- IIRC it's two cans that you mix prior to application, along with a bag
of flakes to make it less slippery to walk on. It's quite expensive
(about 3x the cost of "garage floor paint" cans) - however, I don't think
it's been available in DIY stores for that long, so maybe it's one of
those things that will come down in price in a year or two.

cheers

Jules

On Saturday 26 October 2013 21:01 Jules Richardson wrote in uk.d-i-y:


Oh, they do epoxy garage floor covering stuff this side of the Pond, too
- IIRC it's two cans that you mix prior to application, along with a bag
of flakes to make it less slippery to walk on. It's quite expensive
(about 3x the cost of "garage floor paint" cans) - however, I don't think
it's been available in DIY stores for that long, so maybe it's one of
those things that will come down in price in a year or two.

http://www.directflooringcentre.co.u...topgap-f75-5kg

That's a "proper" epoxy DPM - I've used it - it works and is easy to apply
(but you have to be quick which is not difficult if you get everything
prepped, clear and ready beforehand.

Best applied with a roller on a long pole so you can apply whilst standing.



--
Tim Watts Personal Blog: http://squiddy.blog.dionic.net/

http://www.sensorly.com/ Crowd mapping of 2G/3G/4G mobile signal coverage

On 24/10/2013 14:53, Richard Tobin wrote:
Consider the patch of concrete floor shown at

http://www.cogsci.ed.ac.uk/~richard/concretefloor.jpg

It's on the ground floor (which is below ground level at the front)
of a Victorian house. The dark brown and blue patches are bits of
underlay rubber that have stuck to the floor.

Am I right in thinking that the thin rubbery surface on most of the
floor is intended to seal against damp? And that its absence in
places would explain a patch of mould on the carpet? It was under
a chest of drawers.




Just looks like flooring cover adhesive to me
Anti-damp treatements are either bitumen form providing a rubber
barrier, or a 'soaked in' clear surface treatemnet.



--
UK SelfBuild: http://uk.groups.yahoo.com/group/UK_Selfbuild/

On 23/02/14 15:17, Rick Hughes wrote:
On 24/10/2013 14:53, Richard Tobin wrote:
Consider the patch of concrete floor shown at

http://www.cogsci.ed.ac.uk/~richard/concretefloor.jpg

It's on the ground floor (which is below ground level at the front)
of a Victorian house. The dark brown and blue patches are bits of
underlay rubber that have stuck to the floor.

Am I right in thinking that the thin rubbery surface on most of the
floor is intended to seal against damp? And that its absence in
places would explain a patch of mould on the carpet? It was under
a chest of drawers.




Just looks like flooring cover adhesive to me
Anti-damp treatements are either bitumen form providing a rubber
barrier, or a 'soaked in' clear surface treatemnet.




Missed one - you can also apply an epoxy DPM as I did on one room with a
shot damp proof layer. Personally I'd rate the epoxy as the best. See
f-ball.co.uk for various products and guide notes.