On Monday, November 5, 2012 9:35:32 AM UTC, stuart noble wrote:
On 05/11/2012 02:27, wrote:
On Sunday, November 4, 2012 5:32:13 PM UTC, stuart noble wrote:
On 04/11/2012 14:51, wrote:
On Sunday, November 4, 2012 2:07:35 PM UTC, stuart noble wrote:
On 04/11/2012 12:39, wrote:
On Sunday, November 4, 2012 12:17:08 PM UTC, stuart noble wrote:
On 04/11/2012 12:07, wrote:
On Sunday, November 4, 2012 9:50:06 AM UTC, stuart noble
wrote:
On 04/11/2012 09:03, wrote:
On Friday, November 2, 2012 9:26:17 PM UTC,
wrote:


The most likely cause is condensation, caused primarily
by too high an interior RH. This type of thing is often
misdiagosed as rising damp, which although it exists, is
unusual. The solution is normally to address interior
sources of dampness, eg showers without adequate
ventilation, hob cooking on excessively high heat, drying
clothes indoors, unvented gas heating, inadequate
ventilation in rooms etc.

The gradual movement of water vapour is from interior to
exterior, since interior RH is higher on average. Thus
evaporation of water from the exterior of the wall is
necessary to avoid dampness. You mentioned a black paint,
if you mean bitumen on the exterior then this can
gradually cause damp problems by preventing evaporation.
Painted cement render can occasionally too in walls that
are borderline in terms of how they handle damp, but
that's not likely to apply to a cavity wall. Are you sure
they're cavity walls, as everything you describe is a lot
more likely to occur with non-cavity walls?

Thank you for that glimpse into 1950s Britain before
central heating was the norm

Damp, the subject you can't be bothered to read up on

Where do you get the idea that indoor RH is normally higher
than outdoor? Do you live in a cave?

Well lets see, there's breathing, cooking, bathing, laundry, all
put water vapour into the indoor air.

So where does it go? it goes outdoors via ventilation, and to a
small extent out through walls.

The warm air indoors is quite able to carry a bit of extra
moisture,
yes

so it doesn't go anywhere.

People keep breathing, washing and cooking, so water keeps being put
into the interior air. If it really went nowhere, it would condense
out and flood the house. Its pretty obvious it goes somewhere.


In fact, in what I would term a normal household there is more
danger of low rh than high but,

In some cases yes, in some the reverse.


if you're not going to maintain a temperature fit for human
habitation, then there won't be much difference between inside and
out. No way to live though

Unheated houses have higher indoor RH than out because of the
constant supply of water vapour from breathing, washing and cooking.

Seriously you need to get this figured out beore you can understand
how damp works.

All I need to figure out is why you appear to be living in the land that
time forgot.

That's one lousy answer. Or are you really claiming the basics of physics have changed lately

We have insulation and central heating these days. That is what has
changed.

Indeed, which doesnt change the above one iota.

Breathing, washing and cooking just aren't a problem in the
modern home.

AFAIK they've never been a problem in any home. Excess water vapour however is in some old houses that have been wrongly modified and are now borderline in terms of how they handle water vapour.


NT