Moisture?

  • Thread starter The Medway Handyman
  • Start date

T

The Medway Handyman

My mate over the road had a leak in the bathroom causing water to pour
through the ceiling & soak the hall carpet.

He reported it to his insurance co, who sent Chem Dri around to do a report.

They used a 'moisture meter' and determined that the ceiling had a 20%
moisture content and the flooring 100%. Apparently the 'criteria' is that
below 17% moisture in a floor or ceiling needs no action, anything above
does.

My mate doesn't care because the insurance co are paying, but do I detect
the smell of bullshite here?

I thought moisture meters were only useable on wood, not floors & ceilings?
Where does the 17% 'criteria' come from? And isn't 100% moisture content -
just water?
 
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B

Bertie Doe

"The Medway Handyman" wrote in message
I thought moisture meters were only useable on wood, not floors &
ceilings?
Building surveyors use moisture meters on the brickwork of old buildings, to
check if the dampcourse hasn't been breached.

Bertie
 
T

Tanner-'op

The said:
My mate over the road had a leak in the bathroom causing water to pour
through the ceiling & soak the hall carpet.

He reported it to his insurance co, who sent Chem Dri around to do a
report.
They used a 'moisture meter' and determined that the ceiling had a 20%
moisture content and the flooring 100%. Apparently the 'criteria' is
that below 17% moisture in a floor or ceiling needs no action,
anything above does.
If the ceiling is plasterboard and it is not actually 'falling' apart (some
minor bulging is allowed) - then if it's left alone to dry naturally it will
be ok.
My mate doesn't care because the insurance co are paying, but do I
detect the smell of bullshite here?
Depends on the severity of the damage - and if the ceiling has retained its
position after a 'soaking' and a moisture meter has to be used to detect the
damp, then the answer is *no*.
I thought moisture meters were only useable on wood, not floors &
ceilings? Where does the 17% 'criteria' come from? And isn't 100%
moisture content - just water?
One can also be used on walls (to detect rising damp etc) - and as for
'moisture content' your own body is around 90% moisture (IIRC so don't hang
me on that one) and the moisture content of the timber that you use in your
decking is around 18% - 22% - oh! and a 100% moisture content of the
plasterboard will guarantee a new ceiling. :)

A tip BTW, to reduce water damage to a plasterboard ceiling after a leak,
find the lowest point where the water is coming from and simply bang a
screwdriver through the ceiling and let the water drain into a bucket
below - and then leave well alone until the ceiling is dry - This will
usually 'save' around 60% to 80% of them.

Seen hundreds of 'em Dave over the years - even in my own house when the CH
sprang a leak.

Tanner-'op

Who must be in a good mood tonight.
 
A

Andrew Gabriel

I thought moisture meters were only useable on wood, not floors & ceilings?
The reading is only valid on wood.
The meter (or any multi meter) is useful to indicate presence of
moisture in masonary, but the only way to actually measure it is
to take a lump of the masonary, weigh it, dry it out, and weigh
it again to see how much mosture was present.
 
T

The Medway Handyman

Andrew said:
The reading is only valid on wood.
The meter (or any multi meter) is useful to indicate presence of
moisture in masonary, but the only way to actually measure it is
to take a lump of the masonary, weigh it, dry it out, and weigh
it again to see how much mosture was present.
Thats what I thought. I wonder where this 17% is acceptable 'criteria' came
from?

The 100% moisture content also confuses me. If we adopt your rational test,
100% moisture content must be water?
 
M

meow2222

My mate over the road had a leak in the bathroom causing water to pour
through the ceiling & soak the hall carpet.

He reported it to his insurance co, who sent Chem Dri around to do a report.

They used a 'moisture meter' and determined that the ceiling had a 20%
moisture content and the flooring 100%.  Apparently the 'criteria' is that
below 17% moisture in a floor or ceiling needs no action, anything above
does.

My mate doesn't care because the insurance co are paying, but do I detect
the smell of bullshite here?

I thought moisture meters were only useable on wood, not floors & ceilings?
Where does the 17% 'criteria' come from?  And isn't 100% moisture content -
just water?
Indeed. An unusual ceiling construction there. Seriosly those meters
are well known for their inaccuracy when used on things other than
wood.


NT
 
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D

dom

I'm told that the salts that may be present in many materials can
strongly influence conductivity, particularly where it's caused my
migrating damp, as salts can be transported and concentrated.

I'd imagine to get an accurate reading you would need a set of samples
of that material at known moisture levels to calibrate from, as I
wouldn't expect conductivity to be particularly linear with moisture
content, or consistent between different materials.
 
B

Bertie Doe

Handyman"
My mate over the road had a leak in the bathroom causing water to pour
through the ceiling & soak the hall carpet.

He reported it to his insurance co, who sent Chem Dri around to do a
report.

They used a 'moisture meter' and determined that the ceiling had a 20%
moisture content and the flooring 100%. Apparently the 'criteria' is that
below 17% moisture in a floor or ceiling needs no action, anything above
does.

My mate doesn't care because the insurance co are paying, but do I detect
the smell of bullshite here?

I thought moisture meters were only useable on wood, not floors &
ceilings?
Where does the 17% 'criteria' come from? And isn't 100% moisture content -
just water?
Indeed. An unusual ceiling construction there. Seriosly those meters
are well known for their inaccuracy when used on things other than
wood.

This is a handy ref by buildingpreservation.com, highlighting the difference
between carbide (invasive) and electric (non-invasive) moisture meters
http://preview.tinyurl.com/4fnwya
I know the RICS caution surveyors about relying overmuch on meters and
prefer experience, touch, smell etc to determine damp. However the may be
some further notes in the links in RICS Books:
http://preview.tinyurl.com/3toz74

Bertie
 
S

stuart noble

The said:
My mate over the road had a leak in the bathroom causing water to pour
through the ceiling & soak the hall carpet.

He reported it to his insurance co, who sent Chem Dri around to do a report.

They used a 'moisture meter' and determined that the ceiling had a 20%
moisture content and the flooring 100%. Apparently the 'criteria' is that
below 17% moisture in a floor or ceiling needs no action, anything above
does.

My mate doesn't care because the insurance co are paying, but do I detect
the smell of bullshite here?

I thought moisture meters were only useable on wood, not floors & ceilings?
Where does the 17% 'criteria' come from? And isn't 100% moisture content -
just water?
17% is the level at which softwood supposedly ceases to be vulnerable to
a whole load of fungal infections. Scandinavian redwood is termed
"shipping dry" at 17%, mainly to avoid the dreaded blue stain.
 
T

The Natural Philosopher

stuart said:
17% is the level at which softwood supposedly ceases to be vulnerable to
a whole load of fungal infections. Scandinavian redwood is termed
"shipping dry" at 17%, mainly to avoid the dreaded blue stain.

I rather thought 17% was the average 'outdoors but undercover' content
that wood dried out to if left long enough.
 
S

stuart noble

The said:
I rather thought 17% was the average 'outdoors but undercover' content
that wood dried out to if left long enough.
Well, it's that too, and the level at which it can be machined without
tearing the grain. All good reasons why timber exporters need to get it
down to that level prior to shipping, especially as it often spends
months strapped up in 5 cubic metre packs without any circulation of air
between the pieces.
 
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M

meow2222

Handyman"









Indeed. An unusual ceiling construction there. Seriosly those meters
are well known for their inaccuracy when used on things other than
wood.

This is a handy ref by buildingpreservation.com, highlighting the difference
between carbide (invasive) and electric (non-invasive) moisture metershttp://preview.tinyurl.com/4fnwya
Some interesting points in that article, but at the end of the day its
just another example of very biased writing reaching a conclusion not
logically supported.

To explain further:

Frst the article completely ignores a number of real world issues,
such as changes in conductitivety caused by:
past spills
contamination deposits from past leaks
kitchen cooking contamination
detergent contamination
inappropriately applied foil backed paper
lime mortar behind cement mortar

These things are common in century old properties, which is the type
of property these damp detectors are most used on.

Then there are several issues the article mentions, but then chooses
to overlook:
Lime mortar giving high readings
Lime plaster ditto
Presence of salts from sources other than a present damp problem
Damp at non-problem levels
"Unfortunately, the majority of surveyors do not appear to understand
how an electrical moisture meter should be used"
"using it like this will almost certainly lead to a high number of
wrong diagnoses!"
transient surface condensation
condensation
Surface readings being a problem in winter
Surface readings being a problem in summer
"The isolated individual readings obtained during most surveys are of
little value and will certainly increase the chances of misdiagnosis!"


There are some good points made in the article, but as a piece of
logical writing it simply isn't.


NT
 
B

Bertie Doe

Some interesting points in that article, but at the end of the day its
just another example of very biased writing reaching a conclusion not
logically supported.
To explain further:
Frst the article completely ignores a number of real world issues,
such as changes in conductitivety caused by:
past spills
contamination deposits from past leaks
kitchen cooking contamination
detergent contamination
inappropriately applied foil backed paper
lime mortar behind cement mortar
<snip>

Agreed and this is a much better article by Jeff Howell of South Bank Uni
http://tinyurl.com/485onl

BD
 
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My mate over the road had a leak in the bathroom causing water to pour
through the ceiling & soak the hall carpet.

He reported it to his insurance co, who sent Chem Dri around to do a report.

They used a 'moisture meter' and determined that the ceiling had a 20%
moisture content and the flooring 100%. Apparently the 'criteria' is that
below 17% moisture in a floor or ceiling needs no action, anything above
does.

My mate doesn't care because the insurance co are paying, but do I detect
the smell of bullshite here?

I thought moisture meters were only useable on wood, not floors & ceilings?
Where does the 17% 'criteria' come from? And isn't 100% moisture content -
just water?


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk
Hi Dave
All moisture meters are calibrated to wood and are successful in determining the actual moisture content within the wood. Moisture meters can also be used for the measurement of moisture in concrete and other masonary products like brick and plaster and so on. But with these other materials, the meter can only be used as an indication of moisture content and give results as a percentage base. If the moisture meter does indicate high moisture levels then further action has to be taken.
Paul
 
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