I've noticed (I wish I hadn't) that the floorboards on the upper floor
of my house are a bit cupped. It's an old-ish house (1940s) so is this
something that just happens over the years?

There's no smell of damp and no evidence of moisture, though one wall
does get a little condensation on it.

Do people live with it or should I get it sorted. Am concerned down
the line that a buyer or surveyor might think it's damp.

Thanks, Ed.

"Ed_Zep" wrote in message
oups.com...
I've noticed (I wish I hadn't) that the floorboards on the upper
floor
of my house are a bit cupped. It's an old-ish house (1940s) so is
this
something that just happens over the years?

There's no smell of damp and no evidence of moisture, though one
wall
does get a little condensation on it.

Do people live with it or should I get it sorted. Am concerned down
the line that a buyer or surveyor might think it's damp.

Thanks, Ed.


On the contrary, it is most likely a drying out effect.

The way the boards were cut from the tree means that there is a
tendancy for them to cup as they dry - look at the end grain of a
board at it becomes obvious. Most likely your house has had central
heating added (and possibly new windows) which has significantly
reduced the moisture content.

AWEM

Ed_Zep wrote:
I've noticed (I wish I hadn't) that the floorboards on the upper floor
of my house are a bit cupped. It's an old-ish house (1940s) so is this
something that just happens over the years?

There's no smell of damp and no evidence of moisture, though one wall
does get a little condensation on it.

Do people live with it or should I get it sorted. Am concerned down
the line that a buyer or surveyor might think it's damp.

Thanks, Ed.

It happened when cheap floorboards meet central hearing.

Pre 1950 central heating was a rarity, and so winter RH levels never
plummeted to the depths they do today.

Wood cut in any direction except straight towards the heartwood (true
quarter sawn) will always cup as the humidity changes. This is due to
the fact the the wood cells are aligned, and expansion and contraction
is not isomorphic at all..being least along the grain, modest in the
direction between the heart and the bark and huge in a circumferential
direction.

You can see this in cut logs. They will shrink and split radially almost
always, rarely tangentially, and never *across* the bole.

On Thu, 22 Mar 2007 16:31:07 -0000, "Andrew Mawson"
wrote:

|!
|!"Ed_Zep" wrote in message
groups.com...
|! I've noticed (I wish I hadn't) that the floorboards on the upper
|!floor
|! of my house are a bit cupped. It's an old-ish house (1940s) so is
|!this
|! something that just happens over the years?
|!
|! There's no smell of damp and no evidence of moisture, though one
|!wall
|! does get a little condensation on it.
|!
|! Do people live with it or should I get it sorted. Am concerned down
|! the line that a buyer or surveyor might think it's damp.
|!
|! Thanks, Ed.
|!
|!
|!On the contrary, it is most likely a drying out effect.
|!
|!The way the boards were cut from the tree means that there is a
|!tendancy for them to cup as they dry - look at the end grain of a
|!board at it becomes obvious. Most likely your house has had central
|!heating added (and possibly new windows) which has significantly
|!reduced the moisture content.

Your 1940s floor boards will be thick enough to sand level with a power
sander, if you wish.
--
Dave Fawthrop sf hyphenologist.co.uk 165 *Free* SF ebooks.
165 Sci Fi books on CDROM, from Project Gutenberg
http://www.gutenberg.org/wiki/Main_Page Completely Free to any
address in the UK. Contact me on the *above* email address.

Thanks for taking the time to reply, chaps. The house does have CH and
DG so those answers would be spot-on.

Regards, Ed.

On 2007-03-22 18:52:45 +0000, "Ed_Zep" said:

Thanks for taking the time to reply, chaps. The house does have CH and
DG so those answers would be spot-on.

Regards, Ed.

If it really concerned you, you could sand the floor flat if the amount
is not too much, otherwise they *could* be lifted and run through a
planer.

An alternative would be to advertise this as a character feature when you sell.

In article .com,
"Ed_Zep" writes:
I've noticed (I wish I hadn't) that the floorboards on the upper floor
of my house are a bit cupped. It's an old-ish house (1940s) so is this
something that just happens over the years?

There's no smell of damp and no evidence of moisture, though one wall
does get a little condensation on it.

Do people live with it or should I get it sorted. Am concerned down
the line that a buyer or surveyor might think it's damp.

It can be caused by running a dehumidifier in the house.
You end up with significantly different relative humidity
in different rooms. Have you done this?

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

On Mar 22, 8:17 pm, (Andrew Gabriel)
wrote:
In article .com,
"Ed_Zep" writes:

I've noticed (I wish I hadn't) that the floorboards on the upper floor
of my house are a bit cupped. It's an old-ish house (1940s) so is this
something that just happens over the years?

There's no smell of damp and no evidence of moisture, though one wall
does get a little condensation on it.

Do people live with it or should I get it sorted. Am concerned down
the line that a buyer or surveyor might think it's damp.

It can be caused by running a dehumidifier in the house.
You end up with significantly different relative humidity
in different rooms. Have you done this?

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

I haven't. I think the boards were pretty cupped when I moved in 3
years ago. I've probably just become more aware of it.

I certainly won't be getting a dehumidifier now, though!

Andy Hall wrote:
On 2007-03-22 18:52:45 +0000, "Ed_Zep" said:

Thanks for taking the time to reply, chaps. The house does have CH and
DG so those answers would be spot-on.

Regards, Ed.

If it really concerned you, you could sand the floor flat if the amount
is not too much, otherwise they *could* be lifted and run through a planer.

An alternative would be to advertise this as a character feature when
you sell.



Main thing is, the cupping is a one-off event.

Stuart Noble wrote:
Andy Hall wrote:
On 2007-03-22 18:52:45 +0000, "Ed_Zep" said:

Thanks for taking the time to reply, chaps. The house does have CH and
DG so those answers would be spot-on.

Regards, Ed.

If it really concerned you, you could sand the floor flat if the
amount is not too much, otherwise they *could* be lifted and run
through a planer.

An alternative would be to advertise this as a character feature when
you sell.



Main thing is, the cupping is a one-off event.

Main thing is, cupping is not a one off event but happens on an annual
basis as summer to winter humidity varies by a huge amount.

The Natural Philosopher wrote:
Stuart Noble wrote:
Andy Hall wrote:
On 2007-03-22 18:52:45 +0000, "Ed_Zep" said:

Thanks for taking the time to reply, chaps. The house does have CH and
DG so those answers would be spot-on.

Regards, Ed.

If it really concerned you, you could sand the floor flat if the
amount is not too much, otherwise they *could* be lifted and run
through a planer.

An alternative would be to advertise this as a character feature when
you sell.



Main thing is, the cupping is a one-off event.

Main thing is, cupping is not a one off event but happens on an annual
basis as summer to winter humidity varies by a huge amount.

So gaps in floorboards should open and close with the seasons then?
Can't say I've noticed it, and where boards have been lifted and
re-fixed without gaps, they haven't swollen. The shrinkage of new timber
in a centrally heated home is essentially a one way process in my experience

Stuart Noble wrote:
The Natural Philosopher wrote:
Stuart Noble wrote:
Andy Hall wrote:
On 2007-03-22 18:52:45 +0000, "Ed_Zep" said:

Thanks for taking the time to reply, chaps. The house does have CH and
DG so those answers would be spot-on.

Regards, Ed.

If it really concerned you, you could sand the floor flat if the
amount is not too much, otherwise they *could* be lifted and run
through a planer.

An alternative would be to advertise this as a character feature
when you sell.



Main thing is, the cupping is a one-off event.

Main thing is, cupping is not a one off event but happens on an annual
basis as summer to winter humidity varies by a huge amount.

So gaps in floorboards should open and close with the seasons then?

Yes.

Can't say I've noticed it,

I have.

and where boards have been lifted and
re-fixed without gaps, they haven't swollen. The shrinkage of new timber
in a centrally heated home is essentially a one way process in my
experience

No. There is an initial shrinkage to more or less the average RH of the
home, but in summer RH is very hight - maybe 70% - in winter it can be
very very low indeed.

I had a friend whose father owned an old mahogany bureau with the top
cut very near the heartwood. In winter it would curl up and leave an
inch gap..in summer it was flat..

Roughly you may expect a 1% shift in dimenson around the grain , and
0.5% in a radial direction, with respect to the original tree, summer to
winter. About 0.1% is reasonable along the grain.

Cupping is caused by the difference between the 1% and the 0.5% which
will happen in a plank cut near to the heartwood.

The figures are only about 10% of the shrinkage that happens from green
to fully dried, and about 50% of the figure from kiln dried to fully
dried, but they are still there.

"Stuart Noble" wrote in message
...
The Natural Philosopher wrote:
Stuart Noble wrote:
Andy Hall wrote:
On 2007-03-22 18:52:45 +0000, "Ed_Zep"
said:

Thanks for taking the time to reply, chaps. The house does have
CH and
DG so those answers would be spot-on.

Regards, Ed.

If it really concerned you, you could sand the floor flat if the
amount is not too much, otherwise they *could* be lifted and run
through a planer.

An alternative would be to advertise this as a character feature
when
you sell.



Main thing is, the cupping is a one-off event.

Main thing is, cupping is not a one off event but happens on an
annual
basis as summer to winter humidity varies by a huge amount.

So gaps in floorboards should open and close with the seasons then?
Can't say I've noticed it, and where boards have been lifted and
re-fixed without gaps, they haven't swollen. The shrinkage of new
timber
in a centrally heated home is essentially a one way process in my
experience

Oh they do! The effect is much more pronounced in doors - fitting in
the summer and tight in the spring

AWEM

Andrew Mawson wrote:
"Stuart Noble" wrote in message
...
The Natural Philosopher wrote:
Stuart Noble wrote:
Andy Hall wrote:
On 2007-03-22 18:52:45 +0000, "Ed_Zep"
said:
Thanks for taking the time to reply, chaps. The house does have
CH and
DG so those answers would be spot-on.

Regards, Ed.
If it really concerned you, you could sand the floor flat if the
amount is not too much, otherwise they *could* be lifted and run
through a planer.

An alternative would be to advertise this as a character feature
when
you sell.



Main thing is, the cupping is a one-off event.
Main thing is, cupping is not a one off event but happens on an
annual
basis as summer to winter humidity varies by a huge amount.
So gaps in floorboards should open and close with the seasons then?
Can't say I've noticed it, and where boards have been lifted and
re-fixed without gaps, they haven't swollen. The shrinkage of new
timber
in a centrally heated home is essentially a one way process in my
experience

Oh they do! The effect is much more pronounced in doors - fitting in
the summer and tight in the spring

That's outside doors.

Inside doors fit in winter and jam in the summer!




AWEM

The Natural Philosopher wrote:
Stuart Noble wrote:
The Natural Philosopher wrote:
Stuart Noble wrote:
Andy Hall wrote:
On 2007-03-22 18:52:45 +0000, "Ed_Zep" said:

Thanks for taking the time to reply, chaps. The house does have CH
and
DG so those answers would be spot-on.

Regards, Ed.

If it really concerned you, you could sand the floor flat if the
amount is not too much, otherwise they *could* be lifted and run
through a planer.

An alternative would be to advertise this as a character feature
when you sell.



Main thing is, the cupping is a one-off event.

Main thing is, cupping is not a one off event but happens on an
annual basis as summer to winter humidity varies by a huge amount.

So gaps in floorboards should open and close with the seasons then?

Yes.

Can't say I've noticed it,

I have.

and where boards have been lifted and re-fixed without gaps, they
haven't swollen. The shrinkage of new timber in a centrally heated
home is essentially a one way process in my experience

No. There is an initial shrinkage to more or less the average RH of the
home, but in summer RH is very hight - maybe 70% - in winter it can be
very very low indeed.

I had a friend whose father owned an old mahogany bureau with the top
cut very near the heartwood. In winter it would curl up and leave an
inch gap..in summer it was flat..

Roughly you may expect a 1% shift in dimenson around the grain , and
0.5% in a radial direction, with respect to the original tree, summer to
winter. About 0.1% is reasonable along the grain.

Cupping is caused by the difference between the 1% and the 0.5% which
will happen in a plank cut near to the heartwood.

The figures are only about 10% of the shrinkage that happens from green
to fully dried, and about 50% of the figure from kiln dried to fully
dried, but they are still there.

The Natural Philosopher wrote:
Andrew Mawson wrote:
"Stuart Noble" wrote in message
...
The Natural Philosopher wrote:
Stuart Noble wrote:
Andy Hall wrote:
On 2007-03-22 18:52:45 +0000, "Ed_Zep"
said:
Thanks for taking the time to reply, chaps. The house does have
CH and
DG so those answers would be spot-on.

Regards, Ed.
If it really concerned you, you could sand the floor flat if the
amount is not too much, otherwise they *could* be lifted and run
through a planer.

An alternative would be to advertise this as a character feature
when
you sell.



Main thing is, the cupping is a one-off event.
Main thing is, cupping is not a one off event but happens on an
annual
basis as summer to winter humidity varies by a huge amount.
So gaps in floorboards should open and close with the seasons then?
Can't say I've noticed it, and where boards have been lifted and
re-fixed without gaps, they haven't swollen. The shrinkage of new
timber
in a centrally heated home is essentially a one way process in my
experience

Oh they do! The effect is much more pronounced in doors - fitting in
the summer and tight in the spring

That's outside doors.

Exterior doors are different

Inside doors fit in winter and jam in the summer!

Ever wondered how they dry timber in the tropics with permanently high
humidity?

Stuart Noble wrote:

Ever wondered how they dry timber in the tropics with permanently high
humidity?

I can't say it's ever been the sort of thing to keep me awake at night, no..

The Natural Philosopher wrote:
Stuart Noble wrote:

Ever wondered how they dry timber in the tropics with permanently high
humidity?

I can't say it's ever been the sort of thing to keep me awake at night,
no..

Well, sufficient to say that high humidity doesn't stop things drying.
All this humid weather we have in summer, and the clothes on the line
still dry. Similarly, wood continues to dry at 100% humidity if the
temperature is high enough.
I saw a graph explaining all this somewhere. I didn't understand it but
it looked convincing :-)

AJH wrote:
On Sat, 24 Mar 2007 10:35:43 GMT, Stuart Noble
wrote:

Similarly, wood continues to dry at 100% humidity if the
temperature is high enough.

Yes but the temperature will have to be above the local boiling point
won't it?

Our wood dryer runs at 150C ;-)

AJH

I have never seen wood dry underwater, which IS 100% humidity..

AJH wrote:
On Sat, 24 Mar 2007 13:14:54 +0000, The Natural Philosopher
wrote:

I have never seen wood dry underwater, which IS 100% humidity..

No that's just wet, 100% humidity just means a sample of air cannot
hold any more water vapour,

No, that's 100% *relative* humidity.

a hot body of wood can still dry in 100%
humidity air if the water is boiled off.

Only by raising the air temprature so the local relative humidity is
LESS than 100%.


AJH

AJH wrote:
On Sat, 24 Mar 2007 16:43:14 +0000, The Natural Philosopher
wrote:

No that's just wet, 100% humidity just means a sample of air cannot
hold any more water vapour,
No, that's 100% *relative* humidity.

Yes, I should have specified RH but the fact it's given as a
percentage rather than grammes/m3 or grammes/kg implies that it's
relative rather than absolute.
a hot body of wood can still dry in 100%
humidity air if the water is boiled off.
Only by raising the air temprature so the local relative humidity is
LESS than 100%.

As long at the temperature is above the local boiling point then water
will leave it as vapour. This will occur at all humidity ratios of the
surrounding atmosphere.

The fact that the temperature is above the dew point means that the RH
IS LESS THAN 100%!!!

Boiling point has nowt to do with it.


AJH