[The Medway Handyman]

Sorry, I've been thinking again.

Deck boards supplied by the sheds are flat one side & grooved on the other,
the grooves being about half the surface area of the board.

I have 3 decking books, all published in the USA which show predominately
flat decking boards - rare to see a photo of grooved boards.

The idea of the groove I suppose is to make the board less slippery. It
would achieve that in part by keeping water off the surface & in the
grooves. However when the grooves fill with dirt, that advantage is lost.

On the other hand, the grooved surface means that only 50% of the surface
area of the board would be in contact with your foot at any one time,
whereas a plain board would have 100% contact.

So which has the higher slip resistance? And in what conditions?

P.S. My deck has been down since July 2000 and no one has ever slipped on
it - despite many drunken parties.


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257

[Mark]

On the other hand, the grooved surface means that only 50% of the surface
area of the board would be in contact with your foot at any one time,


Your foot would to some extent mould itself to the grooves and therefore
provide a mechanical grip as well as a friction grip.


mark

[Harry Bloomfield[_3_]]

It happens that mark formulated :
On the other hand, the grooved surface means that only 50% of the surface
area of the board would be in contact with your foot at any one time,


Your foot would to some extent mould itself to the grooves and therefore
provide a mechanical grip as well as a friction grip.

...and the grooves would provide somewhere for the water to be pushed
out of the way into - just like a normal road tyre versus a slick.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

[Bazza]

Harry Bloomfield wrote:
It happens that mark formulated :
On the other hand, the grooved surface means that only 50% of the
surface
area of the board would be in contact with your foot at any one time,


Your foot would to some extent mould itself to the grooves and
therefore provide a mechanical grip as well as a friction grip.

..and the grooves would provide somewhere for the water to be pushed out
of the way into - just like a normal road tyre versus a slick.

Sod all the slipping theory, now what about your drunken parties!!
sounds much more interesting.

[The Medway Handyman]

mark wrote:
On the other hand, the grooved surface means that only 50% of the
surface area of the board would be in contact with your foot at any
one time,


Your foot would to some extent mould itself to the grooves and
therefore provide a mechanical grip as well as a friction grip.

I can see that with bare feet, but shoes? Would a rubber sole be
pliable/soft enough? And what about if you are facing in the same direction
as the grooves?

Hmmm.


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257

[George]

"The Medway Handyman" wrote in message


P.S. My deck has been down since July 2000 and no one has ever slipped on
it - despite many drunken parties.



Perhaps its because you don't hold the parties when snow or ice is on the
ground.

[Frank Erskine]

On Mon, 24 Mar 2008 18:27:25 GMT, "The Medway Handyman"
wrote:

Sorry, I've been thinking again.

Deck boards supplied by the sheds are flat one side & grooved on the other,
the grooves being about half the surface area of the board.

I have 3 decking books, all published in the USA which show predominately
flat decking boards - rare to see a photo of grooved boards.

The idea of the groove I suppose is to make the board less slippery. It
would achieve that in part by keeping water off the surface & in the
grooves. However when the grooves fill with dirt, that advantage is lost.

On the other hand, the grooved surface means that only 50% of the surface
area of the board would be in contact with your foot at any one time,
whereas a plain board would have 100% contact.

Your weight is applied to 50% less area, so the pressure on the
contacted surface is doubled...

Also the ridges in the planks break up the surface tension of any
water lying there.

--
Frank Erskine

[The Medway Handyman]

Frank Erskine wrote:
On Mon, 24 Mar 2008 18:27:25 GMT, "The Medway Handyman"
wrote:

Sorry, I've been thinking again.

Deck boards supplied by the sheds are flat one side & grooved on the
other, the grooves being about half the surface area of the board.

I have 3 decking books, all published in the USA which show
predominately flat decking boards - rare to see a photo of grooved
boards.

The idea of the groove I suppose is to make the board less slippery.
It would achieve that in part by keeping water off the surface & in
the grooves. However when the grooves fill with dirt, that advantage
is lost.

On the other hand, the grooved surface means that only 50% of the
surface area of the board would be in contact with your foot at any
one time, whereas a plain board would have 100% contact.

Your weight is applied to 50% less area, so the pressure on the
contacted surface is doubled...

Yes, I can see that. So 50% higher pressure but 50% less contact area -
which is better for slip resistance?

Also the ridges in the planks break up the surface tension of any
water lying there.

Indeed. Good point.


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257

[The Medway Handyman]

Bazza wrote:
Harry Bloomfield wrote:
It happens that mark formulated :
On the other hand, the grooved surface means that only 50% of the
surface
area of the board would be in contact with your foot at any one
time,


Your foot would to some extent mould itself to the grooves and
therefore provide a mechanical grip as well as a friction grip.

..and the grooves would provide somewhere for the water to be pushed
out of the way into - just like a normal road tyre versus a slick.

Sod all the slipping theory, now what about your drunken parties!!
sounds much more interesting.

Thats what the deck was designed for - entertaining. I have two very
attractive daughters who invite their mates to our BBQ parties, so it often
sees 30+ people. Decking can cause hangovers :-)


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257

[Andy Champ]

The Medway Handyman wrote:
Bazza wrote:
Sod all the slipping theory, now what about your drunken parties!!
sounds much more interesting.

Thats what the deck was designed for - entertaining. I have two very
attractive daughters who invite their mates to our BBQ parties, so it often
sees 30+ people. Decking can cause hangovers :-)


Sod the parties, what about the daughters? :P

Andy







(It gets sad when you find your friend's daughters attractive. Perhaps
they'd like to meet my sons...)

[The Medway Handyman]

Andy Champ wrote:
The Medway Handyman wrote:
Bazza wrote:
Sod all the slipping theory, now what about your drunken parties!!
sounds much more interesting.

Thats what the deck was designed for - entertaining. I have two very
attractive daughters who invite their mates to our BBQ parties, so
it often sees 30+ people. Decking can cause hangovers :-)


Sod the parties, what about the daughters? :P

Andy

(It gets sad when you find your friend's daughters attractive. Perhaps
they'd like to meet my sons...)

Stunners the pair of them, both blue eyed blonds. Both with plenty of
attitude however :-)


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257

[Andy Dingley]

On 24 Mar, 22:37, "The Medway Handyman"
wrote:

Yes, I can see that. So 50% higher pressure but 50% less contact area -
which is better for slip resistance?

Friction increases with pressure, so it's somewhat inversely
proportional to the area. Grooves are thus good.

Although we all learn at school that "friction is _independent_ of
area", this is about as much use in practical methods as the "light
rods" and "inextensible string" used in all the other physics
experiments that fail to work in practice.

[somebody]

In message , Bazza
writes
Harry Bloomfield wrote:
It happens that mark formulated :
On the other hand, the grooved surface means that only 50% of the
surface
area of the board would be in contact with your foot at any one time,


Your foot would to some extent mould itself to the grooves and
therefore provide a mechanical grip as well as a friction grip.
..and the grooves would provide somewhere for the water to be pushed
out of the way into - just like a normal road tyre versus a slick.

Sod all the slipping theory, now what about your drunken parties!!
sounds much more interesting.

aol
yeah me too :-)
/aol

When, where? Should I bring my own beer?
--
Someone

[somebody]

In message , The Medway
Handyman writes
Bazza wrote:
Harry Bloomfield wrote:
It happens that mark formulated :
On the other hand, the grooved surface means that only 50% of the
surface
area of the board would be in contact with your foot at any one
time,


Your foot would to some extent mould itself to the grooves and
therefore provide a mechanical grip as well as a friction grip.

..and the grooves would provide somewhere for the water to be pushed
out of the way into - just like a normal road tyre versus a slick.

Sod all the slipping theory, now what about your drunken parties!!
sounds much more interesting.

Thats what the deck was designed for - entertaining. I have two very
attractive daughters who invite their mates to our BBQ parties, so it often
sees 30+ people. Decking can cause hangovers :-)


Forget my other post, it should have read...

aol
yeah me, me, me, me, me.... too too too too too too too
/aol


--
Someone

[The Natural Philosopher]

The Medway Handyman wrote:
Sorry, I've been thinking again.

Deck boards supplied by the sheds are flat one side & grooved on the other,
the grooves being about half the surface area of the board.

I have 3 decking books, all published in the USA which show predominately
flat decking boards - rare to see a photo of grooved boards.

The idea of the groove I suppose is to make the board less slippery. It
would achieve that in part by keeping water off the surface & in the
grooves. However when the grooves fill with dirt, that advantage is lost.

On the other hand, the grooved surface means that only 50% of the surface
area of the board would be in contact with your foot at any one time,
whereas a plain board would have 100% contact.

So which has the higher slip resistance? And in what conditions?


Why do cars not have slick tyres except on dry rcaing tracks?


P.S. My deck has been down since July 2000 and no one has ever slipped on
it - despite many drunken parties.

[[email protected]]

On 24 Mar, 18:27, "The Medway Handyman"
wrote:
Sorry, I've been thinking again.

Deck boards supplied by the sheds are flat one side & grooved on the other,
the grooves being about half the surface area of the board.

I have 3 decking books, all published in the USA which show predominately
flat decking boards - rare to see a photo of grooved boards.

The idea of the groove I suppose is to make the board less slippery. *It
would achieve that in part by keeping water off the surface & in the
grooves. However when the grooves fill with dirt, that advantage is lost.

On the other hand, the grooved surface means that only 50% of the surface
area of the board would be in contact with your foot at any one time,
whereas a plain board would have 100% contact.

So which has the higher slip resistance? *And in what conditions?

P.S. My deck has been down since July 2000 and no one has ever slipped on
it - despite many drunken parties.

--
Dave - The Medway Handymanwww.medwayhandyman.co.uk
01634 717930
07850 597257

The only deck I ever made was done with rough sawn tanalised timber.
No grooves etc. And not a slip to be had.

The comments later in the thread about surface area are right in a
sense, but when my (shoe-wearing) foot is down on rough sawn timber I
would imagine that there is a similar contact area as there is with
nicely planed grooved decking boards. My shoes have gaps in them, and
as the surface of the rough timber is, well, rough I don't imagine
more than 50% of the soles of my shoes are actually in contact with
the surface of the timber anyway.

Perhaps the grooves do have some benefit, certainly cross ways, but
I've found on several occassions (in public places too) that the
grooves which run length ways can be just as slippy as any flat,
smooth surface would have been in the same circumstances.

I think its more of a design thing; people like the grooved timber as
its "smarter" and timber companies like it because they can charge a
premium for it.

I'll be doing another deck in the next few months, and plain rough
sawn timber will be going down there too.

Matt

[Franko]

"The Medway Handyman" wrote in message
...
Sorry, I've been thinking again.

Deck boards supplied by the sheds are flat one side & grooved on the
other, the grooves being about half the surface area of the board.

I have 3 decking books, all published in the USA which show predominately
flat decking boards - rare to see a photo of grooved boards.

The idea of the groove I suppose is to make the board less slippery. It
would achieve that in part by keeping water off the surface & in the
grooves. However when the grooves fill with dirt, that advantage is lost.

On the other hand, the grooved surface means that only 50% of the surface
area of the board would be in contact with your foot at any one time,
whereas a plain board would have 100% contact.

So which has the higher slip resistance? And in what conditions?

P.S. My deck has been down since July 2000 and no one has ever slipped on
it - despite many drunken parties.


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257


I laid my deck was laid last year using grooved boards, when we had frosty
weather the decking was like a skating rink when walking with the grooves
but much firmer underfoot when walking across the grooves.
I get the impression that the grooves can give a false sense of security and
I will probably give it a coat of non slip paint this year.

Franko.

[Donwill]

"Franko" wrote in message
...
"The Medway Handyman" wrote in message
...
Sorry, I've been thinking again.

Deck boards supplied by the sheds are flat one side & grooved on the
other, the grooves being about half the surface area of the board.

I have 3 decking books, all published in the USA which show predominately
flat decking boards - rare to see a photo of grooved boards.

The idea of the groove I suppose is to make the board less slippery. It
would achieve that in part by keeping water off the surface & in the
grooves. However when the grooves fill with dirt, that advantage is lost.

On the other hand, the grooved surface means that only 50% of the surface
area of the board would be in contact with your foot at any one time,
whereas a plain board would have 100% contact.

So which has the higher slip resistance? And in what conditions?

P.S. My deck has been down since July 2000 and no one has ever slipped on
it - despite many drunken parties.


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257


I laid my deck was laid last year using grooved boards, when we had frosty
weather the decking was like a skating rink when walking with the grooves
but much firmer underfoot when walking across the grooves.
I get the impression that the grooves can give a false sense of security
and I will probably give it a coat of non slip paint this year.

Franko.
It would be safer to have the grooves going across the boards as well as
longitudinally making a checkerboard pattern. Are there any manufacturers
that make boards like that? I don't think I've seen any.
Maybe there are some clever people out there that can design some kind of
grooving machine to retrospectively groove the boards in situ.
Don

[Frank Erskine]

On Tue, 25 Mar 2008 15:58:52 -0000, "Donwill" popple @diddle .dot
wrote:


It would be safer to have the grooves going across the boards as well as
longitudinally making a checkerboard pattern.

That would seriously weaken the planks.

--
Frank Erskine

[Bob Mannix]

"Frank Erskine" wrote in message
...
On Tue, 25 Mar 2008 15:58:52 -0000, "Donwill" popple @diddle .dot
wrote:


It would be safer to have the grooves going across the boards as well as
longitudinally making a checkerboard pattern.

That would seriously weaken the planks.

--

Don't think it would as the depth is a small percentage of the total. Got me
thinking however - wouldn't it be better all round if the grooves were cut
at 45deg to the plank dimensions? That would give better grip if they were
laid herring-bone style, and they might look nicer too.


--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not)

[Martin Bonner]

On Mar 25, 12:12 am, "The Medway Handyman"
wrote:
Andy Champ wrote:
The Medway Handyman wrote:
Bazza wrote:
Sod all the slipping theory, now what about your drunken parties!!
sounds much more interesting.

Thats what the deck was designed for - entertaining. I have two very
attractive daughters who invite their mates to our BBQ parties, so
it often sees 30+ people. Decking can cause hangovers :-)

Sod the parties, what about the daughters? :P

Andy
(It gets sad when you find your friend's daughters attractive. Perhaps
they'd like to meet my sons...)

Stunners the pair of them, both blue eyed blonds.
This of course from a *totally* unbiased observer :-)

Both with plenty of attitude however :-)

That's not what worries me. It's the father with a van full of power
tools and experience in cutting people in half (and then making the
bits disappear) that worries me :-)

--
Dave - The Medway Handymanwww.medwayhandyman.co.uk
01634 717930
07850 597257

[Bob Mannix]

"Martin Bonner" wrote in message
...
On Mar 25, 12:12 am, "The Medway Handyman"
wrote:
Andy Champ wrote:
The Medway Handyman wrote:
Bazza wrote:
Sod all the slipping theory, now what about your drunken parties!!
sounds much more interesting.

Thats what the deck was designed for - entertaining. I have two very
attractive daughters who invite their mates to our BBQ parties, so
it often sees 30+ people. Decking can cause hangovers :-)

Sod the parties, what about the daughters? :P

Andy
(It gets sad when you find your friend's daughters attractive. Perhaps
they'd like to meet my sons...)

Stunners the pair of them, both blue eyed blonds.

/pedant mode on

It's blondes actually. The word is unique in the English language (I
believe) in being the only one in the language to take a gender ending
(blond for a male, blonde for a female)

I'll get me coat.......
/pedant mode off


--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not)

[Donwill]

"Bob Mannix" wrote in message
...

Don't think it would as the depth is a small percentage of the total. Got
me thinking however - wouldn't it be better all round if the grooves were
cut at 45deg to the plank dimensions? That would give better grip if they
were laid herring-bone style, and they might look nicer too.

Like the old blue grooved engineering bricks that were laid as a non slip
floor.
Don

[Rod]

Bob Mannix wrote:
snip

/pedant mode on

It's blondes actually. The word is unique in the English language (I
believe) in being the only one in the language to take a gender ending
(blond for a male, blonde for a female)

I'll get me coat.......
/pedant mode off


brunette/brunet ?

--
Rod

Hypothyroidism is a seriously debilitating condition with an insidious
onset.
Although common it frequently goes undiagnosed.
www.thyromind.info www.thyroiduk.org www.altsupportthyroid.org

[The Medway Handyman]

Bob Mannix wrote:


/pedant mode on

It's blondes actually. The word is unique in the English language (I
believe) in being the only one in the language to take a gender ending
(blond for a male, blonde for a female)

I'll get me coat.......
/pedant mode off

I stand corrected Bob. I am a wiser man. An interesting fact that. Don't
get me started on 'manageress'.


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257

[Tony Bryer]

On Tue, 25 Mar 2008 16:23:55 -0000 Bob Mannix wrote :
Don't think it would as the depth is a small percentage of the total.

Stiffness is a function of depth cubed, so changing it is significant.

The real problem of cross or diagonal grooving is that it would expose
a lot of end grain.

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk

[Andy Champ]

Andy Dingley wrote:
Friction increases with pressure, so it's somewhat inversely
proportional to the area. Grooves are thus good.

So why do fast cars have fat tyres, and in fact, racing cars have slicks?

The Natural Philosopher wrote:
Why do cars not have slick tyres except on dry rcaing tracks?

And on that one - because on a wet surface, you need to get rid of the
water before the tyre can touch the surface. Much easier to move it 1cm
to the nearest groove, than 10cm to the edge of the tyre.

Andy

[Andy Dingley]

On Tue, 25 Mar 2008 19:43:43 +0000, Andy Champ
wrote:

Andy Dingley wrote:
Friction increases with pressure, so it's somewhat inversely
proportional to the area. Grooves are thus good.

So why do fast cars have fat tyres, and in fact, racing cars have slicks?

Because under _those_ conditions, friction is somewhat proportional to
area (not inversely). However we're talking about wet wood here, not
dry rubber.

Really friction just doesn't have any simple relationship to anything.
Either do it empirically by measuring, or else just a much more
sophisticated model.

[dennis@home]

"Andy Dingley" wrote in message
...
On Tue, 25 Mar 2008 19:43:43 +0000, Andy Champ
wrote:

Andy Dingley wrote:
Friction increases with pressure, so it's somewhat inversely
proportional to the area. Grooves are thus good.

So why do fast cars have fat tyres, and in fact, racing cars have slicks?

Because under _those_ conditions, friction is somewhat proportional to
area (not inversely). However we're talking about wet wood here, not
dry rubber.

Not a lot to do with friction as such.. the tyres leave bits of themselves
all over the track.. so its not friction. You have less rubber so more wear
and less stiffness so less control if you cut blocks in the rubber like a
rain tyre.


Really friction just doesn't have any simple relationship to anything.

Friction is easy and has a known relationship.
Tyres are stiction.

Either do it empirically by measuring, or else just a much more
sophisticated model.

[The Medway Handyman]

"dennis@home" wrote in message
...


"Andy Dingley" wrote in message
...
On Tue, 25 Mar 2008 19:43:43 +0000, Andy Champ
wrote:

Andy Dingley wrote:
Friction increases with pressure, so it's somewhat inversely
proportional to the area. Grooves are thus good.

So why do fast cars have fat tyres, and in fact, racing cars have slicks?

Because under _those_ conditions, friction is somewhat proportional to
area (not inversely). However we're talking about wet wood here, not
dry rubber.

Not a lot to do with friction as such.. the tyres leave bits of themselves
all over the track.. so its not friction. You have less rubber so more
wear and less stiffness so less control if you cut blocks in the rubber
like a rain tyre.


Really friction just doesn't have any simple relationship to anything.

Friction is easy and has a known relationship.
Tyres are stiction.

What a great word! Stiction! Interesting article here
http://en.wikipedia.org/wiki/Stiction


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257