![Thanks](https://www.renovateforums.com.au/dbtech/thanks/images/thanks.png)
![Likes](https://www.renovateforums.com.au/dbtech/thanks/images/likes.png)
![Needs Pictures](https://www.woodworkforums.com/images/smilies/happy/photo4.gif)
![Picture(s) thanks](https://www.ubeaut.biz/wave.gif)
Results 1 to 15 of 18
Thread: Controlling timber movement
-
15th May 2006, 09:54 PM #1
Controlling timber movement
I've just been reading an article in "Australian Wood Review" titled "Why Wood Moves". It makes mention of using species with low unit shrinkage or shrinkage gradient, & so I am wondering if any of the experts out there have some kind of timber species reference that has this info. It would be very handy to know which species provide the best level of stability, particularly with a situation like T&G flooring.
"the bitterness of poor quality is remembered long after the sweetness of low price is forgotten"
-
15th May 2006, 10:14 PM #2
-
15th May 2006, 10:26 PM #3
Ceramic tiles.
-
16th May 2006, 10:28 AM #4
Most books on timber will list some properties, strength, density, hardness and shrinkage from green. The shrinkage is related to the stability, and is a percentage from green to 8 or 12% MC. The less srinkage then generally the more stable the wood. Also look at the difference between radial and tangential shrinkage, a large difference there is worse than just a high but even shrinkage.
So if you look at bluegum (E.saligna) it has shrinkage values of 7% (tan.) and 3.8% (rad.) Compare to Tassie blackwood at 2.7 and 1.3%.
So blackwood is more stable than bluegum. No surprise there
The other figures will let you compare hardness, strength and density.
You can look up a lot of the Aussie wood properties here.
http://www2.dpi.qld.gov.au/hardwoodsqld/7680.html
Cheers
Ian
-
16th May 2006, 10:56 AM #5
another rule of thumb could he to look at species that tool makers use. eg ebony, casurina, jarrah, rosewood etc.
eg colen clenton uses ebony and casurina - i understand he buys a "whole trees worth of casuria" and works his way thru it...
cheersZed
-
16th May 2006, 05:28 PM #6
G'day.
Unit of shrinkage.
mm movement per 1% moisture loss or gain.
Blackbutt = 0.3mm. This means that for every 1%moisture loss or gain, Blackbutt that has been Kiln dried will move .3mm per 1% moisture content change.
Thus BBT @ 12% manufacture 80mm cover width.
BBT @ 14% = 80.6mm cover width.
BBT= 0.3mm
S/Gum= 0.28mm
GIBK= 0.26mm
Blue Gum= 0.31mm
Rose Gum= 0.33mmHooroo.
Regards, Trevor
Grafton
-
16th May 2006, 06:05 PM #7
As usual, excellent info! Thanks all.
"the bitterness of poor quality is remembered long after the sweetness of low price is forgotten"
-
16th May 2006, 06:27 PM #8
TIMBER FLOOR CONTRACTOR
- Join Date
- May 2006
- Location
- sydney
- Age
- 65
- Posts
- 346
movement
Originally Posted by Carpenter
As a timber floor installer, over the years i have noticed that the softer woods seem to shrink more, however all timbers shrink . I should say that all timbers , and i am only refering to tongue and grove, will stabilise to its enviorment depending of the content of moisture in the air. In the buisness of ensuring that a floor wont shrink or expand out side its required working conditions, we need a E.M.C (equilibreim mosture content) to be in effect. All flooring should be kiln dried and arrive on site withn a content of moisture between 9 to 13 percent. Whilst on site, and stacked correctly over a period of about 2 weeks, E.M.C will be achieved. Prior to installation, consideration has to be given in regard to large glass surfaces that will have direct sun shining through it onto the floor for long periods of time. this factor will cause a kiln effect and dry that section of floor out and you will experence shrinkage confined to that area. The same may apply to areas that are exposed to heated areas caused by gas or elec heaters. In my opinion, all species a good to use, we have a rich source of textures and colours to choose from here in Australia, all you need to do is correctly install it with consideration to its working enviorment.
-
16th May 2006, 07:54 PM #9
Hammer Head
- Join Date
- Jan 2005
- Location
- Sydney
- Posts
- 191
What Larry saws is correct about acclimatization on site, but recently State Forest NSW (Charlie Herbart) has been saying that it is OK to install a floor that has been delivered as the new drying techniques ensure that the flooring is more stable and less likely to be effected by moisture.
Gapping of a floor is more like to happen in a wide board floor (ie 130mm / 180mm +) than a 80mm wide floor as the boards have a greater surface / face area to be effected thus change. Gapping also occurs when flooring is installed incorrectly ie no glue (polyurethane ONLY) or where the subsurface is incorrect.
My own house has 80mm brushbox which was installed correctly and has gapped but the reason is it is cooled in summer to 18deg then heated in winter to 25deg. Gaps are no big deal to me just part and part of having the floor and heat/cooling.
-
16th May 2006, 11:26 PM #10
G'day.
Yep.
We dry to suit insitu conditions with an EMC of 10%.
So, laying direct from the pack is fine, provided conditions are right.
If a floor is laid in a location that has a higher EMC, intermediate expansion gaps need to be left every 1000mm across a floor 6 metres or wider.
It takes a pro installer who can read conditions and make an educated guess as to the climatisation needs of the floor.
So many floor problems come from flybynight installers or builders who think floor laying is not important.
Even knowing what I know about timber flooring, I would not install a floor myself. I would get a pro to do it.Hooroo.
Regards, Trevor
Grafton
-
17th May 2006, 06:05 PM #11
This discussion indicates the importance of knowing the moisture content of you're timber, which leads me to another question; whats the best type of moisture meter? There are spike/probe units & I've seen one from Carbatec that uses some other method. Which one would give the most accurate indication of EMC - I'm supposing that the one which can measure deepest would give the best indication?
"the bitterness of poor quality is remembered long after the sweetness of low price is forgotten"
-
17th May 2006, 08:14 PM #12
TIMBER FLOOR CONTRACTOR
- Join Date
- May 2006
- Location
- sydney
- Age
- 65
- Posts
- 346
Originally Posted by Carpenter
-
17th May 2006, 08:20 PM #13
TIMBER FLOOR CONTRACTOR
- Join Date
- May 2006
- Location
- sydney
- Age
- 65
- Posts
- 346
Originally Posted by Carpenter
-
17th May 2006, 08:42 PM #14
TIMBER FLOOR CONTRACTOR
- Join Date
- May 2006
- Location
- sydney
- Age
- 65
- Posts
- 346
Here is something else for ya all....... when i know that the internal enviorment of a house or comercial office is going to be under constant refridgated air conditioning...... i will doa site conditioning of the tounge and grove in a refridgerated container.........................u see, airconditioners dry out the timber to much lower levels, down to nearly nothing some times. so it makes sence to gain emc to that air enviorment.i will also make sure the air con is on when installation takes place. The end result is a perfect floor no gapping . You dont even need expansion gaps. The floor stays permantly stable. You can go from cold to hot conditioning with out any adverse reactions. This is only achieveable when the floor is in a totally enclosed and a controlled conditioned site. Offices in big buildings are great for this. NO humidity, the only water is when some one spills a cup of coffe on the floor....
-
17th May 2006, 09:00 PM #15
Hammer Head
- Join Date
- Jan 2005
- Location
- Sydney
- Posts
- 191
Here is something else for ya all....... when i know that the internal enviorment of a house or comercial office is going to be under constant refridgated air conditioning...... i will doa site conditioning of the tounge and grove in a refridgerated container.........................u see, airconditioners dry out the timber to much lower levels, down to nearly nothing some times. so it makes sence to gain emc to that air enviorment.i will also make sure the air con is on when installation takes place. The end result is a perfect floor no gapping . You dont even need expansion gaps. The floor stays permantly stable. You can go from cold to hot conditioning with out any adverse reactions. This is only achieveable when the floor is in a totally enclosed and a controlled conditioned site. Offices in big buildings are great for this. NO humidity, the only water is when some one spills a cup of coffe on the floor....
A major Timber floor company in Sydney has a big flash show room with a wide board floor sure enough there is significant gapping of the floor due to AC (upto 3mm per row)
Today were laying a 6in floor in an extension it butt end on to a floor that was laid within last 5 yrs. when we lined the rows of boards up the first couple of rows matched no problem, but as went further across the opening the new floor was about 3mm out from the existing. This is because the existing floor had opened up over the last 5yrs. Result we laid the new floor with a small spacer so that the boards look like a continuous run dived by a 3mm flat bar,
Similar Threads
-
Deceptive timber
By Suresh in forum HAVE YOUR SAYReplies: 1Last Post: 17th September 2005, 12:42 AM -
Movement in timber floors when walking
By SJH747 in forum FLOORINGReplies: 5Last Post: 5th March 2004, 10:59 PM