Sr. No.
|
POP ceiling
|
Aluminium ‘T’ ceiling
|
1.
|
Made
with GI frame work and POP tiles
|
Made
with Aluminium T framework and tiles [of either particleboard or fibreboard
or Thermocole or plastic sheets or POP or Mineral wool tiles] are just placed
in the frame work.
|
2.
|
Curved
profiles are possible & very common.
|
Curved
profiles are not possible.
|
3.
|
Cornices
are made easily.
|
Cornices
of this material are not possible.
|
4.
|
Relatively
heavy weight ceiling.
|
Very
light in weight with low density fiber or plastic or Thermocole or Phenotherm
tiles or Mineral wool tiles.
|
5.
|
Takes
relatively longer time for erection.
|
Takes
relatively short time for erection.
|
6.
|
Access
above the ceiling is virtually ruled out.
|
Access
above the ceiling after erection is easy & without damage.
|
7.
|
Can
develop cracks due to vibrations of the floor.
|
Cracks
cannot be developed since the tile fitment is loose.
|
8.
|
Much
cheaper than Al ‘T’ ceiling. Costs around Rs.
450=00
/Sq. Met.
|
Costlier
than POP ceiling. Costs around 750=00 Rs. / Sq. Met.
|
Interior Materials
Sunday 1 September 2013
Compare ‘POP ceiling’ with ‘Suspended Al T ceiling or modular ceiling’.
Saturday 31 August 2013
Explain seasoning of timber.
Timber contains water. Timber does require a definite percentage of water in it, in order to retain its fibers strongly adhered to each other.
Timber releases a part of this moisture in dry and hot atmosphere. And absorbs moisture in cold and humid conditions. This absorption and release, makes the timber bent, warped, shrunk or swollen etc. This change in the shape of a member can endanger the structure of which it is a part of.
It has been found that if the percentage of moisture is controlled to a certain level, there is a least transfer of water between the timber and the atmosphere. And thereby the structure is prevented from damaging or deforming. This percentage to be controlled depends upon tropical conditions where the timber is to be used.
Moisture
content = Weight of water in timber.
Timber releases a part of this moisture in dry and hot atmosphere. And absorbs moisture in cold and humid conditions. This absorption and release, makes the timber bent, warped, shrunk or swollen etc. This change in the shape of a member can endanger the structure of which it is a part of.
It has been found that if the percentage of moisture is controlled to a certain level, there is a least transfer of water between the timber and the atmosphere. And thereby the structure is prevented from damaging or deforming. This percentage to be controlled depends upon tropical conditions where the timber is to be used.
‘Controlling water
percentage in timber to an extent that least moisture transfers take place
between timber and environment, for the given ambient conditions’, is called as
‘Seasoning’.
Weight of dry timber.
Moisture
content in the felled tree is 50 %. The desired moisture content for timber in
Asian countries is between 10 to 20 %. For Mumbai, a humid place, it is 17 to
20%. For Nagpur, a dry place, it is 10 to 12%. And for Pune, a moderate place,
it is 14 to 16%.
In
order to control moisture in sawn timber sections, there are two methods:
1.
Natural
/ air seasoning method.
2.
Artificial
seasoning methods.
1. Natural / air seasoning method.
Swan timber sections
are stacked horizontally on a 30cm raised platform as shown. These are arranged
in layers one above other. The layers are separated by sound dry wood spacers.
Gap of about 50cm is kept between two adjoining members for free air
circulation. Roof covers the stack and the timber is not exposed to direct
sunlight or dew. The process
of seasoning is very slow & takes even upto 2 years. Capital cost and operating
costs are least in this method.
2) Artificial
seasoning:
There are various
methods of artificial seasoning as follows:
a)
Kiln
seasoning
b)
Chemical
seasoning
c)
Electrical
seasoning
d)
Water
seasoning
e)
Boiling
Brief information of
above methods is as under:
a) Kiln seasoning:
In this method, the
drying of timber is carried-out inside an airtight chamber or oven. Timber is
placed in such a way that free air circulates around. The steam is first forced
inside in order to control the termites. Then the temperature is raised and
maintained till the desired degree of moisture content is attained. The kiln
seasoning, though costly, gives well seasoned timber as it controls three
important conditions, namely, circulating air, humidity and temperature.
b) Chemical
seasoning: This is also known as the salt seasoning. In this the timber is
immersed in a solution of suitable salt. The salt is hygroscopic in nature and
attracts the water content of timber. This water is then wiped out by cloth.
But this method affects the elasticity and strength of wood.
c) Electrical
seasoning: In this method, the use is made of high frequency alternating
currents. The timber, when it is green, offers less resistance to the flow of
electric current. The resistance increases as the wood dries internally which
also results in the production of heat. This is the most rapid method of
seasoning. But the initial and maintenance costs are so high that it becomes
uneconomical to season timber on commercial base by this method.
d) Water seasoning:
In this method the timber is cut in suitable sizes and immersed wholly in
water, preferably in running water. The timber is taken out after 2 to 4 weeks.
During this period the sap contained in wood is washed away. Then the timber is
allowed to dry under a shed having free circulation of air. And the timber is
seasoned.
e] Boiling: In this
method the timber is immersed in water and then it is boiled. This is a very
quick method. The timber is boiled for three to four hours. Then it is dried
very slowly in shed. The periods of seasoning and shrinkage are reduced by this
method, but its affects the elasticity and Strength of wood. This method is
costly as compared to others.
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