Monocoque
fibreglass swimming pools
What are they?
They are made in one piece
in a factory.
The factory shop floor will
have a number of male moulds set down on the floor so that
the pool is made upside down.
The Manufacturing Process
The process is as follows:-
1. The male mould is cleaned
up
2. One or several layers of gel coat are sprayed onto the
male mold and allowed to cure (Dry). This becomes the hard
surface of the pool that you walk on.
3. The main waterproofing layer is sprayed onto the male
mold over the gel coats - this is what stops the water
from attacking the fibreglass structure. The fibreglass
structure is very vulnerable to moisture and so if this
layer fails the structure will deteriorate. Some manufacturers
do not even bother with the waterproofing layer but just
rely on the gel coat.
4. The fibreglass matting is then applied and covered with
resin. Reinforcing strips of light timber like balsa wood
or lightweight plastic strips are often used to stiffen
the pool sides and connect up the lifting points etc.
5. The whole pool is allowed to cure for the requisite
period.
6. The finished pool is lifted off the mould and the process
starts again.
The main problems with Fibreglass
pools arise from lack of expertise and poor quality control.
There are manufacturers that make an excellent product
and many more that do not.
Fibreglass Roman Steps
Some readers are probably
wondering about fibreglass roman steps that are for sale
in every French pool shop and that are often used by artisan
pool builders that use concrete blocks to build their pools.
It is probable that quality control on the production of
fibreglass steps is even less stringent than for whole
swimming pools.
Moreover the steps are highly
loaded by the water inside the pool at the junction between
the steps and the walls - and this is where the ends of
the fibreglass strands are normally exposed and subject
to moisture that travels along the strands deep into the
structure of the steps. The pool structure is also weakest
at this point.
When the fibreglass gets wet
it just deteriorates into a soggy mess. The only thing
that protects the fibreglass is the very hard gel coat
that eventually suffers from microscopic cracking. As soon
as this happens the water gets into the vulnerable fibreglass
backing and deterioration is then quite rapid. This happens
very frequently with fibreglass boats where it is mistakenly
known as "osmosis".
I expect that everyone with
a fibreglass pool or roman end will be very unhappy with
their pool in 5 to 10 years time. All fibreglass is susceptible
but it is true that very high standards of manufacture
under strictly controlled conditions following Lloyds Register
of Shipping Specifications for Marine Applications will
allow both pools and roman steps to last much longer -
but I wonder how many French fibreglass manufacturers do
this?
Fibreglass Pools - Summary
Cost - Low to medium
Advantages
Disadvantages
- Highly prone to manufacturing
defects because the pool should be made in a factory
with controlled humidity and temperature. Defects will
not be immediately apparent because they manifest themselves
through osmosis where the water in the fibre-glass moves
to the surface causing osmotic blisters within a few
years. In 5 years the pool could look terrible and you
will not get much help if you claim on your pool installer
- he will be long gone. Many cheap fibre-glass yachts
suffer from the same defect and it is all caused by lack
of temperature and humidity control in the factory.
- Prone to damage during
transport and installation because of the size of the
unit - may need a very large crane or even a helicopter
to get them into the required location.
- Most have a maximum life
of 10 years and surface deterioration in less than 10
years - very high quality units with strict quality control
may provide a much longer guarantee - so look out for
these!
- Can "POP" out
of ground if the ground water at your property reaches
the ground surface and the pool water is held at mid-point
of the skimmers where it should be. In this instance
the net flotation force is at least 150 kg per square
metre of pool or about 11 tonnes - much more than the
weight of the fibre-glass shell
- Are highly unsuitable for
swelling clay soils that can just push the sides of the
pool in.
- The sizes quoted are misleading
because the suppliers quote the external area of the
whole unit - the actual swimming area is about 20% less
in an 8 x 4 pool
- Often sold by fly by night
firms - make sure that your supplier has been in business
for at least 5 years at his current business address.
Normally they pack up business and move on when the level
of complaints and the local grapevine reduces their sales!
- Choice of colour is very
limited and colours are dull and lifeless. Friezes cannot
be provided around the top of the pool and it is the
frieze that really makes a pool look good.
- Often provided with inadequate
filtration systems providing a full water change in 24
hours and not the 6 to 8 hours that is required to guarantee
water quality.
I can hear some of you thinking
- this is all bullshit - I have never heard of such problems
with fibreglass pools.
The Australian Fibre-glass
Experience
If you are thinking in this
way just type "fibreglass pool repairs Australia"
into Google.
Evidently such pools have
been popular in Australia for a lot longer than in Europe
and now there are dozens of firms that do nothing but repair
fibreglass pools. When these repairs are made the old gel
coat is taken off and the fibreglass structure is repaired
and then the whole pool is coated with an epoxy resin.
Epoxy resins are a lot more expensive than polyester resin
and this often causes the repair costs to be higher than
the original pool cost.
One last point about fibreglass
pools - if you read the small print on the contract it
will probably say that "The pool should never be emptied
and if you must do so then get the pool installer to do
it"
This is because more and more
fibreglass pools are "POPPING" out of the ground.
Just bear in mind that every pools will need to be emptied
a few times in its life for all kinds of different reasons.
Having one that you cannot empty is preposterous!
In the 1990's UFI Pools Limited
made about 450 fibreglass pools in NEW South Wales, Australia,
that have all had to be repaired by the NSW because of
Australian law. The laws in France do not operate on this
basis.
|
