What type of padding is best to put under Berber carpet?
Carpet Cushion or "padding" is just as important as the carpet
itself. There are various different types of materials used in
carpet cushion. Many years ago, natural fibres (horse hair etc)
were used to make a "felt" pad. Synthetic fibres are now used. Felt
is used typically were there is commercial traffic and a greater
need for sound/acoustic insulation. The large majority of carpet
cushion sold/used today is made from rebonded urethane foam chip
material. This rebonded (rebond) product combines both reclaimed
urethane chips from recycling old mattress/upholstery foam and new
(prime) urethane foam. This method is the most cost effective and
is scalable in both density and thickness. A moisture barrier is
attached to resist absorption of liquid spills penetrating through
the carpet. This underlayment (underlay) does a good job providing
support for all types of stretched installations. Many years ago a
composite material of clay & rubber was used to make carpet
cushion. This provided an extremely dense and low profile
underlayment (underlay). Unfortunately, the bonding of the clay and
rubber does not stay intact. Also, rubber tends to change its shape
as a result of environmental changes (humidity/temperature) modern
rubber underlayment (underlay) utilizes much more stable, closed
cell SBR rubber. However, a "waffle" texture to the surface of the
rubber padding can, add to the lack of a proper stretch if a power
stretcher is not used on larger room sizes. A special webbed layer
is attached to the top of rubber (and some rebond chip products) to
allow a "double-stik" installation method. This allows the carpet
to be glued directly to the surface of the underlayment (underlay)
and the underlayment glued (typically with a release adhesive)
directly to the substrate (concrete/plywood). There are now virgin
foam padding products available that are made from natural oils and
are closed cell construction (won't absorb moisture). These are
premium products that provide the very best in support for all
carpets; they also offer very good comfort. The principle density
ratings of carpet cushion is expressed by either pounds per cubic
foot or total weight of a square yard. the bare mininum density
found in rebond is typically a 4lb density. Contractors use this
quality as it offers a short term performance at minimal cost. The
flooring industry considers a 6lb or more density a "High Density"
product. Many manufacture's warranties are null & void without
this minimal density being used. There is also 7lb, 8lb,9lb and 10
lb carpet cushions in rebond chip products. Again, because the raw
material is taken from recycled foam, density can be inconsistant.
Rubber underlayment (underlay) is generally very high 18lb to 35lb
density. Rubber padding can also be made much thinner then rebond
chip because of this higher density. When using carpet cushion in a
stretched installation, the tack strips (smoothedge) that is
nailed/glued around the base of the room walls is typically 5/16"
high. The thickness of the underlayment (underlay) is almost
completely comfort related. Manufactures quite often offer various
thicknesses measured within 1/32" increments as this does effect
costs but most consumers would never be able to feel the
diffrerence between a 7/16" padding a 13/32" padding. Padding over
7/16" in thickness is not very installation-friendly as the
smoothedge is only 5/16" high and the carpet can "pull back" away
from the wall causing a loose fitted section. The same can be said
about padding thinner then 3/8" as the carpet is literally getting
"stretched" over the thickness of the padding "down" across the
5/16" smoothedge. Finally, there is another term of performance
regarding underlayment (underlay), the compression/recovery factor.
It simply means how resilent is the padding from onging traffic.
Rebonded chip padding tends to "compress" down in high traffic
areas; the lower the density the more this becomes apparent. SBR
rubber and virgin/prime urethane foams have very little compression
issues. The higher the density, the more "ridgid" the feel. The
thinner the padding the less "compression" happens. It is simply a
user-based decision. Carpet cleaning can cause the most problems if
excessive moisture is used with a padding that is not closed
cell.
