Screed, when used in
reference to underfloor heating, is the floor substrate that
surrounds the pipes that carry the heated water or electric
cable (depending upon the heating system being used) and
helps to efficiently transfer the heat throughout the floor
of a home.
proper screed can help to spread the heat more evenly throughout
the floor and thus the home. Typically, when installed in
structures with a slab floor, the base slab is poured first and
then the heating system is placed above that and the screed is
poured over the heat source and the slab. The finished floor is
applied over the screed.
Screed can also act as a leveling compound to
help level out imperfect slabs. Concrete and sand can be used as
screed for under floor heating. Many other proprietary types of
screed are available in the market today. The ideal floor screed
will not have any air voids that hamper the transmittal of thermal
energy from the heating system.
installing underfloor heating, the effect of heat on timber framing
or subfloors should be carefully considered. A rigid cement board
may need to be used as a screed. The effect of heat on some forms
of vinyl and laminate flooring should also be considered.
Definitely consult the manufacturer if in doubt. Using a heavy
carpet and/or a heavy carpet pad may restrict heat output of the
heating system. Be sure to consider the advantages and
disadvantages of all types of flooring when using underfloor
Underfloor heating provides a superior
level of warmth over a forced air heating unit.
The proper screed helps to transmit heat
throughout the floor and warms the home from the floor up. No air
registers are mounted at the base of the walls so the placement of
furniture in the home is not restricted. Floors in areas that can
become damp, such as kitchens or bathrooms, dry much quicker
because the heat is directly under the flooring.
Underfloor Heating Screed
Underfloor heating does have
some disadvantages. It warms up the room rather slowly, especially when compared to
its forced air counterpart.
Cabinets or dressers should
not be placed over underfloor heated areas. In a kitchen or bathroom this isn’t so
much of an issue because the base cabinets are typically fixed.
In other rooms it becomes an
issue because furnishings such as dressers and bureaus can be moved around. When
heat is directly under dressers or cabinetry, it can cause condensation issues
leading to mold and mildew problems.
Even with the proper floor
screed, keeping pipes from freezing in an underfloor heating system is a high
priority. Frozen pipes can burst causing untold amounts of water
Many homeowners have an
alternative source of energy to keep the pump running in the event of a power
outage such as a generator. Other homeowners use alternate forms of heat such
as wood stoves, wood burners, coal burners or kerosene heaters in case of power
Some water based heating
systems can use antifreeze in the system to keep the water from
There are numerous suppliers of water underfloor heating systems and we
are not here to recommend one supplier over another. Instead we want to give you the
independant facts to help you make up your own mind based on your own individual needs.