Bauexperte
2014-09-22 13:48:04
- #1
Hello,
All forums have in common that at some point, discussion-wise, they drift into the micro range; in this case with the question parquet or carpet. In this topic, in my opinion, other factors must be considered than the question of whether physics yes/no or minimal additional efforts.
Here is an interesting text from an expert office in Koblenz:
**It is known that there are surface heating systems, which differ between warm water underfloor heating and electric underfloor heating. Furthermore, a distinction is made between underfloor direct heating and underfloor storage heating. The actual user of heated floor constructions, whether tenant or owner, is primarily interested in the economic aspects regarding energy consumption etc. For the user, it is essentially important that the surface heating systems are not too sluggish but heat the rooms relatively quickly to provide comfort and a feeling of coziness. In this regard, it plays a subordinate role for the consumer/user whether it concerns porcelain stoneware tiles, marble elements, textile or elastic floor coverings and/or a parquet layer/country house plank layer. The aforementioned floor coverings, including parquet, however, show very different linear thermal expansion coefficients that must indispensably be taken into account in heated constructions.
The floor damages predominantly detected in the past in the form of cracks and crack markings, including detachment joints, have decreased in the flooring industry because the planner and the specialist companies have complied with or taken into account the topic of "underfloor heating movement joints, edge joints/room joints, and field delimitation joints".
What damage patterns/manifestations within floor constructions/heated load distribution layers are known?
Referring to ceramic tiles/slabs including natural stone elements, marble slabs, and porcelain stoneware tiles, deformations, detachment joints, and coinciding cracks still occur depending on the geometry of the respective rooms and constraints/constrictions. Elastic and textile floor coverings either show dimensional changes/shrinkage or, due to "detachment joints" and/or cracks within the screed construction, "worm-like elevations" appear on the surface of the floor covering. Solid parquet and wooden block elements also show detachment joints and/or unusual joints within the wooden block/parquet surfaces at increased heat exposure. Multilayer parquet surfaces also form joints, but mostly surface layer delaminations and/or "dry cracks".
Underfloor heating/surface heating causes radiant heat
Due to radiant heat/radiant temperature, an excessive drying out occurs in both solid parquet and multilayer parquet, which causes not only "dry cracks" in multilayer parquet (within the surface layer lamella) but also deformations of the parquet elements and unusual joints within solid parquet surfaces. From expert activities, it is known that a large number of "dry cracks" and other parquet damages are caused by tenants/users additionally laying very thick tailored carpets on parquet surfaces. The author of this expert article has determined floor temperatures > 40 °C on the surface of parquet elements that were covered with carpets. The latter circumstance will repeatedly lead to parquet damages especially in the winter months due to the increased heat exposure/radiant heat on parquet surfaces beneath laid carpets.
How do courts rule in such damage cases?
The author of this expert article is aware of several court rulings where the court sided with the client/user because the contractor did not specially point out in the obligation to inform regarding a heated floor construction that the surface temperature/floor temperature must not exceed > 27 °C – 29 °C even with tailored carpets. The courts refer in this regard to the specialist companies and their obligation to inform.
Do such notices apply only to parquet surfaces?
Design floor covering manufacturers also write in their technical data sheet: "… suitable for underfloor heating, temperatures > 27 °C – 29 °C are not permitted."
In this case as well, the contractor has no influence on the conditions on site whether and to what extent the client/user additionally lays tailored carpets on design coverings. Radiation temperatures/heat loads of > 35 °C to 40 °C are common in this case. The definition/specification "suitable for underfloor heating" says nothing about whether or to what extent discolorations and/or color deviations occur due to heat load and/or dry cracks within a parquet layer. The statement "suitable for underfloor heating" relates predominantly only to the thermal resistance of a parquet layer/floor covering layer, which should not exceed the value of 0.17 m² K/W.
Heated floor constructions and relative humidity
Due to the higher surface temperatures on a heated screed, the humidity in the air layer directly adjacent to the floor changes. Such relationships can be calculated. With a room climate at a certain temperature to which a water vapor saturation pressure can be assigned, a water vapor partial pressure is established at a certain relative humidity. Since the water vapor partial pressure in a closed air volume remains constant, the relative humidity decreases depending on the water vapor saturation pressure at the floor surface.
It can be calculated that in heated screeds with a surface temperature of only 25 °C, the moisture content of the parquet material is reduced by about 2%, i.e., from e.g. 9% to a wood moisture of 7%. If, for example, surface temperatures of 29 °C on the screed or along the edges toward the window front of 35 °C are assumed, very low wood moisture levels result. Also, under today’s usual living conditions with temperatures significantly above 20 °C and humidity significantly below 50% relative humidity, a wood moisture of 7% is a value often undershot in practice, so that wood moisture below 5% in parquet woods on heated screeds is not uncommon, especially if the parquet surfaces/the woods are additionally covered with tailored carpets. From the aforementioned changed wood moisture results a shrinkage, i.e., a shrinkage process of the parquet woods.
In summary, it can be stated that wooden floors/parquet surfaces must not be covered with thick, dense carpets, i.e., tailored carpets, because besides the impermissible increase in thermal resistance, the temperature on the surface of the wooden floor/parquet surfaces is further excessively increased. An increased surface temperature is always associated with a reduction in humidity, which is why wooden floors/parquet surfaces on heated screeds that are covered with carpets get significant gaps underneath these carpets but also dry cracks, the aforementioned detachment joints as well as shearing of the surface layer lamellae in multilayer parquet.
More than ever, due to today’s case law and the described conditions, the contractor is obliged within the scope of his obligation to inform the client/user about the heat loads and their consequences in heated floor constructions. The aforesaid circumstance also applies to elastic floor coverings, especially design coverings, which tend to discolor under heat loads of > 29 °C.
Rhenish greetings
Smile, it could get worse ... I do it tooAlways this sarcasm here.
All forums have in common that at some point, discussion-wise, they drift into the micro range; in this case with the question parquet or carpet. In this topic, in my opinion, other factors must be considered than the question of whether physics yes/no or minimal additional efforts.
Here is an interesting text from an expert office in Koblenz:
**It is known that there are surface heating systems, which differ between warm water underfloor heating and electric underfloor heating. Furthermore, a distinction is made between underfloor direct heating and underfloor storage heating. The actual user of heated floor constructions, whether tenant or owner, is primarily interested in the economic aspects regarding energy consumption etc. For the user, it is essentially important that the surface heating systems are not too sluggish but heat the rooms relatively quickly to provide comfort and a feeling of coziness. In this regard, it plays a subordinate role for the consumer/user whether it concerns porcelain stoneware tiles, marble elements, textile or elastic floor coverings and/or a parquet layer/country house plank layer. The aforementioned floor coverings, including parquet, however, show very different linear thermal expansion coefficients that must indispensably be taken into account in heated constructions.
The floor damages predominantly detected in the past in the form of cracks and crack markings, including detachment joints, have decreased in the flooring industry because the planner and the specialist companies have complied with or taken into account the topic of "underfloor heating movement joints, edge joints/room joints, and field delimitation joints".
What damage patterns/manifestations within floor constructions/heated load distribution layers are known?
Referring to ceramic tiles/slabs including natural stone elements, marble slabs, and porcelain stoneware tiles, deformations, detachment joints, and coinciding cracks still occur depending on the geometry of the respective rooms and constraints/constrictions. Elastic and textile floor coverings either show dimensional changes/shrinkage or, due to "detachment joints" and/or cracks within the screed construction, "worm-like elevations" appear on the surface of the floor covering. Solid parquet and wooden block elements also show detachment joints and/or unusual joints within the wooden block/parquet surfaces at increased heat exposure. Multilayer parquet surfaces also form joints, but mostly surface layer delaminations and/or "dry cracks".
Underfloor heating/surface heating causes radiant heat
Due to radiant heat/radiant temperature, an excessive drying out occurs in both solid parquet and multilayer parquet, which causes not only "dry cracks" in multilayer parquet (within the surface layer lamella) but also deformations of the parquet elements and unusual joints within solid parquet surfaces. From expert activities, it is known that a large number of "dry cracks" and other parquet damages are caused by tenants/users additionally laying very thick tailored carpets on parquet surfaces. The author of this expert article has determined floor temperatures > 40 °C on the surface of parquet elements that were covered with carpets. The latter circumstance will repeatedly lead to parquet damages especially in the winter months due to the increased heat exposure/radiant heat on parquet surfaces beneath laid carpets.
How do courts rule in such damage cases?
The author of this expert article is aware of several court rulings where the court sided with the client/user because the contractor did not specially point out in the obligation to inform regarding a heated floor construction that the surface temperature/floor temperature must not exceed > 27 °C – 29 °C even with tailored carpets. The courts refer in this regard to the specialist companies and their obligation to inform.
Do such notices apply only to parquet surfaces?
Design floor covering manufacturers also write in their technical data sheet: "… suitable for underfloor heating, temperatures > 27 °C – 29 °C are not permitted."
In this case as well, the contractor has no influence on the conditions on site whether and to what extent the client/user additionally lays tailored carpets on design coverings. Radiation temperatures/heat loads of > 35 °C to 40 °C are common in this case. The definition/specification "suitable for underfloor heating" says nothing about whether or to what extent discolorations and/or color deviations occur due to heat load and/or dry cracks within a parquet layer. The statement "suitable for underfloor heating" relates predominantly only to the thermal resistance of a parquet layer/floor covering layer, which should not exceed the value of 0.17 m² K/W.
Heated floor constructions and relative humidity
Due to the higher surface temperatures on a heated screed, the humidity in the air layer directly adjacent to the floor changes. Such relationships can be calculated. With a room climate at a certain temperature to which a water vapor saturation pressure can be assigned, a water vapor partial pressure is established at a certain relative humidity. Since the water vapor partial pressure in a closed air volume remains constant, the relative humidity decreases depending on the water vapor saturation pressure at the floor surface.
It can be calculated that in heated screeds with a surface temperature of only 25 °C, the moisture content of the parquet material is reduced by about 2%, i.e., from e.g. 9% to a wood moisture of 7%. If, for example, surface temperatures of 29 °C on the screed or along the edges toward the window front of 35 °C are assumed, very low wood moisture levels result. Also, under today’s usual living conditions with temperatures significantly above 20 °C and humidity significantly below 50% relative humidity, a wood moisture of 7% is a value often undershot in practice, so that wood moisture below 5% in parquet woods on heated screeds is not uncommon, especially if the parquet surfaces/the woods are additionally covered with tailored carpets. From the aforementioned changed wood moisture results a shrinkage, i.e., a shrinkage process of the parquet woods.
In summary, it can be stated that wooden floors/parquet surfaces must not be covered with thick, dense carpets, i.e., tailored carpets, because besides the impermissible increase in thermal resistance, the temperature on the surface of the wooden floor/parquet surfaces is further excessively increased. An increased surface temperature is always associated with a reduction in humidity, which is why wooden floors/parquet surfaces on heated screeds that are covered with carpets get significant gaps underneath these carpets but also dry cracks, the aforementioned detachment joints as well as shearing of the surface layer lamellae in multilayer parquet.
More than ever, due to today’s case law and the described conditions, the contractor is obliged within the scope of his obligation to inform the client/user about the heat loads and their consequences in heated floor constructions. The aforesaid circumstance also applies to elastic floor coverings, especially design coverings, which tend to discolor under heat loads of > 29 °C.
I also have 2 monsters; an old diva (European Shorthair) and a youngster (Norwegian Forest/Ragdoll mix). Since both are allowed everywhere, I know the problem well and can therefore only recommend vacuuming the preferred resting places more often; otherwise, you won’t get a grip on the hair issueMy only concern now is pet hair. We have two Maine Coon cats. Carpet anyway?
Rhenish greetings