Flooring underlayment

A flooring underlayment comprises a membrane that includes a body panel having a panel top surface and a panel underside surface spaced apart from the panel top surface by a panel thickness. The membrane further includes a plurality of dimples projecting downward from the panel underside surface, each dimple having a dimple upper end open to the panel top surface, a closed dimple lower end spaced apart from the dimple upper end by a dimple height, and a dimple sidewall extending between the dimple upper end and the dimple lower end, the dimple sidewall configured to inhibit collapse of the dimple height when a load is applied to the flooring underlayment during use. The membrane includes a plurality of grooves open to the panel top surface and formed within a groove body projecting downward from the panel underside surface, each groove shaped to receive an elongated heating element therein.

FIELD

The specification relates generally to flooring, and, more specifically, to flooring underlayment for heated floors.

BACKGROUND

U.S. Pat. No. 6,434,901 (Schluter) purports to disclose a support and/or drainage plate made of a foil-like plastic material, for use with a plate-lined floor structure or a wall so as to create a space between the ground and the surface lining to be applied onto the foil-like plate. Schlüter purports to disclose that the structure of the plate is such that cavities are created by means of, on the one side, projections extending substantially in one direction and, on the other side, raised areas at the same level between which chambers are embodied for receiving a hardening contact medium, such as mortar or adhesive, which forms a contact layer with the surface lining to be applied. Schlüter also purports to disclose that the structure consists of projections (N1, N2) or (51, S2) which extend in at least two directions and intersect, and that the resulting chambers (M1) are delimited in their circumference by the projections (S1, S2), which are open towards the other side of the plate.

U.S. Pat. No. 9,328,520 (Kriser) purports to disclose a flexible membrane defining pathways for receiving a flexible conduit, and further defining attachment regions between the pathways formed with overhanging walls. Kriser purports to disclose that the membrane may be vacuum-formed plastic sheet material and that the flexible conduits may conduct electricity or heat transfer fluids. Kriser also purports to disclose that the overhanging walls in the attachment regions may provide improved vertical attachment strength to a rigid planar substrate placed over a mortar filled into the attachment regions.

United States Patent App. Pub. No. 2022/0146118 (Schluter) purports to disclose an uncoupling mat that include a flexible layer made of a film-like plastic with structuring that define indentations provided with undercuts on a first, top side and a series of annular cavities formed on an opposite second, bottom side. Schluter purports to disclose that the annular cavities on the bottom side each define a recess on the first side, the indentations have a cross-section adapted to receive a heating cable therein such that the cable can be held in position by the indentations, and a plurality of weakening zones each extends between two rows of annular cavities in a straight line to allow the plastic layer to move substantially transversely to the direction of extension of the weakening zones.

SUMMARY

The following summary is intended to introduce the reader to various aspects of the applicant's teaching, but not to define any invention.

According to some aspects, a flooring underlayment comprises a membrane. The membrane includes a body panel having a panel top surface and a panel underside surface spaced apart from the panel top surface by a panel thickness, the panel top surface and panel bottom surface oriented generally horizontally when in use. The membrane further includes a plurality of discrete dimples projecting downward from the panel underside surface, each dimple having a dimple upper end open to the panel top surface, a closed dimple lower end spaced apart from the dimple upper end by a dimple height, and a dimple sidewall extending between the dimple upper end and the dimple lower end, the dimple sidewall configured to inhibit collapse of the dimple height when a load is applied to the flooring underlayment during use. In addition, the membrane includes a plurality of grooves open to the panel top surface and formed within a groove body projecting downward from the panel underside surface, each groove shaped to receive an elongated heating element therein.

In some examples of the flooring underlayment, when viewed in vertical cross-section, each dimple sidewall extends generally linearly along at least most of the dimple height and is oriented at a sidewall angle of between about 80 degrees and 100 degrees relative to the panel underside surface laterally outward of the dimple sidewall. In some examples, the sidewall angle is less than 90 degrees to provide a negative draft angle along the sidewall for facilitating interlocking engagement between the membrane and cured mortar received therein.

In some examples, when viewed in horizontal cross-section, each dimple sidewall is shaped as a circular annulus. In some examples, each dimple sidewall has a dimple sidewall thickness that is generally equal to the panel thickness.

In some examples, each groove body includes a groove end wall spaced from the panel underside surface by a groove height, and groove sidewalls extending from the panel underside surface to the groove end wall. In some examples, the groove end wall and groove sidewalls each have a groove wall thickness that is generally equal to the panel thickness. In some examples, the groove sidewalls and end wall of each groove are generally of concave arcuate shape when viewed in cross-section.

In some examples, the groove height is less than the dimple height, wherein a ventilation gap is provided below the groove bodies and an underlying surface to facilitate ventilation below the panel underside surface and around adjacent ones of the plurality of dimples. In some examples, the groove height is in a range from about 30 percent of the dimple height to about 90 percent of the dimple height. In some examples, the dimple height is in a range from about 3 mm to about 10 mm, and the groove height is in a range from about 1 mm to about 9 mm. In some examples, the dimple height is in a range from about 4 mm to about 8 mm, and the groove height is in a range from about 2 mm to about 6 mm

In some examples, the dimple lower end is closed by a dimple end wall, and the flooring underlayment further includes a fabric sheet releasably adhered to the end walls of the dimples, and the underlayment comprising a continuous ventilation chamber extending laterally around exteriors of adjacent dimples and vertically between the body panel and the fabric sheet.

According to some aspects, a flooring underlayment includes a thermoformed membrane and a fabric sheet releasably adhered to the membrane. The membrane includes a panel having a panel top surface for supporting a finished flooring material and a panel underside surface opposite the panel top surface. The membrane further includes a plurality of dimples projecting from the panel underside surface, each dimple having a closed dimple lower end spaced apart from the panel underside surface by a dimple height. The membrane also includes a plurality of grooves open to the top surface for receiving at least a portion of an elongated heating element therein, each groove formed within a groove body projecting from the panel underside surface, the groove body having a closed groove lower end spaced apart from the panel underside surface by a groove height that is between 30 percent and 90 percent of the dimple height. The fabric sheet has an upper surface releasably adhered to the dimple lower ends of the plurality of dimples by respective frangible bonds. The fabric sheet has a lower surface for anchoring in a layer of adhesive mortar applied to a subfloor surface. The frangible bonds facilitate decoupling of the membrane from the fabric sheet after installation to isolate the finished flooring material from reaction forces exerted between the subfloor and the membrane.

In some examples, the dimples are arranged in a matrix of rows and columns, and the groove bodies extend in straight lines spaced apart from the dimples. In some examples, a ventilation gap is provided between a lowermost surface of each groove body and the upper surface of the fabric sheet, the ventilation gap beneath each of the plurality of groove bodies providing fluid communication between space around adjacent dimples on either side of each groove body for facilitating evacuation of moisture from beneath the membrane. In some examples, the flooring underlayment further includes a heating element in the form of an electrical heating cable inserted in portions of at least some of the plurality of grooves.

According to some aspects, a method of installing flooring includes (a) applying a first adhesive mortar layer to a subfloor surface, and (b) laying a flooring underlayment on the first adhesive mortar layer, the flooring underlayment including a fabric sheet releasably secured to closed ends of dimples projecting downward from a panel underside surface of a membrane body panel, the laying step including anchoring a lower surface of the fabric sheet in the adhesive mortar first layer, the dimples having dimple sidewalls defining a dimple height and holding the membrane body panel above the fabric sheet. The method also includes (c) installing an electrical heating cable in a groove of the membrane, the groove open to an upper surface of the membrane body panel and formed within a groove body projecting from the panel underside surface, the groove body having a closed groove lower end spaced apart from the panel underside surface by a groove height that is between 30 percent and 90 percent of the dimple height wherein a ventilation gap is provided beneath a lowermost surface of the groove body and an upper surface of the fabric sheet.

In some examples, the method includes, after step c), applying an adhesive mortar second layer onto the upper surface of the membrane body panel, the adhesive mortar second layer filling interior spaces of the dimples and grooves, and encasing and covering the electrical heating cable. In some examples, the method includes installing a finished flooring material over the adhesive mortar second layer. In some examples, the method includes activating the electrical heating cable and ventilating the space beneath the membrane body panel via the ventilation gap to facilitate removal of moisture from beneath the membrane.

DETAILED DESCRIPTION

Referring toFIGS.1and2, an example underlayment100is shown. The underlayment100can be used as a flooring underlayment installed between a base surface (e.g. a subfloor) and a finished flooring material (e.g. ceramic tile). When used in a flooring system, the underlayment100spaces the finished flooring material above the base surface, and can help provide a thermal break between the base surface and the finished flooring material, and dampen noise and/or vibration. The underlayment100further operates to provide ventilation underneath the finished flooring material and above the base surface, which can facilitate evacuation of any water or moisture that might otherwise collect between the base surface and flooring material, and the evacuation of which can help prevent moisture damage and microbial growth (e.g. mold). In addition, in some examples the membrane100can decouple the finished flooring material from the base surface, so that reaction forces exerted by the base surface (for example, due to shifting, settling, or thermal expansion and contraction of the base surface) are not transferred or not fully transferred to the finished flooring material. This can help prevent damage to the finished flooring material, including cracking of the finished flooring material or loosening of the finished flooring material from the installed flooring system.

Referring now toFIGS.3and4, the underlayment100is installed between flooring material102and a base layer104. In some examples, the base layer104is a sub-floor such as a layer of wood or concrete. In some examples, the flooring material102is a finished flooring material such as carpet, hardwood, laminate, or vinyl, or tile. In the example illustrated, the flooring material102is a finished flooring material in the form of ceramic tile.

Referring again toFIGS.3and4, in the example illustrated, the underlayment100is used with an adhesive mortar first layer106and an adhesive mortar second layer108. The adhesive mortar may be, for example, a thin-set mortar or epoxy mortar. The adhesive mortar first layer106is provided between the underlayment100and the base layer104. The adhesive mortar first layer106provides support for the underlayment100and flooring material102, and may adhere the underlayment100to the base layer104, at least during installation of the flooring system.

The adhesive mortar second layer108is provided between the underlayment100and the flooring material102. The adhesive mortar second layer108provides further support for the flooring material102, and in the example illustrated, adheres the flooring material102in fixed position to the underlayment100.

In the example illustrated, the underlayment100includes a dimpled membrane140and a fabric sheet260that is releasably bonded to a bottom exterior surface of the dimpled membrane with a frangible bond. In some examples, the flooring system110may include one or more additional layers between the flooring material102and the base layer104.

In the example illustrated, the underlayment100is configured to be used with an optional heating element120to warm the finished flooring. The heating element120can include any heat transferring element, such as, for example, an electrical heating cable or a fluid conduit for conveying a heated fluid. In the example illustrated, the underlayment100is configured for use with a heating element in the form of a heating cable122. Using a heating cable122as the heating element can offer advantages over other heating elements, for example, ease of installation and minimum space requirements. In the example illustrated, the heating cable122is sized to have a relatively small diameter124which can help provide a modest overall height of flooring system110.

Referring again toFIGS.1and2, the membrane140of the underlayment100is generally formed of a moisture impermeable polymeric material. In some examples, the membrane140is formed of a thermoplastic elastomer. In some examples, the membrane140is made from a plastic or composite such as polyethylene, high-density polyethylene, and/or polypropylene. In the example illustrated, the membrane140is of integral, unitary, one-piece construction.

The membrane140includes a body panel150that has a generally planar panel top surface152and a generally planar panel underside surface154spaced apart from the panel top surface154by a panel thickness155(FIG.5). When in use, the panel top surface152is directed upward toward the flooring material102, and the panel underside surface154is directed downward toward the base layer104(FIG.3).

Referring still toFIGS.1and2, the body panel150has a longitudinal axis156extending between a panel front end158and a panel rear end160opposite the front end158. The body panel150also has a transverse axis162perpendicular to the longitudinal axis156and extending between a panel first lateral end164and a panel second lateral end166opposite the first lateral end164.

The membrane140further includes a plurality of discrete dimples170projecting from the underside surface154of the panel150. The dimples170are configured to support the body panel150above an underlying surface. For example, when the underlayment100is positioned for use on the adhesive mortar first layer106, the dimples170hold the body panel150of the membrane140above the mortar first layer106.

With reference again toFIGS.1and2, the dimples170are discrete elements spaced apart from one another and, in the example illustrated, arranged in a matrix of rows (parallel to axis162) and columns (parallel to axis156). Each dimple170has a dimple upper end170athat is open to, and coplanar with, the top surface152of the body panel, and a dimple lower end170bspaced vertically below the upper end170aby a dimple height172In the example illustrated, the dimple lower end170bof each dimple170is closed by a dimple end wall190having an end wall inner surface190adirected toward a dimple interior188of the dimple170, and an end wall outer surface190bopposite the end wall inner surface190a. In the example illustrated, each dimple end wall190has an end wall thickness191(FIG.5) that extends between the end wall inner surface190aand the end wall outer surface190b. The end wall thickness191of the dimple end wall190of each dimple170is, in the example illustrated, generally equal to the panel thickness155.

Each dimple170, in the example illustrated, has an upper peripheral edge194generally circumscribing the upper open end170aof the dimple170. The upper edge194is proximate the body panel150. In the example illustrated, the body panel150generally extends horizontally between the upper edges194of the dimples170when the membrane140is installed.

Each dimple further includes, in the example illustrated, a dimple sidewall192that extends between a periphery of the dimple upper end170aand a periphery of the dimple lower end170b. The dimple sidewall192is configured to inhibit collapse of the dimple height172(e.g. vertical collapse of the dimple) when a load is applied to the underlayment during use. Configuring the dimple sidewalls to be generally straight (linear) along their vertical extent, and oriented parallel to, or near-parallel to, the vertical when in use can facilitate inhibiting collapse of the dimple height172. More particularly, good resistance to collapse has been achieved with dimple sidewalls192oriented within about 10 degrees of vertical.

In the example illustrated, each dimple sidewall192has a sidewall thickness196(FIG.5) that extends between a sidewall inner surface192adirected toward the dimple interior188and a sidewall outer surface192bopposite the sidewall inner surface192a. The sidewall thickness196of the dimple sidewall192of each dimple170is, in the example illustrated, generally equal to the panel thickness155.

In the example illustrated, when viewed in vertical cross-section, each dimple sidewall192extends generally linearly along at least most of the dimple height172(and almost the entire dimple height172in the example illustrated) and is oriented at a sidewall angle174(FIG.5) of between about 80 degrees and 100 degrees relative to the panel underside surface154laterally outward of the dimple sidewall. The panel150and its underside surface154are, in the example illustrated, configured to lie in a generally horizontal plane when installed for use, so that a sidewall angle174within about 10 degrees of perpendicular to the panel underside surface results in a sidewall that is oriented within about 10 degrees of vertical.

Furthermore, in the example illustrated, the sidewall angle174is optionally less than 90 degrees to provide a negative draft angle along the sidewall192for facilitating interlocking engagement between the membrane and cured mortar received therein. More particularly, in the example illustrated, the dimple sidewall angle172is about 85 degrees, providing a reverse taper such that a dimple lower width200(FIG.4) extending between opposed sidewall surfaces proximate the dimple lower end170bis greater than a dimple upper width198(FIG.4) of the dimple170proximate the dimple upper end170a(FIG.4). This can provide an undercut in which adhesive mortar inside the dimple interior188is overlapped above by a portion of the membrane140. Such an undercut can help to lock the adhesive mortar second layer108(once cured) and the membrane140together, and in particular, can inhibit vertical movement of the membrane140relative to the adhesive mortar second layer108.

The dimples170are, in the example illustrated, generally circular when viewed along a vertical axis (or e.g., generally circular in cross-section taken in a plane parallel to the panel top surface152). A circular cross-section can help avoid trapping air inside the dimple when the dimple fills with adhesive mortar during application of the adhesive mortar second layer108. Mare particularly, in the example illustrated, each dimple170sidewall192has the shape of a circular annulus extending radially between the sidewall inner surface192aand the sidewall outer surface192b. The sidewall192extends continuously about (or encircles) the dimple interior188.

In the example illustrated, the membrane102including the body panel150and dimples170is of one-piece, unitary, integral construction. An open ventilation space180is formed below the panel underside surface154and around the sidewall outer surfaces192bof the dimple sidewalls192of each dimple170.

Referring again toFIGS.3to5, when the membrane140rests on an underlying surface with the dimples170in contact with the underlying surface, a continuous chamber182is formed between the underside surface156of the panel150and the underlying surface. The chamber182is generally defined by all of the open spaces180around the exterior of each dimple being in fluid communication with one another. The chamber182facilitates moisture movement below the underside surface154of the panel150.

As mentioned previously, the membrane140further includes grooves130configured to receive a heating element therein. In the example illustrated, each groove130is open to the top surface152of the body panel150. In the example illustrated, each groove130presents an elongate concave arcuate depression sized to receive a heating cable122of the heating element120.

In the example illustrated, the grooves130extend linearly along the length and width of the membrane between adjacent dimples170, forming a gridwork of grooves130and delineating the dimples170into respective rows and columns. The plurality of grooves130intersect one another and open laterally into one another at the points of intersection. An elongated heating element120may be installed along portions of multiple ones of the grooves130by bending the heating element120at one or more points of intersection of the grooves130to change between row-oriented grooves and a column-oriented grooves.

In the example illustrated, each groove130is formed within a groove body240that projects downwardly from the underside surface154of the body panel150(FIG.5). The groove body240is integrally formed with the membrane140and includes one or more groove walls each having a groove wall thickness that is equal to the panel thickness and the dimple sidewall thickness. In the example illustrated, the cross-sectional thickness of the membrane material is generally uniform throughout the membrane. In the example illustrated, the groove body240(and groove walls thereof) includes a groove end wall242spaced from the underside surface154by a groove height250, and groove side walls244extending from the panel underside surface154to the groove end wall242. In the example illustrated, the groove end wall242and groove side walls244form a generally continuous arcuate portion of a circle when viewed in cross-section.

In the example illustrated, inner surfaces of the groove end wall242and groove side walls244partially bound a groove interior246of the groove130. In the example illustrated, an inner surface of the groove end wall242defines a groove floor portion220of the groove130, and inner surface of the opposed groove side walls244define groove side portions222of the groove130.

Each groove130further includes a groove mouth224that is open to the panel top surface154. The groove depth250is sized to receive at least half of the width (or diameter)124(FIG.4) of the heating element120to facilitate preventing undesired movement of the heating element out of the grooves. In some examples, an upper portion of the heating element120may protrude upward above the top surface152of the body panel150, projecting through the mouth224. Any upwardly protruding portion of the heating element would subsequently be covered by, and embedded within, the adhesive mortar second layer108.

Referring again toFIG.5, in some examples, the groove130is provided with one or more retaining elements proximate the mouth of the groove to help retain the heating element in position in the groove130. In the example illustrated, the groove130is provided with laterally inwardly directed protrusions230a,230bat upper edges of the groove side walls244, formed by converging portions of the groove side walls244. The opposed protrusions230a,230bprovide a narrowed width230of the mouth224of the groove130(proximate the groove upper end226) that is narrower than a largest width228of the groove130at a position below the mouth224. The largest groove width228is sized to snugly receive the diameter124of the heating cable122. In use, an installer can push the heating element120through the mouth224of the groove130, temporarily urging the protrusions230a,230bapart for snap-fit assembly of the heating element into the groove130. Once installed the protrusions230a,230breturn at least partially toward their relaxed position (defining the narrowed width230) under the biasing force of the resiliently flexible groove sidewalls244.

In the example illustrated, the grove height250of the grooves130is less than the dimple height172, providing a ventilation gap below the groove bodies240and above an upward facing surface of material underlying the membrane to facilitate ventilation of the space underneath the body panel150and around the exterior surface of adjacent dimples170.

In some examples, a preferred groove height is in a range from about 30 percent of the dimple height to about 90 percent of the dimple height. In some examples, a preferred dimple height is in a range from about 3 mm to about 10 mm, and a preferred groove height is in a range from about 1 mm to about 9 mm. In the example illustrated, the dimple height172is about 8 mm and the groove height250is about 5 mm, providing a ventilation gap height of about 3 mm. The heating cable122, in the example illustrated, has a dimeter124of about 6 mm.

In use, the heating element120can be installed in one or more grooves prior to application of the adhesive mortar second layer108. When applying the second mortar layer108, the mortar can fill the dimple interiors188, fill the empty grooves130, and fill any space in the groove interiors246around the heating elements for those grooves in which a heating element has been installed. In some examples, allowing the mortar of the mortar second layer108to enter grooves130with heating elements therein can improve thermal transfer from the heating element120to the flooring material102.

In some examples, the underlayment100includes a fabric layer260. The example fabric layer260is a generally planar sheet of nonwoven material. In some examples, the fabric layer can be of another material, including, for example, fleece, felt, or synthetic material. The fabric layer260can be attached to a bottom surface of the membrane140. In the example illustrated, the fabric layer260is releasably adhered by a frangible bond to an outer surface of the end walls190of some or all of the dimples170. The frangible bond may be provided by an adhesive that bonds weakly to one or both of the fabric layer and the membrane surface.

When the underlayment100is positioned on the adhesive mortar first layer106for installation, the fabric layer260contacts, and is pressed against, an exposed upper surface of the mortar first layer106prior to curing thereof. The fabric layer260of the underlayment100is thereby securely adhered to the mortar first layer106. Accordingly, the fabric layer260is fixed to move and shift with the subfloor104and mortar first layer106applied thereto. After application of adhesive mortar second layer108, the membrane140of the underlayment100is fixed to move with the mortar second layer108and flooring material applied thereto. A first instance of a relative force exerted by one on the other of the upper and lower fixed subassemblies will release the frangible bond between the fabric layer260and the membrane140of the underlayment100, such that no reaction force (e.g. lateral shifting force) can be transferred through the underlayment100from the subfloor to the finished flooring material. The membrane (and materials fixed above the membrane) are able to “float” relative to fabric layer260(and materials to which it is affixed thereunder), thereby accommodating transverse shifting of one relative to the other without damage to the flooring material102.

Referring now toFIG.5, illustrated is an example method300of installing flooring.

In some examples, the method300includes, at step302applying the adhesive mortar first layer106to the base layer104. Applying the mortar first layer106may include depositing adhesive mortar on the base layer104. Step302may include spreading the adhesive mortar over the base layer104. In some examples, the adhesive mortar is thin-set mortar.

At step304, the underlayment100is laid on the mortar first layer106. The underlayment100includes the fabric layer260, and the fabric layer260is pressed into contact with the lower layer106. The membrane140is above the fabric sheet260and the body panel150is held separate from the fabric sheet260by the dimples170.

At step306, the heating element120is installed in the groove130of the underlayment100. In some examples, the heating element120has a larger cross-sectional dimension than the mouth224of the groove130, the width230of the mouth224being narrower than a deeper portion of the groove130. Step306may include snapping the heating element120into the groove130. The heating element120is an elongated element and is passed through a mouth of the groove to extend along the groove130. The heating element120may project though the mouth when installed. For example, a portion of a lateral wall of the heating element120may extend out through the mouth224. In some examples, the heating element120is a heating cable.

In some examples, method300includes step308. At step308, an adhesive mortar second layer is laid over the flooring underlayment100and installed heating element120. Applying the mortar second layer108may include depositing adhesive mortar on the membrane140. Step308may include spreading the adhesive mortar over the membrane140. Step308includes depositing the adhesive mortar inside the interior of the dimples170. Step308follows step306.

In some examples, method300includes step310. At step310, flooring material102is installed over the upper layer108. In some examples, the flooring material102is tile. In some examples, tiles312(FIG.3) are laid on the adhesive mortar. It will be appreciated that in some examples the method300may include installing one or more additional layer between or over the layers recited above.