c03D - MATERIAL GUIDE - CUSHION
C03D-1 Choosing the right carpet cushion
C03D-2 Carpet Cushion
C03D-3 Carpet Cushion Types
C03D-4 Carpet Cushion Selection
C03D-5 Carpet / Cushion adhesives
C03D-2 Carpet Cushion
C03D-3 Carpet Cushion Types
C03D-4 Carpet Cushion Selection
C03D-5 Carpet / Cushion adhesives
Preface:
This study guide covers carpet cushion and related materials and their recommended uses. Specifiers and/or persons selecting such products should verify all facts relative to the particular project requirements.
1 • CHOOSING THE RIGHT CARPET CUSHION
.01 The use of a cushion under a carpet whether the cushion is loose laid, glued down, or an integral part of a carpet's construction not only affects the feel of the installation but will also influence the wear and performance of a carpet and may extend the carpet's life expectancy by up to 50%. In addition, the use of a cushion under a carpet may also add to the acoustical and thermal performance of the carpet installation.
.02 In determining whether a cushion is appropriate for use under carpets in residential, commercial, and institutional settings and selecting the right cushion when it is, must be done by paying careful attention to a number of factors. In addition to selecting an appropriate carpet (refer to Part C03C - Material Guide - Carpet) this entails, amongst other things, determining the use or function of the area or room, the amount of traffic it will be subjected to, as well as the feel or comfort level desired.
This study guide covers carpet cushion and related materials and their recommended uses. Specifiers and/or persons selecting such products should verify all facts relative to the particular project requirements.
1 • CHOOSING THE RIGHT CARPET CUSHION
.01 The use of a cushion under a carpet whether the cushion is loose laid, glued down, or an integral part of a carpet's construction not only affects the feel of the installation but will also influence the wear and performance of a carpet and may extend the carpet's life expectancy by up to 50%. In addition, the use of a cushion under a carpet may also add to the acoustical and thermal performance of the carpet installation.
.02 In determining whether a cushion is appropriate for use under carpets in residential, commercial, and institutional settings and selecting the right cushion when it is, must be done by paying careful attention to a number of factors. In addition to selecting an appropriate carpet (refer to Part C03C - Material Guide - Carpet) this entails, amongst other things, determining the use or function of the area or room, the amount of traffic it will be subjected to, as well as the feel or comfort level desired.
2 • CARPET CUSHION
.01 Carpet cushion can be defined as any kind of resilient material placed under a carpet to provide softness and adequate support when it is walked upon. Carpet cushion is usually separate but in some cases it may be attached to the carpet backing when the carpet is manufactured. Although "cushion" is the preferred term, it is also referred to as undercushion, underpad, underlay, or padding.
.02 The primary purpose of carpet cushion is to extend the life of the carpet installation. Other advantages are the enhancement of both acoustical and thermal (RSI or R) values as well as providing walking and standing comfort underfoot. The addition of a firm but resilient layer between a carpet and a substrate will even out any irregularities in the substrate surface and will also provide protection for the carpet backing, allowing the pile to recover from the heaviest wear forces. In addition, the porosity of a carpet cushion will allow air to circulate under the carpet thereby facilitating carpet cleaning and minimizing wear from dirt and grit.
.03 Carpet cushion should be selected according to the traffic patterns in the area of installation and in accordance with the manufacturer's specific requirements for thickness and density.
.04 Only firm cushions are recommended for commercial applications while softer ones may be more viable in residential installations. The degree of firmness has, of course, to be reconciled with the required comfort. As it is essential that a cushion continue to function throughout the life of a carpet, it is therefore important to ensure that the initial properties of the cushion will be substantially maintained throughout the period for which the carpet is expected to last. A firm cushion with a strong smooth backing will facilitate carpet installation and will minimize recalls for stretch-in carpet. In most cases a better pattern match may also be achieved over a cushion.
.05 The most conventional method of carpet installation, particularly in residential applications, is the "stretch-in" method over carpet cushion. This method entails installing carpet cushion up to the tackless strips around the perimeter of a stretch-in carpet installation. The cushion may be loose laid, periodically fixed, or in some instances glued down to the substrate before the carpet is "stretched-in" over the cushion.
.06 For large areas, where maximum dimensional stability is required, and for installations that cannot be accommodated by the stretch-in method a "double stick" method is used. This entails gluing the cushion to the floor and then gluing the carpet to the cushion.
.07 The method of installation should be decided early in the project and the carpet specification drawn up with this in mind. In the case of a "direct glue- down" method or the "double stick" method particular attention should be paid to the type of adhesive used.
.01 Carpet cushion can be defined as any kind of resilient material placed under a carpet to provide softness and adequate support when it is walked upon. Carpet cushion is usually separate but in some cases it may be attached to the carpet backing when the carpet is manufactured. Although "cushion" is the preferred term, it is also referred to as undercushion, underpad, underlay, or padding.
.02 The primary purpose of carpet cushion is to extend the life of the carpet installation. Other advantages are the enhancement of both acoustical and thermal (RSI or R) values as well as providing walking and standing comfort underfoot. The addition of a firm but resilient layer between a carpet and a substrate will even out any irregularities in the substrate surface and will also provide protection for the carpet backing, allowing the pile to recover from the heaviest wear forces. In addition, the porosity of a carpet cushion will allow air to circulate under the carpet thereby facilitating carpet cleaning and minimizing wear from dirt and grit.
.03 Carpet cushion should be selected according to the traffic patterns in the area of installation and in accordance with the manufacturer's specific requirements for thickness and density.
.04 Only firm cushions are recommended for commercial applications while softer ones may be more viable in residential installations. The degree of firmness has, of course, to be reconciled with the required comfort. As it is essential that a cushion continue to function throughout the life of a carpet, it is therefore important to ensure that the initial properties of the cushion will be substantially maintained throughout the period for which the carpet is expected to last. A firm cushion with a strong smooth backing will facilitate carpet installation and will minimize recalls for stretch-in carpet. In most cases a better pattern match may also be achieved over a cushion.
.05 The most conventional method of carpet installation, particularly in residential applications, is the "stretch-in" method over carpet cushion. This method entails installing carpet cushion up to the tackless strips around the perimeter of a stretch-in carpet installation. The cushion may be loose laid, periodically fixed, or in some instances glued down to the substrate before the carpet is "stretched-in" over the cushion.
.06 For large areas, where maximum dimensional stability is required, and for installations that cannot be accommodated by the stretch-in method a "double stick" method is used. This entails gluing the cushion to the floor and then gluing the carpet to the cushion.
.07 The method of installation should be decided early in the project and the carpet specification drawn up with this in mind. In the case of a "direct glue- down" method or the "double stick" method particular attention should be paid to the type of adhesive used.
3 • CARPET CUSHION TYPES
.01 Carpet cushion can be made from a variety of synthetic and natural materials. Many of these contain a significant amount of recycled material which is an environmental plus. The actual amount of recycled content should be verified with each cushion manufacturer. In all cases a facing is included to enhance handling and to ensure ease of installation beneath the carpet.
.02 There are three basic types of carpet cushion available with each variety having characteristics that make it useful in particular types of carpet installation. Each variety also has grades, which vary by weight (also called density), thickness, and the amount of force it takes to compress the cushion. In addition each type of cushion material may come complete with a woven or non-woven scrim facing bonded to one or both sides for added strength, stability, and ease of installation.
.01 Carpet cushion can be made from a variety of synthetic and natural materials. Many of these contain a significant amount of recycled material which is an environmental plus. The actual amount of recycled content should be verified with each cushion manufacturer. In all cases a facing is included to enhance handling and to ensure ease of installation beneath the carpet.
.02 There are three basic types of carpet cushion available with each variety having characteristics that make it useful in particular types of carpet installation. Each variety also has grades, which vary by weight (also called density), thickness, and the amount of force it takes to compress the cushion. In addition each type of cushion material may come complete with a woven or non-woven scrim facing bonded to one or both sides for added strength, stability, and ease of installation.
- Urethane Foam Cushions: a polyurethane mixture that is cured and fabricated into a continuous sheet of predetermined thickness and weight. These types of cushion come in three recognized, and clearly different varieties:
- Prime polyurethane foam cushion: a cushion material that is manufactured by combining two liquid petrochemical ingredients results in an exothermic reaction producing a large mass of foam, which is then sliced into sheets for use as carpet cushion. This foam is a firmer version of the same cushioning used in upholstered furniture, mattresses, and automobile seats. There are three types of prime urethane carpet cushion: conventional prime, grafted prime, and densified prime cushion. Once the standard, prime polyurethane foam has now been replaced by more cost effective products, though quality prime polyurethane foam still has its place.
- Prime Urethane Foam Bonded Urethane Foam
- Bonded polyurethane foam cushion: (sometimes called rebond or chip foam) a unique cushion material formed by combining chopped and shredded pieces of scrap foam of different sizes and (usually) colours with a bonding agent with the blend compressed into one solid block or roll of a predetermined density that is then sliced or peeled into continuous sheets of required thicknesses. Frequently a scrim net is adhered to one or both surfaces for ease of installation and to improve performance. Bonded foam is one of the most amazing recycling projects of all time in that foam waste material from the manufacturing of prime urethane or from recycled foam cushion, that would otherwise be thrown out, is recycled once again, easing the strain on landfills.
- Froth or Densified polyurethane foam cushion: a cushion material made in a process similar to prime urethane but with air whipped into the mixture to produce a thin higher density foam material. This cushion material is frequently applied directly to the back of some carpet styles using carpet backing machinery but may also be applied to a non-woven material for separate cushions. This type of cushion backing is particularly useful in commercial applications with wide expanses of carpet.
- Mechanically Frothed Urethane Foam
- Rubber Cushions: These types of cushion come in three recognized, and clearly different varieties:
- Natural and Synthetic Rubber Cushions: cushion material of natural rubber (from the sap of the rubber tree which is marketed as Latex or dried into sheet form) or a mixture of natural and/or synthetic rubber, fillers (usually calcium carbonate) and other chemicals fabricated in continuous sheets. The mixture is varied to produce different (predetermined) thickness / density levels and firmness. Synthetic rubber cushion handles and behaves in much the same way as natural rubber cushion.
- Recycled / Reclaimed Rubber Cushions: cushion material of reclaimed rubber from a variety of sources (primarily from rubber tires) that is ground up into crumb form. The crumb is bonded with latex and moulded into sheet form and may have a reinforcing grid backing on one or both sides.
- Sponge Rubber Cushion: natural or synthetic rubber fabricated as noted above but with the addition of a blowing agent with the amount of agent used determining the density. The mixture is then heat cured on a chain or between plates, which predetermine its thickness.
- This type of cushion comes in two recognized, and clearly different varieties:
- Flat sponge rubber cushion: a firm, dense cushion with a flat surface normally used in large-scale commercial applications and with loop type (or Berber) carpet.
- Flat sponge rubber foam
- Waffled or rippled sponge rubber cushion: a soft, resilient cushion with a waffle or rippled surface made by moulding natural or synthetic rubber in a form and heat setting it to cure the material. The "luxurious" feel is particularly useful for residential installations. Waffle rubber pad is often used improperly. The waffle part of the padding gives it a thickness that is mostly air, and as a result, any cushion rated less than 90 ounces is still too soft for today's carpets. Frequently, the rubber used to make this type of cushion is held together with clay binders that break down with use.
- Waffled sponge rubber foam
- Foam Rubber Cushion: a mix of natural or synthetic rubber latex and other curing agents that add body and colour that is mechanically foamed or frothed and spread to the desired thickness using a blade or roll and then cured in an oven. The amount of filler and air foamed into the product determines the density.
- Latex foam: fabricated as noted above and usually in a high-density flat version although a softer rippled version is also available.
- Reinforced foam: fabricated as noted above except discreet but relatively coarse particles of ground recycled tire rubber are added to the foam mix resulting in a higher density open cell cushion.
- Felt or Fibre Cushions: a mixture of both virgin and/or recycled natural or synthetic fibres that are interlocked into a useful sheet of felt. There are two distinct varieties of fibre used in the manufacture of felt cushions:
- Natural fibre felt: one of the oldest types of carpet cushion, dating back to the earliest days of machine-made carpet was made from animal hair (usually horse) and/or jute fibre (the material used to make some kinds of rope and heavy burlap bags). Not used today, natural felts were susceptible to rotting if over-wetted, odour development, and natural degradation. In addition, some natural fibre cushions were treated with a water-soluble dye that can stain a wet carpet.
- Natural fibre felt
- Synthetic fibre felt: nylon, polyester, polypropylene, and acrylic fibres, principally of post-industrial scrap synthetic carpet material, with no outside additives. The fibres are needle-punched into relatively dense firm non-woven felt sheets that is described as needled synthetic felt. As with other types of cushion, synthetic felt cushion can be made in virtually any weight, to stand up under light, medium, or heavy traffic, which is how they are usually classified. Such felts are non-allergenic, and odour, moth-proof, and mildew resistant.
- Synthetic fibre felt Felt or fibre cushions can be made by using one or a combination of the above noted fibres as noted below.
- Hair Felt: i.e., made using only animal hair (not commonly used today).
- Combination Felt: i.e., made using animal hair plus other fibres types.
- Fibre Felt: i.e., made using all fibres types.
- Rubberized Felt: i.e., made using hair, jute, or a combination of all fibres that are encapsulated in rubber.
- Carpet is highly effective in controlling noise in buildings by absorbing airborne sound, reducing surface noise generation, and reducing impact sound transmission to rooms below.
- The addition of a cushion under a carpet will increase the Noise Reduction Coefficient (NRC) rating of the installation and will certainly result in better NRC values than carpet over concrete. As a general rule, the more permeable the carpet backing, the more sound energy can penetrate into the cushion and the higher the resulting NRC.
- Acoustical ratings vary with each type of cushion. Generally the higher the weight and thickness of a cushion the higher the NRC rating. Weight for weight, more permeable hair, hair-jute, and foam rubber cushions tend to produce higher NRCs than less permeable, rubber-coated, hair-jute and sponge rubber cushions.
- Foam-backed loop construction results in an increased NRC value compared to conventional secondary backed carpet. NRC values of cushions bonded to carpet may also vary due to the permeability caused by air spaces between the layers of carpet and cushion.
- In regard to impact noise reduction (INR) on carpet installed directly to concrete (i.e. no cushion) higher pile weights will result in higher INR ratings. Cushion materials, in general, add significantly to increased INR values. Sponge rubber cushion, which has lower NRC characteristics, will have a higher INR rating. In such tests, weight for weight, foam rubber cushion will deliver larger INR numbers.
- Properly specified carpet / cushion combinations have proven to handle the vast majority of sound absorption requirements in architectural spaces. Specifying for critical areas such as theaters, broadcast studios, and open plan office areas may require full details of impact insulation properties and noise absorption characteristics.
- Refer also to NFCA Reference Manual Part A08C - Acoustical Issues.
.04 Density: one of the most important parameters of any type of cushion, density equals weight divided by thickness, and it is measured in pounds per cubic foot. All cushion types can be made denser (more material), or lighter (more air), or any grade in between, so they can be soft or firm, resilient or supportive, according to the type of room and expected traffic on the carpet that they support.
.05 Carpet and Cushion over Radiant Heated Substrates:- Carpet and cushion is, by design, a thermal insulator. The insulation value (expressed as an RSI or R-value) is often greater for a carpet cushion than for the carpet itself. The type and density of cushion will greatly impact the amount of heat that will radiate through the cushion (and carpet) to the room above. For example 10 mm (3/8") prime urethane cushion has an approximate R-Value of 1.62 while 6 mm (1/4") slab rubber foam has an approximate value of R-0.31 (which is over five times less restrictive). This means that the floor under the urethane cushion must be approximately 4°C (40°F) warmer than under the rubber cushion to transfer an equal amount of heat to the surface. It will also take longer for the heat to transfer through the urethane cushion on initial start-up. The impact on radiant floor design is obvious. A radiant floor design that may be perfectly adequate if a rubber cushion is used could end up unable to meet the heating requirements when a urethane cushion is used. In all cases the insulation value of both the carpet and particularly the cushion should be verified with the material manufacturer and this information passed on to the radiant heating system designer.
- Another concern is the use of clay fillers in some cushions which have an oily substance that may leach out over time, particularly when heat is applied. The result is a cushion which may crumble when it gets old.
- For more information on radiant heating and carpet visit the Radiant Panel Association website at www.radiantpanelassociation.org.
4 • CARPET CUSHION SELECTION
.01 The carpet manufacturer must be contacted to obtain their recommendations in regard to the type, thickness, and density of cushion to be used in order to prevent problems resulting from improper selection and the possible voiding of applicable warranties. The type of cushion chosen will play a key roll in achieving satisfactory results and prolonging the life of the carpet.
.02 Carpet cushion should be selected based on the type of carpet installation (commercial, institutional, or residential), the amount of traffic and traffic patterns that the application area will be subject to, and the manufacturer's requirements for thickness and density.
.03 The quality of a carpet cushion is determined by density (the weight of one cubic foot of the cushion), not thickness and softness. The type of cushion selected should be of sufficient density to support the carpet and limit flexing of the backing. Too soft a cushion will contribute to carpet fatigue, which in turn may contribute to premature wear and serviceability. In other words, if a cushion is too soft and thick, the carpet will flex excessively with traffic putting the backing under enormous strain, which will result in the carpet delaminating. As a general rule a cushion should not lose more than half its thickness when pinched.
.04 Cushions that are too soft or have an uneven or non-uniform density (including those that contain deep bubbles or ripples or have a high profile i.e. waffle pads) are not recommended for tufted carpet, as they are frequently the cause of re-stretch calls and seam splitting.
.05 Only firm cushions are recommended for commercial applications and high traffic areas while softer ones may be more viable in residential installations. The degree of firmness has, of course, to be reconciled with the required comfort. As it is essential that a cushion continues to function throughout the life of a carpet, it is therefore important to ensure that the initial properties of the cushion will be substantially maintained throughout the period for which the carpet is expected to last. A firm cushion with a strong smooth backing will facilitate carpet installation and will minimize recalls for stretch-in carpet. In most cases a better pattern match may also be achieved over a cushion.
.06 Where cushion and carpet is installed over radiant heated concrete substrates a cushion that is not an effective insulator, but one that allows the heat from the heating system to penetrate the carpet system and heat the room should be used. A relatively thin, flat cellular sponge rubber or synthetic fibre cushion works well under these circumstances.
.07 Cushion Thickness:
.08 Cost Considerations:
.09 Environmental Considerations:
.10 Inappropriate Cushion Selection:
.01 The carpet manufacturer must be contacted to obtain their recommendations in regard to the type, thickness, and density of cushion to be used in order to prevent problems resulting from improper selection and the possible voiding of applicable warranties. The type of cushion chosen will play a key roll in achieving satisfactory results and prolonging the life of the carpet.
.02 Carpet cushion should be selected based on the type of carpet installation (commercial, institutional, or residential), the amount of traffic and traffic patterns that the application area will be subject to, and the manufacturer's requirements for thickness and density.
.03 The quality of a carpet cushion is determined by density (the weight of one cubic foot of the cushion), not thickness and softness. The type of cushion selected should be of sufficient density to support the carpet and limit flexing of the backing. Too soft a cushion will contribute to carpet fatigue, which in turn may contribute to premature wear and serviceability. In other words, if a cushion is too soft and thick, the carpet will flex excessively with traffic putting the backing under enormous strain, which will result in the carpet delaminating. As a general rule a cushion should not lose more than half its thickness when pinched.
.04 Cushions that are too soft or have an uneven or non-uniform density (including those that contain deep bubbles or ripples or have a high profile i.e. waffle pads) are not recommended for tufted carpet, as they are frequently the cause of re-stretch calls and seam splitting.
.05 Only firm cushions are recommended for commercial applications and high traffic areas while softer ones may be more viable in residential installations. The degree of firmness has, of course, to be reconciled with the required comfort. As it is essential that a cushion continues to function throughout the life of a carpet, it is therefore important to ensure that the initial properties of the cushion will be substantially maintained throughout the period for which the carpet is expected to last. A firm cushion with a strong smooth backing will facilitate carpet installation and will minimize recalls for stretch-in carpet. In most cases a better pattern match may also be achieved over a cushion.
.06 Where cushion and carpet is installed over radiant heated concrete substrates a cushion that is not an effective insulator, but one that allows the heat from the heating system to penetrate the carpet system and heat the room should be used. A relatively thin, flat cellular sponge rubber or synthetic fibre cushion works well under these circumstances.
.07 Cushion Thickness:
- Cushion for commercial carpet installations should not exceed 10 mm (3/8") thick.
- Cushion for most residential carpet installations should not exceed 11 mm (7/16") thick.
- Denser cushions of the same thickness as adjacent areas are recommended for higher traffic areas. For example if a 2.25 kg (5 lb) 10 mm (3/8") thick cushion is used in light traffic areas such as a living room then a 3 kg (6.5 lb) cushion should be used in heavy traffic such as hallways.
.08 Cost Considerations:
- Some factors that may influence carpet cushion selection and resultant costing are:
- Amount of traffic.
- Comfort level required.
- Long-term economic benefit (carpet life extended).
- Easier day-to-day care.
- Improved sound absorption (especially impact noise).
- Increased insulation value - i.e., higher RSI (R) value (except refer to Radiant heated floor requirements).
.09 Environmental Considerations:
- Some environmental factors that may influence carpet cushion selection are:
- Many cushions are made using significant quantities of recycled materials that would otherwise have gone to landfill. This is a saving of energy and space.
- Indoor Air Quality: The Canadian Carpet Institute (CCI) and the Institute of Canadian Undercushion Manufacturers (ICUM) in conjunction with the Carpet and Rug Institute (CRI) in the U.S. have developed a program which examines chemical emission levels from carpet and cushion and authorizes the use of a "Green Label" on products which meet the programs chemical emission test criteria. This is an ongoing program with quarterly testing of all approved materials. Most Canadian and American carpet cushion manufacturers participate in this program and many of their products carry the Green Label.
.10 Inappropriate Cushion Selection:
- An inappropriate choice of a carpet cushion may result in:
- Wrinkling and buckling, separation of carpet backing and accelerated loss of appearance. Too soft a cushion will result in stress on the carpet backing and crushing and matting of carpet fibres due to improper loading. A denser cushion must be selected to properly support the carpet backing, and to prevent wrinkling / buckling and fibre crushing / matting.
- Splitting or opening of seams. This is due to excessive vertical movement as a result of too soft a cushion. This "trampoline" effect is not an installation-related problem but one due to the selection and installation of an incorrect cushion.
- Note: This may be temporarily solved by removing the furniture from the room and the carpet from the tack strip. The existing seaming tape is then removed and the seam reconstructed, and the seam reinstalled. However, because the cushion allows too much movement, this situation will occur again. A permanent solution is to replace the cushion with a denser cushion suitable for the installation.
- Furniture indentations. The carpet backing is stretched when heavy furniture comes in contact with the face pile. This is noticed when the furniture is periodically moved leaving an indentation. With extremely heavy articles, indentations are an inherent characteristic.
- Note: Indentations may be removed by applying steam. In most cases, synthetic fibres can be lifted and restored to an acceptable appearance. If the condition is severe, this action may not work. If the cushion is too soft or too thick, this corrective procedure will have no effect. To eliminate future problems, the cushion will require replacement.
- Fatigue of users. A very soft cushion will create a feeling of "walking in sand" or sinking which results in making users tired. A firmer cushion is required, and the only solution to this problem is to replace the cushion with a denser product.
- Installing of new cushion over an existing cushion is NOT recommended.
- In the majority of circumstances, a low profile and denser cushion, will provide better protection for the carpet backing.
- Generally, carpet that is glued directly to the floor will result in a loss of pile height much sooner than one installed over a quality cushion.
- Consideration must also be directed to the substrate as well as the use, realizing that one product does not fulfill all requirements. For example, if moisture is a problem, the waffle, or bubble-rubber product should be considered.
- Firmer cushions provide more support for areas receiving heavy / rolling traffic (office chairs, wheelchairs or kitchen caster chairs).
- Softer cushions allow carpet to stretch in heavily traveled areas and pivotal points.
5 • CARPET / CUSHION ADHESIVES
.01 The term adhesive (sometimes referred to as cement) applies to the total line of bonding materials, sealers, seam welding agents used in the installation of carpet and cushion, seaming tapes, hardware and trim.
.02 The type of adhesive used shall be as recommended by both the material and adhesive manufacturer. There are a number of variations and restrictions based on the following that must be verified with the manufacturer:
.03 Adhesive Types: In general carpet and cushion adhesives fall into the following categories:
.01 The term adhesive (sometimes referred to as cement) applies to the total line of bonding materials, sealers, seam welding agents used in the installation of carpet and cushion, seaming tapes, hardware and trim.
.02 The type of adhesive used shall be as recommended by both the material and adhesive manufacturer. There are a number of variations and restrictions based on the following that must be verified with the manufacturer:
- Type of substrate.
- Type of carpet backing.
- Type of cushion.
- Type of accessory.
- Indoor and/or outdoor installation.
- Grade level (especially below and on-grade installation).
- Moisture / hydrostatic pressure and alkali levels.
- Solvent and/or water based and VOC levels.
- Tack time
.03 Adhesive Types: In general carpet and cushion adhesives fall into the following categories:
- Multi-Purpose Adhesive: Specially designed for a wide range of glue-down installations and substrate types.
- Carpet Cushion Adhesive: Type used for securing all types of cushion to all types of substrate surfaces. This adhesive may also be used to secure loose laid carpet cushion to prevent it from slipping during stretch-in carpet installations. This type is usually a flammable solvent-rubber base type.
- Releasable Carpet Adhesive: Pressure sensitive type designed for the installation of both broadloom carpets and modular or tile carpet where later removal is a consideration. This type of adhesive may have to be used in conjunction with a sealer over porous floors and it is not recommended for some foam-backed or urethane foam-backed carpets. Suitable over all types of substrates including well-bonded resilient floors at all grade levels. This type of adhesive should attach more securely to the carpet backing than to the substrate, so that if the application has been done correctly the carpet can easily be removed.
- Note: For additional information on adhesives refer to Part A14 - Adhesives and Fastenings
- Where cushion is to be adhered to a substrate surface the adhesive type and trowel notch size shall be as recommended by the cushion and adhesive manufacturer and in the case of carpet adhered to a cushion, by the carpet manufacturer as well.
- The texture of the cushion face is an important consideration in the selection of the correct trowel notch size required for the proper adhesion of the cushion to the substrate and of the carpet to the cushion in double glue installations. The trowel notch must be large enough to apply a continuous film (i.e. full coverage) of the adhesive to the substrate or cushion surface to ensure 100% transfer of the adhesive into the cushion and carpet backing.
- For minimum trowel notch size refer to Part C04B - Installation Guide, item 6.03.
- The adhesive must be spread uniformly over the substrate or cushion using the correct trowel. After sufficient open time the cushion must be pressed into the adhesive on the substrate and the carpet pressed into the adhesive on the cushion and rolled with the appropriate roller in order to ensure full transfer of the adhesive. Proper open time considerations are critical for a successful installation.
- Ensuring that the correct amount of adhesive is used is dependent on maintaining the correct trowel notch size. Care shall be taken to ensure that this is done by replacing trowels that have worn down from use.