Double-Glue Carpet Installation
May 23, 2007
The double-glue method of installation is a method of adhering a separate cushion to the floor with adhesive, followed by a total adhesive bonding of the carpet to the cushion. This is one of the best applications for the professional flooring contractors and the client when performed correctly. Because of the shortcuts taken by those who are unskilled, this method is not as widely used, as it should be.
Once again, those who are ill equipped to be identified as professionals control the industry! The information that follows WORKS and provides the client with an installation that performs.
The double-glue type of installation is recommended for commercial use in large areas where correct power stretching is difficult to achieve. It’s also an ideal method if carpet receives unusual, excessive or rolling traffic. Using this method also provides the installation professional with an advantage when installing borders - both in commercial and residential applications.
Carpet performs better over cushion and protects the investment. By adhering cushion directly to the floor, and adhering the carpet to the cushion, eliminates seam peaking and the need for restretching. Yes, carpet with attached cushion works, but we need committed body builders to do the work!
The following are several points to keep in mind:
1. Don’t cut corners. Qualified personnel can only perform this type of installation. Using the service of unqualified individuals will result in disaster.
2. Know your costs: Prior to submitting a quote for the cost, research all costs associated with professional products and installation requirements.
3. Use only carpet, cushion, adhesives and installation supplies that have the manufacturer’s written approval for this method. There are no exceptions to this rule!
4. The double-glue method is ideal for commercial, hospitality and patterned carpet applications.
5. It works fine in a residential setting, especially if border or accent work is involved.
6. Sufficient carpet must be ordered to allow for problems that could surface due to pattern tolerances.
7. Proper floor preparation is crucial.
Greg Szalay of T&A Supply once stated, “There are five rules to a successful double-glue installation. Installers might miss one and be successful, but by missing two - the job is doomed to fail!”
• Rolling the installation correctly
• Floor Preparation
• Use of proper adhesives and correct notched trowels
• Absolutely no traffic of any type on the installation for 24/48 hours.
Let’s add one more critical thing – always allow sufficient tack time. If the carpet is laid in wet adhesive, then the adhesive will migrate into the backing of the carpet.
Section 1: ProductsCarpet Backing Recommended for Double-Glue Installation: Use a minimum of 10-pick Tufted – Polypropylene ribbon secondary backing. Why?
• Less contamination of fillers from SB latex will occur.
• Provides greater surface to which the adhesive can bond.
• Minimum of 8-pick Tufted – Staple polypropylene secondary backing.
• Constructed of staple yarn.
• Texture of the staple yarn is compatible with adhesive bonding.
• Woven carpet, check with manufacturer.
Carpet Construction Recommendations (Check with manufacturer first):
• Straight-row stitch construction is recommended – a step-over-stitch is not.
• Minimum 10-gauge yarn construction.
Cushion Recommendations (Check with manufacturer first):
• Only cushions that are approved by the cushion manufacturer are suitable for this application.
Adhesive Recommendations (Check with manufacturer first):
• Cushion-to-Floor Adhesives: Pressure-sensitive adhesive is recommended, but a manufacturer – recommended multipurpose is also acceptable.
• Carpet-to-Cushion Adhesives: Premium multipurpose that is high in solids and recommended by the adhesive manufacturer.
• Pressure-sensitive adhesive is not to be used over existing multipurpose adhesive. Multipurpose adhesive can be used over existing pressure-sensitive adhesive.
Trowel or Spray Application Recommendations:
• Trowel (cushion to floor): Recommended: 1/16” x 1/16” x 1/16” square-notched trowel.
• Trowel (carpet to cushion): Recommended: 1/8” x 1/8” x 1/16” U-notched trowel. Use a trowel notch of 1/8” x 3/16” x 1/8”, or a U-notch for heavily textured backings.
• Spray (cushion to floor): Pressure-sensitive or acrylic adhesive – manufacturer recommended.
• Spray (carpet to cushion): Manufacturer-recommended adhesive by completely covering the substrate and misting the backing of the carpet to achieve a total bonding of the two products.
• If tackstrip is not used, it is recommended that wood base or wall base with toe be installed after the carpet is installed.
• If tackstrip is used, then all edges of the carpet can be tucked into the gully and secured without the use of wallbase. This procedure positions and holds the carpet in place during the curing of the adhesive. This also assists if restretching is required in the future.
• If tackstrip is used, the cushion must be 1/4” or higher or “picture framing” will occur.
Section 2: Job Site RecommendationsIt must be recognized that the Floor Covering Contractor does not have any control over the following conditions:
1. Area temperature (between 65 F to 95 F is recommended).
2. Relative humidity (between 10- to 65-percent is recommended).
3. Slab temperature (a minimum of 65 F 24 hours prior to starting the installation).
4. Indoor temperature should never fall below 55 F, regardless of the age of the installation.
5. All installations and materials must be protected from extreme conditions.
6. Carpet should be stored on a flat surface (no more than three rolls high) to prevent damage to the product.
7. All areas to receive flooring must be free of other trades and workers that hamper the proper installation procedures.
Section 3: Requirements of the Floor Covering Installation ContractorNote: This section should be addressed by the owner, the general contractor or the dealer.
1. Submit proof of a minimum of four-years installing commercial installations; a CFI Certified Installer with a Commercial-II or above certification or installer with proof of recognized installation training.
2. Installation contractors should be held accountable to ensure that a qualified and a knowledgeable installation team is employed (one who'll adhere to the correct and recommended installation procedures).
3. Comply with all OSHA and EPA regulations, as well as all local and national government regulations.
4. Use all specified materials without deviating from the specifications. If contractors deviate from specified materials, then the responsibility for the performance of these products is also assumed.
5. Installers should check that the names on all materials match the work order.
6. Maintain records of all purchased supplies used during installation for future reference.
Section 4: Procedures for Installing CushionThe following describe the various methods and tools used in stalling cushion.
Cushion Installation Using a Trowel
1. Whenever possible, install the cushion at a 90-degree angle from the lay of the carpet. If not possible, offset the carpet seams at least 6-inches from the cushion seams.
2. Dry lay the cushion prior to the installation application.
3. Position the cushion flat.
4. Fold back the cushion in order to apply the adhesive.
5. It is recommended that the cushion to the floor is secured with a pressure-sensitive adhesive applied with a 1/16” x 1/16” x 1/16” square-notched trowel; notch maintained throughout the installation or rolled according to the manufacturer’s specifications.
6. Pressure-sensitive adhesive is to be thoroughly dry before the cushion is placed into it. There are to be no gaps between the edges of the cushion.
7. Cut cushion net at the wall with no voids. Do not force the material into a compression fit; it must lay in a natural position and cannot be stretched.
8. Avoid using tape on cushion seams.
9. Important: Do not leave the floor void of adhesive next to wall. Apply adhesive in a uniform manner to cover this area.
10. With a lightweight roller, apply minimal amount of pressure to push bubbles away so cushion will lay flat and the adhesive will be transferred onto the backing of the carpet.
11. Once the cushion is secured to the floor, it is to lay flat and the seams butted together firmly.
Cushion Installation Using the Spray System
This is an acceptable method of installation when performed by a Spray Certified Installation Technician using materials that are approved for this type of application by the manufacturer.
Section 5: Installation ProceduresCutting Length Seams
Unroll the carpet and check for: width bow; skew; and pattern elongation or distortion.
Note: All manufacturers do not use the same tolerances. As carpets possess different characteristics, consideration must be allowed for each type. If necessary, check specifics with the carpet manufacturer.
It is understood that defects may not surface prior to installation. However, it is extremely important due to the replacement cost of a double-glue installation that the flooring contractor report visible defects immediately. If situations are present that could hinder the installation, do not proceed without authorization in writing.
Seam Construction Using Hot Melt Seaming Tape
1. Always reference the seaming diagram.
2. Do not use the factory edges to construct seams.
3. The majority of carpets are cut from face, running a row and using an appropriate cutter.
Width Cut Seam
1. In the majority of applications, a straightedge and square are required when constructing seams across the width of the carpet. Always run a row, whenever possible.
2. Tools required for construction of width seams: square; sharp knife; and straightedge.
Note: Width seams should be kept to a minimum.
Seams Constructed Using Hot-Melt Seaming Tape
1. After the carpet is cut, position the center of the seaming tape directly under the seam.
2. Use only seaming tape specifically designed and recommended for double-glue installation.
3. Apply appropriate seam sealer to the thickness of the primary and secondary backings on both sides of the edges to be seamed.
4. Position carpet seams at 90-degree angles to the seams in the cushion. If not possible, offset the seams in the cushion and the carpet by a minimum of six inches.
5. Fold carpet back and spread adhesive up to the edge of the seaming tape.
6. A 1/8” x 1/8” x 1/16” notch U-shaped trowel is recommended. This is the standard notched trowel for smooth-backed carpet.
7. When applying adhesive, hold the trowel in the correct position to apply the proper amount of adhesive. Slide it across the top of the cushion with minimal amount of pressure.
8. Begin by applying adhesive up to edge of seaming tape and work away from the area.
9. Allow adhesive to tack up before laying material into it. When it becomes tacky, lay the carpet into the adhesive. Seams are to remain butted together.
10. Periodically, check to ensure that both the floor and the cushion are completely covered with adhesive to achieve a total bonding of the two products.
11. Make necessary adjustments at this point with the use of a knee kicker, restretcher or power stretcher and hold in position with the use of stay nails.
1. The temperature of the iron will vary according to the quality of tape, type of seaming iron and the type of carpet and backing. There is an exception: to achieve a good transfer for rough backed carpet, use a heavier tape and a heavier notched trowel.
2. A star roller or carpet tractor is not to be used on cut-pile carpet. It is acceptable on loop-pile carpet. The use of a six-inch roller is mandatory to ensure the transfer of the thermoplastic onto the backing of the carpet.
3. When multiple breadths of carpet are required, dry lay as many breadths as possible.
4. Align the pattern, starting in the center of each breadth.
5. If pattern alignment is satisfactory, fold back sections approximately six-feet.
6. Apply adhesive using a 1/8” x 1/8” x 1/16” U-notched trowel.
7. If patterns do not align and pattern runoff occurs after attempting to match in the center of the pattern, apply adhesive to within 18” of each side of the seam.
8. Lay the carpet into the wet adhesive. This will allow the sections to move easily. Align the patterns and use stay nails to achieve an acceptable match.
9. After seam is completed, spread the adhesive to within 18” of the next seam.
10. Repeat above procedure.
Procedures to Follow After Seaming
1. Properly trim the edges of the carpet at the wall with a wall trimmer.
2. Remove all excessive scrap.
3. When adjoining a double-glue installation to a surface where no transition bars are used, apply seam sealer to the adjoined surface to ensure that the edges of the carpet are sealed. This avoids edge raveling and curling.
4. Roll the carpet in four directions using a lightweight roller that does not exceed 35 pounds. This transfer ensures total adhesive coverage of the backing, which is equal to the total coverage of the substrate, creating a bonding of the products.
5. If quarter round or wall base is present, remove and extend the carpet underneath. If not present, it is recommended that quarter round or wall base be installed. An optional method is the installation of tackstrip to secure the carpet to prevent the edges from curling due to the extreme variances in temperature around the exterior walls.
6. Use an appropriate solvent to remove any adhesive from face pile.
Section 6: Installation of Patterned Carpet1. Prior to cutting the carpet, check bow, skew and pattern elongation according to manufacturer’s tolerance. If tolerance exceeds the following, consult with the manufacturer:
• Bow: 1” in 12-feet
• Skew: 1-1/2” in 12-feet
• Pattern elongation: 1” in 12-feet
2. Lay the carpet in the designated area.
3. When preparing to construct the seam, begin with matching the patterns in the center of the seam.
4. Fold sections of carpet back on each side and spread adhesive using proper-size notched trowel.
5. Lay the sections in wet.
6. Seal the edges with the appropriate seam sealer.
7. Using kneekicker, deadman and powerstretcher, align the pattern while constructing the seam and use stay nails to hold the carpet.
Note: To align the pattern and to utilize the slippage in the adhesive, construct the seam as soon as possible.
8. Fold the carpet back until the adhesive is visible.
9. Spread adhesive out six additional feet or to the wall.
10. Draw the chalk line across the designated pattern points to align the pattern.
11. Repeat procedure as necessary until job is completed.
Section 7: Stair Upholstery Procedures1. Stairs that are to receive carpet should have a 3/4-inch rounded bullnose.
2. Position the tackstrip on the tread and riser as with a conventional installation.
3. Install specified cushion that is suitable for stair upholstery.
4. Extend cushion completely over bullnose of the step.
5. After the cushion is adhered, apply the double-glue adhesive on top of the cushion.
6. Install carpet into wet adhesive, which will soften and become pliable and easier to stretch.
7. It is recommended that all stair carpet be precut and dry fitted before commencing the stair installation.
Section 8: After the Installation1. Use caution tape to alert others that the floor cannot be walked on for 24-48 hours following the installation.
2. The carpet is not to be cleaned for 30 days following the installation.
3. It is suggested that you test all procedures before widespread use to determine results in your specific situation, as every circumstance is different.
This information serves as recommended guidelines based on the CFI Proven Methods of Installation. It is not intended to take the place of good judgment, common sense or the manufacturer’s written guidelines.