FAQs - Subfloor Preparation (Technical)
Can I install a new floor covering over old adhesive residue?
When installing new resilient tile such as Premium EXCELON VCTand Standard EXCELON VCT, Armstrong allows the use of S-89,
S-515, S-700 and S-750 Resilient Tile Adhesives over old adhesive residue as long as the adhesive residue has no ridges or
puddles evident and what remains is a thin, smooth film.
Should I use an adhesive remover to remove adhesive residue from a subfloor before installing a new floor?
Many adhesive removal products contain solvents that leave a residue within the subfloor. This residue can negatively affect
the new adhesive and bleed through the new floor covering. Floor covering warranties do not cover instances where existing
subfloor conditions cause damage to the flooring or installation failure.
Can I install an Armstrong floor on a radiant-heated substrate?
Armstrong flooring may be installed over radiant-heated subfloors as long as the surface temperature does not exceed 85°F
(29°C). Temperatures above 85°F (29°C) will cause the flooring to soften and increase the risk of irreversible indentation.
Why does Armstrong recommend not smoothing true expansion joints with any type of underlayment product?
True expansion joints are those placed between separate pours of concrete. These joints are designed to absorb the movement
of the concrete and are normally filled with elastomeric fillers which absorb the movement of the separate pieces of concrete.
If an underlayment is placed across or in these joints, the movement of the concrete will cause them to break up or will push
them out of the joint. Additionally, any flooring placed across these joints will break with the movement of the concrete.
Expansion joint covers, which are designed to span these joints, should be used in these areas.
Why can't you install flooring directly over paint or other coatings on a subfloor?
The bond of the flooring to the subfloor is only as good as what you bond to. If you bond to old paint, sealers, polish, or
other foreign matter, you are dependent upon the bond of that material to the subfloor to hold the flooring in place. Since
we cannot determine how strong that bond may be, it is best to bond directly to the substrate.
If you have a subfloor such as particleboard or hardboard, which are underlayments not recommended for Armstrong felt-backed
sheet flooring, do you need to replace that underlayment?
If the particleboard or hardboard subfloor is in good condition, you can install an Armstrong Interflex® floor. Particleboard
and hardboard are not recommended for fully bonded floors due to dimensional instability. They expand and contract at unpredictable
levels and can cause a fully adhered floor to push up at the joints of the boards. Interflex floors are designed to span these
irregularities in subfloors. They are installed perimeter bond only, and the flooring can expand and contract along with the
movement of the subfloor so there is no buckling of the flooring at joints.
What is a sleeper-constructed subfloor and why can't I install flooring over this?
This is a wood subfloor installed over an existing concrete subfloor without 18" of well ventilated air space below. Concrete
on or below grade will have some moisture in it due to its proximity to the ground. When there is not enough ventilation,
moisture will build up causing not only installation failure, but possible rotting of the wood. Suspended grade subfloors
that are not sufficiently dry can experience the the same problems.
Why should new tile not be installed over existing tile that is below grade?
Tile over tile is not recommended on a floor below grade. A basement is below grade and concrete below grade will almost always
have moisture in it. A single layer of tile allows any moisture in the concrete to escape through tile joints. When you place
new tile over existing tile, you cover the tile joints and cut off the escape route for the moisture. This traps the moisture
beneath the tile and can cause loosening of the old tile as well as the new tile.
Does Armstrong have a product which can be used to level underlayment boards?
Armstrong S-184 Fast-Setting Patch & Underlayment with water or S-194 Patch & Underlayment with S-195 Latex can be used for
overall leveling of approved suspended wood underlayments, but are not recommended over stripwood floors. Both are Portland-cement
based with a compressive strength of 4,500 psi (pounds per square inch) and can also be used over concrete, ceramic tile,
quarry tile, terrazzo, and existing asphalt adhesive residue. Once spread, it is dry and ready for flooring installation in
about one hour.
What board underlayment products should I put in place before installing resilient floor products?
Underlayments for resilient floors should be structurally sound and designed for resilient flooring underlayment purposes,
with a minimum thickness of 1/4". The panels should be smooth enough so that the texture or graining will not show through
the finished flooring. They should also resist dents and punctures from concentrated loads. The panels should not contain
any substance that may stain vinyl such as edge patching compounds, marking inks, paints, solvents, adhesives, asphalt, dye,
etc. Check with your supplier or panel manufacturer. Install the underlayment in strict accordance with the board manufacturer's
What is APA trademarked plywood?
APA trademarked plywood is plywood underlayment approved as suitable for the installation of resilient flooring by APA - The
Engineered Wood Association.
Can Armstrong floors be installed directly over strip wood, board or plank-type subflooring?
These subfloors must meet structural requirements. Regardless of whether the subfloor is single- or double-layer, Armstrong
recommends the following: If the top layer is tongue-and-groove and the strip wood is 3" or less in face width, cover with
1/4" or thicker underlayment panels. All others should be covered with 1/2" or thicker underlayment panels.
What can be done to prevent a cracking sound when installing underlayment boards over a tacky residue?
Place a layer of felt or polyethylene sheeting over the residue before installing the underlayment boards.
There are two vinyl floors already down, is there any option other than removal?
If over wood, a new wood underlayment may be installed over the vinyl floors and then the new vinyl. If over concrete, the
vinyl floor must be removed.