LVT Glue Down Installation Guide

1. SUBFLOOR PREPARATION

1.1 General Requirements

Proper subfloor preparation is essential to ensure a successful long-lasting installation. The surface must be clean, dry, level, and structurally sound. All contaminants such as oil, paint, or adhesive residues must be removed before installation.

Surface regularity must not deviate more than 5mm over a 2m straight edge. For intricate LVT patterns, a stricter tolerance of 3mm over 2m is recommended.

1.2 Moisture & Damp Control

Critical: Moisture is the most common cause of LVT installation failure. Whether due to construction moisture or the absence of a damp-proof membrane (DPM), it can lead to debonding and adhesive breakdown.

New concrete/screed: Due to variable factors influencing the rate of drying, an exact drying time cannot be determined. As a guide, allow one month per 25mm for the first 50mm of thickness. Greater thicknesses require proportionally more time. For example, an 150mm thick slab drying from one face may take up to 12 months.

Testing Requirements:

All subfloors must be tested using a hygrometer over a 72-hour period. Installation should only proceed if the relative humidity (RH) is 75% or lower.

If RH exceeds 75%, apply a suitable surface DPM before installation.

1.3 Specific Subfloor Types

1.3.1 Concrete & Screed (BS 8204)

Must include an effective DPM. If absent or damaged, apply a surface DPM. In all instances, a minimum 3mm smoothing compound must be applied prior to LVT flooring installation. The smoothing underlayment supplier will advise on the correct product to use from their range that suits both the end use application and subfloor construction.

1.3.2 Power-Floated Concrete

If laid directly to the ground, an effective DPM must be used. Smooth dense concrete subfloors — such as those created by a power floated finish — can prove difficult to bond to, due to the impervious nature of the surface. In such instances, the floor should initially be shot blasted to remove the top surface and then made good. In all instances, a minimum 3mm smoothing compound must be applied prior to LVT flooring installation.

1.3.3 Mastic Asphalt

Ensure at least a 15-20mm thickness is applied and brought to a finish with a wooden float. In all instances, a minimum 3mm smoothing compound must be applied prior to LVT flooring installation. The asphalt must not just be skim coated, it is important to ensure that the smoothing underlayment is of a type recommended for use on asphalt floors and that a suitable primer key coat is applied if directed. Never adhere LVT floor coverings directly onto a mastic asphalt subfloor.

1.3.4 Timber Substrates

New timber suspended floors should be constructed of either plywood or chipboard specifically manufactured for flooring. Spacing of the supportive joists should be in accordance with the manufacturer's recommendations in relation to the board's thickness.

For joist centres up to 450mm use 18mm thick load bearing chipboard
For joist centres of 610mm use 22mm thick chipboard
All chipboard should comply with EN312, be P grade P4, P5, P6 or P7

1.3.5 Existing Wooden Floors

Existing wooden floors may have received a preservative treatment that will cause poor bonding, due to a chemical interaction between the preservative and the adhesive. In such cases, they should not be laid onto directly.

All loose boards should be firmly nailed to the joists and any worn or broken boards replaced. The floor should be sanded to remove high spots and any hollows or cracks filled with a suitable flexible underlayment. The existing wooden floors should then be overlaid with suitable flooring grade plywood of a minimum thickness of 5.5mm which conforms to EN 636-3 and EN 314-2 Class 3.

2. LVT INSTALLATION

2.1 Receipt & Storage

Upon receipt of LVT:

Check that colours correspond to those ordered, that quantities are correct and there is no damage
In particular, check that tiles/planks are from one batch, if that was requested on the order
On arrival at site, the tiles should be stored indoors, together with the adhesive, at a consistent temperature of between 18°C and 27°C for at least 24 hours prior to laying
Following off-loading, boxes should be stacked no more than five high during the conditioning period

2.2 Prior To Installation (Underfloor Heating)

Temperature Requirements: A maximum subfloor temperature (at the adhesive line) of 27°C should never be exceeded.

On installations where underfloor heating is used:

The system should be fully tested and commissioned prior to the flooring installation commencing
Underfloor Heating systems should be switched off and be fully cooled for a minimum of 48 hours prior to the installation commencing
The system should remain off and fully cooled during the installation and for a minimum of 48 hours afterwards
It should then be slowly brought back up to the working temperature incrementally over several days
Only specialist high temperature or epoxy adhesives should be used in areas with underfloor heating, direct sunlight, and areas of high solar gain

2.3 Product Conditioning

Critical Success Factor:

The majority of installation failures are not caused by poor fitting but instead simply by failure to condition the vinyl tiles and planks correctly prior to installation.

Conditioning Period: The tiles and planks plus any other products such as borders, feature strips, design strips, tozzettos and adhesives and new plywood bases should be conditioned together for at least 24 hours prior to installation.
Storage Requirements: Boxes of tiles/planks must be stacked less than 5 boxes high and planks/tiles removed 30 minutes before use.
Temperature Control: The room temperature should ideally be between 18°C and 27°C but more importantly should be constant and not varying by more than 2°C.
Location: Conditioning / acclimatisation should always take place in the area that is to receive the installation.
Extended Conditioning: The conditioning time should be increased to at least 48 hours where the planks/tiles have been stored and/or delivered at temperatures below 10°C.

2.4 Setting Out and Installation

The optimum appearance can be produced by carefully planning and setting out of tiles and/or planks:

It is advantageous to dry lay a section of the floor so that it can be determined whether the appearance of the pattern is acceptable
Traditionally the starting point for tiling is the centre of the room
Before adhering confirm that the overall appearance of the flooring is acceptable
Some designs require directional laying and will feature arrows on the reverse side of the tile or plank

Setting out Planks for Straight Fitting

Prior to laying the first plank, ensure all cuts are of an acceptable length (min. 150mm)
As the planks are not required to be laid 'in bond' in the length, it is possible to begin installing from an end wall
Planks must be staggered to obtain a random finish, however ensure that plank ends are not within 150mm of adjacent planks

2.5 Spreading the Adhesive

Important: Always follow closely the approved adhesive manufacturer's instructions.

Sectioning: Once the start point has been established, depending on the size of the area and the type of adhesive to be used, it may be necessary to section off the area so that the adhesive can be applied to areas that can be laid within the recommended open time.
Application: Spread the adhesive using a suitable trowel to the manufacturer's recommendations ensuring that the correct notch size is maintained throughout the installation. If the notch on the trowel shows signs of wear it should be renewed immediately.
Rolling: When a section has been laid, except for the perimeter, it should be thoroughly rolled in both directions with a 68kg articulated floor roller. Repeat for each section until the main field of tiles has been laid.
Perimeter Installation: It is advantageous to leave the last full tile or plank and the cut at the perimeter without adhesive until all planks have been cut to size.

2.6 Adhesives

In areas subjected to direct sunlight or extremes/fluctuations in temperatures manufacturers always recommend the use of an approved polyurethane; epoxy or suitable high temperature adhesive. Manufacturers provide this information only as guidance and the legal responsibility for the supply and performance is that of the adhesive manufacturer. Use of the correct adhesives is important if the installation is to be successful.

Need Additional Support?

For technical support or additional questions about your Lattia glue down installation, please visit lattia.co.uk or contact our customer service team.

LVT GLUE DOWN INSTALLATION GUIDE