Full spread is also called 'full stick', meaning the material is stuck down with adhesive that's spread right across the floor.

Manufacturers generally specify acrylic adhesive for lay flat vinyl flooring.

The installation procedure is as follows:

1. Cut and fit the vinyl in the same way as for loose lay.
   
   
2. Once the vinyl has been fitted, fold it back and apply adhesive to the subfloor.

3. Wait for the adhesive to 'tack up' and then press the vinyl into position. Broom out any air bubbles.
   
   
4. Roll the floor thoroughly with a roller, making sure that all trapped air has been removed.

5. Cold weld the seams with a suitable seam sealer.

Adhesive 'open time'

Once an adhesive has been spread on the floor, you need to wait until the open time has elapsed before placing the floor covering in position.

This is also called the tack up time, because the ridges in the adhesive start to 'skin over'.

But don't wait until it becomes touch dry - for the adhesive to grab it needs to be able to stick to your fingers and pull back when you lift your hand off.

Installers describe this stickiness as 'having legs'.

Having said that, you should also make sure that the flooring isn't placed into the adhesive too soon.

Wet adhesive gives off gasses, and if it isn't allowed sufficient time to tack up, the gasses can get trapped under the floor covering and cause bubbles under the surface.

Adhesive 'working time'

When the adhesive is ready for the flooring to be placed on top, the working time begins.

This is the time you have available to lay the material and complete all cutting and fitting.

If you place flooring into the adhesive after the working time has passed, the flooring won't bond properly.

Note that the open time and working time of an adhesive will vary depending on the temperature, humidity and porosity of the surface.

High temperatures, low humidity and porous surfaces will all reduce these times.

For very porous surfaces, such as wood-based underlays, manufacturers generally specify that a primer be applied first with a brush.

This helps to avoid the problem of late placement, where the adhesive has already set and will no longer bond to the flooring covering.

Manufacturers often combine the open time and working time and specify a working open time for their adhesives.

The duration begins when the adhesive is spread and continues through to the time when you should no longer place the flooring into the adhesive.

It particularly applies to adhesives that skin over almost immediately.

Notched trowels

Most adhesives are designed to be spread on the floor with a notched trowel.

These trowels have square or V shaped notches cut into one or both sides of the blade.

Their purpose is to control the amount of adhesive that's spread on the substrate.

Trowels are designed to be held at a 60° angle to the floor while you're spreading.

If the angle is too flat, the ridges in the adhesive will be too low, so there won't be enough to ooze out and fill the spaces when the floor covering is pushed down on top.

Manufacturers sometimes specify different trowel notchings for particular flooring and adhesive products.

It's important to follow these specifications, because if you don't, you'll end up applying either too much or too little adhesive.

Applying too much adhesive can result in the ridges showing through the floor covering surface, or 'bleeding' at the joints.

Applying too little will mean that there is less adhesive available for a firm bond, as well as a reduced working time for placement.

This photo shows what can happen if the adhesive isn't spread evenly.

Large gaps are sometimes called 'windows of opportunity' - because they create the opportunity for a very bad outcome when the material doesn't stick properly!

Over time, the notches in the trowel will gradually wear down and reduce the depths, especially when you're working on cement-based substrates.

So whenever the trowel starts to show signs of wear, it should be replaced. Alternatively, you can reshape the notches using a triangular file.

For more details on the sorts of problems that can occur with adhesives and a troubleshooting table on problems and their causes, see the lesson 'Problems with adhesives' in the unit: Commercial vinyl.

Rollers

Once the floor covering has been placed in position and fitted, it needs to be pushed firmly into the adhesive.

You should do this with a heavy floor roller, running lengthwise and then across the floor.

In areas that can't be reached with a floor roller, use a hand roller.

Be sure to roll the edges and seams properly, because these are the areas where adhesive failures tend to start.