How to Fill Your Walls to Create a Smooth Surface before Decorating

There is an abundance of wall fillers on the market. Choosing the right one for your needs and applying it correctly is a key step in achieving a sound surface prior to painting.

Over the years, we have used many types of filler and, based upon our experience, I have limited my choice to what we consider to be the best on the market. These are:

1. Gyproc Easifill - this is a powder filler and needs to be mixed with water

2. Polycell Wood and Wall Filler - this comes premixed in a tube

3. Bonding - like EasiFill, this is a powder and needs to be mixed with water

Tip #1 - Use the right filler for the job!

The successful filling of a hole or crack is mainly reliant on using the right filler. Choosing which one to apply will depend upon the hole size and the type of surface that is damaged, whether it be plasterboard or a solid brick and wet plastered wall.

With both plasterboard and masonry walls, a common problem is the use of a dry powder filler (one that needs to be mixed with water) to fill shallows marks, such as those less than 1mm in depth. The issue occurs when a roller or brush passes over it, and effectively lifts it back out. I have found that in these instances the Polycell tube filler works the best. It also has the added advantage of a rapid drying time. If your walls need very little attention I would recommend using this for the entire job.

Gyproc EasiFill would be my recommended choice if the walls are in bad repair and have several deep holes and cracks. It comes in both a 20 minute and 60 minute drying time, if you have large areas to fill I would recommend the latter as it is workable for longer.

Where, for example, cables have been channelled through a masonry wall, it may be the best option to apply bonding as the initial fill. This should be applied to just below the surface level of the surrounding area. I like to try to leave it short by about 2mm to give the top filler enough of a grip. EasiFill can then be used over the bonding to blend the damaged area and the surround, giving a smooth, even finish.

Tip #2 - Ensure the area is ready to be filled

If any loose debris is present in the area to be filled, it must be cleared or sealed before filler is applied. I often apply a glue such as PVA to crumbling surfaces and allow it to dry before filling over it.

Tip #3 - Layer it up

Depending on the depth of the hole or crack, you made need more than one application of the filler. If you attempt to put too much filler in at once it will inevitably crack. Follow the instructions for the respective filler that you are using.

Tip #3 - Sometimes filler alone is not enough...

An example of this would be where a socket has been moved in a stud-partition wall and has left a void. Inevitably there will be nothing here to attach the filler to. In instances such as these, a backing has to be inserted into the void first. The backing should ideally be made of the same material as the surrounding area. In the above example I would suggest cutting a piece of new plasterboard to fit snuggly into the hole. This should be mounted by gluing it in position so that it lays about 2mm below the surrounding surface level. Once set, it can be filled over.

Tip #5 - Sand back to create a flat surface

Once the filler has dried it needs to be sanded back to create a smooth finish. The best technique to ensure the filler will almost entirely disappear once painted, is to use 120 grit paper to initially get the filler flat. I then use 240 grit paper over the edges of the filler where it meets the wall. This secondary sanding will blend the filler into the existing wall surface.

Tip #6 - A finish made to last

It is important to mention that any filler will need to be sealed before applying your full coating of paint. This is done by diluting emulsion with approximately 10% water. This can either be brushed or rolled over the filled area. It is an important step that will prevent subsequent paint coatings from peeling and cracking.

Finally, there are some cracks that cannot be rectified by using decorator's fillers. These are commonly settlement cracks. You may be able to address the problem for a short period of time, but they will inevitably reappear. If you are worried about the look of these or if they are causing concern, it may be advisable to seek professional help to remedy them.