Applying external wall insulation to the wall can be a bit daunting to those new to it. There are several different layers to the system. Therefore, in this blog we are going to describe the basic tools needed to get the job done, but we are also going to look at the some of the additional tools you might want on site if you are looking for that professional finish!

Paddle mixer (plasters mix)

Our external wall insulation and render systems all involve adhesive. For the insulation systems, the adhesive is used to stick the insulation boards to the wall as well as the basecoat layer – in render only systems, adhesive is only required as part of the basecoat layer.

The first thing you are going to need then is a paddle mix. These come in a huge number of sizes and types. It is not something we would scrimp on because as an EWI installer, much like a plaster, you are going to be using this on a daily basis – we would recommend something like the Mikata UT1400.

Likewise, we have a few different mixing paddles – although here we certainly have a new favourite. The OX Pro Mix M8 Rubber Blade Mixing Paddle is relatively new to market, but it is designed to reduce mixing time, prevent damage to buckets and provide much longer tool life – the difference is basically it is made from tough rubber rather than steel – you need to try it for yourself!

TOL-211 Mixing Drill Piece

Notched trowel

Next on our list is our Notched trowels. Typically, there are 2 that are used – the 10mm notched trowel and also the 4mm trowel. The 10mm trowel is used to apply adhesive to the back of the board (if you are covering the whole board) as well as for the basecoat layer. The notched trowel allows you to get an even depth of adhesive on the surface – by holding the angle of the notched trowel at 45 degrees, a dragging the trowel across the surface, a 6mm layer of adhesive will be deposited on the wall or insulation board.

The 4mm notched trowel is used specifically for brick slips – the adhesive in this case is applied as a much thinner layer than the basecoat or when the adhesive is applied to the back of the insulation boards.

TOL-103 Square Notched Trowel

Bucket trowel

The bucket trowel is an essential tool for any plastering, rendering or EWI job. This is used for loading adhesive on to the notched trowel or for putting adhesive on a surface. We do offer a premium bucket trowel with a rubber handle that some of our installers prefer!

TOL-106 Bucket Trowel

Drill bits

There are only 2 drill bits you need when carrying out EWI, one for the rawlplugs for the starter track and the other for the mechanical fixings that go through the insulation boards into the substrate.

The rawlplugs / screws that hold the starter track to the wall require a 6mm drill bit.

The mechanical fixings require either an 8mm drill bit for the metal fixings or a 10mm drill bit for the plastic fixings.


EPS rasp

The EPS rasp is only used for external wall insulation systems – it basically works like a large cheese grater, allowing you to shape the surface of the EPS insulation, to provide a flat surface on which to apply the basecoat part of the EWI system. Also you will sometimes find the surface of the EPS insulation is quite oily, therefore the rasp can be used to remove this top oily layer which may aid the adhesion of the basecoat adhesive.

TOL-109 Steel EPS Rasp

Bucket trowel + steel float

Prior to using the plastic render float to achieve the finish on the top coat render, you need to get the render on the wall. We suggest using a combination of a bucket trowel and a steel float to get the render where it needs to be! We won’t go into any further detail here as most builders will have a pretty good understanding of how these work – the key though is to apply the render as thinly as possible.

TOL-112 Plastic Render Float

Plastic render float

Once the render has been applied to the wall you need to use a plastic render float to get the textured finish. This is done by putting the plastic render float flat on the wall and moving it in quick circular motions. This pulls the aggregate to the surface of the render and is the required finish!

PVC float trowel side