EWI ADHESIVE  | BASECOAT

The basecoat adhesive for the K-rend or EWI system, serves as mortar for securing EPS polystyrene boards, Kingspan K5 Phenolic boards, or Rockwool Mineral Dual Density insulation boards. Additionally, it functions as an armored protection layer for insulating newly constructed structures and buildings undergoing thermal renovation, and can be applied on concrete, blocks, and hollow bricks. This versatile product also acts as a reinforcement layer for applying fiberglass armor on EPS boards. Being dual-purpose, this product allows installers to have only one type of bag on-site. The adhesive is waterproof, frost proof and vapour permeable, ensuring that your EWI system remains stable and structurally sound for years to come. It is sold in pre-mixed powder form in 25kg paper bags, approx. coverage: 1.8kg for 1mm thickness per one m2.

ADHESIVE INSTALLATION PROCEDURE

Adhesive renders should be applied to the rear of the board, and should follow either a dot and dab method, with renders to the board edges, or a fully applied adhesive using a serrated trowel. Paddle can be used to mix adhesive with the water until you achieve an even consistency mortar. Once the basecoat adhesive has been mixed, leave the bucket for 5-10 minutes and then remix using the paddle mix – the adhesive is then ready for use.

You can apply adhesive in two ways. Either by applying adhesive to the whole surface of the board using a notched trowel or apply it to the perimeter of the insulation board with 3 dabs across the middle. When using a partial bond method a minimum adhesive surface area of 40 % is to be applied. When using the fully bonded method a minimum adhesive surface area of 100 % is to be applied to the insulation board.

A notched trowel is usually used to apply the adhesive to the back of the insulation boards in order to provide a good key. If using the basecoat adhesive for the base coat layer, apply it using a 10mm notched trowel to the substrate. Next, embed overlapping pieces of fibreglass mesh. The mesh should sit within the middle of the base-coat layer. Once embedded, the basecoat layer should be 6mm in total.

Gaps between boards should never be filled using adhesives. This is because spray foam adhesives are best for preventing thermal bridging, as they have a low thermal conductivity – insulation adhesives will just let all the heat escape through the gaps and cracks. It is most important to keep the insulation boards restrained to the substrate so that no external air can circulate between the insulation boards and the substrate otherwise this can lead to a chimney effect which can result in large heat losses. Bear in mind if the insulation boards finished surface is out of line once installed, additional costs may be incurred due to more base-coat material being required to level out the external surface of the insulation boards. 

TYPES OF EWI ADHESIVE

There are several rules to follow when installing external wall insulation, one of which is to always use the correct insulation adhesive. Some components of EWI systems have limitations on temperatures between which they can be installed, as well as additional requirements which can involve limiting exposure to precipitation or strong sunlight (particularly in warmer climates) during installation to control rates of drying, or prevent excess moisture being trapped within the system. If you’re installing EWI during the winter months, then you may want to consider using Winter Adhesive.

ADHESIVE FOR POLYSTYRENE BOARDS

Because EPS is such a lightweight insulation board, it does not require as much of a heavy-duty adhesive as other materials.

EWI-220 EPS Basecoat creates a strong, long-lasting adhesion, securing the boards to the substrate for years to come. It can also be used within the basecoat reinforcement layer, whereby a Fibreglass Mesh is embedded within the adhesive. The purpose of this is to create a smooth, strong surface ready for the render to be applied to. 

EWI-221 Winter Adhesive - this insulation adhesive can be used for EPS and XPS, at temperatures even down to zero degrees.

Ceresit ZU mortar is designed to apply EPS-boards within Ceresit ETICS (External Thermal Insulation Composite Systems) Ceresit Ceretherm. It is used for applying to the EPS boards as well as to prepare rainforced layers.

Ceresit CT 84 Express is a low expansion polyurethane adhesive for fixing External Wall Insulation boards such as Phenolic, PIR, Expanded Polystyrene to different surfaces such as timber, OSB boards, ceramic bricks and concrete. Fixing of 1 m2 of EPS (Expanded Polystyrene) boards with CT84 weights 100g versus 5kg in case of cement adhesive! It has 15 % higher adhesive strength than traditional cement adhesives.

Ceresit CT 87 mortar is used for fixing EPS or mineral wool facade boards and for applying the reinforcing protection layer. CT 87 is additionally reinforced with fibres, therefore it is more resistant to the formation of cracks and hairlines. The application of CT 87 (colour, surface and organic modifiers) allows for omitting the substrate preparation process by priming with the priming paints before the application of any Ceresit plasters. The content of special light fillers gives the more flexible, light and homogenous consistency, it is easier to be stirred, applied and spread, thus increasing the efficiency of the mortar.

K-Rend HP12 Base Coat is a cost effective enhanced performance high polymer base-coat reinforcing render designed for difficult substrates within External Wall Insulation systems. It's ideal solution as a stipple coat or for dense backgrounds and has increased water resistance with great flexibility, strength and adhesion. HP12 K-rend can also be used as an insulation bedding adhesive as part of a fixing system (appropriate fixings needed) for polystyrene boards onto masonry substrates.

ADHESIVE FOR MINERAL WOOL

EWI-225 Premium Basecoat is the strongest adhesive, designed for securing Mineral Wool, Wood Fibre and Kingspan K5 insulation boards to substrates. This particular adhesive contains portland cement and fibres which create a highly adhesive material, able to support the weight of these heavier insulation boards. Much like the EWI-220, this insulation adhesive can also be used within the basecoat reinforcement layer. Because the product is so strong, it’s also ideal for use in the base-coat layer for render-only systems.

Ceresit CT 180 mortar is designed to warm up external walls of the buildings by application of external thermal insulation composite system using mineral wool facade boards. It is an element of Ceresit Wool Classic and Ceresit Wool Premium insulation systems. 

Ceresit CT 190 mortar is used for fixing of mineral wool facade boards and for applying the reinforcing protection layer to insulate the newly constructed objects.

ADHESIVE FOR PHENOLIC BOARDS

Either EWI-225 Premium Basecoat, Ceresit CT84 Express or Ceresit CT87 or should be used to fix phenolic insulation boards such as Kingspan K5.

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Video credit:https://www.youtube.com/watch?v=N1juCG6adcI&t=235s