Kingspan K5 is new to our product line-up, so we’ve put together a few tips for installers to bear in mind when installing this type of insulation as part of external wall insulation systems.
Securing Kingspan K5 Boards to the Substrate
When using Kingspan K5 insulation boards, installers should use the Premium Basecoat as an adhesive. This needs to be dotted and dabbed (in the usual method) on the back of the boards.
The real difference between installing K5 boards and EPS boards is that K5 cannot be rasped because it has a glass tissue outer facing. This means that any slight imperfections cannot be levelled using the rasp. The boards therefore need to be perfectly aligned during application to ensure that they are completely flat – otherwise you will be able to see the joints underneath the render. To do this, you’ll need a long spirit level and a fair amount of patience and strength.
To ensure this level of accuracy, the boards need to be cut very precisely – you can’t use a hot wire cutter with K5 boards so it’ll have to be done by hand. Once they are secured to the substrate, any slight cracks should be filled with a spray foam, which should then be smoothed out (note: never fill cracks using the adhesive).
We recommend using the metal pin screw fixings (as opposed to hammer fixings) because the K5 boards are far more tough than EPS, and the screw fixings are guaranteed to achieve a flat finish.
Applying the Basecoat to Kingspan K5 Boards
With external wall insulation, you cannot put a levelling coat on top of insulation boards. Any basecoats thicker than 3-5mm will crack – the basecoat is not for levelling it is for enhancing the tensile strength of the system. This really heightens the importance of getting a level surface with the insulation boards, as any basecoats over 5mm thick will void a system warranty.
Because of the glass tissue outer facing, it’s slightly harder to apply the basecoat to the K5 boards than with EPS. If you’ve installed Mineral Wool before, this shouldn’t be a problem. All you have to do is section by section apply a very thin, flat layer of the basecoat before applying the second notched layer (taking it up to the maximum 5mm) and embedding the mesh.
Once the basecoat reinforcement layer has gone off, the render can be applied in the usual way. The end result should be a cosier home with a seamless render finish!