This is a common install of Thermabead wall cavity insulation for us. Its a bungalow thats had a recent extension built. The extension has insulation built tin but the rest of the home does not.
With a job like this we fill the remaining exterior walls of the home. So this house had its front and side walls insulated.
They will notice the home will be significantly more comfortable and thermally efficient as these homes are often very cold.
There will be no issue with the material in the extension and the product used in the older section for insulating.
The timing works well too, as the home is about to be rendered after all the building work, so will look great, safe energy and have a better EPC rating when sold.