Do not use this firm. They will install cavity wall insulation regardless of whether your property is suitable or not. The assessor will not be expert in his survey but operating on a commission led sales basis. When problems arise later they will never admit any liability and blame it all on your lifestyle, creating your own streaming condensation, damp and mould, by not airing the property enough. Further independent Inspections may show up voids, walls absent of any insulation, and your own research that they have breached conditions of their product certification, codes of practice, contract law etc. Nobody will ever answer to this or admit wrongdoing. They will ignore you completely for long periods and meanwhile try to cover up their tracks with excuses and deception. Avoid like the plague because the 25yr CIGA Guarantee will NOT automatically cover you whereby you will have another enormous fight on your hands, however legally right your case may be. Finally, don't think there will be an ombudsman that you can turn to in your hour of need. Warmerhome are not obliged to sign up to these services under the Green Deal - so they haven't. I retain proof of all this. Caveat Emptor!