My Father in law had them out to coat his roof (£2200) for end terraced and was very happy for the first year and a half but when his roof started to flake and peal he ccouldn't get any one from aquaseal to come back to fix it...seems like they have issues with their warranties with several franchises going into liquidation, be careful. Several houses around here have been done by Aquashield and they look like new, perhaps investigate them but sorry don't know their costs.