In my experience, certain banks can be cautious about giving top ups for stock market investments and if they are asking for estimates for building work now, they will more than likely ask for receipts later for work done, so you may be giving yourself further headaches down the line. A better solution if you really want to do this might be to remortgage for 220,000 e.g. with Ulster Bank, who will pay your solicitor fees involved in the transfer and may even give you a better rate (not sure about details of your mortgage with EBS, but UB U-First tracker is quite good and it might be worth your while switching anyway). It's best to be honest I think.