No matter the size of the build you need to work out your budget and stick to it. Of course sums need to be included for contingency and professional fees. When costing the build you need a detailed spreadsheet which contains each and every single element of the build and their cost.
Beware of clay! Investigate the ground you are to build on and investigate it thoroughly. Many pounds can be lost in the ground and getting out of the ground can sometimes be the most painful as there can be so many unforeseen challenges if you go in blind.
Keep it simple! The similar the design the cheaper the design - a very general statement but should be taken on board. Adding curved walls and complicated roof designs soon up the costs. Complicated engineered designs may blow the budget before you get off the paper.
Barter! Don't accept your first price, on everything, get at least three prices and then you can still try to barter the best price down. This may sound time consuming, it is, but the savings can be tremendous. Search for bargains and think outside the box - how can you get what you need in a simpler, cheaper way? There will be alternatives you just need to do your research.
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