+1 what previous posters have commented on plus I note the following -
If you are employing your brothers as direct labour, you will be undertaking the role of Contractor, with significant Health and Safety implications.
You will also have to deal with co-ordination of arrivals and deliveries, the normal builder's insurances (plural), scaffolding hire, erection and maintenance and all the other duties of a contractor.
This leads into the level of competence of your two brothers
- are they skilled tradesmen, able to work "on their tools" and contribute to the work
- are they experienced administrators, able to run the site as the contractor and relieve you of that burden, or
- are they occasional labourers who have worked as blockie's mates, chippies' mates and do forth, but have no trade or experience of running a site.
If its the latter, and you have no experience yourself, you might be foolish to entrust a quarter of a million Euro investment to your brothers.
Finally, certification of the monies if you are drawing from the bank is one thing, certification of compliance quite another.
Who will you get to design the house so that it meets planning requirements and later complies with the requirements of the Building Regulations.
Who will you employ to detail the building to ensure it is built compliantly and who will issue Opinions of Compliance so that you can sell on when the time comes?
This won't be your only house and you don't want to be stuck with a house that is difficult to sell because the necessary work wasn't carried out through lack of knowledge or experience.
Taking professional advice and ensuring the house is built compliantly allow it to be certified by a building professional to a standard that should be acceptable to a prospective purchaser or his solicitor.
You say your brother built his own - to what standard?
These are the questions a prospective purchaser will ask of you if you don't take adequate advice and ensure the house is built compliantly.
Poor compliance will mean that the house will cost a fortune to heat and the primary means of reducing heating bills is good design, followed by good insulation and use of ambient energy sources.
FWIW
ONQ.
[broken link removed]
All advice on AAM is remote from the situation and cannot be relied upon as a defence or support - in and of itself - should legal action be taken.
Competent legal and building professionals should be asked to advise in Real Life with rights to inspect and issue reports on the matters at hand.