I understand it this way: Due to the scaffolding, the rear house cannot be built independently of the front house, as the access becomes too narrow because of scaffolding on the front house. It is logical to start the rear house and advance the work to the point where the front house can be scaffolded and work can continue on the rear house – the vehicles for the interior fitters are usually significantly narrower and would have space to pass alongside the scaffolding of the front house. For moving into the rear house, if moving vans are used, the scaffolding on the front house should be removed again. It is fair that price increases are excluded in writing for the front house. So, there is a temporal overlap. Is this reflected in the agreed deadlines? I find the proposed written form somewhat complicated but not further problematic. With or without paper, it is clear that the construction time of the front house is connected with that of the rear house. Writing this down creates clarity and prevents disputes. Only if the clients insist on a clause that guarantees them penalties for late completion will they find it difficult to sign.