1. A licence for construction work
In Portugal, construction companies need an IMPIC certificate or licence (alvará) that covers the value of the works. Ask for the number and check it on the IMPIC website. Be wary of anyone without one for a renovation.
2. Insurance
Ask for proof of civil liability insurance and, if the company has employees, workers' accident insurance. Check the expiry dates.
3. A detailed written quote
A good quote separates labour and materials, says what is and isn't included, and gives a timeline. Compare quotes line by line, not only by the total.
4. Staged payments
Avoid paying most of it up front. Tie payments to completed stages and keep a small part until the end. Payments held until you approve protect both sides.
5. Your condominium and noise hours
Tell the condominium administration before work starts. In residential buildings, the General Noise Regulation only allows works on working days between 8am and 8pm, with a notice posted.