You do not enter this into your T1 unless it specifically relates to renovations for the elderly or handicapped improved access.  If you are looking for a GST rebate on new construction or substantial renovation of a home, you will need to apply for it using one of these forms:

http://www.cra-arc.gc.ca/E/pub/gp/rc4028/README.html

You will need to fill in all of the information, and send all invoices relating to your expenses, and it will take approx 4-6 months to get an answer or a refund back.  Read the forms carefully.