I was surfing abt renovation restrictions on HDB website when i saw this. But its only applicable to The Premier. Nevertheless, I guess most of it will be applicable to The Peak too. (copy n paste the whole url)
http://www.hdb.gov.sg/fi10/fi10297p.nsf/ImageView/THE_PREMIERE@TAMPINES_(RENO_GUIDELINES)/$file/The+Premiere@Tampines+(Reno+Guidelines).pdf