without investing any perks in heavy or light armor or exploiting a bug?

Will I reach the armor cap in fully upgraded Deadric and 100 Heavy Armor skill?

Oh, I'm pretty sure you will if you use a shield. If not, I'm pretty sure you'll come extremely close.

EDIT: Changed would to will.

Armor cap is 567 armor rating.

Yes.
-Loth

thanks guys. Guess no sense wasting perks in Heavy Armor then

is the conditioning perk worth wasting 4 perks for?

You might find a couple in the bottom perk makes it happen quite a bit sooner though. I have 80 Heavy and all the bottom perk and I just hit 567 at level 40. All Deadric smithed at 100 and improved with a blacksmith 30% potion and about 30% worth of enchanted apparel. Legendary. I found a 50% balcksmith potion but I used it on the weapons.

in respose to title only: yes it is possile to hit the armor cap.

He asked if he can hit the Armor Cap without investing any perks into Juggernaut or Agile Defender, which i don't think you can, considering having 5/5 in those perks increases your Armor Rating by 100%, and that's not even considering Well Fitted or Matching Set, for an additional 25% for each of those perks, for a total of +150% Armor Rating. Only way i think you can, is if you seriously abuse the Alchemy/Enchanting/Blacksmithing loop along with Fortify Restoration in order to enhance your Armor to an obscene degree at the Workbench.

If you abuse Smithing yes. You can hit the armor cap in Fur Armor if you abuse Smithing hard enough.

The exact numbers to hit the Armor cap in full Daedric (no shield) with zero perks in heavy armor and 100 in heavy armor skill: an effective 332 in smithing, which is doable via enchanted smithing gear and a +smithing potion.

-Loth

PS The above number assumes that you do not wear enchantments to raise your heavy armor skill. Using an enchant like this will drastically lower the smithing level required to hit the cap.