Is this house rule replacing encumbrance balanced?

Question

My group finds it boring to compute encumbrance. Having to manage dozen of meaning-less items and having to sum up their individual weights is really awkward. We decided to drastically reduce the number of items we have to carry, so that characters can have at maximum a number of significative items that allow them to walk at full speed (we don't compute speed at all). Additional items have to be stored somewhere (ship/caravan/chest). So we've instituted the following house rules:

Encumbrance

Worn items do not count toward encumbrance. A creature maximum carry capacity is as follows:

• High Base Attack Bonus: 3 heavy items + 5 medium items + 16 light items (minimum 1 heavy, medium, and light item).
• Medium Base Attack Bonus: 1 heavy items + 2 medium items + 11 light items (minimum 1 heavy, medium, and light item).
• Low Base Attack Bonus: 1 medium items + 8 light items (minimum 1 in medium and light item categories).

Current house rules forbid multiclassing.

Strength modifies these numbers as follows:

• (Str modifier) ×1/2 more or fewer heavy items.
• (Str modifier) more or fewer medium items.
• (Str modifier) ×2 more or fewer light items.

Light Items

• pouches
• daggers
• most exotic weapons
• gems
• potions
• buckler

Medium items

• leather armor
• backpacks
• regular weapons
• shields

Heavy Items

• armor other than leather
• two handed weapons
• tower shield

Containers

• Each character is allowed to bring with him only worn gear/weapons and 3 items
• The maximum carry capacity can be reached only by wearing "containers"
• So by wearing a backpack a character is able to put inside it 2/4/8 extra items (beyond to the 3 items limit, but up to the maximum carry capacity)
• Very small containers (like gem pouches) can contain a limited amount of many small items (like coins, gems/rings) so they can be used to fill a small slot with many small items.
• Books are small items, and scrolls can just be fitted between pages of the book.

Really heavy items

• Really heavy items can only be pulled by lifting after a Str check and will emit loud sounds (gold giant sword, statue, chest)
• Lifting a heavy items cause opportunity attacks

Other items are the DM's call. An item can occupy a heavier slot but not a lighter slot.

Will this alternative encumbrance rule unbalance the game? That is, is there a way that it can be exploited so that characters are significantly overpowered and capable of overcoming challenges significantly above their levels? Likewise, will these rules prevent PCs from doing things they could normally do to such a degree that my group would be better served tallying encumbrance the old-fashioned way?

The above list was already edited a bit keeping into account answers and comments and test play sessions.

Answer 1

I've had some experience with an encumbrance system like the one you've laid out, albiet from the other direction - it was a military themed homebrew system that started out with fixed kit for all players and gradually increased customisability.

Over the course of a few iterations we discovered a couple of balance-related concerns:

1. Multi Slot items

   You've considered carrying many little things, but less so a few big things - expect players with low encumbrance requirements to eventually want multi-slot items. The Barbarian probably has 18 strength and after the greatsword, some armour, and maybe a bow that's 3 heavy slots they'll want to fill with something fun - like maybe a sword the size of the party Elf made of magically hardened solid gold.

   While you can obviously just veto this, if you allow it you'll need to pay attention to how easily you give away power this way or you may break the power curve because 'raw power' is the obvious advantage to 'bigger'. We found the most satisfying way of handling this was to balance steep costs with small but novel improvements on the setting standard - your giant Greatestsword weighs four heavy slots but does 2d8 damage and is absolutely the biggest damn sword known to medium humanoids.

2. Undervalued items getting hedged out

   The flipside is that anything neither big and impressive, vital to class functioning, or a commonly expended consumable will tend to get hedged out. Classes with high encumbrance needs will be most susceptible, like archers who need to pack around arrows in volume. Anything they normally may or may not carry will tend to disappear in favour of more ammo, or more specialist ammo, or whatnot - especially now that there's a clear cost.

   We saw this happening with grenades - once we had to evaluate say, bringing an extra rocket vs a couple of grenades the grenades started disappearing from everyone's loadouts (to the point where the GM just started having NPCs bring them in case they were needed). This may well happen for you with potions and scrolls. Consider providing special slots for boring but useful things like healing potions.

Answer 2

I'm going to challenge the frame.

You've said your group finds it boring to compute encumbrance. So to solve that you've... created another system for encumbrance? That just calculates things differently? That doesn't seem to solve your actual problem.

If your group doesn't want to deal with encumbrance, have you considered just ignoring it? You're adventurers, you'll figure out some way to move the loot from point A to point B, even if it's just piling all the stuff on a sledge and dragging it around; if you don't want to worry about the details of how you accomplish that, you don't actually have to.

If hitting myself on the head with a hammer hurts, then the solution isn't to look for a rubber mallet so that it will hurt less when I hit myself, the solution is to stop hitting myself. You play RPGs to have fun (I hope); if there's a part that isn't fun, skip that part.

Caveat: Some people do enjoy encumbrance mechanics. It's 100% OK for those people to use the existing mechanics or adapt/create their own. My point is that people who don't enjoy encumbrance shouldn't feel obligated to keep using it just because it's in the rulebook.

Even groups that do get some value from encumbrance may find it worthwhile to drop the actual rules for it. It seems like you're putting a lot of work into developing house rules to cover encumbrance, and worrying about whether those rules are balanced (always an appropriate question to ask about house rules), when maybe that's not the simplest solution. If you trust your DM to adjudicate encumbrance, then why not just have people carry however much seems appropriate to them and let the DM decide if someone is over the line.

Answer 3

Cut out the nitty-gritties. Use common sense.

A warrior can't reasonably carry 10 greatswords, 5 battleaxes, and an anvil. There is no need to calculate encumbrance or enforce mechanical rules to see that it's totally ridiculous.

I've never played with encumbrance mechanics or food rationing. The thing that kept us from carrying too much stuff and sleeping between every battle was common sense and a sort of agreement to have fun and not abuse the rules.

If you must, give all your players a bag of holding.

You can completely sidestep encumbrance to a never-have-to-worry state by giving all of them a bag of infinite holding. This will appease the players who want to follow all the rules as well as the players who don't want to bother calculating encumbrance.