What are the rules for the adventuring gear Hammer and Sledgehammer?

Question

A hammer and sledgehammer appear in the Adventuring Gear table on page 150 of the Player's Handbook; however, there aren't any rules for either of them.

My players have asked about them before. I told them the sledgehammer gives you advantage on Strength checks where you could smash something sort of similar to the crowbar. As for the hammer, I wasn't sure. It's technically not a tool or a weapon, although I would allow some improvisation for either.

Has anyone found or made any rulings for hammers and sledgehammers?

Answer 1

It's up to the DM's discretion.

Notably, a light hammer is a simple melee weapon that deal 1d4 bludgeoning damage and has the light and thrown (20/60) properties.

Per Improvised Weapons (PHB page 147),

Often, an improvised weapon is similar to an actual weapon and can be treated as such. ... At the DM's option, a character proficient with a weapon can use a similar object as if it were that weapon and use his or her proficiency bonus. ... An improvised thrown weapon has a normal range of 20 feet and a long range of 60 feet.

So if we assume that the hammer in the adventuring gear table is not a light hammer in the weapons table, then the only real difference between the light hammer and an improvised weapon is that, for ranged attacks, the light hammer can use a character's Strength modifier for the attack roll and damage, while the improvised weapon would need to use Dexterity.

The sledgehammer would either be an improvised weapon, or looking at the weights (which is not a criteria for the DM to consider), a greatclub or maul. The DM could also just choose to let the sledge hammer represent any other weapon.

The hammer is also a component in several tools, according to the optional rules in Xanathar's Guide to Everything: Carpenter's Tools, Cobbler's Tools, Jeweler's Tools, Leatherworker's Tools, Mason's Tools, and Smith's Tools. For Jeweler's Tools it specifies a "small hammer" and for Leatherworker's Tools is specifies a "mallet", but I have included them in this list for the sake of completion.

The hammer is additionally included in the Burglar's Pack (PHB page 151), so it would be reasonable to conclude that they are used to destroy small or fragile objects, such as a window.

This next section is not based on game mechanics, but just describes how a hammer might be used by real-world artisans. With Carpenter's Tools, the hammer seems to be used to hammer nails into place, and as a way to apply force to a chisel to remove wood. The Cobbler's Tools and Leatherworker's Tools seem to have included it as a way to compress or flatten the thread and leather. For Jeweler's Tools and Smith's Tools, the hammer is used to shape metals (cold for Jeweler's Tools, and hot for Smith's Tools). For Mason's Tools, the hammer seems to have been included as a way to apply force to a chisel to chip away stone.

Per Objects (DMG page 246),

...given enough time and the right tools, characters can destroy any destructible objects. Use common sense when determining a character's success at damaging an object.

Per the Sledgehammer Wikipedia article,

Sledgehammers are often used in demolition work, for breaking through drywall or masonry walls. Sledgehammers are seldom used in modern mining operations, particularly hand steel. Sledgehammers are also used when substantial force is necessary to dislodge a trapped object (often in farm or oil field work), or for fracturing concrete. Another common use is for driving fence posts into the ground. Sledgehammers are used by police forces in raids on property to gain entry by force, commonly through doors. They were and still are commonly used by blacksmiths to shape heavy sections of iron.

Ultimately, the Adventuring Gear section on page 148 of the PHB may say it best,

This section describes items that have special rules or require further explanation.

So by virtue of the fact that the hammer and the sledgehammer lack special rules or further explanation, they function as they would in the real world, at the DM's discretion.

With this in mind, I think a common sense ruling would be that a hammer functions as a light hammer as described in the weapons table, and a sledgehammer can be used to demolish structures made from wood or brick, but not necessarily natural stone formations such as cave walls. That is common sense to me, but may not be common sense to another DM, so as usual it's "per DM's option" on how effective these pieces of gear are in any given situation.

Answer 2

The Hammer can be used with Iron Spikes

Both the hammer and sledgehammer are tools so they can help do what the tool is designed for. If you want to dig a hole but you don't have a shovel it will be more difficult. Similarly it is hard to hammer in a nail of you don't have a hammer. This can translate to game mechanics in two ways:

First if an attempted action requires a tool that the characters do not have then the DM can rule the attempt automatically fails unless the players find a substitute. For example if you want to hammer in a nail but lack a hammer the DM could say you fail unless you find a rock or similar object to use instead.
The other side of this is there might be cases where having the appropriate tool negates the need for a skill check. You probably don't need a skill check to hammer in a nail if you have a hammer.

Secondly lacking an appropriate tool could translate to a higher DC or to disadvantage when attempting the task. Perhaps you find a rock but because it is a poor substitute for a hammer the DM says you have disadvantage on the check.

As a final point Iron Spikes state that they are usually used with a hammer. In turn the Hunting Trap says that it must be fixed to an immovable object such as a spike driven into the ground. This demonstrates how an appropriate tool can expand the available options.

Answer 3

It's up to the DM to determine how to adjudicate most adventuring gear. At my table, in general, I allow an appropriate tool (or tool set) to either give advantage on a check that the PCs could easily attempt without a tool, or if the task is something they couldn't easily attempt without a tool, they either can try it at all, or they can try it without suffering disadvantage.

Based on the equipment packs, hammers are mostly used for pounding pitons in or similar work, and while you could drive a piton with a rock, that sounds like something that would apply disadvantage on the roll, so the hammer just means you don't take disadvantage.

Using tools as weapons should just follow the usual improvised weapon rules -- the DM should look at the tool and decide if it counts as a weapon for proficiency and damage purposes or just make it a generic 1d4 improvised weapon. It's pretty easy to draw lines between a sledgehammer and a warhammer or a prybar and a club, so those shouldn't be too difficult to work out. A hammer is probably an improvised light hammer -- it's a little heavier, but close enough for a quick ruling.