Starting from Robinson Crusoe

Although the chimney was not aesthetically pleasing, it finally solved the smoke-leakage problem, and fires could be made for cooking inside the cave.

...

After being busy for several days, once the stove was officially in use, Chen Zhou immediately started on the second project—

Constructing the fire barrier and kang bed-stove.

Before building these two "heating devices," he preemptively sealed off the relatively narrow crevice.

Meanwhile, during this period, Paul and Bi Kai continuously transported food into the cave and began moving quality firewood into the large crevice.

As for the best quality firewood, such as tree burls and roots, they were directly stacked inside the cave.

Chen Zhou specifically set up a "firewood area" for them, separated by a stone wall, to avoid having a disorderly pile of wood in plain sight.

Even though there wasn’t any aesthetic requirement for spending the winter hidden in a cave, his mild OCD couldn’t tolerate having such a large heap of disorganized, unarranged items together in his dwelling.

As for why Paul and Bi Kai weren’t troubled by this—

Because they didn’t have Chen Zhou’s good eyesight; entering the cave was almost like entering a world of near-complete darkness, and at night they couldn’t see anything.

However, the situation slightly improved after Chen Zhou set up the stove.

The light from the fire didn’t cover a large area, but it was just enough to help them see their beds and made cooking easier.

Previously, in order to eat a hot meal, they had to light a fire outside the cave, and it was impossible to compare that cold, harsh outside to the warmth of indoors.

...

Kang bed-stove and fire wall structures are quite similar, both constructed by gradually layering mountain walls, base bricks, beams, top bricks, and mud into a hollow entity.

Packing a kang bed-stove is a craft that seems simple but actually contains many intricacies.

A stove bed made by a master craftsman heats up quickly, retains warmth, and cools down slowly, providing soothing warmth all over.

A poorly built stove bed, however, is not only cold but also uncomfortable to lie on.

Internally, the kang bed-stove is constructed of brick-aligned channels whose key function is allowing the heat and smoke from the stove to evenly warm the bed-stove while expelling unusable smoke.

The principle of the fire wall is similar; however, it’s essentially a segmented version of the kang bed-stove, usually with only two channels, allowing heat to circulate more smoothly and making the structure simpler, but also removing its function as a sleeping surface.

Chen Zhou had seen kang bed-stove construction a few times in his hometown and understood the principles, but implementing it in practice was quite challenging.

Especially because the stove in the cave was small, hoping that the generated heat could supply both the fire wall and the kang bed-stove seemed a bit ambitious.

Considering the pros and cons, he decided to build the fire wall first; once the cave’s temperature stabilized around 20°, he planned to construct a large stove on top of it to heat the bed-stove.

Of course, compared to more crucial preparations like storing fats, constructing the bed-stove could wait.

Currently, apart from eating and sleeping, the group of three was primarily working outside all day.

Taking advantage of the bearable temperatures, they needed to complete indoor tasks and store as much food and firewood as possible. When outdoor work could no longer be done, they’d shift focus back indoors without delay.

...

After testing the reliability of the fire wall with several fires, Chen Zhou began crafting the wooden ladder.

He didn’t want to make the ladder before building the chimney because he was concerned that he might not estimate the chimney’s size accurately, and making the ladder beforehand could affect the chimney’s construction.

Now, it turned out this decision was indeed wise.

After numerous adjustments, the chimney’s diameter exceeded initial expectations, severely constraining the ladder’s space. What initially required 1.8m long lumber now needed only 1.5m. If he had followed the initial ladder plans, the chimney might not have been feasible at all.

...

Due to the steep angle of the cave’s entrance, to ensure the wooden ladder stayed in place without slipping down,

Chen Zhou not only chose densely grained, extremely heavy wood but also painstakingly shaped each ladder section’s connection into a mortise and tenon structure, allowing them to interlock.

The more complex the structure, the more complicated the process, requiring more time and effort.

Fortunately, from the cave entrance to inside was only 9m, and it was easy to find massive logs exceeding a diameter of 1m on the mountain. Chen Zhou crafted "oversized" steps from these, cleverly saving time, and completed the ladder ahead of schedule with only 12 steps.

The "scraps" from ladder making were left by the stove as fuel for recent fires, and with the prospect of snow approaching, Chen Zhou hurriedly organized Paul and Bi Kai to start building a snow shelter at the cave entrance.

Each of the snow shelter’s four corners was supported by sturdy wooden stakes, leaning on the mountainside at the entrance, primarily functioning to block wind and snow blowing into the cave from above.

The most challenging part of this project was digging pits for the stakes.

In warmer weather, even if the mountain had many rocks, the excavation would proceed, albeit slowly.

But now it was winter, and any excavation work was hindered by the severe cold. The wooden shovels they used for digging met the rock-hard soil to no avail.

In the end, they resorted to an old trick—

They dug while burning a fire, working hard until they blackened the cave entrance before completing the task.

Of course, everything comes with a trade-off.

Digging was tough, but thanks to the cold climate, setting the stakes was relatively effortless. They just needed to pour some water into the filled soil.

The frozen water formed icy masses mixed with dirt and stones, creating a solid and heavy "foundation." With this firm base, even if the wind broke a stake with an 80 cm diameter, the bottom would remain unharmed.

However, this opportunistic method only worked in winter. Come the warmth of spring, stakes with an unstable foundation soaked in water would at most hold until late summer before becoming wobbly.

But that scenario wasn’t within their plan—

If they could survive this chilling winter of -65 degrees, they’d surely complete the challenge, returning to their own world with rewards as ultimate victors. Who would worry about the shelter collapsing or find living here very enjoyable?

With four solid stakes supporting it, the upper structure was easy to build, just a matter of securing some less hefty logs to cover the entrance, as they would for a shed.

After the main framework was completed, the finishing work involved filling in some gaps with moss lichens.

This simple task was assigned to Paul by Chen Zhou.

Currently, Paul had moved most of his work indoors, and Bi Kai affectionately called him the salt merchant, as Paul’s main task was purifying rock salt by lighting a fire and boiling water daily.

As someone from the martial world, Bi Kai had dealt with illegal salt sellers often.

Selling illicit salt was lucrative but competed with government profits, opposing the court.

The saying goes "Heroes break the law with force," and as a renowned Sword Hero in the martial world, Bi Kai naturally knew many big salt smugglers. His deceased brother Gao Yao was even part of a northern salt smuggling group.

Due to this influence, Bi Kai instinctively felt some affinity towards the "salt merchant" profession.

His coined nickname for Paul wasn’t meant to denigrate him but was rather a sign of recognition or even a compliment.

...

Working indoors was much more comfortable than outdoor work. Paul was not only a Slav but also genetically modified, and being near the stove for extended periods even made him feel hot, sweaty all over.

Previously, while living in the mid-mountain shelter, he had attempted brewing alcohol, but due to the shelter’s internal coldness, the berries couldn’t ferment, and his attempt was abandoned.

With a suitable environment available now, Paul couldn’t help but go back to his old trade of brewing using hollowed out tree stumps as containers.

Chen Zhou noticed his actions but didn’t discourage him.

Firstly, this brewing didn’t interfere with Paul’s main work.

Secondly, currently, all three were residing in the cave, and as soon as they opened their eyes each day, they’d have to venture out or start a fire to work. Life was quite monotonous, and the pitch-black cave intensified a sense of oppression.

In such an atmosphere, having a task to relieve stress was good; otherwise, staying too long could lead to psychological issues.