A teahouse is not a hotel. It is somebody's home with rooms in it, run by a family who live in the same building, often at the end of a supply chain that arrives on a mule or a back. Understanding that changes almost every decision you make in one, and it is the difference between being a guest and being a customer.
The arrangement, plainly
Rooms are cheap — often a few hundred rupees, sometimes free — because the teahouse makes its money on food. You are expected to eat dinner and breakfast where you sleep. This is not a rule anyone will recite to you, and it is the single most important convention on the trail.
Eating elsewhere and then coming back to sleep is the one thing that genuinely causes offence, because it takes the room at cost and gives the margin to someone else. If you want to try another lodge's apple pie, do it at lunch.
The dining room is the point
Bedrooms are unheated. The dining room has a stove, usually lit around five in the afternoon and burning yak dung or wood carried up the valley, and it is where everyone spends the evening.
This is the social heart of a trek. It is where you meet the group coming down who can tell you what the pass looks like, where your guide talks to other guides about conditions, and where the day gets discussed. Trekkers who eat quickly and retreat to a cold room miss most of what makes a teahouse trek different from a hotel tour.
Sit near the stove if you are cold. Do not put wet boots directly against it — it is a cooking and heating stove, not a drying rack, and the smell carries.
Ordering, and dal bhat
Menus in the Khumbu and Annapurna are near-identical from lodge to lodge and get shorter as you climb. Order early — the kitchen is often one or two people cooking on a single stove, and twelve separate orders take a long time.
If the group can agree on the same dish, the food arrives sooner and warmer. Guides will often suggest this, and they are not being lazy.
Dal bhat is lentil soup, rice, vegetable curry and pickle, and it comes with free refills. It is the meal the porters and guides eat every day for a reason: it is fresh, it is hot, and it is the best-value calories on the mountain. "Dal bhat power, twenty-four hour" is a joke that is also true.
Above about 4,000 m, avoid meat. It has been carried up unrefrigerated for days. Every guide on the trail will tell you the same thing, and the ones who did not listen have a story about it.
Water, and the plastic problem
Bottled water is sold everywhere and costs more the higher you go. It also creates a waste problem the valley has no way to process — every empty bottle either burns or is carried out on somebody's back.
Boiled water is sold at every teahouse by the litre, it is cheaper, and it doubles as a hot water bottle if you fill your flask at dinner. Purification tablets or a filter with tap water are cheaper again. Any of the three is better than a plastic bottle.
Charging, wifi and hot showers
All three cost money, and all three get more expensive with altitude. Above Namche, electricity is usually solar, and a cloudy day means there is less of it.
A hot shower may mean a bucket of hot water, and it may not be available at all when it is cold. Take the shower low and accept baby wipes high — this is normal, everyone smells the same, and nobody minds.
Bring a power bank. It is cheaper than paying to charge a phone every evening, and it works when the panel has had a bad day.
Toilets
Usually a squat toilet, often outside the main building, sometimes shared. Bring your own paper — it is rarely provided — and a small bag for used paper, because in most lodges it does not go down the pan.
There is often a bucket of water for flushing. Use it.
The things that cause offence, and the things that do not
Take your boots off where you see other boots off — usually at the door of the dining room or the sleeping wing.
Ask before photographing people, especially older people and anyone working. A trail is not a set.
Walk on the left of a mani wall, chorten or prayer wheel, so the structure passes on your right. Spin prayer wheels clockwise. These take no effort and are noticed.
Yaks have right of way, always. Stand on the uphill side of the trail when they pass. A loaded yak has knocked people off the outer edge before.
Keep your voice down after about nine. The walls are thin, and the family is up before you are.
Nobody minds that you do not speak Nepali. Namaste on arrival and dhanyabad for anything handed to you covers most of it, and the effort registers.
Tipping
Tipping is expected on a guided trek, but it is not built into anything you have already paid.
The convention is to tip as a group at the end, in Nepali rupees, handed over at a final meal rather than pressed into hands on the trail. Guides and porters are usually tipped separately, with the guide taking a larger share. Ask your guide what is customary rather than guessing — they will tell you honestly, and it is far less awkward than the alternative.
If someone carried 15 kg of your belongings up a valley for a fortnight, the tip is not a gratuity for good service. It is part of what the work is worth.