Ages for building a house: how Kim Lau, Hoang Oc and Tam Tai are worked out, and practical considerations

The feng shui content below is traditional belief that many families consult; it is not a legal rule and has not been scientifically verified. The calculations differ between sources — see References. Updated 23/10/2026.

If you are about to build a house, a common question is "am I affected this year?". In feng shui belief, three kinds of misfortune are usually considered: Tam Tai, Kim Lau and Hoang Oc. You can work them out quickly with the three methods below, then cross-check against your financial plan and construction schedule.

Traditional age (tuoi mu): the reference point

Kim Lau and Hoang Oc are usually calculated by traditional age (tuoi mu): tuoi mu = year of building − birth year + 1. For example, born in 1990 and building in 2026, tuoi mu is 2026 − 1990 + 1 = 37.

Kim Lau

Common method: divide tuoi mu by 9 and look at the remainder.

Remainder	Name according to some sources
1	Kim Lau Than (self)
3	Kim Lau The (spouse; some sources write Tu, children)
6	Kim Lau Tu (children; some sources write The)
8	Kim Lau Suc (livestock, "Luc Suc")
0, 2, 4, 5, 7	Not affected

Two reference articles label remainders 3, 6 and 8 differently. This shows it is folk knowledge with no single agreed table. With the example of tuoi mu 37: 37 divided by 9 leaves 1 — by this method, Kim Lau applies.

Hoang Oc

Hoang Oc divides the cycle into six palaces: Nhat Cat, Nhi Nghi, Tam Dia Sat, Tu Tan Tai, Ngu Tho Tu, Luc Hoang Oc. The first three are more favourable; Tam Dia Sat, Ngu Tho Tu and Luc Hoang Oc are considered bad. The counting method differs by place: some use traditional age, some use lunar age, some count on finger joints. So the same person can get different results on different sites. If you care, pick one source and use it consistently, or ask a knowledgeable relative.

Tam Tai

Tam Tai is a misfortune lasting three consecutive years by age group:

• People born in the years of Than (Monkey), Ty (Rat) and Thin (Dragon) meet Tam Tai in the years of Dan, Mao and Thin.
• People born in Dan (Tiger), Ngo (Horse) and Tuat (Dog) meet it in the years of Than, Dau and Tuat.
• People born in Hoi (Pig), Mao (Cat) and Mui (Goat) meet it in the years of Ty, Ngo and Mui.
• People born in Ty (Snake), Dau (Rooster) and Suu (Buffalo) meet it in the years of Hoi, Ty and Suu.

For example, 2026 is the year of Ngo (Horse), so by this method people born in Hoi, Mao and Mui are in Tam Tai.

What is "borrowing an age"?

When the owner is affected but still needs to build, many families ask someone of a suitable age to perform the ground-breaking, roof-topping or moving-in ceremony on their behalf. Sources usually state the conditions: the person borrowed is not affected by Tam Tai, Kim Lau or Hoang Oc that year, is in good health, has a stable family life, and should not lend to many projects at once. Tradition usually picks an older man, while modern views may allow a woman. Borrowing an age is only a ritual; the construction permit, the construction contract and the land-use rights remain in the real land owner's name — do not put the borrower's name on legal documents without a lawful agreement.

Practical corner when choosing when to build

Many experts quoted in the press say land and direction matter more than age, and some say the rules lack a practical basis. Whether or not you follow them, weigh the following in parallel:

1. Finance: do you have enough capital to build and a reserve for extras? Waiting a year to have enough money is usually safer than a half-built house.
2. Legal: does the land meet the conditions, and is there a construction permit (if one is required)? See also legal checks when buying land or a home in a project.
3. Weather: avoid pouring concrete or doing outdoor finishing in a long rainy season or fierce sun; ask the contractor for the local seasonal schedule.
4. Material and labour prices: these move with the timing; compare quotes from at least a few contractors and state the price-adjustment clause clearly in the contract.
5. Family schedule: the children's school year, the current lease term, work schedules.

If you buy an apartment or a home in a project

Buying a ready-built home or an apartment on handover has no "building" stage like a new construction. Many families still choose the handover day and moving-in day by auspicious dates — see choosing a date for moving in and ground-breaking and construction-start ceremonies. The deposit, payment schedule and handover date are already in the contract; give these milestones priority over dates and hours.

A sensible balance

• If the family values feng shui: choose a year without misfortune when possible, or borrow an age as a ritual, while keeping the documents truthful.
• If the financial schedule or the need to live there is urgent: go ahead on the real plan, and choose a start date and hour that are favourable by belief for peace of mind.
• Talk it over in the family first. A decision the whole family agrees on is usually better than one imposed by worry.

Note: This article is for cultural reference and does not replace legal, architectural or financial advice for a specific case. HPR does not promise fortune or luck from choosing an age or a date.

• Feng shui: FPT Shop — Xem tuổi làm nhà 2026: Cách tính tuổi đẹp, tuổi cần tránh và những điều nên biết (definitions of Tam Tai, Kim Lau, borrowing an age, traditional-age formula; the article gives no specific publication date), accessed 23/10/2026.
• Batdongsan.com.vn Wiki — Năm 2026 tuổi nào làm nhà đẹp nhất? Tất tật thông tin về xem tuổi làm nhà 2026 (how Kim Lau, Hoang Oc, Tam Tai and borrowing an age are worked out; published 24/11/2025, updated 13/01/2026).