Building a Chicken Coop for a Philippine Climate

Almost every chicken coop guide a Filipino can find was written for a country where the problem is keeping birds warm. Here the problem runs the other way for about eleven months of the year, and a design that solves the wrong problem does it quietly: the birds do not die of it, they just eat more and grow less and you never find out why.

There is exactly one Philippine standard with numbers in it. PNS/BAFS 262:2018 sets indoor stocking at 17 kg per square metre for broilers in fixed housing. Hold that against Aviagen’s own guidance for open-sided houses, which caps them at 16 to 18 kg/m² at the hottest times of the year (Ross Broiler Management Handbook 2025).

The Philippine standard sits inside the hot-season band. All year. Iyon pala ang sinasabi nito, at wala akong nakitang nagsasabi niyan nang malinaw. Somebody made that call on purpose, and it is the most useful single fact about building a kulungan in this country.

How many birds actually fit?

PNS/BAFS 262:2018 is the national standard for free range chicken, from the Bureau of Agriculture and Fisheries Standards, with BAI and Central Luzon State University on the technical working group. Its § 6.3.1 is the only Philippine stocking density anybody publishes for a meat bird. Layers have a second one, in a different standard, and it is worked through on the movable-coop page.

The broiler row has two limits and most guides quote only the first. They meet at exactly 1.7 kg a bird, which is 17 divided by 10, and 1.7 kg is the top of the liveweight Philippine broiler farms target. Below that the bird count binds; above it the mass limit binds and ten birds per square metre becomes too many. Sa araw ng harvest pinakamasikip ang kulungan, and that is the day the coop has to be sized for.

Dahil hindi magkatugma ang broiler line at ang native line, sulit basahin ang dalawa nang magkatabi minsan. One is written in kilos and the other in birds, so past 2.83 kg a square metre holds fewer broilers than native chickens, and the mass the same floor carries is nothing like the same.

Ten birds per square metre is also what Philippine farms actually do

A standard tells you what is allowed, not what anybody builds. Ancog and colleagues at UPLB measured six commercial broiler houses for a 2023 life-cycle assessment, and their Table 1 is the only published record of density inside real Philippine broiler housing I have found. All four conventional open-sided houses ran at 10 birds/m², PNS 262’s count limit exactly. The two tunnel houses ran at 17, one of them at 15.

Ang ventilation ang bumibili ng dagdag na manok sa parehong sahig. Aviagen’s ladder has a third rung PNS 262 has no equivalent for: open-sided houses cap at 20 to 25 kg/m², dropping to 16 to 18 in the hottest months, and a controlled-environment house is allowed 30 kg/m² (Ross Broiler Management Handbook 2025).

The density column is the paper’s. The two loss columns are this page’s arithmetic on its head counts, which it prints as birds and never as rates: 18,009 chicks placed, 17,196 after brooding, 16,890 at harvest in the conventional houses, against 135,072, 133,890 and 128,567 in the tunnel.

Read the brooding column first. The open-sided houses lose 4.5% before the birds leave the brooder and 6.2% across the cycle, so three quarters of what they lose goes early. The tunnel houses lose 0.9% and 4.8%, the other way round. Sa bakuran, ang unang linggo ang pinakamahal.

None of those six houses is a bakuran coop. At 1 July 2026, 89,298,658 birds of a national 228,489,122 stood in holdings of 500 birds or fewer, 39.1% of the country’s chickens, and not one of them has been measured for density.

What does the standard not cover?

PNS 262 is the free-range standard. Its scope is free range production, and most Philippine backyard flocks are confined, often entirely.

The resulting gap is real, and it is narrower than it looks. Gap G-18 stays open for meat birds, broilers and native chicken raised for meat, where no Philippine body publishes a confined-housing density at all. It is closed for layers, by PNS/BAFS 312:2021 § 6.2, which requires 0.14 m² a bird single-tier and 0.1 m² multi-tier, tighter than the 6 birds/m² PNS 262 allows a layer. The movable-coop page works the hen figures through and the gaps register carries the narrowed version.

For a confined meat flock the free-range indoor figure is the only one there is, so borrow it and say which standard you borrowed it from when somebody asks. Hindi ito ang tamang numero, ito ang tanging numero.

Two other holes in PNS 262 itself. It states no nest box dimensions, so the coop tool gives none from that standard, and PNS 312 does state them in the next section. Its shade allowance of 8 to 16 m² per 1,000 birds computes to 0.16 m² at 20 birds, which is plainly not what anybody meant. Gamitin mo ang density rows at sentido komun sa lilim.

The rest of § 6 is worth reading once even at twenty birds. § 6.3.2e wants two popholes per 500 birds and two every 10 m along one side, each 46 cm high by 100 cm wide, more wall than most bakuran coops give up. § 6.4.4 opens pasture from day 30 and § 6.6.1 prohibits beak trimming outright. And § 6.4 rests pasture a month between batches “except for batches with less than 50 birds”, a backyard exemption inside a commercial standard and the only line that reads as though somebody pictured a bakuran while drafting.

The perch and the nest box: two BAFS standards, two answers

PNS/BAFS 312:2021, the Code of Practice for Cage-free Egg Production, fills in most of what PNS 262 leaves blank for hens. It also contradicts it.

PNS 262 gives 31 cm of linear perch a bird. PNS 312 § 6.6.1 requires “a minimum of 15 cm linear perch space per hen”. Two standards from one bureau, a factor of two apart, both current, neither withdrawn, and nothing in either explains the gap. I am not averaging them and not picking one. Build to 31 cm where the wall allows and you satisfy both. Kung 15 lang ang kasya sa kulungan mo, sumusunod ka pa rin sa isa sa dalawa, at alamin mo kung alin.

On nest boxes, 312 supplies what 262 lacks: § 6.5.2 asks for “a minimum of 35 cm length x 35 cm width x 35 cm height per hens for individual boxes, or 1m² of nesting substrate per 120 hens for group nesting”, enclosed and draught-free, § 6.5.5 wanting a curtain overlapping by at least 1 cm. Mas malaki iyon kaysa sa karaniwang pugad sa bakuran.

Neither standard publishes a height for a perch or for a nest box, so the arrangement below is a build decision rather than a reading of either one. Perch above, boxes underneath, para hindi matulog ang inahin sa ibabaw ng itlog.

Ammonia at head height is the row I would write on the wall. Aviagen puts its ideal below 10 ppm, says you can smell it at 20, and reports growth may be reduced above 25 (Ross Broiler Management Handbook 2025). The Philippine trigger sits where a human nose first notices.

On pullets, Mississippi State allows “2 to 3 square feet per bird if raised in confinement”, which converts here to 3.6 to 5.4 birds/m². Both ends of that are looser than either Philippine figure for a bird the same age: 6 birds/m² under PNS 262 for a layer, and 0.14 m² a bird under PNS 312, which the movable-coop page works out at 7.14 birds/m². Mas malawak ang sahig na ibinibigay ng isang Amerikanong extension service kaysa sa dalawang BAFS standard.

There were 52,103,982 laying birds in the country at 1 July 2026, and two BAFS standards telling their keepers different things about the perch each one needs.

Why does the roof decide the feed bill?

Because a hot bird eats less and grows slower, and the arithmetic is not small.

Cyclic heat stress cuts broiler feed intake by about 15%, roughly 1.5% for every degree C. Constant heat stress cuts it 25 to 45%, and it is the constant figure that carries a stated range: about 3.5% per degree C between 22°C and 35°C (Teyssier et al., 2022). That band belongs to the constant figure and gets quoted against the cyclic 1.5% often enough to be worth checking, because they are different claims.

At 32°C, weight gain falls 21% under cyclical heat stress and 36% under constant. Those two reach us through Kpomasse et al. (2021), which is reporting de Souza et al. (2016) rather than measuring anything itself, and that matters if you go looking for the method behind them.

Both are imported reviews, and paliwanag lang sila. Multiply a European growth curve by a review-paper percentage and what falls out is a Philippine growth curve nobody measured, carrying a decimal point it has not earned.

What they explain is the FCR gap in the broiler cluster, where the sixteen open-sided growers in that survey set themselves a 1.50 to 1.83 feed conversion against a breed table near 1.26, and a third of the growers in it say they miss what they set. Nobody has published what those farms reach. The roof is a large part of why the aim has to be set that high in the first place. Ventilation, shade and stocking density are not comfort decisions here. They are the feed bill.

Aviagen’s own limit is the blunt version: in an open-sided house with no environmental control, “it is not recommended that birds grow to live weights above 3 kg”. Walang fan, walang cooling, at may sukat na hindi na lalampasan ng manok mo. Ang bubong ang nagtatakda ng harvest weight bago ka pa bumili ng sisiw.

Which way the coop faces, and what the roof is made of

Aviagen gives one instruction about orientation and it is unambiguous: “Open-sided houses should be positioned so that the length of the house is oriented in an East-West direction to minimize solar heat gain through the sidewall” (Ross Broiler Management Handbook 2025). The sun then works on the short ends and the long sides sit in the building’s own shade. Libre iyon, at hindi mo na mababawi kapag nakatayo na ang poste.

The roof is where the instruction and Philippine practice part company. Ancog et al. (2023) describe the four conventional houses as “Elevated, open sided with lumber on concrete columns”, floored with bamboo slats, no sidewalls, tarpaulin curtains adjusted by hand, roofed with “Corrugated GI sheets without insulation, monitor type with wood trusses”. The tunnel houses in the same study have GI roofs with insulation. PNS 262 § 6.3.2d asks for insulation over a veranda; the measured open-sided sector has none over the birds.

One more line from that paper is worth quoting whole: “the flock man does not have any measuring device to determine the temperature and humidity levels inside the house.” Walang thermometer sa loob ng commercial broiler house, at ang tao pa rin ang nagpapasya kung kailan itataas ang tarpaulin.

The monitor roof those houses use, a raised ridge venting the hottest air at the peak, does part of the job insulation would otherwise do. Iyon ang tanging bahagi ng disenyong iyon na kokopyahin ko sa maliit na kulungan, at mura ito sa kawayan.

No series in this archive tracks roofing material, insulation or orientation, and none is likely to. Ancog’s Table 1 is the closest thing to a record of what Philippine houses are actually built from.

38.5°C and 50 m/s: the two numbers a bakuran roof is designed against

PAGASA puts the mean annual temperature at 26.6°C, the coolest month at 25.5°C in January and the warmest at 28.3°C in May. Those are national means, and they understate what a roof has to survive.

The station records are the numbers to build against. At Science Garden in Quezon City the 1991 to 2020 normals put the April mean daily maximum at 34.6°C, May at 34.4, the annual mean maximum at 32.1°C. That is the average April afternoon, not a bad one. The extremes record for the same station, covering 1961 to 2025, holds the all-time high at 38.5°C on 14 May 1987 and the April record at 38.2°C on 27 April 2024, so April’s record moved two years ago. Every month from March to November has recorded at least 35.0°C there, and January’s highest is 34.7°C.

Penn State bands what that does to a bird. Its hot-weather guidance puts the start of heat stress “above 80 degrees Fahrenheit”:

The Fahrenheit column is Penn State’s. The Celsius column is this page converting it, because PAGASA publishes Celsius and Penn State publishes Fahrenheit and the two cannot be read against each other until somebody does the sum.

The national mean of 26.6°C is 79.9°F, a tenth of a degree below where heat stress begins, so the Philippine average day sits at the top of the slight-feed-reduction band all year. Science Garden’s April mean daily maximum of 34.6°C is 94.3°F, inside cooling practices necessary. Ordinaryong Abril lang iyon sa Quezon City. It also settles a claim below: a closed brooder box under a GI roof needs no lamp to pass 32.2°C in April, because the outside air is already there.

The second number is wind, and the strongest gust in the Science Garden record is 50 m/s from the NNW on 3 November 1995, or 180 km/h. Ang bubong na lumilipad ay hindi magaan, ito ay hindi nakakabit nang maayos, so the answer lives in the fixings rather than the sheet.

Humidity is the half nobody prices in

Temperature is the half everybody builds for. Humidity decides whether that temperature is survivable, and I have not read a Philippine coop guide that prices it in.

Aviagen wants 50 to 60% relative humidity after brooding, and states the interaction rather than leaving it implied: “When temperature is >29°C, if RH is >70% or <50%… performance will be affected” (Ross Broiler Management Handbook 2025).

The Philippine readings do not come close. PAGASA puts the national monthly average between 71% in March and 85% in September (Climate of the Philippines), and per station it is worse: Science Garden 68% in April to 85% in August, Mactan 78 to 85%, Legazpi 82 to 87% and never below 82 in any month.

Aviagen’s ideal tops out at 60% and the driest monthly mean at any of those stations is 68%. Wala kang mararating na 60% sa Legazpi, kahit anong gawin mo sa bubong, so the ideal is not a target here and should not be written as one. Which leaves the >29°C with RH >70% clause doing the real work, and at Legazpi it holds for much of the year.

The brooder has the opposite problem and one Philippine measurement of it. Pediongco and Simbulan (2025) observed native chicks huddling above 75% humidity and concluded that “the RH lower than 70% during this brooding period is even better”. Their pens ran litter moisture of 2.50 to 6.25%, with “no ammonia produce in the experimental pen”. Ang tuyong litter ang humidity control at ammonia control nang sabay.

One cooling trick to leave alone: Aviagen cautions against wetting the roof, because the runoff evaporates around the house and pushes in-house humidity up. Above 70% already, that trades a degree for a problem you cannot see.

No series in this archive carries humidity. PAGASA publishes the station normals as PDFs, one station at a time, and your nearest station is the one to pull.

What does a brooder actually need?

Week one is the exception to everything above. A day-old sisiw cannot hold its own body temperature and heat is the entire job.

The two schedules a keeper is most likely to meet disagree, and they are kept apart here rather than averaged.

MSD steps down 2.8°C a week until 21.1°C. Mississippi State reaches the same 21.1°C by the end of week three, two weeks earlier. Averaging two sources that disagree is not synthesis, so the brooder tool prints both.

Now the Philippine complication. PAGASA puts the mean annual temperature here at 26.6°C and the warmest month at 28.3°C, at or above the week-three target in either schedule. Kaya pagsapit ng week 3, ang tanong dito ay kung kailan papatayin ang init. Walang idinadagdag. Which schedule you follow stops being academic in weeks 1 and 2, where the two give opposite instructions at some Philippine readings.

The 31°C ± 1°C figure that circulates for Philippine native chicks is routinely attributed to the wrong document, including here until 15 August 2026. Pediongco and Simbulan (2025) do print it, but as a requirement they worked inside rather than a result they measured: “within the ambient temperature requirement for brooding which is 31℃ + 1℃ [4]”. Their reference [4] is Lambio’s Poultry Production in the Tropics (2010), a UPLB textbook. Their own pens ran 30.42 to 32.58°C.

That makes the provenance better rather than worse: a Los Baños textbook on tropical poultry is a wider foundation than one trial on one campus. It is still not a national standard and hindi ko ito ipapasa bilang ganoon.

There is a third brooder schedule, and it runs hotter than both

Two things about the table above need saying before you use it.

The Mississippi State column is partly arithmetic done here. MSU publishes prose, not a table: 90°F for day-olds, then lower it “five to seven degrees each week until 70 degrees”, arriving “at the end of the third week”. The week-1 figure is MSU’s. The week-2 and week-3 bands are steps computed here from that instruction and the stated endpoint, and MSU prints neither.

There is a third published schedule and it disagrees with both. Penn State Extension runs hotter at the start than either:

Penn State’s week one starts above MSD’s ceiling and above MSU’s single figure. It also asks you to preheat the brooder “to 92°F at least 24 hours prior to placing chicks”, probably the one instruction all three would agree on and the only one that states it. Painitin mo muna ang kahon bago dumating ang sisiw, hindi habang nakapasok na sila.

Then the tail, and this is where a Philippine reader should stop. Penn State says to “Decrease the heat by 5°F per week until the normal daily temperature or the building reaches 62-65°F”, which is 16.7 to 18.3°C. No month at Science Garden, Mactan or Legazpi has a mean near it, and neither does any night. Followed literally it would have you heating a building already warmer than its target.

Tatlong schedule, tatlong sagot, at wala ni isang Pilipino sa kanila. The brooder tool carries the first two week by week, beside the one Philippine band there is, which is a native-chick figure covering the brooding period only. This third one it leaves off, and the tail above is the reason: a schedule that ends by asking you to heat a building already warmer than its target is not a row to hand a keeper here. One Penn State instruction travels intact: “Always measure the temperature at the chick’s level, directly under the heat source.”

How much wattage per chick?

There is no general rule, though the flat version of that claim, that nobody anywhere prints a wattage, goes a step too far.

Mississippi State Extension does publish a wattage, for one enclosure: “a disposable version can be made from a cardboard box that will brood up to twenty-five chicks… A 60-watt incandescent light bulb will provide adequate heat.” An extension service naming a bulb, which divides out here to 2.4 watts a chick for a cardboard box holding 25 of them.

What survives is the general claim. No veterinary manual, breed company or standard publishes watts per chick as a figure you can scale, because the answer moves with the enclosure, the ambient temperature and the insulation. Ang 60-watt bulb sa Mississippi tuwing Marso ay hindi sagot sa bakuran mo tuwing Abril. The brooder tool prints the bird-behaviour checks where a wattage would have gone.

Use the birds instead. It is what the sources themselves fall back on, and it is more reliable than a thermometer on a wall three feet from where the chicks are sitting (Aviagen, Ross Broiler Management Handbook 2025, Figure 2.10):

• Huddled tight under the lamp, cheeping loudly: too cold.
• Pressed to the edges of the guard, panting, wings out: too hot.
• All on one side: a draught is coming from the other side.
• Spread evenly, eating and drinking, quiet: correct.

That last one is the whole target, and no number in this article beats it.

How big should the brooder ring be?

Small at first and growing every week, which is a thing most backyard brooders get wrong in one direction and then the other.

The age labels are Penn State’s own, and they are easy to misquote because the bands overlap at their edges: 3 to 5 weeks and 5 to 8 weeks share week five between them. The bottom row is the one most guides drop and the one a native or layer keeper needs most. Ibang kulungan na ang kailangan doon: a native bird is still inside long after week 8, and 0.139 to 0.279 m² is a different building from 0.093.

The Philippine native-chick figure of 0.30 ft² per bird (Pediongco & Simbulan, 2025) works out to 0.028 m² and does land between the week-1 and week-2 rows. Read its own sentence, though, and it is a specification rather than a result: “the floor space requirement for the chicks which should not be less than .30 square feet”. The pens were built to satisfy a number the paper never attributes, so what agrees with Penn State is that number’s unnamed source and not a Philippine measurement. Hindi ito ikalawang testigo. Its own finding is the huddling, below 31°C and above 75% humidity.

Mississippi State does not graduate it at all: “Each chick needs one square foot of floor space until it reaches 6-weeks of age.” Flat, which is Penn State’s 5-to-8-week row from day one and four times its week-one figure. Malaking pagkakaiba iyon kung 50 sisiw ang bibilhin mo.

The chick guard is where the two give genuinely different instructions. Mississippi State puts it about 24 inches, or 61 cm, from the edge of the heat source, “used only during the first 3-4 days” and “should be removed by the seventh day of brooding”. Penn State says to “limit their chicks to a smaller area for the first 2-4 weeks”, up to four times as long, and gives geometry MSU does not: 18 to 24 inches high, 4 feet across for the first 25 chicks, growing 2 feet per further 25 to 10 feet at 100.

Both cannot be right, and the failure modes point opposite ways. Take it down on day seven in a cool week and the chicks scatter off the heat. Leave it up to week four in a Philippine April and they are crowded for no reason, at doon nagsisimula ang pagtutukaan. Sundin mo ang manok at hindi ang kalendaryo: it stays while they huddle and comes down when they stop.

What week one costs you

Pediongco and Simbulan (2025) crossed three heat sources with three litter materials on native chicks at Pampanga State Agricultural University, 28 birds a pen at 7 chicks per square metre. The spread in their results is why this section exists.

Mortality ran from 17.86% to 78.57%. The best treatment was hanging charcoal over white wood shavings, the worst a kerosene lamp over rice hull. ROI across the same pens ran from 109.22% down to −44.20%, so the same chicks and the same four weeks either returned the money with interest or lost half of it, depending on what hung above the birds and what lay underneath.

Put the archive against that. Day-old chicks were at ₱33.50 per head on 13 July 2026, so 50 chicks is ₱1,675 of stock before a sack of feed. The 60.71-point gap between best and worst treatment is ₱1,017 of that, gone inside four weeks. Ang pinakamahal na desisyon sa buong batch ay ginagawa mo bago pa dumating ang sisiw.

Rice hull deserves singling out, kasi ito ang pinakamurang litter sa bawat agrivet sa bansa. The paper’s explanation for its poor weight gain is blunt: “the birds are feeding on rice hull which makes them unable to feed the right amount of feeds.” The chicks eat the bedding, a litter-material problem rather than a heat problem, and it does not show on a mortality chart.

Litter depth is where four sources give four answers.

MSU’s floor is deeper than Aviagen’s ceiling by a factor of two and a half, on the same job. The only Philippine figure sits between them at 5 cm. Sa gitna ako magsisimula, at basa o tuyo ang titingnan ko pagkatapos. Ang lalim ang huli sa tatlo.

One health note, and no dosage attached. MSU states that coccidia “require damp or wet litter conditions to continue their life-cycle”, which is litter management rather than treatment. Anything beyond keeping the litter dry belongs with a veterinarian.

How many feeders and drinkers?

Equipment ratios travel better across climates than density figures, because a nipple delivers the same water in Bulacan as in Georgia.

The two sources behind that table are Penn State Extension and Aviagen, and neither of them is Philippine.

The water rows are the ones most often quoted flat, usually at 2.54 cm a bird, which is the bottom of the 8-week-and-up range applied to every age. Take it that way and a week-one chick gets twice the trough it needs while a grown bird gets half of what the range allows at the top.

One deliberate choice worth flagging. Aviagen also publishes 2.5 cm per bird for a chain feeder, half the Penn State figure, and this site uses Penn State’s. A mechanical chain runs continuously so the birds eat in shifts. A backyard flock arrives at the trough all at once, which is the case Penn State’s number describes. Sabay-sabay silang kumakain sa bakuran, kaya doble ang kailangan.

Two placement rules travel better than any ratio in that table. Aviagen asks that no bird be more than 2 m from water; Mississippi State puts feed and water within 10 feet of the chicks in a brooder. Ang layo ng lakad ang usapin doon, hindi ang haba ng labangan.

Quantity is the figure this climate moves most. Aviagen states that “Each 1°C rise above 21°C increases water requirements by about 6.5%”, and that “In tropical areas, prolonged high environmental temperatures will double daily water consumption.” Doble. Read that beside Science Garden’s April mean daily maximum of 34.6°C and size the drinkers for the hot months.

Then one from MSU that almost nobody plans for: “Chickens will reduce water consumption if the water temperature is warmer than 100 degrees F.” A black plastic drum on a GI roof through a Philippine April produces water the birds will refuse. Sa lilim ang tangke, at sa umaga ang refill.

What to settle before you buy a single piece of lumber

Only one thing here is hard to change later, and it is not the one most guides lead on.

Set the long axis east to west, and settle the roof before the posts go in. Libre ang orientation sa araw na tinuturo mo pa lang kung saan tatayo ang kulungan, at hindi na mababawi pagkatapos. The roof decides how much of a Philippine April reaches the birds, and by way of feed intake it decides part of the feed bill too. Everything below this line can be changed on a Saturday.

Decide free-range or confined now. The outdoor rows are large: one bird per square metre of range means twenty native chickens need 20 m² of outdoor space on top of their house. Kung hindi kaya ng lupa mo, confined ang kulungan mo, at huwag mong tawaging free-range.

Size the floor for harvest weight, which past 1.7 kg a bird means the 17 kg/m² rule rather than the bird-count one. The coop tool says which of the two binds, and the movable-coop page works the square metres through flock size by flock size.

Then equipment, the cheap part and the easy part to fix. Feeders and drinkers from the table above, a chick guard taken down when the birds stop huddling, nest boxes at 35 cm square if you follow PNS 312, and between 15 and 31 cm of perch a bird depending on which BAFS standard you are reading.

If you are pricing a batch rather than a building, what a 50-bird broiler batch actually costs has the money side line by line, and raising broilers in the Philippines is the wider picture. Every gap named on this page is in the gaps register with the date it was last checked.

Questions people actually ask

How many chickens fit in a square metre in the Philippines?

Under PNS/BAFS 262:2018, ten broilers per square metre or 17 kg per square metre in fixed housing, whichever binds first, and six birds per square metre for layers and native chickens. Those two broiler limits meet at exactly 1.7 kg a bird. PNS 262 is written for free-range production, so using it for a closed backyard coop is a substitution for meat birds. Hens have their own Philippine figure: PNS/BAFS 312:2021 sets 0.14 square metres a bird for single-tier cage-free housing and 0.1 for multi-tier, which is tighter still.

What temperature should a brooder be? Show the answer

Three published schedules, and they do not agree. The MSD Veterinary Manual starts day-old chicks at 29.4 to 32.2 degrees C and steps down 2.8 degrees a week to 21.1. Mississippi State Extension starts at 32.2 and reaches 21.1 by the end of week three. Penn State Extension is hotter than both in week one, at 33.3 to 35.0 degrees C. None of them should be averaged into the others. The 31 degrees C plus or minus one usually quoted for Philippine native chicks traces to a UPLB textbook, Lambio 2010, rather than to a field measurement.

Do I need a heat lamp in a Philippine brooder? Show the answer

For week one almost certainly. After that the question reverses. PAGASA puts the mean annual temperature at 26.6 degrees C and the warmest month at 28.3, which is at or above the week-three target in every published schedule, so from week three the usual Philippine problem is getting heat out rather than in. At Science Garden in Quezon City the April mean daily maximum is 34.6 degrees C, which is already above the week-one ceiling in two of the three schedules.

How much heat lamp wattage per chick? Show the answer

There is no general rule. No veterinary manual, breed company or standard publishes watts per chick as a figure you can scale. One extension service publishes a single case: Mississippi State says a cardboard-box brooder holding up to twenty-five chicks is adequately heated by a 60-watt incandescent bulb, which works out at 2.4 watts a chick for that one enclosure and nothing wider. Use the bird behaviour checks instead, which is what the sources themselves fall back on.