Interior Doors and Trim: What Do I Pick? Honest 2026

What do interior doors and trim actually cover?

Interior doors and trim cover every door inside the house that is not an exterior door, plus every piece of wood that hides a joint. That is door slabs, the jambs they hang in, hinges, stops, door hardware, casing around doors and windows, base at the floor, window stool and apron, closet shelf and rod, stair parts, and whatever happens at the ceiling if anything does.

Most clients think of interior doors and trim as the pretty part at the end. It is not. The doors drive framing, the trim drives the millwork schedule, and both of them get ordered months before anybody sees them. A door you change your mind about in October is a rough opening somebody framed in June.

Here is the part people do not expect: on a 3,000 square foot house you are usually looking at something like 20 to 30 interior door openings and roughly a thousand feet of base and casing. It is one of the largest line items in the finish package by quantity, and it is the one clients spend the least time on during design.

Cabinetry and millwork for our builds run through our shop in Rigby, mostly alder and walnut, and our finish crew hangs and cases the house. You are not calling a millwork shop yourself and you are not coordinating it. That is our job, and it starts in the design phase, not at the paint stage.

Solid core or hollow core: which doors should I buy?

Of every choice inside the interior doors and trim package, this is the one you will notice daily. Buy solid core anywhere you would ever close the door on purpose. Bedrooms, bathrooms, the office, the laundry, the mechanical room. Hollow core belongs on a closet or a pantry, and honestly on a custom build I would rather you spend the money and be done with it.

This is not an abstract upgrade. A hollow core door is a cardboard honeycomb between two thin skins, and it weighs about 25 pounds. A solid core door the same size runs closer to 70. You feel the difference in your hand every time you close it, and you hear the difference every time somebody runs a shower at 6 a.m. Hollow core doors land in the low twenties for sound rating, solid core in the low thirties, and that ten-point gap is roughly the difference between hearing a conversation and hearing that a conversation is happening.

The weight has consequences our crew has to plan for. Solid core slabs need heavier hinges, usually a third or fourth hinge, and the hinge screws need to catch the king stud instead of just the jamb. That is a framing and install detail, not a shopping decision.

Door type	Weight, 3068 slab	Sound	How it behaves in dry air	Where it belongs
Hollow core	About 25 lb	Low twenties STC	Stable, but skins can telegraph the honeycomb	Closets and pantries only
Solid core composite with wood veneer	About 65 to 70 lb	Low thirties STC	Most stable option, very little seasonal movement	Bedrooms, baths, office, laundry, mechanical
Solid wood stile and rail	70 lb and up by species	Low thirties STC	Moves the most, panels shrink in winter	Where the look is worth the maintenance
20-minute rated	Varies by assembly	Good, but the closer is the sound path	Stable	Garage to house, if you are not using a solid slab

One honest caveat. The sound rating on the door is theoretical until you deal with the gap under it, and most houses have a gap under it on purpose. More on that below, because it is the single most misunderstood thing about doors in a modern tight house.

What happens to interior doors and trim in a dry Idaho winter?

Wood shrinks here, and it shrinks more than clients expect. Indoor relative humidity in Teton Valley and the upper Snake River plain routinely drops into the teens in January, lower in a house with a hot wood stove going. A solid wood panel door that was built and finished at 40 percent humidity will give up moisture until the panels pull back in their grooves.

What that looks like on your door, in February, in the third winter: a thin unstained line at the edge of each panel where the panel used to sit. Nothing is broken. The door is doing exactly what wood does. But if nobody told you it was coming, it reads as a defect.

Three things prevent it, and all three are interior doors and trim decisions made during design, not luck.

• Finish all six sides. Including the top and bottom edges, which the factory often leaves raw and nobody ever sees. An unsealed edge is a moisture highway and it makes seasonal movement worse on that slab specifically.
• Acclimate inside the conditioned house. Not the garage, not a job trailer, not a room that is still being heated by a salamander. Doors and trim come in after the house is dried in and the permanent heat is running. That is one of several reasons we care so much about being dried in before winter.
• Pick the right material for the room. Composite-core doors with a wood veneer move far less than stile and rail. MDF trim is dimensionally stable and takes paint beautifully, and it also turns to oatmeal if it sits in standing water, so it does not belong at a mudroom boot bench where snow melts off boots every day. Poplar there instead.

Swing, pocket or barn: which door goes where?

This is the part of interior doors and trim that the framers care about. Pick swings for anything that needs to seal, pockets where a swing would block something, and barn doors only where privacy and sound genuinely do not matter. All three are framing decisions, which means they are locked before the framers leave, not during selections.

The pocket door is the one that causes real trouble, and it is almost never the door’s fault. A pocket frame occupies the full width of the opening inside the wall. You cannot run electrical through that wall, you cannot run plumbing through it, and you cannot put blocking in it for a towel bar, a grab bar or a wall-hung vanity. I have watched a beautiful pocket door plan collide with the only logical wall for the bathroom switch, and somebody has to lose.

Door style	Decide by	What it costs you	Honest verdict
Standard swing	Before framing (swing direction too)	Floor space in front of the door	Best seal, best sound, cheapest to hang and trim. The default for a reason.
Pocket	Before framing, no exceptions	The entire wall cavity: no wiring, no plumbing, no blocking	Worth it in a tight powder room or a primary closet. Spec a quality steel-frame kit, not the cheap one.
Barn / wall slider	Before drywall (header blocking)	Wall space to park the door, and the casing has to clear the track	No real privacy, no sound control, and it bumps the wall. Fine on a pantry, wrong on a bathroom.
Double / French pair	Before framing	A wider opening and header, plus safety glass if it is glazed	Good on an office or a den. Check the swing clearance against furniture early.

Swing direction sounds trivial and is not. The door swing determines which side the switch goes on, whether the door blocks a closet when it is open, and whether two doors in a hallway hit each other. We walk every swing on the plan during design and again at the pre-drywall walkthrough, because that is the last hour where moving one is free.

What does Idaho code require for the door from my garage?

Of all the interior doors and trim in the house, the door between an attached garage and the house is the only interior door in your home with real code requirements, and Idaho makes the wall around it stricter than the national model code does.

Start with the door itself. Section R302.5.1 of the 2018 International Residential Code requires that opening to be a solid wood door not less than 1 3/8 inches thick, a solid or honeycomb-core steel door not less than 1 3/8 inches thick, or a 20-minute fire-rated door. It must be equipped with a self-closing or automatic-closing device. And it can never open into a room used for sleeping.

Idaho adopts the 2018 IRC through IDAPA 24.39.30, and I pulled the actual amendment list rather than trusting a summary. Idaho amends Table R302.1(1), amends R302.4, deletes R302.13, and deletes Table R302.6 outright. It does not touch R302.5.1. So the door rule above applies in Idaho exactly as printed, self-closing device and all.

Here is the find. The base 2018 IRC Table R302.6 asks for not less than 1/2-inch gypsum board on the garage side where the garage separates from the residence and attics, and reserves 5/8-inch Type X for habitable rooms above the garage. Idaho threw that table out and replaced every row with not less than 5/8-inch Type X gypsum board or equivalent. In an Idaho house, the entire garage side of that separation is 5/8 Type X, whether or not there is a bedroom over the garage. That is a real upgrade over the model code and most online guidance will tell you otherwise.

That has a direct consequence for your door package that nobody mentions until the jambs show up. Stock prehung jamb widths are 4 9/16 inches and 6 9/16 inches, and both of those assume 1/2-inch drywall on each side. A 2×6 garage wall with 5/8 Type X on the garage face is an eighth of an inch thicker than the stock jamb accounts for. Either the jamb gets ordered wide, or it gets extended, or your casing sits proud of the drywall on one side and the painter tries to caulk away a shadow line. We order that jamb to the actual wall thickness.

Requirement	What it says	Source
Door construction	1 3/8 in. solid wood, 1 3/8 in. solid or honeycomb-core steel, or 20-minute rated	2018 IRC R302.5.1, not amended by Idaho
Closing device	Self-closing or automatic-closing device required	2018 IRC R302.5.1
Where it can open	Never into a room used for sleeping	2018 IRC R302.5.1
Wall and ceiling separation	Not less than 5/8-inch Type X gypsum board on the garage side, every condition	IDAPA 24.39.30 Sec. 600, replaces Table R302.6
Jamb width	Must account for 5/8 board on the garage face; stock 6 9/16 jamb does not	Field consequence of the above

One more practical note. Everybody takes the self-closing hinges off. It closes on your hands when you are carrying groceries, so it comes off, and then the house does not comply with the code it was inspected under. If that door annoys you, the fix is a better closer, not no closer. If you are conditioning that space at all, see whether a heated garage is worth it in Idaho before you decide how hard that door has to work.

You can read the Idaho amendments yourself in IDAPA 24.39.30, Rules of Building Safety. Section 600 is where the IRC amendments live.

Where do I need safety glass in and around doors?

Any glass in your interior doors and trim needs to be safety glazing, and so does glass near a door. Section R308.4.1 of the IRC covers glazing in doors. R308.4.2 covers glazing adjacent to doors: if the glass sits within 24 inches of the vertical edge of the door in its closed position and the bottom edge is less than 60 inches above the floor, it is a hazardous location and it has to be tempered or laminated. Idaho does not amend R308, so that applies here as written.

In a real house that means the sidelite next to the mudroom door, both leaves of a glazed French pair, the glass panel in a pantry door, and anything at a shower or tub enclosure.

The consequence is the whole reason this belongs in a doors and trim conversation: tempered glass cannot be cut, drilled or modified after it is made. It is tempered to final size. Deciding in month eight that you want a glass panel in the office door is not a modification, it is a reorder, with the full lead time attached. That is also why it shows up in our finish selections sequence rather than in the punch list.

Why does a closed bedroom door matter to my heating system?

Because interior doors and trim are part of your mechanical system whether anybody designed them that way or not. In most houses the bedrooms get supply air and the hallway gets the return. Close the bedroom door and you have a room being pumped full of air with nowhere to send it back. The room pressurizes, the hallway goes negative, and the only way out for that air is through your walls.

That is the cold bedroom nobody can explain. It is usually not an undersized register. It is a pressure problem, and the door is the valve.

The numbers are worth knowing. Building science research cited by the U.S. Department of Energy’s Building America Solution Center puts airflow through a door undercut at roughly 2 cfm per square inch of opening, so a one-inch undercut on a standard door passes something like 60 cfm. That sounds adequate until you learn that the bedroom supply in a decent system is often more than that, and that carpet across the opening cuts the number down hard. Building Science Corporation’s guidance in Information Sheet 804 is to keep the pressure difference across a closed door below 3 pascals, and to provide a real return path rather than relying on the gap.

In a Teton Valley winter the stakes are higher than comfort. A pressurized bedroom pushes warm, moist indoor air into the wall and ceiling cavities. At twenty below, that air hits a cold surface inside the assembly and gives up its moisture there. You do not see it. You find it later.

Return path	What it is	Sound	Decide by	Verdict
Door undercut	Gap between slab and finished floor, about 2 cfm per square inch	Worst. Defeats a solid core door entirely.	Before flooring is set, since finished floor height sets the gap	Fine for a low-airflow room. Not a plan on its own.
Through-wall transfer grille	Grilles on both sides of the wall, often offset, air stays inside the conditioned space	Better if you spec a baffled or Z-duct type	Before drywall, and the wall needs to be free of wiring	My default. Keeps the air in the house.
Jump duct	Short flex duct up through the attic from room to hall	Good, the duct absorbs sound	Before drywall and insulation	Works, but it puts conditioned air in a vented attic. Seal it properly.
Dedicated return per room	A real return duct in each bedroom	Best	During mechanical design	Cleanest answer, most ductwork, best result.

Here is the trade-off nobody tells you: the transfer grille that fixes your pressure problem is also a hole in the wall for sound. You bought a solid core door for quiet and then put a 10×20 grille next to it. Spec a baffled grille or a jump duct with a length of flex in it, not a straight pass-through, and you keep most of both. This is the same system conversation as whole house ventilation and air filtration, and it gets designed once, together, not in three separate meetings.

What trim profile should I pick, and how much trim is in a house?

On the trim half of interior doors and trim, pick one casing profile and one base profile and run them through the whole house. Then decide what happens at windows, which is the only place where there is a real fork in the road.

Trim is three decisions, not thirty:

• Casing. The piece around doors and windows. Modern mountain work is usually flat stock, square edges, 1×4 or wider. Traditional work is a milled profile. Either is right, but mixing them in one house reads as an accident.
• Base. The piece at the floor. Taller base reads more finished and costs more per foot in both material and install. A 1×6 flat base with a small cap is a good middle.
• Windows: cased or drywall return. Cased windows get a stool and apron, or a picture-frame surround with no stool. Drywall returns wrap the opening with no wood at all. Returns look clean and modern, and they need near-perfect drywall with a bullnose or square bead, and they chip when a vacuum hits them. Casing is more forgiving and easier to repair.

Now the quantity, because this is where the budget surprise lives. A standard door opening takes about 17 feet of casing per side, so roughly 34 feet per opening when it is cased on both faces. Twenty-five interior openings is 800 feet of casing before you have touched a single window. Base is the perimeter of every room minus the openings, and on a 3,000 square foot plan it is commonly in the 900 to 1,200 foot range. We take all of it off the plan during design rather than carrying a guess.

That takeoff is exactly the problem with vague allowances and a big part of why three bids never compare. One builder counted your trim. One used a square-foot multiplier. They are not the same number, and only one of them survives contact with the house.

Last detail that separates good trim from average trim: the reveal. Leave a consistent 3/16-inch reveal on the jamb edge all the way around every opening. It is a small thing and it is the thing your eye reads as “this was done right.”

Paint grade or stain grade: what actually drives the price?

Labor drives it, not material. Pick one finish system for your interior doors and trim and commit to it through the whole house.

Paint grade means MDF or poplar, joints filled, nail holes filled, everything caulked, then sprayed. The filler and the caulk forgive a lot, so install goes faster and the finished result is uniform. Paint grade is not the cheap option, it is a different option.

Stain grade means the joinery is the finish. No filler, no caulk, nothing to hide behind. The material has to be sorted for grain and color before it goes up, miters have to be tight and stay tight through a dry winter, and returns get mitered instead of cut flat. That sorting and that joinery is the cost, and it is the reason a stain grade house takes meaningfully longer to trim than a paint grade house of the same size.

Alder is what we run most for stain grade here. It takes stain evenly, it is stable enough for this climate, and it suits the valley. Walnut is a different conversation and a different number.

The combination that almost never works: paint grade doors with stain grade trim, or the reverse. You end up with two finishes arguing at every opening. If you want contrast, do it deliberately, like stain grade doors and painted base with a stain grade casing, and look at a real sample in the actual house light before you order 900 feet of it.

What door hardware do I pick, and when?

Hardware is the last piece of the interior doors and trim package and the one most likely to be forgotten. Pick hardware before the doors are bored, because the boring is part of the order. Hardware is also the piece most likely to arrive late and hold up your final walkthrough over a box of knobs.

There are four functions and you need to know which goes where before anybody can count them:

• Privacy – locks from inside with an emergency release outside. Every bedroom and every bathroom.
• Passage – latches, does not lock. Hallways, most closets, the laundry.
• Dummy – a pull with no latch. Double closet doors, pantry doors with a roller catch.
• Keyed – exterior doors and the garage door. Ask to have them keyed alike so you carry one key, and sort that out at the order, not after.

Two specs that quietly matter. Backset is the distance from the door edge to the center of the bore, and it is either 2 3/8 or 2 3/4 inches. Mixing them across a house is how you end up with a lever that hits the casing. And finish: unlacquered brass is beautiful and it is going to patina, which is the point, so do not order it expecting it to stay bright. Matte black shows every water spot in a house with hard water, which is most of this valley, so read the water softener question before you fall in love with it in a showroom.

Hinges count as hardware. Match the hinge finish to the lever, or contrast it on purpose, and remember that a solid core slab usually wants a heavier hinge and sometimes a fourth one.

When are interior doors and trim decisions due?

Earlier than you think, and in a specific order. Interior doors and trim are not one deadline, they are five, spread from before framing to before paint. Here is the sequence we build backward from on every job.

Decision	Due by	Why that deadline	What it locks
Pocket and barn door locations	Before framing	The pocket frame owns the wall cavity	Wiring routes, plumbing walls, blocking for towel bars and vanities
Door sizes and swing directions	Before framing	Rough openings and headers get built once	Switch locations, furniture clearance, closet access
Return air path per bedroom	Before drywall	Grilles and jump ducts need open walls or attic access	Door undercut height, grille locations, how quiet the room really is
Door type, jamb width, glass	Before the order goes in	Lead time, and tempered glass cannot be cut later	Hinge spec, wall thickness match, safety glazing locations
Trim profile and paint vs stain	Before the millwork order	Shop time and material sorting	Casing, base, window treatment, reveal, and the finish schedule
Hardware function, backset, finish	Before trim install	Boring happens at the factory or in the shop	Which doors lock, and whether the final walkthrough slips

Two of those deadlines land before a framer has gone home, which is the part clients find hardest to believe. It is also why the finish selections schedule starts in design and why the pre-drywall walkthrough exists. Miss them and you are not making a selection anymore, you are writing a change order.

What does this cost, and what is not included?

I am not going to publish a per-door or per-foot number, because the honest answer depends on your door count, your species, your profile and what your trim carpenter has to do at each opening, and a number I make up today would be wrong by the time you read it. We price interior doors and trim off your actual plan, counted opening by opening, during design, and that takeoff is part of the design deliverable rather than an allowance.

What I can tell you precisely is what a change costs you at each stage, measured in how many trades have to come back. That is the number that actually governs your budget.

When you change your mind	Who has to come back	Practical impact
During design	Nobody. A drawing changes.	Free. This is the whole argument for a real design phase.
After framing, before rough-in	Framer	Half a day, usually absorbed. Swings and sizes still movable.
After rough-in, before drywall	Framer, electrician, sometimes HVAC, plus a re-inspection	Real money and schedule. Idaho charges $65 per electrical reinspection when work is not ready or locations are wrong.
After drywall, before trim	All of the above plus rock, tape, texture and paint	Expensive, and the patch is visible in raking light for the life of the house.
After trim is installed	All of the above plus a reorder at full lead time	Worst case. The casing is already cut to that opening.

On overall budget: our custom home work on the Teton Valley and Idaho side starts at $450 per square foot of conditioned space and goes up, and Jackson Hole work starts at $1,000 per square foot and goes up. Design is sold as a fixed design fee, starting at $25,000 and quoted per project. Those are construction numbers on conditioned square footage, which means they do not include your land, your well and septic, site work, landscaping, furniture, window coverings or anything you buy after you have the keys.

What is not included in an interior doors and trim scope specifically, and gets missed in other people’s bids: closet shelving systems, stair rail and balusters, window stools, the shower door, interior glass, and the hardware itself. Ask whether those are in or out before you compare two numbers.

Who handles interior doors and trim on your build?

We do, start to finish. Interior doors and trim are handled in house from the design agreement and the drawings, the door schedule, the millwork through our shop in Rigby, the lead times, the order, and the finish crew that hangs and cases the house. You are not hiring a millwork shop, chasing a hardware order or explaining jamb widths to anybody.

I am involved in every phase of every build, which on interior doors and trim means the door schedule and the trim takeoff get reviewed against the actual plan before anything is ordered, and the swings get walked twice. If you want to see how much of this you personally have to be present for, we wrote that up in how involved you need to be. The short version: less than you fear, and more at the two or three moments that matter.

If you want the full sequence of what gets decided when, start with the month-by-month build timeline, then read what gets checked at each inspection and what to look for at the final walkthrough. Interior doors and trim show up in all three. For the broader question of where finish money is well spent, see which upgrades are actually worth it here.

Frequently asked questions

Should I use solid core doors throughout my custom home?

Yes, everywhere you would close the door on purpose: bedrooms, bathrooms, the office, the laundry and the mechanical room. A solid core slab weighs about 70 pounds against roughly 25 for hollow core, and it tests about ten points higher on sound. Closets and pantries are the only places I would accept hollow core on a custom build. Budget for heavier hinges and sometimes a fourth hinge per door.

Do pocket doors cause problems in a custom home?

They cause problems when they are decided late. A pocket frame occupies the entire wall cavity, so that wall cannot carry electrical, plumbing or blocking for a towel bar, grab bar or wall-hung vanity. Decided during design and coordinated against the electrical and plumbing plan, a pocket door is a good answer in a tight powder room or a primary closet. Spec a steel-frame kit, not the cheapest one on the shelf.

Does Idaho require a self-closing door between the garage and the house?

Yes. Idaho adopts the 2018 IRC and does not amend Section R302.5.1, which requires that door to be a 1 3/8 inch solid wood door, a 1 3/8 inch solid or honeycomb-core steel door, or a 20-minute rated door, equipped with a self-closing or automatic-closing device, and it may never open into a sleeping room. Idaho also replaced Table R302.6 so the garage side of that separation is 5/8-inch Type X gypsum board in every condition, not the 1/2-inch the national model code allows.

When do I have to pick my interior doors and trim?

In stages. Pocket and barn locations, door sizes and swing directions are due before framing. The return air path for each bedroom is due before drywall. Door type, jamb width and any glass are due before the order, because tempered glass cannot be cut after it is made. Trim profile and paint versus stain are due before the millwork order. Hardware is due before trim install.

Is MDF trim okay in a custom home?

For paint grade, yes. MDF is dimensionally stable, which matters in a climate where indoor humidity drops into the teens in January, and it takes paint better than almost anything else. It is wrong anywhere it will sit in water, so use poplar at a mudroom boot bench and anywhere snow comes off boots. For stain grade you want real wood, and alder is what we run most here.

Get a real number on your build

If you are planning a custom home in Teton Valley, the upper Snake River valley or Jackson Hole and you want your interior doors and trim handled properly, with the door schedule and the trim takeoff counted off your actual plan instead of buried in an allowance, get in touch and we will walk your plan together. You can also see how we work on our custom homes page.

Built different. Built right. Built by SwagerBuilds.