De tochtstrip sluit elke kier.

Because Dutch normally writes compound nouns as a single word.
So tochtstrip is made from:

• tocht = draft / cold air current
• strip = strip

Together, tochtstrip means a draft excluder, weather strip, or seal strip.

This is very normal in Dutch. English often uses separate words where Dutch prefers one combined noun.

No. That is a very common point of confusion.

Dutch tocht can mean different things depending on context, including:

• tocht = trip, tour, journey
• tocht = draft, especially a cold current of air indoors

In tochtstrip, it clearly means draft. So this is not a journey-strip; it is a strip that stops cold air from coming through gaps.

Sluit is the third-person singular present tense of sluiten.

The verb is:

• sluiten = to close, shut, seal

Present tense:

• ik sluit
• jij sluit
• hij/zij/het sluit

Since de tochtstrip is singular, Dutch uses sluit.

Dutch sluiten is broader than English close in some contexts. It can mean:

• to close
• to shut
• to seal off

In this sentence, the idea is that the draft strip closes off or seals every gap. In natural English, seals every gap sounds better than closes every gap, even though Dutch uses sluit.

A more explicit Dutch verb would be afdichten (to seal), but sluiten is perfectly natural here.

Because elke means every or each, and in Dutch it is followed by a singular noun:

• elke kier = every gap

If you wanted a plural idea, you could say:

• alle kieren = all gaps

So:

• elke kier = focusing on each one individually
• alle kieren = all of them as a group

Both are possible in Dutch, but they are slightly different in feel.

Kier means a small gap, crack, or opening, especially one that lets air or light through.

Typical examples:

• a gap under a door
• a crack around a window
• a slightly open space where air comes in

It is more specific than a general word like opening. In this sentence, kier is exactly the kind of small gap a draft strip is meant to block.

Because tochtstrip is a de-word.

In Dutch, every singular noun takes either de or het. Unfortunately, this usually has to be learned with the noun.

So:

• de tochtstrip
• plural: de tochtstrips

There is no special grammar trick in this sentence; it is simply the correct article for that noun.

The word order is the normal Dutch main-clause pattern:

Subject + verb + object

• De tochtstrip = subject
• sluit = verb
• elke kier = object

So the sentence is very straightforward in structure.

Yes. Elke and iedere are often interchangeable here.

So both are natural:

• De tochtstrip sluit elke kier.
• De tochtstrip sluit iedere kier.

In many everyday contexts, elke is slightly more common and a bit more neutral, but both are correct.

A rough guide:

• tochtstrip: the ch in tocht is the harsh Dutch throat sound, not the English ch in chair
• kier sounds roughly like keer in English spelling, but with a Dutch ie sound like ee

A rough approximation:

• tochtstrip ≈ tokht-strip
• kier ≈ keer

The hardest part for English speakers is usually the ch in tocht.

It can be understood as either, depending on context.

• De tochtstrip can mean the draft strip if you are talking about a specific one.
• In product descriptions, instructions, or advertising, Dutch often uses de for a general statement about a type of thing.

So this sentence could mean:

• This/The draft strip seals every gap or
• A draft strip seals every gap in a general descriptive sense

That kind of generic use is very common in Dutch.