Don't guess or approximate. Look at the manufacturer's installation specifications for your cooktop and downdraft hood and be sure. They are usually available online, and hopefully my links will get you where you need to go.

A 24" deep cabinet is pretty standard in the US. I'd be surprised if there were no way to make this work. The guys doing your counters will need to know what appliances you'll have.

Will you have the minimum clearance around the cooktop?

Benje, isn't that a counter templater's issue? She already has a cooktop and downdraft in that spot I think.

It's not necessarily a "counter templater's issue". How was the cooktop/island planned? If it is planned for the minimum 9" behind the cooktop (really should be 18" with no seating / 24" with seating), then that means the island is not 24" deep and you may be able to build out into the 9".

Carolesullivan, what is the full setup? That's information we need b/f we can give you a realistic answer - otherwise, we're just guessing.

BTW...a telescoping downdraft in the middle would be more effective than one in the back - or at least as effective as any drowndraft can be (they're not very good vents in general). The middle is more effective b/c it's next to all the burners, not just two.

You would be much, much better off with a true hood hanging from the ceiling!

Be sure to have your fabricators leave some material so I'll have something to work with when you tear that thing out in a few years, please.

Ordering a 27" deep cabinet is pretty standard when you're doing a downdraft. You need the extra depth. Who designed this?

carolesullivan I think I may have misunderstood the first time I read your post. This is just a new countertop install, right? You didn't install new cabinets?

Benje I think you are correct. She was getting a new counter so she decided to buy a new cooktop and downdraft hood. My understanding is that she is replacing older versions of both. It doesn't sound planned at all, and my guess is we've heard the last of the op.

Doesn't anyone own a measuring tape anymore? Sheesh.

No. Nearly all of us have to make one measuring error before we learn to measure and read the manuals....

I own three...

I use my measuring tape almost every day.

I probably have 1 or 2 on each floor of the house (3 plus the basement) and one that lives in my purse. I'm not even renovating right now..... I think I've been hanging out here too long.

I have one in my pantry, hidden from DH, so it doesn't wander.

I'm lost without a measuring tape. I measure everything. Several in the house, big ones in the garage, and at least one in my car.

One in my purse, 3 in garage, 1 in my work supply bag, 1 in the kitchen junk drawer and 1 in my car organizer. I measure everything.(almost)

The downdraft requires 2 1/4". The cooktop requires 19 1/8". Total of 21 5/8". It's not clear what the 'lip' measurement is of the cooktop, but I'll guess about 1/4". Brings us to 21 7/8". So whats the interior measurement of your 24" cabinet? And how deep is your counter top?

And you need a 3" rail, front and back. Which is why I always use a 27"D cabinet.

3" rail... of counter material. It'll be fine.

Regardless, I'm fundamentally opposed to helping people who ask for help and never return to receive it let alone say thank you. Would that we could block this type of user.

She's probably read all these comments.....