Extractor Fan Vent Roof Tile

11 Nov 2017
Reaction score
United Kingdom

My kitchen extractor fan is supposed to use a 150mm pipe, or at least 120mm according to the installation instructions. My builder has installed a 100mm pipe, presumably because that's what the vent tile it attaches to at the other end is expecting. So it looks like I need a new vent tile that is designed for a wider pipe.

My question is how to choose the vent tile. Am I right in thinking that all vent tiles are designed so the vent area is equivalent to the pipe that attaches to it, as this stops the issue where the pipe size is irrelevant because the amount of air that can pass through is limited by the tile's vent area itself? If that assumption's right then I guess I just need any vent tile that accepts a 150mm pipe (and is the right size for the roof!). If it's not right, then how do I make sure I get a vent that can really cope with my fan sending up the equivalent of a 150mm pipe's worth of air?

Alternatively, am I barking up the wrong tree, and you can get lots of different adaptors to connect the pipe to the tile? (My connector looks like this.) In which case I guess it's the same question: if I can get a bigger adaptor, how do I know if my tile vent is limiting how much air I can pump out?

Thanks :)
Last edited:
Sponsored Links
some vents are designed so they will fit a couple of sizes of pipe. 100mm and 125mm are the ones I have seen but there may be others.

100mm used to be the most common size for cooker hoods, but they are usually 125mm now. Bigger ones carry more airflow with less noise.

Post some photos please.

You can get reducing adaptors, but the airflow won't be as good. If you already have a 110mm hole in the wall, or if a roofer has fitted the tile, it will be difficult to enlarge.
Pictures attached. Let me know if you wanted any other angles!

Tile is already fitted but I have good access to it from above and below if needed.


  • tile1.jpg
    470.9 KB · Views: 452
  • tile2.jpg
    479.7 KB · Views: 437
I don't know, but it looks to me like the design will restrict airflow somewhat. In which case I'd be happier with a bigger one. 150mm if it will fit.

Your next kitchen extractor might be even more powerful.
Sponsored Links
Yeah, so my question is do I just need to look for a tile that expects a 150mm pipe and I can be confident that the tile is designed to have a big enough vent to cope with the equivalent amount of air? Or is that naive to think that just because a tile takes a 150mm pipe that means it can vent the equivalent amount of air?
I have never seen a vent tile to take a 150mm direct. You could however have a 150mm lead slate, pipe , collar and cowl. it'll show more than an inline vent tile but you get the full flow
Ok but I could get a 125 tile which is at least above the minimum for the fan. If I got a tile that had a 125 pipe can I be confident that the tile’s vent will be big enough to let through the equivalent amount of air? Thanks
That looks like a roof space vent to me. Unlikely you will be able to get a TVT with a 125mm spigot. Go out through the wall.
The fan hangs from the ceiling in the middle of the room (above an island) so we can’t go through the wall
The fan hangs from the ceiling in the middle of the room (above an island) so we can’t go through the wall
You need to look away from TVT's and do as Data has said. We often form our own exit points through the roofs using (black) plastic drain pipe, lead slates and mushroom cowls etc. However, this is usually the 110mm stuff. I'll guess that 150mm gear is a lot more scarce and 3-4 times the price.

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links