Cooker Hood Vented and Terminated in Loft ?

11 Sep 2014
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United Kingdom
Had a visit from local builder this morning supposedly to fit a roof or wall vent for cooker hood. After looking at the job he suggested that a flexy pipe was fitted to the cooker hood and vented INTO the LOFT !

I sent him away in disbelief of his proposals, can anyone please give the pro's and con's of fitting a flexy tube to the cooker hood then simply lying it in the loft so that the steam is diverted into the loft, I don't imagine there will be many pro's ?

Is this utter Madness or has slate learnt to breath overnight ?
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never let that stupid bodger into your house again.

I suppose the cooker is not on an external wall? How far is it from the nearest external wall,, and what is between? e.g. duct can go on top of or inside wall cabinets, or in the angle wall:ceiling (rectangular looks best here)

rigid white duct can be painted to blend in with ceiling or wall.

If you have to duct into the loft, you can continue the duct until it exhausts either through a wall, or through the eaves or soffit. Holes in the roof itself are undesirable as they potentially leak.
The pros are that it is a cheap and quick way of doing it.

The cons are:

- significantly increased risk of fire penetrating from the kitchen into the loft, which will make it a lot easier for a small pan fire to completely destroy your house to the point of rebuilding being required (once the roof timbers fail they fall inwards and push the walls out)
- significantly increased airborne grease and food particles vented into the loft, which will make your loft stink and be attractive to rodents and insects
- significantly increased steam and water vapour vented into the loft which can cause your loft timbers to rot, eventually requiring reroofing or possibly even rebuilding the roof

Flexy pipe will offer high levels of resistance to airflow, decreasing hood effectiveness and accumulating grease, which will burn in a fire.
I did this style of set up before, but it was in my mums bungalow.

Both the bathroom fan and the kitchen extractor fan were vented separately into the loft, then connected into flex pipe before coming out of the soffit on the outside of the house.

When I bought my house(3 bed semi) there had been a bodged attempt at venting a bathroom fan directly into the loft and luckily it had either stopped working or never been completed right as it looked like mold had started to appear in the loft, as can be expected venting steam(water) into there.

So if his idea was to go directly into the loft space, then this is very bad, it needs to be extracted out of the house.
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It's amazing how some so-called professionals can be stupid or plain lazy.

I had an electrician fit a bathroom fan with duct in the loft. When I told him I couldn't see any holes in the soffit from outside, he said the duct terminated in the eaves and that's how it should be, that he had fitted thousands of those over the years. He did seem to know his electrical stuff so I believed him. I was quite naive at that time. Soon after my loft was full of condensation and mould. I called him to ask him to come and fix it. He said he would call me back. Unsurprisingly, he never did. But then I didn't want him to step in my house ever again, so it didn't bother me.

I learnt my lesson and now try to do as much work in the house as I can. I'd rather do a costly mistake than pay these so-called builders or professionals to make a mistake.

I still employed another electrician to terminate the duct properly as I didn't fancy crawling into a tiny space in the loft full of insulation.

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