Bathroom and cooker extraction with no external extraction option

[DaveS79]

Hello all

Got vest on and ready to be shot down. Wondering what options got still early days for me. Been asked to provide extraction for bathroom and cooker. Unfortunately he lives on ground floor of house with wooden joists between floors. He has asked me to provide external extraction but really got my concerns about this as if do will have to possibly cut few big holes out to drill joists for the 4 inch ducting. My question is would other people attempt this? If not have I any viable decent options? And is there possibly any case at all the be made for just extracting into voids? Cheers

 

[Geoff1946]

I most certainly wouldn't cut four inch holes in any joist.  If the only possible extract route is across joist direction then you are stuck with ducting below ceiling level. The rectangular PVC stuff isn't that obtrusive.

I had a similar problem in my old house and put a suspended ceiling in to accommodate the extract and other services.

 

[Doc Hudson]

You would probably benefit from reading up on the relevant building regulation topics to get an idea of what solutions you can offer a customer. Such as the approved documents; https://www.gov.uk/government/collections/approved-documents    And other various LABC publications e.g.  https://www.labc.co.uk/news/how-get-it-right-notches-holes-solid-timber-joists   Even as an electrician you have a duty to comply with all other building regulations, not just the Part-P electrical bit, Structure, Fire, Ventilation, Sound, Moisture, Heat, Energy etc are all regularly encountered during typical electrical installation work.

Doc H.

 

[Murdoch]

You have 2 realistic options:

1. Ducting and boxing in

2. Declining to quote

Sorry if this isn't what you want to hear

BTW venting into voids is a big no no

 

[DaveS79]

I most certainly wouldn't cut four inch holes in any joist.  If the only possible extract route is across joist direction then you are stuck with ducting below ceiling level. The rectangular PVC stuff isn't that obtrusive.

I had a similar problem in my old house and put a suspended ceiling in to accommodate the extract and other services.

Thanks Geoff very helpful. Would you by any chance know of anywhere stocks the surface PVC ducting. My concern would be how I would make a decent join between this and external extractor 

You have 2 realistic options:

1. Ducting and boxing in

2. Declining to quote

Sorry if this isn't what you want to hear

BTW venting into voids is a big no no

Thanks Murdoch I am pretty much there in deciding to not take on. Thanks for confirming void extraction didn't think it was a real option but just good to have it confirmed 

 

[DaveS79]

You would probably benefit from reading up on the relevant building regulation topics to get an idea of what solutions you can offer a customer. Such as the approved documents; https://www.gov.uk/government/collections/approved-documents    And other various LABC publications e.g.  https://www.labc.co.uk/news/how-get-it-right-notches-holes-solid-timber-joists   Even as an electrician you have a duty to comply with all other building regulations, not just the Part-P electrical bit, Structure, Fire, Ventilation, Sound, Moisture, Heat, Energy etc are all regularly encountered during typical electrical installation work.

Doc H.

Thanks Doc. Acknowledged where joists concerned and to be honest hadn't even considered real effects of moisture or heat 

 

[Sharpend]

Your local Screwfix should have it all 

https://www.screwfix.com/c/heating-plumbing/ducting/cat840506

 

[DaveS79]

Your local Screwfix should have it all 

https://www.screwfix.com/c/heating-plumbing/ducting/cat840506

Cheers Sharpend. Rarely automatically think screwfix but seem like have decent selection might be up to job. Still not sure if will attempt to take on though seems like would be job sourcing bathroom and cooker extractor would be suitable to take this ducting straight out of sides with then got issue of how best to fit elbow from rectangular to circular before taking outside....without it all Looking like a bit of a joke

 

[Sharpend]

Is it part of your job to box all ducting in? 

 

[Sharpend]

Remember the kitchen will need Min 6” duct to comply. 
 

with the bathroom what you do is take the flat duct level to edge of wall with the adaptors fitted into the core hole and short piece of straight round duct to grill. Some grills will accept the rectangle pipe direct. 

 

[Doc Hudson]

Remember the kitchen will need Min 6” duct to comply.  

Whilst 6" may be preferable, most domestic kitchen extractor hood only have 4" duct coming out the back.

Doc H.

 

[DaveS79]

Is it part of your job to box all ducting in? 

No. Would say surface ducting might be possibility but I wouldn't get involved with the boxing. Would be up to him I suppose to either leave the plastic or get boxed in. Still not sure how I get from either front or side of cooker extractor. Do I need one specifically designed for this

 

[Sharpend]

Whilst 6" may be preferable, most domestic kitchen extractor hood only have 4" duct coming out the back.

Doc H.

this is true and is sufficient if going straight out through wall behind the hood but any sort of duct then it is required to be larger to comply. 

@DaveS79

Is this hood a flat hood standard non decorative ie with metallic funnel appearance? 
 

a flat hood usually has a duct hole to top so you’ll need the round to flat adapter, can get a 90° version. 
if decorative then the funnel cover will need cutting. 

 

[DaveS79]

this is true and is sufficient if going straight out through wall behind the hood but any sort of duct then it is required to be larger to comply. 

@DaveS79

Is this hood a flat hood standard non decorative ie with metallic funnel appearance? 
 

a flat hood usually has a duct hole to top so you’ll need the round to flat adapter, can get a 90° version. 
if decorative then the funnel cover will need cutting. 

Yeah Sharpend unfortunately mate funnel type

 

[Sharpend]

If you can fit duct near to ceiling then it would be easier and look better? 

 

[Murdoch]

Remember the kitchen will need Min 6” duct to comply. 
 

with the bathroom what you do is take the flat duct level to edge of wall with the adaptors fitted into the core hole and short piece of straight round duct to grill. Some grills will accept the rectangle pipe direct. 

What makes you state that, as nearly all the cooker hoods I come across are 4"

 

[Sharpend]

Quite right they are, however if you measure the follow rates on those installed with a 4”ducting over any length they do not meet requirements unless it is directly out of the wall at the hood point. Therefore it is recommended that a larger duct is fitted on those not directly out the wall. This has been a recommendation for many years. 

 

[Murdoch]

Quite right they are, however if you measure the follow rates on those installed with a 4”ducting over any length they do not meet requirements unless it is directly out of the wall at the hood point. Therefore it is recommended that a larger duct is fitted on those not directly out the wall. This has been a recommendation for many years. 

Thats all well and good, but not every body has a cooker hood, and those who do, not all extract outside ......

our BCO’s seem clueless on the subject

 

[Sharpend]

Thats all well and good, but not every body has a cooker hood, and those who do, not all extract outside ......

our BCO’s seem clueless on the subject

I’m sure you know, those that do not extract externally, extract via a charcoal filter so flow extraction is not taken into consideration. 

 

[Murdoch]

I’m sure you know, those that do not extract externally, extract via a charcoal filter so flow extraction is not taken into consideration. 

Guildford bcos state that extensions and new builds must have extractors that go outside ...