Building Regs Question

[Kevin (Mr T)]

I know we have at least one person on here who is very familiar with current regs @Mark (smokey mow)

I'm having an argument with a builder at the moment on a new build where I am overseeing the installation of the kitchen.

In a new build, does there have to be mechanical extraction to the outside from the kitchen area?

Is there anything in the regs that says that a kitchen extractor installed in a new build has to extract to the outside?

Basically, the builder is saying we (the kitchen suppler) should have made an allowance for extraction when designing the kitchen and I am arguing that there should have been provision in the design of the house itself, if extraction does form part of the regs.

I love my job!

[Mark (smokey mow)]

Kev, give me a call in the office on 01206 282431 if you want I'll be in till 4:30 or i can type a long reply later tonight.

[Kevin (Mr T)]

27 minutes ago, Mark (smokey mow) said:

Kev, give me a call in the office on 01206 282431 if you want I'll be in till 4:30 or i can type a long reply later tonight.

Sorry Mark, missed your message!

[Geoffrey Carter (Buttercup)]

You need to mechanically extract the kitchen to outside.

[Mark (smokey mow)]

Hi Kevin, I'll give the quick short answer first and that is to say that yes, all kitchens to new build houses require extract ventilation to the outside, although I will correct Geoffrey slightly in to say that it doesn't necessarily have to be by mechanical means.

Part F (Ventilation) of the Building Regulations and more specifically Approved Document F 2013 splits ventilation of new dwellings into 4 systems which i shall try to briefly summarise. 

 

System 1 - Background ventilators and intermittent extract fans

System 2 - Passive Stack Ventilation

System 3 - Continuous Mechanical Extract

System 4 - Continuous Mechanical Supply and Extract With Heat Recovery

 

System 1 is probably the most familiar to a lot of people as it is bar far the most common fitted to buildings whereby background ventilation for the management of fresh air and control of condensation is typically provided by trickle vents, whilst purge ventilation for the removal of odours and water vapour is achieved through the use of extract fans to all wet areas (kitchens, bathrooms, toilets, utility etc). With system 1 mechanical extract ventilation to the kitchen would be achieved either by uses of a fan rated at a minimum of 60l/s installed anywhere within the room or alternatively via a cooker extract hood rated at a minimum of 30l/s.

 

System 2 Passive stack ventilation uses the natural pressure difference of air moving over the roof of the house to draw air out from the building through a series of passive ducts.  Ducts with an internal diameter of 125mm are installed to all the "wet areas" whilst the infiltration air is supplied via trickle vents. I see this most often in social housing schemes.

 

System 3 as you'd expect is a constantly running extract fan system comprising of a centralised fan unit with ducts to each of the "wet areas" although the kitchen may use its own extract hood rather than the centralised system.  Ventilation to the wet areas is normally linked to humidistats so having a high/low extract rating.  As with System 2 the infiltration air is provided by trickle vents. In 15 years of doing this job I can't recall ever seeing a system 3 install.

 

System 4 is probably the second most common method of ventilating a dwelling and much more likely seen in more "high end" properties and flats etc where external noise can be a problem and it's less likely to be opening a window. I'd expect to see your kitchens going in more new houses with this ventilation system than those having system 1.

 

With a system 4 a centralised MVHR ventilation system is installed running continuously and constantly changing the air within the building.  The centralised system has both supply and extract grills to the outside of the building, drawing the fresh air in and then expelling the stale air back out again.  The fresh air is delivered through ducts to the habitable rooms (bedrooms, living rooms), circulated through the house and then extracted from the "wet areas".  Like system 3 humidistats are used to provide a high/low system but unlike system 3 the warm air being expelled is passed across a heat exchanger to pre-warm the incoming air.   As the MVHR unit provides supply air there is no need to trickle vents with the system and this type of property probably also wouldn't require a cooker extract hood.

 

Hopefully you're still following by this point!!! 

 

Which system of ventilation is ultimately installed will depend on a few factors; the clients brief, architect suggestion or a need to achieve a particular energy rating for the building so as to comply with building regulations.

 

As a kitchen supplier is it reasonable to expect you to know which system the builder has been designed for? I would say absolutely not.  Of the 4 different systems I outlined NONE specifically require an extract hood to be installed over the hob and only two of them would require a cooker extract hood to be fitted if the building ventilation system itself is not extended into the kitchen.

IMO it would be the responsibility of the principle contractor or the project manager to provide their suppliers and subcontractors with sufficient detail about the design and construction of the building as part of their brief or order.  It's not for you to second guess the design and make provision, particularly if as can be seen above it may not even be required.

 

Sorry that explanation didn't end up quite as brief as I was hoping for 

[Kevin (Mr T)]

36 minutes ago, Mark (smokey mow) said:

Hi Kevin, I'll give the quick short answer first and that is to say that yes, all kitchens to new build houses require extract ventilation to the outside, although I will correct Geoffrey slightly in to say that it doesn't necessarily have to be by mechanical means.

Part F (Ventilation) of the Building Regulations and more specifically Approved Document F 2013 splits ventilation of new dwellings into 4 systems which i shall try to briefly summarise. 

 

System 1 - Background ventilators and intermittent extract fans

System 2 - Passive Stack Ventilation

System 3 - Continuous Mechanical Extract

System 4 - Continuous Mechanical Supply and Extract With Heat Recovery

 

System 1 is probably the most familiar to a lot of people as it is bar far the most common fitted to buildings whereby background ventilation for the management of fresh air and control of condensation is typically provided by trickle vents, whilst purge ventilation for the removal of odours and water vapour is achieved through the use of extract fans to all wet areas (kitchens, bathrooms, toilets, utility etc). With system 1 mechanical extract ventilation to the kitchen would be achieved either by uses of a fan rated at a minimum of 60l/s installed anywhere within the room or alternatively via a cooker extract hood rated at a minimum of 30l/s.

 

System 2 Passive stack ventilation uses the natural pressure difference of air moving over the roof of the house to draw air out from the building through a series of passive ducts.  Ducts with an internal diameter of 125mm are installed to all the "wet areas" whilst the infiltration air is supplied via trickle vents. I see this most often in social housing schemes.

 

System 3 as you'd expect is a constantly running extract fan system comprising of a centralised fan unit with ducts to each of the "wet areas" although the kitchen may use its own extract hood rather than the centralised system.  Ventilation to the wet areas is normally linked to humidistats so having a high/low extract rating.  As with System 2 the infiltration air is provided by trickle vents. In 15 years of doing this job I can't recall ever seeing a system 3 install.

 

System 4 is probably the second most common method of ventilating a dwelling and much more likely seen in more "high end" properties and flats etc where external noise can be a problem and it's less likely to be opening a window. I'd expect to see your kitchens going in more new houses with this ventilation system than those having system 1.

 

With a system 4 a centralised MVHR ventilation system is installed running continuously and constantly changing the air within the building.  The centralised system has both supply and extract grills to the outside of the building, drawing the fresh air in and then expelling the stale air back out again.  The fresh air is delivered through ducts to the habitable rooms (bedrooms, living rooms), circulated through the house and then extracted from the "wet areas".  Like system 3 humidistats are used to provide a high/low system but unlike system 3 the warm air being expelled is passed across a heat exchanger to pre-warm the incoming air.   As the MVHR unit provides supply air there is no need to trickle vents with the system and this type of property probably also wouldn't require a cooker extract hood.

 

Hopefully you're still following by this point!!! 

 

Which system of ventilation is ultimately installed will depend on a few factors; the clients brief, architect suggestion or a need to achieve a particular energy rating for the building so as to comply with building regulations.

 

As a kitchen supplier is it reasonable to expect you to know which system the builder has been designed for? I would say absolutely not.  Of the 4 different systems I outlined NONE specifically require an extract hood to be installed over the hob and only two of them would require a cooker extract hood to be fitted if the building ventilation system itself is not extended into the kitchen.

IMO it would be the responsibility of the principle contractor or the project manager to provide their suppliers and subcontractors with sufficient detail about the design and construction of the building as part of their brief or order.  It's not for you to second guess the design and make provision, particularly if as can be seen above it may not even be required.

 

Sorry that explanation didn't end up quite as brief as I was hoping for 

That's brilliant, thanks Mark.