Can I seal off a utility room if I have both extraction and supply vents in there?

[hendriQ]

I'm keen to have an airtight sound insulating seal on the doorframe between the kitchen/open-plan lounge and the utility room. I was going to fit one of these at the base of the door and then rubber seals on the door frame, as well as a door closer. The reason for this is that we do a lot of laundry and don't want to hear it when we are watching TV or having dinner. But having no gap under the door would obviously not be compatible with the MVHR system we are also installing as part of our refurb.

 

I can think of two solutions to this that won't compromise the sound isolation I want:

 

1. Have both supply and extract vents in the utility room so that that room is separate from the rest of the system - would this work? It would be an independent area, albeit with ocassional leakage between it and the adjacent kitchen whenever the door was opened, but that might only happen 4 - 6 times a day for the amount of time it takes to go through the door (because of the door closer) so maybe 4 seconds each time.
2. Install trickle vents in the utility room window, a regular extractor fan, and forget about running MVHR into the utility room at all. I am getting a new window anyway, so I could specify it with trickle vents if I wanted to.

 

I would prefer to go with option 1 as that way I still get the benefit of MVHR in the utility room, and it will be a lot more energy efficient as the machines in there, particularly the tumble dryer generates a lot of heat. A lot of people on this forum also comment on how easy it is to dry clothes on a rack with MVHR and we will have a small rack in that utility room - although our main source of drying is still the tumble dryer.

 

In case it's relevant, the dimensions of the utility room are about 5.7 m2 in floor area and about 2.4m in floor height, so total volume about 13.7m3. The adjacent kitchen/lounge/tv area is about 8 times that. The utility room is small, but being a fairly narrow trianglular space, there is room to have the extract about 2.7m away from the supply, with the supply still being quite close to the window to avoid condensation. Another thought I had which might improve the flow of air in that room, is that I could site the extract vent low down, near the floor, so that air passed across from there diagonally up to the supply above the window - or vice versa. Not sure which is better, but thought supply typically goes above glazing to replicate the function of a trickle vent.

 

 

Edited February 13, 2021 by hendriQ

[tonyshouse]

Option one is fine 

[hendriQ]

2 hours ago, tonyshouse said:

Option one is fine 

Good to know. In this situation, is it better to have the supply in the ceiling by the window and the extract close to the floor on the opposite wall, or vice versa?

[PeterW]

Ok so this will depend on your BCO. MVHR has to be installed and commissioned in line with the Domestic Ventilation Compliance Guide and that requires a 10mm gap below all internal doors.  Table 7 Item 3.0 refers. 

 

You will have to convince the BCO that this installation does not require that gap under the door as this is a non standard install. 
 

Your better way may be to provide the input air into the utility through a wall with a vent size of min 7600mm2. You could do this by hiding the vents under the kick boards which will reduce sound transmission to a minimum, and then you can put the door seal that you want in place. 

[hendriQ]

1 hour ago, PeterW said:

Ok so this will depend on your BCO. MVHR has to be installed and commissioned in line with the Domestic Ventilation Compliance Guide and that requires a 10mm gap below all internal doors.  Table 7 Item 3.0 refers. 

 

You will have to convince the BCO that this installation does not require that gap under the door as this is a non standard install. 
 

Your better way may be to provide the input air into the utility through a wall with a vent size of min 7600mm2. You could do this by hiding the vents under the kick boards which will reduce sound transmission to a minimum, and then you can put the door seal that you want in place. 

If the BCO has any common sense, he will surely realise that there is no disadvantage to what I'm suggesting. If anything, it will provide more circulation of air to the utility room, which given its use is probably one of the rooms that needs most ventilation in the house. But I take your point that no all BCOs have a great deal of common sense.

 

I'm not sure I follow your suggestion. What's a kickboard? Is it the part of the door one would kick if one wanted to open it with one's foot? I'm not entirely sure what you're suggesting. But unless it's airtight, the sound will leak through.

 

Another possibility is that if a door is not actually required between a utility room and a kitchen (does anybody know what the regs say about that) then I could leave the door off completely and add it after the BCO approves the build.

[PeterW]

The Building Regulations aren’t about interpretation and common sense, and sometimes they don’t appear to be logical but they are a legal requirement. 
 

By kickboard I mean the plinth under the cabinets. Just put vents in it or leave a 5mm gap all along the top, and core drill the wall behind the units at floor level.  

[hendriQ]

3 minutes ago, PeterW said:

By kickboard I mean the plinth under the cabinets. Just put vents in it or leave a 5mm gap all along the top, and core drill the wall behind the units at floor level. 

Oh I see. So you're saying that the supply air to the utility room could come from outside the house itself, rather than from the adjacent kitchen? If that's what you're saying then I'm even more confused as I thought for MVHR to work one had to be airtight against the outside so that one had full control of incoming and outgoing air. Sorry I'm being really dense here.

[PeterW]

No. Supply the air for the utility through an internal wall (under the kitchen cabinets for example) but without knowing the layout it’s a bit of a challenge 

[hendriQ]

On 13/02/2021 at 23:10, PeterW said:

No. Supply the air for the utility through an internal wall (under the kitchen cabinets for example) but without knowing the layout it’s a bit of a challenge 

The only internal walls adjacent to the utility are a hallway and the TV/lounge/kitchen openplan area. That hallway also leads to the TV/lounge/kitchen area. It's all fairly compact so distances aren't huge. The issue this presents is that any holes to supply air from these adjacent spaces will also facilitate sound leakage into these spaces. Hence why I wanted to seal the utility room off from these areas and give it its own extract and supply. @PeterW or anyone else reading this: do you see a problem with my suggested approach?

[PeterW]

Sound wil pass through the door more than the wall or baffled vents etc. so I am not sure why you’re focusing on this. Without seeing a proper floor plan it’s difficult to comment as to how to fix this but it sounds like something that should have been considered at design time, especially with an open plan area. 

[tanneja]

Feels like a similar issue if one wanted to have a cinema room with a sound insulated door with minimal air gaps, thanks for posting