Trickle Vents in Cob Cottage

[CornishCobCottage]

Hi all - recently came across this forum and its been fantastic.

My cottage is cob and stone and I am embarking on necessary restoration including new doors and windows. There's some disagreement over the June 2022 regulations re ventilation. Multiple window companies have told me that I need trickle vents in each window (there is one window per room), but I believe that under Section 0.5 C under Approved Document F it clearly states that cob cottages may be exempt from these regs.

https://assets.publishing.service.g...uploads/attachment_data/file/1045918/ADF1.pdf

The cottage is not listed, but falls within a heritage site (not conservation). I'd obviously rather not involve local planners/building regs people if not needed. Is there a consensus on whether trickle vents are needed in my case?

I should add that the windows are a mix of old and not so old, and a miss mash of Georgian and Victorian sash styles. One window obviously replaced in the last 30 years or so has a trickle vent so I understand the replacement would need one in this case.

Thanks in advance.

 

[Cubist]

Do you have some objection to trickle vents?

 

[paulc]

Do you have some objection to trickle vents?

I for one object to trickle vents. Having spent a sizeable chunk of money killing off as many draughts as possible, I do not see why a hole should be put in a window frame to create another. In addition, any trickle vent in the frame would get blocked as I insulate around the window reveal.

Some observations from reading the approval documents:
1) No where in the notes does it say trickle vents must be fitted. Only that background ventilation should be provided. This ventilation can be provided by way of a MHRV or PIV system, or even an air brick through the wall.
2) On the front page of the approval documents, it clearly says that it is guidance and that methods can be varied.
3) Only in a few places is the word "must" is used to indicate a mandatory requirement. In all other places, it is "should" - i.e. Not mandatory.
4) If the windows face on to a busy road, trickle vents need not be fitted if pollution is a concern. They can also be omitted on an exposed elevation if the building is subject to prevailing winds from one direction.

Another cop out to avoid trickle vents is to replace no more than 30% of your windows at a time.

 

[Cubist]

Assuming that there is, or would be after your renovations, adequate air-flow to support the buildings ability to breathe effectively I can understand your objections. But, who is mandating that trickle vents must be included and what enforcement authority do they possess?

 

[CornishCobCottage]

I'm not sure who is enforcing it but believe the installers must notify local authority to get the Fensa certificate or equivalent. Could you get a summons for an inspection and told to change it/rip it out? That's the fear! I wonder how plausible that is.

One side does face prevailing winds which is partly why I'm concerned - my good neighbour isn't a fan of their trickle vents for this reason. 30% rule is interesting, I'd not heard of that - need them done at once unfortunately. Mechanical ventilation is too costly and intrusive to install (thick walls) but an air-brick might be possible.

The legislation text I'm referring to is below - I've added the emphasis. Has anyone had any experience of interpreting this legislation?

Historic and traditional buildings
0.5 Work to the following types of dwellings may not need to comply fully with the ventilation standards in this approved document.
a. Those listed in accordance with section 1 of the Planning (Listed Buildings and Conservation Areas) Act 1990.
b. Those in a conservation area designated in accordance with section 69 of the Planning (Listed Buildings and Conservation Areas) Act 1990.
c. Other historic buildings with a vapour-permeable construction that both absorbs moisture and readily allows moisture to evaporate. These include those built with wattle and daub, cob or stone and constructions using lime render or mortar.

0.6 Work to a building in paragraph 0.5s should comply with the ventilation standards in this approved document where reasonably practicable. The work should not result in either of the following outcomes.
a. Unacceptably affect the significance of the listed building, conservation area or scheduled monument.
b. Increase the risk of long-term deterioration of the building fabric or fittings.

0.7 New extensions to historic and traditional dwellings should comply with all ventilation standards in this approved document unless there is a need to match the external appearance or character of the extension to that of the host building.

0.8 The local authority’s conservation officer should be consulted when undertaking work to a building in paragraphs 0.5a or 0.5b. (note: not 0.5c)

 

[Cubist]

Now I'm confused. A Fensa Certificate signifies that a company has the necessary competence to do the work. It is not associated with the products or materials they may use. Therefore, provided the the Windows and Doors you are proposing to use are compliant with Building Regulations and any similar that are clearly stated by the Conservation Area you should have no problems. With whom is the issue disputed?

 

[CornishCobCottage]

I just meant notifying local authority is part of the necessary install process; therefore my concern was a visit from building control or the like following this. All the window companies I've spoken to have said I need trickle vents (since these June 22 regs); they haven't explicitly said they won't fit them without.

So far it's just my interpretation of the regs that says the cottage may be exempt and I wondered if anyone had more to say on it from experience. I'm not completely against them but the cottage aesthetic would be best protected by their absence in the main. However, if it is reasonably practicable to install a MHRV system in lieu of trickle vents then I will have to go with the vents!

 

[a twig]

Funnily enough I had windows made and fitted without trickle vents, but then ended up retrofitting them due to lack of airflow in the bedrooms…

Very easy to have them attractively done in brass to fit an aesthetic.

 

[a twig]

From the regs - you need to read 0.6 as well as 0.5

You would be hard pushed to argue that trickle vents aren’t reasonably practical imo…

If you don’t want vents, you are then into arguing on not needing them based on 3.14 and 3.15

 

[CornishCobCottage]

From the regs - you need to read 0.6 as well as 0.5

You would be hard pushed to argue that trickle vents aren’t reasonably practical imo…

Yes I agree. It's 0.6a battling with 0.6b in a way. Also the rear wall suffers most from wind so that's a concern. I'm interested that you retrofit your trickle vents - did you experience air quality issues without them?

 

[a twig]

Bedrooms were the only places we retrofitted, and yes humidity was getting to ridiculous levels overnight, massive condensation on windows every morning despite being double glazed etc

Other living areas had fireplaces or other forms of mechanical ventilation so no need on those rooms.

We have since moved and bedrooms here don’t have trickle vents, and again we noticed similar symptoms

 

[malcolm]

From my reading you are up against a bit of nonsense. Trickle vents may be good for new unventilated houses that are coated with waterproof materials. It seems common for people to dry clothes inside and in the absence of any education about how to live in a modern house I guess legislating for trickle vents is probably a good idea to save the NHS from all the mould related breathing difficulties.

At my end I replaced more than 30% of my windows with some nice new sash windows that do not have trickle vents. I have plenty of ventilation other than through the windows (some of which I don't want). I have breathable walls inside and out.

The historic and traditional buildings bit in the regs hints that the people who wrote the regs follow my thinking. I would not have trickle vents and if a window company insisted on them I would find another window company. They are designed to sort a problem that a properly maintained historic building will not have. They have heating cost implications.

EDIT - Cross posted with a twig who has a good point. Bedroom windows will have a lower U value than the walls and will tend to be cold and suck moisture from the air at night.

 

[Lacan07]

From my reading you are up against a bit of nonsense. Trickle vents may be good for new unventilated houses that are coated with waterproof materials. It seems common for people to dry clothes inside and in the absence of any education about how to live in a modern house I guess legislating for trickle vents is probably a good idea to save the NHS from all the mould related breathing difficulties.

At my end I replaced more than 30% of my windows with some nice new sash windows that do not have trickle vents. I have plenty of ventilation other than through the windows (some of which I don't want). I have breathable walls inside and out.

The historic and traditional buildings bit in the regs hints that the people who wrote the regs follow my thinking. I would not have trickle vents and if a window company insisted on them I would find another window company. They are designed to sort a problem that a properly maintained historic building will not have. They have heating cost implications.

EDIT - Cross posted with a twig who has a good point. Bedroom windows will have a lower U value than the walls and will tend to be cold and suck moisture from the air at night.

I was going to ask Twig if his walls were breathable until I read your post Malcolm. Do your breathable walls help condensation issues in your house.

I can remember years back renting a small flat in an old house which suffered a bit of damp and I used to get tremendous moisture on my windows in the morning but later realised it was caused by me pulling the curtains tightly shut every night. I then started opening them before going to bed.

 

[paulc]

The legislation text I'm referring to is below - I've added the emphasis. Has anyone had any experience of interpreting this legislation?

The text you quote is from Approved Document, Part F - This is one of a series of documents (erroneously) referred to as the "Building Regulations". On the first page under the section headed "Introduction", it says that it is guidance only, and there may be alternative ways of meeting the requirements of the legislation not listed in the approval document. It is an argument I have had with several window suppliers/installers earlier in the year. A few were adamant that I had to have trickle vents even although I were still a couple of months away from the June 15th introduction. Eventually found someone that was flexible on interpretation and agreed that I didn't need the darned things. In your shoes, I'd print off the first few pages and highlight the relevant sections, in particular, sections 0.4 and 0.5c. Wave the sheets under the nose of anyone coming to quote for windows, and discount anyone who refuses to be flexible.
Alternatively, stick some dummy vents on the ceiling and hope no one looks too closely.