Trying to understand old house ventilation

[Mark and Jen]

I'm trying to understand the basics of ventilation and humidity control in my new (old) house. It has solid stone wall construction (900mm thick in places as I've just discovered drilling through it for Internet wires!) and inside is plastered and all finished to, what looks like, a reasonably high standard. There are no signs of damp – certainly nothing significant. It all seems pretty good.

Now I know that humidity in the air is supposed to be dealt with by proper finishes on the walls, etc..... but is that all that's needed. The house is reasonably air tight with double glazing (although not new build airtight!), so the only flow of air seems to be through the ground floor air bricks coming in and out of the two log burner chimneys and the extractor fans in the bathrooms. Is it as simple as that. Just keep the air bricks clean and the same for the extractor fans in the bathrooms and the flow of air is enough? The double glazing has no trickle vents.

On which note, I assume in my attached barn, where there is no ventilation in or out because the doors have been replaced with UPVC units and the roof has been lined with insulation and OSB boarding - I'm going to need to install some sort of ventilation (in and out) before using it as my gym!

 

[aockenden]

Yeah that’s not bad, those elements that are already in place will serve you well. Trickle vents are good options as well, and depending on the window construction you might be able to retrofit them in. But in any event, you could be doing a lot worse and if there no major problems then that’s a good indicator.

Beyond those relatively “passive” ventilation options then you get into more comprehensive, full-house, active options like MVHR and PIV. But again, if there’s no problems then just wait and monitor things and make sure nothing develops.

 

[Flyfisher]

If there are no signs of damp then the basic structure is probably ok and it's just the internal humidity generated by everyday modern living that needs to be managed. The new (to the house) DG would likely have reduced the natural ventilation of the house (if the original windows were anything like our draughtly ones - good in the summer, not so good in the winter!) plus you'll likely be generating more humidity than the original occupants (daily showers, washing/drier machines etc), so it's worth keeping an eye out for any cold spots (eg behind furniture against outside walls) where condensation might form. Having said all that, your bathroom has an extractor and, presumably, the kitchen so that all helps and the two woodburners will draw air through the building, which is actually essential for their safe operation (but you do have a CO alarm near each stove, don't you?).

Energy efficiency and ventilation are arguably the two most importaant things to balance in a healthy house. Either one is relatively easy to achieve but it's getting the balance right that's the real trick. I believe the recommendations for a healthy indoor atmosphere are to change the air in 'wet' rooms (kitchens, bathrooms) about 7x every hour and living rooms about 4x every hour, which gives a guide of what to aim for.

I'm quite an advocate of openting windows at every opportunity, which is obviously no problem during warm weather but less convenient during th winter months. Even so, I usually sleep with our bedroom window slightly open and usually open it more fully in the morning for a few hours, even in the winter months. Ultimately, just having the awareness you obviously have means you'll soon learn how your house 'works' and be able to accomodate its little quirks accordingly. That's the beauty (I think!) of living in a period property in which you learn to live happily together rather than simply impose your will on the place by brute force.

 

[Cubist]

A gym? Yes, t extra ventilation will be needed to cope with the by-products of your exertions AND Anoxia.