Sub-floor ventilation using fan

pickles88 · 24 Apr 2018

Hi All,

I am concerned about subfloor ventilation in my Victorian terraced house. The distance between airbricks at the front and back of the house is about 7.5m but there are loads of dwarf walls in between that are not honeycombed. I don't really fancy altering them. Could I install a quiet fan before the airbrick to help move the air from front to back (or vice versa)? This would be pretty simple whilst the floor is up. I could just stick in on a timer to run for a few hours each night and then just forget about it. Has anyone done this, or does anyone think it is a good idea? There is only one airbrick at the back because of a concrete extension.

Cheers

freddiemercurystwin · 24 Apr 2018

Is there actually a problem with ventilation or damp because of a lack of it? Anyway a Radon fan would meet your needs if you really needed to pursue it.

pickles88 · 24 Apr 2018

freddiemercurystwin said:
Is there actually a problem with ventilation or damp because of a lack of it? Anyway a Radon fan would meet your needs if you really needed to pursue it.

It doesn't feel like there is much air movement in the sub-floor void, even if I put my hand next to the air brick. The airbrick is actually just a grate that is fixed in the render that runs about a foot up from the ground. It also just feels a bit damp in the void. You mention a Radon fan - I am struggling on google to find one. Is it https://www.amazon.co.uk/Tjernlund-RV2-Ventilation-Ventilated-Spaces/dp/B00BJ88V30 ? Is there a cheaper one!

Thanks

freddiemercurystwin · 24 Apr 2018

I am sure there are others, why don't you just add an airbrick?

pickles88 · 24 Apr 2018

I am worried that adding an airbrick will not improve ventilation enough, and that it will be a PITA to take up the flooring I wish to put down. I'll try it for now and see if it improves the airflow noticeably. Thanks.

geraldthehamster · 24 Apr 2018

Drill holes in the dwarf walls if you're worried?

^woody^ · 24 Apr 2018

One train of thought would be that if the floor and sleeper walls have been there since Victorian times and there are no issues, then things are fine as they are, likewise for the time since the extension.

You wont feel a gale under the floor, so you won't know if its adequate or not. Damp timbers will tell you that its not, dry ones that it is.

Its not a case of putting a fan in and running it once a day.

JP_ · 24 Apr 2018

I did think about this myself (but am now resolved to put in more air bricks all round).
You can get solar fans, which might not be an ideal size, but in theory, you can install them without worrying about connecting to the electrics, and free to run.

You can get all-in-ones like this:
https://www.ebay.co.uk/p/Solar-Vent...ght-Model-Swf-103/1388553038?iid=161332137076

or ones with larger panels like these:
https://www.solarshop.co.uk/solar-v...le-Solar-Fan-kit/p/66514952/category=19615152

bigger one has 2 fans too, so cheaper per fan.

No idea how effective they would be, I only got as far as thinking about it!

pickles88 · 26 Apr 2018

^woody^ said:
One train of thought would be that if the floor and sleeper walls have been there since Victorian times and there are no issues, then things are fine as they are, likewise for the time since the extension.

The logic makes sense, but I was going to insulate between the joints with rockwool (or equiv.) which will significantly impact the current air flow. I may attempt to honey-comb the dwarf walls. Do you have any tips on how to do this, or is it just a case of getting out the SDS and knocking a few bricks out?

jonbey said:
You can get solar fans, which might not be an ideal size, but in theory, you can install them without worrying about connecting to the electrics, and free to run.

Thanks. I will put one in and if it stops working at a later date I will just swap it to a regular air brick!

enviro fan · 23 Nov 2021

Hi just to respond to Pickles88 from 24 April 2018.
7.5m from the brick vent to put a low voltage ventilation system will do anything especially with dwarf wall (sub walls) to be effective, so it probably prudent (if there is adequate sub floor clearance) to cut manholes in each room with a ring pull to install subfloor ventilation systems. Then you will have a better idea how to approach it.

pilsbury · 23 Nov 2021

Cutting manholes in each room…. With ring pulls? Unless you’re stocking with wine, I can’t see that increasing the value of your home. Anyhow, late to the party as his floors have already rotted through.

JP_ · 23 Nov 2021

Sort of on topic .... I have broken out some new airbricks, but it ain't easy.

Could I core hole some air vents instead?

pilsbury · 23 Nov 2021

Just read your drainage post. Have you got a core drill fetish?!

can you buy round air bricks? I’d have thought it easier to stitch drill the mortar and get angry with a hammer. Then a normal air brick will fit in nicely.

You’ll have some jobs for that core drill another day

JP_ · 23 Nov 2021

It's just it took me ages to open the other air bricks, and the drainage guys cored through relatively easily.

But, I could not find any round airbricks, just vent covers like this

JP_ · 23 Nov 2021

Do you think this is too big for my air vent?

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Sub-floor ventilation using fan

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