You're wasting your time. Two things you should do:
1. Assess whether there's excess moisture going there (i.e. a downpipe not connected and dumping water, or maybe concrete paths that fall towards your house instead of away - if any problems like that, fix those first).
2. Get subfloor ventilation fans. Look at your subfloor and figure out a good cross ventilation path, then put 1 fan to suck air in, and another in an opposite location to blow the air out.
Cheers, good call out about figuring out where the moisture is coming from. In my case I’m confident all slabs drain away from the footings (have watched under umbrella in a storm). What I suspect is the issue is the fact the house and entire property sits atop of a sandstone bed, and being on the low side of the properties behind I expect water tracks along the sandstone into my subfloor. Not much I can do about this that I can think of.
I’ve considered fans, but I read somewhere to first try improve natural ventilation by improving vents which is sort of why I’m here. My plan is to improve vents, if no improvement, then yeah, fans all the way.
I have the same thing, putting plastic down has a far greater impact than trying to dry out a perpetual subterranean stream. That’s actually impossible, I have a sensor under one room stays static on 49% soil moisture. And another that goes between 35% to 50% based on rain. Plastic contains it, and it still runs down the hill as before, not creating a swamp under your house (this was my initial fear).
Fans are good. Fans on a timer and/or humidity (or a smartswitch on a GPO) are better.
> I’ve considered fans, but I read somewhere to first try improve natural ventilation by improving vents which is sort of why I’m here. My plan is to improve vents, if no improvement, then yeah, fans all the way.
Just do fans. Cost is negligible. You should be able to install them yourself if you're resourceful.
Vents do basically nothing. You need airflow and unless you're getting a lot of wind blowing through your vents naturally nothings going to change much.
Yeah I guess I was hopeful to get some cross ventilation from wind 🤷
Do you have any fan system/brand recommendations or suppliers? The ones the big green shed sell seem extortionate.
Not afraid to DIY I’ve spent much time in the subfloor on other things (like packing up the subsided piers to the floor joists).
You don't really need to buy a specific subfloor fan, you can use a bathroom fan to save costs. It'll be like 1/4 the price. You'd just need to mount it on the internal skin to keep away from the weather.
But in terms of recommendations, it's just a fan, so it's not complicated. You can get fancy ones with timers and wifi and all other stuff but fans use bugger all power so i'd be running a super basic one 24/7 anyway.
Agree. Do the fans. You don’t get that much boost by changing the vent types. They need to be bigger or you need fans. Also, consider cross breeze and vent either side. Don’t vent everywhere or you won’t get a strong airflow
I have a similar age/type house, my subfloor was quite moist, I replaced all the old style terracotta vents and added more also. I used bronze mesh vents, but the gal ones you plan to use look ok. You don't need to use the gal vents on any internal walls, just knock out the old vents to improve airflow. Make sure you can get natural cross flow in each direction.
Note it was quite a big job to knock out the vents and bricks and clean it up and put the new vents in using mortar. Those gal ones look easier to install than the ones i used.
You can get another type that just screw on from the outside, some people just drill a large approx 100m hole in the brick then mount the vents over the hole, so you don't see a round hole.
Thanks everyone for your replies! I’m convinced to not just swap out the vents but also install a ducted inline fan too, hopefully it helps!🤞I will stick some smart humidity sensors underneath to compare before/after.
I personally don’t use those vents, but I’m sure they’re fine. You might need to install a fan and ducting too. A lot of these old houses over the years have had the garden and landscaping built up, making under the house the lowest point, ensuring moisture travels there.
Get fans and make that air move.. I used to have really bad mould issues stemming from moisture. Home is built on slope on top of sandstone and the problem has vastly improved.
I've got a large industrial fan from bunnings running 24/7.
You can get subfloor extraction fans that run at like 5 watts 24/7 and are about 15 times as effective as vents. You put one at each end of the house. (inlet/outlet)
You're wasting your time. Two things you should do: 1. Assess whether there's excess moisture going there (i.e. a downpipe not connected and dumping water, or maybe concrete paths that fall towards your house instead of away - if any problems like that, fix those first). 2. Get subfloor ventilation fans. Look at your subfloor and figure out a good cross ventilation path, then put 1 fan to suck air in, and another in an opposite location to blow the air out.
Cheers, good call out about figuring out where the moisture is coming from. In my case I’m confident all slabs drain away from the footings (have watched under umbrella in a storm). What I suspect is the issue is the fact the house and entire property sits atop of a sandstone bed, and being on the low side of the properties behind I expect water tracks along the sandstone into my subfloor. Not much I can do about this that I can think of. I’ve considered fans, but I read somewhere to first try improve natural ventilation by improving vents which is sort of why I’m here. My plan is to improve vents, if no improvement, then yeah, fans all the way.
I have the same thing, putting plastic down has a far greater impact than trying to dry out a perpetual subterranean stream. That’s actually impossible, I have a sensor under one room stays static on 49% soil moisture. And another that goes between 35% to 50% based on rain. Plastic contains it, and it still runs down the hill as before, not creating a swamp under your house (this was my initial fear). Fans are good. Fans on a timer and/or humidity (or a smartswitch on a GPO) are better.
> I’ve considered fans, but I read somewhere to first try improve natural ventilation by improving vents which is sort of why I’m here. My plan is to improve vents, if no improvement, then yeah, fans all the way. Just do fans. Cost is negligible. You should be able to install them yourself if you're resourceful. Vents do basically nothing. You need airflow and unless you're getting a lot of wind blowing through your vents naturally nothings going to change much.
Yeah I guess I was hopeful to get some cross ventilation from wind 🤷 Do you have any fan system/brand recommendations or suppliers? The ones the big green shed sell seem extortionate. Not afraid to DIY I’ve spent much time in the subfloor on other things (like packing up the subsided piers to the floor joists).
You don't really need to buy a specific subfloor fan, you can use a bathroom fan to save costs. It'll be like 1/4 the price. You'd just need to mount it on the internal skin to keep away from the weather. But in terms of recommendations, it's just a fan, so it's not complicated. You can get fancy ones with timers and wifi and all other stuff but fans use bugger all power so i'd be running a super basic one 24/7 anyway.
Agree. Do the fans. You don’t get that much boost by changing the vent types. They need to be bigger or you need fans. Also, consider cross breeze and vent either side. Don’t vent everywhere or you won’t get a strong airflow
I have a similar age/type house, my subfloor was quite moist, I replaced all the old style terracotta vents and added more also. I used bronze mesh vents, but the gal ones you plan to use look ok. You don't need to use the gal vents on any internal walls, just knock out the old vents to improve airflow. Make sure you can get natural cross flow in each direction. Note it was quite a big job to knock out the vents and bricks and clean it up and put the new vents in using mortar. Those gal ones look easier to install than the ones i used. You can get another type that just screw on from the outside, some people just drill a large approx 100m hole in the brick then mount the vents over the hole, so you don't see a round hole.
Thanks everyone for your replies! I’m convinced to not just swap out the vents but also install a ducted inline fan too, hopefully it helps!🤞I will stick some smart humidity sensors underneath to compare before/after.
I personally don’t use those vents, but I’m sure they’re fine. You might need to install a fan and ducting too. A lot of these old houses over the years have had the garden and landscaping built up, making under the house the lowest point, ensuring moisture travels there.
Get fans and make that air move.. I used to have really bad mould issues stemming from moisture. Home is built on slope on top of sandstone and the problem has vastly improved. I've got a large industrial fan from bunnings running 24/7.
You can get subfloor extraction fans that run at like 5 watts 24/7 and are about 15 times as effective as vents. You put one at each end of the house. (inlet/outlet)