Hi Friends.

My single garage, with exposed roof trusses, concrete floor, and brick walls and no insulation (temp regular gets down to 4deg.), is developing a mould problem, particular on backpacks, jackets ect.

We run a fridge, and a condenser tumble dryer. (I suspect the tumble dryer is the culprit)

My question is, what is the best method of reducing humidity and mould growth in the garage. Removing the tumble dryer is not an option. Would an externally vented dryer make a difference? (although not keen to replace dryer as in only a few months old)

Thanks in Advance.

It’s unlikely to be the dryer per-se – they emit very little humid air (go in the garage on a cold night there won;t be a cloud of steam).

Get a dehumidifier would be my advice. I use the desiccant type because they continue to work at far lower temperatures than condenser models.

Edit: also look at whether a bit of ventilation would help if you don’t go down the dehumidifier route.

i have exactly the same type of garage, albeit with no tumble drier (although I do have a wife that parks her car in there…). We do live in a valley with not a lot of wind though.

Ventilation is the key. Dehumidifiers won’t work well enough, as there’s to many gaps. I’ve put a few holes in the barge boards, and covered them with directional vent covers. Any wind now gets channeled up into the roof space. I’ve also rigged up a couple of extractor fans (old ones, left after bathroom development), with ducting. One brings air in, and the other extracts. Couple of hours a day (on timer), after the car goes in, seems to have solved a lot of the problem.

Next time we have some building work, I’ll get them to drill a 200mm circle in the wall to put in a industrial fan. That’ll learn it!

25 year in our house, detatched single wall garage, pitched roof with open loft space. No mould on any fabrics/ rucksacks etc. I also Zwift in there, which causes heat/mousture

I’ve not allowed a dryer in there, of any sort. There will still be moisture, condensing or not. Your fridge will help dry.

Your option would be a dehumidifier – a proper condensing one – you’ll ideally need one with a drain pipe so you can run that outside if wanted (saves you emptying the container). Or more ventilation.

Ventilation.

Not really any point dehumidifying air that’s basically at outside temperatures, you can just swap it for drier air from outside much easier and with no cost.

The inside of the garage should sit a few degrees above the outside air temp anyway because it’s connected to your house, it’s on a concrete slab, the roof absorbs solar gain etc. So you’ll only get condensation inside if the humidity is higher than the outside.

It’s unlikely to be the dryer per-se – they emit very little humid air

Yes and no, it’s still at 100% relative humidity, and above the ambient temperature, It’ll be significantly more humid than the air that would otherwise be in the garage, and will cool down and condense on anything cold.

Can you duct the tumbledryer air out that would help.

insulate potentially.

ventilate if not.

would be a dehumidifier – a proper condensing one

don’t do this – condensing types don’t work in unheated rooms.

^ that.

If you go the humidifier route go with a desiccant one. I just changed to one in my cold, damp cellar and it is much better. Set the desired humidity level, fit drain hose, turn it on and forget about it.
I got this; https://www.amazon.co.uk/gp/product/B07D8SZJGM/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

Obviously that is treating the symptom not the cause though so possibly not the best approach.

I stand corrected on de-humidifiers. I only thought there were the cheap ‘peltier’ types and the condenser ones – we’ve got a condenser one we sometimes use in the house/conservatory.

Depends how far you want to go. Nothing dried in my garage and because of that, I’ve had muddy crap dotted all over the house since we moved in 6 years ago. I made the decision to put in a ceiling and insulate the single skin walls and new ceiling, plus new storage and lighting to actually make it a useable space. Currently a work in progress, but in the end I’ll have somewhere warm enough that I can work at room temperature and dry all my outdoor gear without it being traipsed in the house.

If all you want is no mould, I’d go with the ventilation advice above.

Hi All

Thank you for the information.

I think I may improve ventilation at the front end, and mount a extractor van through the wall at the other end (above the dryer)

Any tips on the best place to purchase a vent fan?

damp & hot air rises.

So high – if possible

if you can do high above the drier, so much the better…

if you think about it (or rather, when I think about my garage), the doors are the bottom 2m, and there’s another ~2m above that into the apex. That is where all the damp hot air goes, and where it condensates (which can then drip). So that’s where you need the air flow.

the other thing I do (which is easy with an electric door) is partly open it, so the door is at an angle of maybe 30 degrees to the vertical. when it’s windy, this obviously directs all the wind up to the apex. Couple of hours of that at weekends seems to help. Nobody can see in still.

Good point about the height, and come to think about it, most of the mould is at the higher levels.