Unheated/Uninsulated Garage Storage

[Supra_UK_]

Hi fellow Supra people.
I'm looking to get information from anyone else hopefully in my situation.
The Supra is the first car I keep in a garage. I did a lot of research and see a lot of contrasting opinions in regards to keeping humidity down, so just looking to hear people's experience, not start a debate.
My garage is a single, detached, uninsulated and unheated garage, bog standard new build.

I fitted:
A new sectional air tight sealed insulated garage door (hormann) which has reduced draft and debris coming in.

On top of the garage door there's a black steel beam with holes letting some air in, and when it's windy I can see the felt under the bricks moving between the rafters. I am not an expert so bear with me with terminology.

Long story short, all I care about is for the Supra not to get mouldy, so I have many dehumidifier bags inside (the pingi ones you recharge) and a unibond, as well as a small cordless fan that stays on 12 hours to move air inside.

Now: I have 2 hygrometers to monitor RH, 1 inside the Supra, and 1 in the garage. On crappy weather (November, East of England) the RH in the garage is between 85%-93%, so extremely high and supposedly mould danger.
Inside the Supra is pretty much always around 52%, at best 49%.
So technically, I should be alright, but I can't help but worry about the super high RH around the car.
Other things I'm going to do are:
- Treat the interior with GTechniq AB Smart Clean water and bacteria repelling coating - Youtube vids really show it works and it was hard to source. Gonna be fiddly to apply.
Next, in 2 weeks I'll have a guy fit an extractor fan linked to the mains, which hopefully promotes ventilation and maybe reduces RH, but don't know. That's about £250...
I'm also thinking of adding a air-mover circulator fan, (these are not like normal fans), it costs around £80 on amazon.

Tomorrow a brand new desiccant dehumidifer arrives, (so it can cope with very cold temps) it's the meaco dd8l, has great reviews - now the issue is I spoke to Meaco and they said better insulate, or it will run on always and cost a lot of money, so I am kind of worried whether this will be an expensive effort with little value add, I'll find out in the next days. Never the less I couldn't bear thinking I didn't at least try it, and worse case I'll just use it to dry laundry inside my home... I already have a compressor one inside so I'd have two...

Finally I'm considering insulating the rafters with PIR celofax for around £800 quoted (which I cannot afford now that I have a Supra...), but roofer reckons if you don' insulate walls too, then it still doesn't affect temperature swings much, and curremtly as it is, I checked and inside the garage is only 1.5 degrees C more than outdoors.

Can anyone share their story/methods with storing their car in a garage like mine?
Did you have any mould issues? What did you to to resolve? Experience with dehumidifiers/insulation jobs/extractors?

Thanks!

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[MoTeC_R]

From my experience as long as the garage doesn’t have mold in it you’ll be fine.

 

[Adrian]

Years ago my mk4 Supra was in an unheated. Uninsulated garage. Never had a problem with any mould. Never even considered it.

 

[yellowsup]

Bit of a late reply, I've been banging my head with this one too......I think you will have sorted it with the new door though. I have a detached garage and when you open the main door in cold damp weather you can see the condensation propagate along the car from the open door. So (I'm no expert) if the outside has a high moisture content and you bring this in with a fan you might actually increase the RH by dragging in damp air?? You might be better off without the vent knowing that the natural gaps will circulate enough air to keep things in check? I'd keep an eye on the bodywork/underside, if it's not getting damp to the touch ..... no problem...... if it's getting damp you might need a heat source. I've kept an eye on mine through the winter and if I keep the doors closed it seems to be OK.... how was yours this winter?

 

[jchadwell]

Seriously overthinking this. Millions of RVs and vehicles are stored in unheated buildings. If there's no mold in the building there will be no mold in the car. You need to be MUCH more concerned about rodents. I keep several mouse traps around the car during it's winter nap and change out the peanut butter used in them every couple weeks just to make sure it stays fresh and easily sniffed by the furry little fuckers.

 

[yellowsup]

Seriously overthinking this. Millions of RVs and vehicles are stored in unheated buildings. If there's no mold in the building there will be no mold in the car. You need to be MUCH more concerned about rodents. I keep several mouse traps around the car during it's winter nap and change out the peanut butter used in them every couple weeks just to make sure it stays fresh and easily sniffed by the furry little fuckers.

yep u are right, way too much time thinking about it......!!! too cold for the mice! they head for the house instead !!!!......

 

[Supra_UK_]

Thanks all for the replies.

Here's my update with the pros and cons, sorry to anyone not in UK but all prices will be in £.

I spent £240 on an extractor fan, that works well and is on 24/7 with a humidistat.

I spent £800 and had fire retardant plasterboard installed on the joists and then 2 layers of thick insulation on on top.

So for now I'm about £1050 into it and I can say generally speaking it's worth it for some things and not for others:

Keeping garage warmer: with no heating unit it is already much warmer, no drafts, but would still require a small heater next to be comfy.

Humidity:
Generally it has reduced the rh% slightly but the main difference is:

The dehumidifier now has less volume of air to dry thanks to plasterboarding so when it's on it works better and can reach 75%/70%.

It also now feels more like a room and no longer a garage so looks and feels much nicer in there and less spiders (lol).

I need some time to skim/fill and paint it white and ultimately it will then look pretty sick almost like a studio. The final touch would be some cool led lights!

So to summarise generally I think they key for me has been to keep RH low INSIDE the car with lots of dehumidifiers and a small desk fan to move air, and also coating everything in GTechniq Smart Fabric AB v2 or v3, and keeping everything dry and clean, I also replaced mats with custom rubber mats - the rh inside the car with everything closed is always around 50%.

If anyone has any questions let me know as I basically tested everything now and poured quite a bit of cash for this experiment.

One last thing is, my new build home like most in UK is poorly finished, so I noticed some damp coming through the lower bricks mortar, that's another job I need to do as soon as it stops freezing to repoint some mortar.

I attached a before and after photos to this post.

Finally to those saying I'm overthinking it, generally speaking for common folk I understand it looks that way, because that's how I am and I like things to be pristine, this is a special Sunday drive car not a daily and unlike most men who change car every 1-2 years this is something I want to keep.

 

[MisterSkiz]

Worried about moisture build up in your car?

I have seen may folks use "DampRid" and place them in the floor of the vehicle.

https://damprid.com/

UK Link:
https://www.amazon.co.uk/damprid-moisture-absorber/s?k=damprid+moisture+absorber

To be honest I would worry more about mice / insects getting into the car while storing it than anything else.

 

[FLtrackdays]

Worried about moisture build up in your car?

I have seen may folks use "DampRid" and place them in the floor of the vehicle.

https://damprid.com/

UK Link:
https://www.amazon.co.uk/damprid-moisture-absorber/s?k=damprid+moisture+absorber

To be honest I would worry more about mice / insects getting into the car while storing it than anything else.

I’ve got a friend that uses damprid for tons of his collector cars. Great mention!

 

[Supra_UK_]

To anyone interested:

Thought I would share here after several months and a few thousand quid of work spent:

Overall I feel I partially wasted money, spent 2k on the insulated garage door (it is very good) and 1k on insulating the roof and boarding it).

It does help humidity a tiny bit but because the walls are single brick and uninsulated all the cold and damp still comes in. It makes it feel more like a room and reduces dust on the car...

So now I need to keep running dehumidifier which is expensive (dessicant heater) and airing out the garage frequently...

However, the silica gel bags inside the car (I have 3 x 1 kg ones) are amazing, and humidity in the car is around 45% even when the garage is 80%.

In summary: if anyone has a detached garage and wants to make it warm and less humid and keep the car in there nice and dry inside and out, you either go all the way and spend big money to get it fully covered, or probably best not do it all...

 

[BrettMRC]

In my garage I have insulated the walls and ceiling, but the doors are bare wood.
On one wall I have a frostwatcher heater, and it's working really well. (kicks in when tempertures get to about 4deg, it's not warm in there - but it's never damp, and opening up the doors at 4am the other day to go to Whifbitz it felt toasty in there vs the ambient)

A dehumidified is only really viable, (IMO) if the area is relatively well sealed and you are not putting the car away wet.

I've noticed the Supra likes to hide water internally for about an hour, then drop four puddles on the floor!

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