Sad shed thread: how to minimise condensation

Breezin

I never thought I'd be posting on the interwebs about sheds, but life is full of surprises... :eek:

I have a reasonably well-built and solid wooden shed, tongue and groove with a decent roof and one window (I asked for none but it came that way anyway). It has a synthetic membrane lining on the inside walls, and the roof inside is wooden. There's a vent in one wall at head height. Condition as new. It's just big enough to fit the bike.

After the winter's now-forgotten marathon spell of miserably damp weather, the clocks on the bike were showing a little condensation at the bottom. It went away after a few outings, but I noticed it returned just a tiny bit after the most recent spell of good weather. I'm guessing that the intense general humidity of the earlier period has left moisture inside them. I'll see if more riding around in mostly dry weather helps the situation. If not, I'll use the hairdryer on them.

My question is: does anyone have advice on what to do to make the shed as dry as possible. Increase ventilation? Or block the vent and seal everything better? I have to admit, I haven't a clue which way to go. (Swapping for a metal one, or building a garage isn't an option, unless I move house.)

listermint

Moisture needs to not get in 1. and if its in get out easily 2.

So make sure its weather tight, check roof check windows check floor.

And increase ventilation.

Agent_47

Near impossible if temp is lower than 10-12 C where high humidity thrives. Reasoning is that you keep the temperature above 10 C and tackle humidity through a dehumidifier.

Unheated shed probably drops to 3 or 4 C during winter. It probably feels damp inside all winter.

My garage is like a fridge in winter, gets down to 7C so I have just put closed cell rafter insulation into the rafters. I have a desicant dehumidifier ready to install after the double PVC glass doors are fitted next week. No draughts, passive solar radiation, dehumidifier and I hope to keep temp above 12C and humidity down to 45 to 50% rh.

Skill Magill

Blade1 on another thread got a bubble thing that you inflate and store the bikes in.

galwaytt

Agent_47 wrote: »

Near impossible if temp is lower than 10-12 C where high humidity thrives. Reasoning is that you keep the temperature above 10 C and tackle humidity through a dehumidifier.

Unheated shed probably drops to 3 or 4 C during winter. It probably feels damp inside all winter.

My garage is like a fridge in winter, gets down to 7C so I have just put closed cell rafter insulation into the rafters. I have a desicant dehumidifier ready to install after the double PVC glass doors are fitted next week. No draughts, passive solar radiation, dehumidifier and I hope to keep temp above 12C and humidity down to 45 to 50% rh.

Just bought a dehumidifier myself and its brilliant.

However my main storage garage is unheated, but highly insulated and well ventilated and I have zero condensation. The dehumidifier is fir the heated garage!

A well insulated wall and roof is one thing: but an uninsulated or non DPC floor means your fighting a losing battle.

Breezin

Thanks for those responses guys. I've been doing some rummaging on the topic and I think I'm going to go the route of putting in a small additional vent to ensure air flow, as well as a thermostatic shed heater, which will require wiring to the shed.
I don't think it's possible to fully seal the shed, so a dehumidifier is probably not going to work in this situation. I can certainly see how it would work in a proper garage or similar.
The bike bubble looks good and not as expensive as I thought it would be. But it looks like it won't fit, going by the dimensions of that Honda classic. My shed is sized to the bike, and the bubble looks bigger. As it is, I have about 1cm leeway on length after I lift the bike back onto its mainstand, and that's only with the wheel at full lock!
One of the most basic pieces of advice I found is to leave the door open whenever possible, so I'll be doing that too.
If none of that works, I might see if I can squeeze in the bubble.

Test For Echo

Keep us posted on how you get on please!

I bought a Steeltech shed last year and it has been an absolute disaster for condensation & damp in Winter. The bikes will now have to be kept in the house during the Winter months. The shed, concrete & electrical work cost >€7500 so I'm well pissed off.

Was going to stick in a few vents but I don't think that's going to be good enough.

Breezin

Test For Echo wrote: »

Keep us posted on how you get on please!

I bought a Steeltech shed last year and it has been an absolute disaster for condensation & damp in Winter. The bikes will now have to be kept in the house during the Winter months. The shed, concrete & electrical work cost >€7500 so I'm well pissed off.

Was going to stick in a few vents but I don't think that's going to be good enough.

Will do. Although it's a mid to long-term experiment! (I was just about to drill the vent just now when I was chased back into the house by a hail shower. In June, ffs. How all our bikes aren't total rust buckets I don't know!)


I had avoided a metal shed, as I'd heard that about them before, but I think there's been some discussion on this forum about how to prevent condensation in them. Maybe not a total write-off?

Test For Echo

Breezin wrote: »

...How all our bikes aren't total rust buckets I don't know!)

I had mine covered and couldn't believe when I seen all the fuzzy mould on them :mad:. Washed the hell out of them and sprayed with ACF50. It's a pain in the face but at least I can get them into the kitchen for Winter months. I thought I'd done my research before ordering a metal shed, but apparently not...

Everything in the shed was on the way to being destroyed :mad:

Baymax2020

I bought a Steeltech shed last year and it has been an absolute disaster for condensation & damp in Winter. The bikes will now have to be kept in the house during the Winter months. The shed, concrete & electrical work cost >€7500 so I'm well pissed off.

Was going to stick in a few vents but I don't think that's going to be good enough.[/quote]

A couple of vents should help your cause. But I'd say to fully salvage use of your shed I'd say it might be worth putting rigid insulation (kingspan or the likes) in and sheet the walls with OSB. If there is no polythene under your concrete slab it would be worth putting batons down on the floor with insulation between and OSB on top. But unfortunately this will all add to your overall cost.

Test For Echo

wrote:

A couple of vents should help your cause. But I'd say to fully salvage use of your shed I'd say it might be worth putting rigid insulation (kingspan or the likes) in and sheet the walls with OSB. If there is no polythene under your concrete slab it would be worth putting batons down on the floor with insulation between and OSB on top. But unfortunately this will all add to your overall cost.

I'll defo be putting some vents in. In the meantime I'm leaving the door open a couple of inches which I'm not happy about. There's DPC under the concrete floor. Steeltech talked me out of Kingspan insulation because I didn't intend heating the shed. In March the non drip coating on walls & ceiling was soaking wet.

blade1

Baymax2020 wrote: »

I bought a Steeltech shed last year and it has been an absolute disaster for condensation & damp in Winter. The bikes will now have to be kept in the house during the Winter months. The shed, concrete & electrical work cost >€7500 so I'm well pissed off.

Was going to stick in a few vents but I don't think that's going to be good enough.

A couple of vents should help your cause. But I'd say to fully salvage use of your shed I'd say it might be worth putting rigid insulation (kingspan or the likes) in and sheet the walls with OSB. If there is no polythene under your concrete slab it would be worth putting batons down on the floor with insulation between and OSB on top. But unfortunately this will all add to your overall cost.[/QUOTE]

And even at that, assuming there is one, you've still got a problem of metal roller door.

Test For Echo

wrote:

...assuming there is one, you've still got a problem of metal roller door.

In my case it's a 4ft sliding door with non-drip coating on the inside. Really surprised at how bad the condensation is because I would have thought there'd be a fair bit of room for air circulation - you can see daylight at the eaves.

@ OP - apologies for the thread hijack.

blade1

Test For Echo wrote: »

In my case it's a 4ft sliding door with non-drip coating on the inside. Really surprised at how bad the condensation is because I would have thought there'd be a fair bit of room for air circulation - you can see daylight at the eaves.

@ OP - apologies for the thread hijack.

Ive bad condensation too and have an air chamber for bikes.
Even that doesn't work as it should because the fans are only blowing damp air into it so I don't use the fans and seal up the holes.
I've a few bags of silica gel inside.
Nice and dry in there like alright.

listermint

Your concrete is most likely still drying out. I'd say that's the source of the moisture.

Needs constant airflow.

blade1

listermint wrote: »

Your concrete is most likely still drying out. I'd say that's the source of the moisture.

Needs constant airflow.

You talking to me, someone else or everyone Lister?

If me, shed is up with 6 years.
DPC under it.
Using the airchamber with 2 or 3 years.
Without it, the bikes were dripping wet in winter especially frosty mornings.
Something to do with the dew point afaik but not that educated on that sort of thing.
You'd know better than me.

Test For Echo

listermint wrote: »

Your concrete is most likely still drying out. I'd say that's the source of the moisture.

Needs constant airflow.

Shed was bolted down on fresh concrete - laid about a month or two - and then a floor was put in on DPC. Whole lot in place almost a year before there was any noticeable issue.

Been on the lookout for some suitable vents that'll fit between the ridges on the walls.

galwaytt

Test For Echo wrote: »

Keep us posted on how you get on please!

I bought a Steeltech shed last year and it has been an absolute disaster for condensation & damp in Winter. The bikes will now have to be kept in the house during the Winter months. The shed, concrete & electrical work cost >€7500 so I'm well pissed off.

Was going to stick in a few vents but I don't think that's going to be good enough.

I suspect your base is contributing to a lot of your problems. A conc base or floor that is uninsulated, sitting on the ground - even on DPC- wiil pull down the performance of the building above it. This is as true of sheds as it is of Passive Houses. Its basically a sponge. And a metal shed over it exacerbates it.

I build low energy houses for a living and used that knowledge for my own shed. Thermally break the atmosphere inside to outside and ventilation are key.

Test For Echo

If I'd known what I was letting myself in for I'd never have bought a steel shed. Due to tight space I had to opt for a 10' x 10' shed - not sure how well that lends itself to retro fitting insulation etc without eating into all the storage space.

Wish I'd put on some kind of small conservatory instead and put the bikes in there. Not ideal but better than a rain forest of a shed.

galwaytt

Test For Echo wrote: »

If I'd known what I was letting myself in for I'd never have bought a steel shed. Due to tight space I had to opt for a 10' x 10' shed - not sure how well that lends itself to retro fitting insulation etc without eating into all the storage space.

Wish I'd put on some kind of small conservatory instead and put the bikes in there. Not ideal but better than a rain forest of a shed.

Vents are easy & cheap: https://www.screwfix.ie/p/manrose-fixed-louvre-vent-white-100-x-100mm/14434

When you say you 'put in a floor' after the base was in, can you give some detail ?

If you need to, it really wouldn't be the end of the world to empty the shed, unbolt it, jack it up a bit and put in insulated floor, and then drop it back down on it.

If I can 'lift' entire houses, a shed should be straightforward !

enrique66_35

Test For Echo wrote: »

If I'd known what I was letting myself in for I'd never have bought a steel shed. Due to tight space I had to opt for a 10' x 10' shed - not sure how well that lends itself to retro fitting insulation etc without eating into all the storage space.

Wish I'd put on some kind of small conservatory instead and put the bikes in there. Not ideal but better than a rain forest of a shed.

I know its of no help now but I have a similar sized steeltech shed and haven't had any condensation issues (keep tools, sports gear and two bikes in it - yes its a tight fit!). The crucial difference being as it was sited on gravel I was too cheap to pour concrete so opted for suspended steel frame/chipboard floor. The shed is mounted on 6 paving slabs.

It can be a bit bouncy but its dry and two years in the floor has coped with me and bikes in and out. My main issue is the height difference so knocked up a ramp out of an old pallet but its still a bit of wrestling match getting bikes back in :rolleyes:

Test For Echo

galwaytt wrote: »

Vents are easy & cheap:

When you say you 'put in a floor' after the base was in, can you give some detail ?

If you need to, it really wouldn't be the end of the world to empty the shed, unbolt it, jack it up a bit and put in insulated floor, and then drop it back down on it.

If I can 'lift' entire houses, a shed should be straightforward !

I've ordered 4 of these at the weekend https://www.raygrahams.com/products/102611-229-x-76mm-aluminium-hit-miss-vents.aspx

Got a small back garden dug up and fully concreted. Shed was bolted down on concrete and then a pour of 1.5" or so of concrete was put in as the floor.

What kind of insulated floor are you thinking of?

galwaytt

Test For Echo wrote: »

I've ordered 4 of these at the weekend https://www.raygrahams.com/products/102611-229-x-76mm-aluminium-hit-miss-vents.aspx

Got a small back garden dug up and fully concreted. Shed was bolted down on concrete and then a pour of 1.5" or so of concrete was put in as the floor.

What kind of insulated floor are you thinking of?

so you had a base, then the shed, and then another 37mm of screed put on that ?

Ideally, 50mm of high density EPS/XPS and screeded over. You might get away with a board of some kind over it instead, but that would wear and depending what it's made from, soak water over time. Or something like Wisadeck, as used on trailer floors could be a solution. Would certainly be warmer.

Test For Echo

galwaytt wrote: »

so you had a base, then the shed, and then another 37mm of screed put on that ?

Ideally, 50mm of high density EPS/XPS and screeded over. You might get away with a board of some kind over it instead, but that would wear and depending what it's made from, soak water over time. Or something like Wisadeck, as used on trailer floors could be a solution. Would certainly be warmer.

Thanks for the advice. Covid meant I couldn't get a hold of the guys that did the work for me to see what the issue / solution was. Got to admit I'm beyond pissed off revisiting it. Damn shed was soaking late Feb and everything in it was wet / covered in mold. The top of one of the walls was absolutely soaking, I could be wrong, but could the floor alone cause that much of an issue?

Pic of the roof this evening

Wonda-Boy

I have a Steeltech shed also 13ft x 15ft or the like.....nothing extra done but I get the bare minimum condensation inside. Its quite cold in the winter and quite warm in the summer but I never have any major issue apart from a small ingress of water where I personally made a bollocks of the floor when I laid it ( I layed the floor in 2 halves and dont think I packed the joint well enough when starting the 2nd half if you get me....so it seeps a little)

Might be an option to screed over the whole thing again but it might start cracking if too thin!

Hotblack Desiato

I have a block-built shed, problem with it is that there is no DPM in the floor.

Had thought about putting down a layer (or two) of DPM and then paving slabs on top - would be a lot easier and cheaper than trying to pour a layer of concrete on top. Someone mentioned OSB earlier, sheets of that would be easier and cheaper again - is that really a runner? Do I have to put battens under them - I want to raise the floor height as little as possible.