I'm lucky enough to have a large (@ 4-berth) garage which is also very high, but it has a major condensation problem thanks to the metal and plastic corrugated sheet roof and some water ingress.

The garage is constructed from hollow blocks and was built approximately twenty years ago. The previous owner has foam filled all the eave gaps and attempted to stop floor leaks by grinding a slot around the outside and filling it with silicone..unsuccessfully imho.

Water still comes in at floor level, but has reduced significantly since I put drainage channels at the front (drive drains water towards the garage!!!). However, one corner, that I can't get to at the moment, is still prone to seepage.

As I have two classic cars in the garage, plus a fair amount of tools/machinery, working around everything is a pain! But I was thinking of removing the eaves filler for a start as the roof condensation is appalling, particularly bad yesterday with sub zero temperatures.

Would this be enough to cure the condensation problem or is it worth buying a dehumidifier? Another thought (and much aggro!) it to re-roof the garage completely, probably using a liner or cement sheets (do they prevent condensation?)

Does anyone have any recommendations please?

Steve

removing the foam will be a good start.

some pics would be good too.

The eaves gaps will help to get rid of the moisture in the garage.

I have had a lot of problems with my garage and the best way I found was to cut a channel on the inside as close as possible to the garage sides as possible. I cut the channel with an angle grinder and diamond disk, then chisseled it so that it was flat. I then drilled some holes on an angle through the channel, so that any water drains to the outside of the garage through the concrete base.


The condensation is another problem, which might be helped by insulation the roof and walls somehow. It depends how much you want to spend really!

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DIY | Donnas dream house

Thanks for confirming the eaves problem.

Regarding the floor...I was thinking of employing a tip I read about which involved putting a cement fillet (mixed with PVA) on the outside to create a 45deg run off. Only thing stopping me is that this type of fillet is used inside concrete garages and apparently is often useless

Will have a look for some pics :)

Steve

Can't find the pics I'm looking for, but these give a rough idea of the size and eaves "problem".

I'm in the middle of planning a major change around to place the cars side by side to free up a proper workspace at the rear of the garage; and install a partial second floor for storage!,Hence it's the perfect time to be thinking about eradicating the damp...








(There's a bird's nest in that gap!)

Steve

You could try a cement fillet.

But I would not use PVA.

An integral waterproofer for cement would be better

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DIY | Donnas dream house

Piccy of the condensation, not usually quite as bad as this, made worse by having snow and ice on top!

Sure you've seen it all before...


Steve

the condensation will always be there even once youve ventilated it..
think about it, first thing in the morning there'll be exactly the same effect on the outside as on the inside whether or not its rained... thats because its a cold hard surface
prolly the cheapest way round this would be to somehow batten out the inside of the roof from the inside if you know what i mean and onto this you could tack some underslaters felt, starting from the top and overlapping until you reach the eaves...
the next problem is the inability to make the felt go past the existing rafters so you'd need some sort of internal gutter to drop the felt edge into..
then tack up some polystrene sheets up underneath the felt, this would keep the felt 'warm' (relatively speaking) and help prevent condensation forming on the underside...

bit of an arseto b*llox way of doing things but without actually removing the roofing sheets i cant think of much else besides replacing them with something like 'onduline' - bitumen coated corrugated cardboard, waterproof and used for stables etc incorpoating felt and insulation underneath and on top of the rafters so you can direct the felt externaly...
as for the walls, batten and tack some polystyrene sheets up against them but expect condenstion to form on the inside of the metal so youd need to direct that outside somehow...

biggest headache apart from that would be where to stash all that gear while you do the job no?

price for polystrene sheets - around 8 quid for a 50mm thick 8' x 4'

underslaters felt - 10-20 quid for a 30m roll 1m wide.. (get breathable if you like but its comparatively expensive)

50 x 25 treated slate lath (for battens) couple of quid per 4.2m length

onduline roofing sheets - http://www.screwfix.com/prods/81696/Bui ... -x-2m-Pk15
(prolly find these cheaper elsewhere, im sure they used to be around 6-8 quid a pop)

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http://www.peterborough-plasterer.co.uk/

Thanks...looks like re-roofing might be the way to go, although I was hoping (being unrealistic!) to avoid huge expense

How about going in the opposite direction...sealing all the gaps and buying a decent dehumidifier?

Steve

i reckon youd have to do a bloomin good job of sealing any gaps which would include the doors etc although a real good dehumidifier would keep the problem to a minimum... helpfull if you could get something that doesnt need emptying... maybe pipe the condensate outside?

you could just try tacking up some 25mm polystyrene and sealing the joins with gaffer tape so any water run off doesnt get through or moisture vapour permeating to the cold void and leave it at that... prolly make a big difference on its own..
sealing the eaves ends thereby making the void above the polystyrene pretty much airtight would stop condensation from forming provided the roof sheets are nice and tight but any timber wont be able to breathe..
however if the roof structure is predominately steel that shouldnt matter..

polystyrene prices pretty much work half the thickness, half the price

id be tempted to try the polystyrene on its own with the gaffer tape first and see how that goes, not too sure about the cost of industrial strength dehumidifiers but im guessing the poly would be cheaper...

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http://www.peterborough-plasterer.co.uk/

The door and both windows are double glazed so that's a start I've already got a tiny little demuhidifier piped outside but it just can't cope. Industrial ones aren't cheap, ebay might turn something up.




I like this idea, don't suppose it's possible to buy shaped polystyrene to fit the roofing sheets...I recall seeing eave fillers a few years ago?

Steve

Would something like Celotex or Kingspan be ok?

Edit: scratch that, found some polystyrene for a third of the price :)

Steve

yeah jablite is half the price of cellotex but also half the insulation value..
be lovely if you find something to fit the sheets, ive never seen it to purchase but ill bet someone somewhere makes it cos ill also bet you can buy insulated corrugated roofing sheet....
let us know if you do find anything similar.....
good luck with it, be great if you could let us know how well it works...

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http://www.peterborough-plasterer.co.uk/

ERRRRR just had a thought.....

and its errrr quite important........

polystyrene is highly flammable.....

the way round this is to either overboard it with 12.5mm plasterboard and skim to finish

or

double skin plasterboard overlapping the joints....

that'll give you 1/2 hour - 1 hour fire protection.....

not really recommended to leave the poly uncoverered, sorry bout that i wasnt thinking too clear last night mate...

hope to god you read this first...

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http://www.peterborough-plasterer.co.uk/

Not to worry, I'd already considered the fire aspect and think I'll go with a proprietary insulating board.

Has a look at a large industrial unit today, looked like it was 50mm board straight up to the steel roof...so my little shed should be fine with 25-50mm board :)

Steve