Damp Garage

[Ian Barkley]

I recently moved into a 1950's detached double garage [with semi bungalow in its grounds]. However, since the weather has turned wet and cold the garage feels distinctly damp, the floor [concrete] has darker patches but I'm not convinced that it is rising damp and the roof is sound. The walls appear to have a damp course and the back of the garage is over a meter above ground level. There are no air bricks or ventilation, is this the problem? Does it need heat? A dehumidifyer?

 

Any ideas please...

 

Ian

 

P.S. It is the first time my 7 has had a garage so I want it to be comfortable!

 

Edited by - Ian Barkley on 10 Nov 2002 08:24:37

[Rob Walker]

Try covering the floor with torch on roofing felt. This will bond to the concrete floor and provide a waterproof layer, you can then cover this with ceramic floor tiles or thin plywood or hardboard to give you a durable finish. I think a dehumidifier is a waste of time sure it will remove some moisture out of the air but unless the garage is sealed you will be trying to dehumidifing the whole atmostphere. If the garage is reasonably insulated then an electric tube heater will help to keep the humidity down and not cost you the earth to run. IMO air vents are a bad idea, your car will get cold on a cold day and then on a warmer damp day the damp air will condense on the cold car, I ruined my Lotus Esprit by using such a garage everthing rotted very quickly.

[John Howe]

Ian, that you have no air bricks would seem to indicate that the garage does not have cavity walls - which is normal for free standing garages.

 

If the floor is damp, the most likely cause would be that the builder did not put down a plastic membrain before pouring the floor. Visit you local building centre for advise, as there are several pour/brush on dressings that you can get for concrete floors to seal them from above.

 

JH

Deliveries by Saffron, the 222bhp yellow Sausage delivery machine

[CHRIS CLARK]

I would say that the investment in a CarCoon would very soon repay itself when these conditions are encountered. I have/had this problem, but the 'Coon is great and leaves me with no worries about the outside getting inside (if you see what I mean!).

[alicat]

Ian

 

Have you seen the 'Garage-dri' units 🤔

 

Have a look at http://www.garage-dri.com/

 

 

[F355GTS]

Another site for dehumidifiers

 

http://www.airconco.com/

 

Mark

[felix.klauser]

Can't really tell just what the garage-dri unit is, whether a temperature and humidity controlled heater/fan or something else. The technical description is sorely lacking which makes me sceptical. Any which way, £400 seems like a lot of money for it.

[Tin Man]

I agree with Chris. Get a Carcoon. A dehumidifier will not work in a cold garage.

[CHRIS CLARK]

De-hum units are OK in the right setting. I used to have a Lotus Esprit that got mighty near seizing its clutch due to inactivity & damp air (only did 21,500 miles in 17 years!). I fitted a de-hum unit in the garage but found that I had to empty it every night.

I ended up with it hung on a wall bracket with a length of fish tank air tubing leading from a (self made) tapped drain in the corner of the plastic receiver 'bin', through a hole in the wall to allow the water to bleed off to outside. I fitted a time clock to run it three times a day for about 4 hours a go.

It was 'pulling' nearly 4ltrs a day from thin air!!!!!!!!!

Clutch never seized again though.

CarCoon is the best way

[Ian Barkley]

Thanks for all your suggestions... and I thought all my problems were over once I got a garage! I could just leave the 7 outside and brush the snow off every now and then but on second thought I think I will sort the damp out.

 

Ian

[pete east]

Where any enclosed space occurs within a building dampness can

be a problem if the space is not adaquately ventilated.For this

reason underfloor and roof voids must be cross ventilated under

current building regulations (see governments `Robust Details') If

your garage is very damp it may be a combination of non existent

or inadequate damp proofing and ditto ventilation.Bear in mind

that we live at the bottom of an ocean of air and that if the air outside the garage is damp it will also be damp inside.Heating the

garage would be one option (expensive for a detached garage!) or

as has been mentioned use a Carcoon,since when this is sealed you

are only trapping a very small amount of moisture in with car which

will not be enough to cause corrosion problems in the long term.

[Buda]

buy some visqueen, this is a thick plastic sheet, lay this on a thin bed of well compacted sand on top of the slab, then put a 100mm concrete screed down on top. down side is it will raise the floor level by about 100mm so youd'd need to adjust the doors etc, other idea is one of the proprietary latex levelling screeds which you just pour on top and it sets hard, not sure if it would take axle jacks etc though. as for ventilation, buy a vent axia type kitchen fan and bung it through a wall (just drill a few holes and knock out the hole), wire it up to the mains and bobs your uncle, you've got forced air movement for about 30 quid. I think I'd try the ventilation option before I went to the expense of messing about with the floor.

[Steve-B]

You may have really hit on something with the extractor fan route. I'd been considering the same and I think you've just saved me several hundred quid. Thats the best idea I've read on this thread so far.

 

So you exhaust air instead of intake air, could set on a timer to kick on once every few hours...slick!!!

 

Steve

SV VHPD

Drive like your wife depended on it....

click here to see our 7 and rallye pictures....

[Ade Ray]

I'm not sure that ventilation on it's own will cure the problem as any mass of air will have a moisture content proportional to the temperature of the air, so that even if you are replacing the air continually that replaced air will be drawing moisture from your floor or whatever the source of moisture might be and the moisture content of the air will not vary significantly. Heating and ventilating will not solve the problem either as warm air will hold more moisture than cold air.

 

The only answer is to stop the source of moisture AND provide good extractor ventilation.

 

Ade

 

Make the world a better place, hug an estate agent

[Buda]

If it is damp rising, and as you have said that the back of the garage is over a meter above ground level I'd assume that this was a retaining wall, if it is has it got any weep holes in it, otherwise it may be holding water, otherwise the water would just drain away, as for ade's comments, I'd broadly agree but in my view if youve got damp air inside and dry air outside (it has been known)just changing the air is bound to help, air movement/circulation around the car will dry it out more efficiently than none at all, the other point is that now is the wrong time to muck about with the garage floor as its wet, wait till its dry, like summer (as if) and then sort the problem.

 

FWIW my garage floor is not sealed and gets wet but my garage door is invisible, therfore the car has air circulation at all times, so far if itys wet it seems to dry very quickly. Even if its raining outside.

 

Just to confound stuff (and upset ade) if you think of timber suspended floors in houses, these have no dpc, just a void above the ground, they stay dry because they are ventilated with air bricks in the external walls, just the same thing, unless we are going to get into an argument about capillary action through the concrete etc etc - that would lead to staining anyway as the salts in the concrete come out of suspension probably, then again what do I know, I paint my arse blue and run around naked on thursdays.

[Buda]

Sorry should have put a 😬 after the last bit, anyway heres an alternative brought to you curtosey of some memories induced by smoking marlborough on the back stairs, just waxoil the car in the garage, if you spill the waxoil (get it nice and hot first) that'll seal the floor, (you will get a bit messy if you decide to lie on it though). Car will be protected and the floor'll be sorted 😬

 

Or you could buy a cheap hairdryer and leave it turned on in the garage.

 

[Ade Ray]

Hi Buda, hope you (and your blue behind) are well.

 

I would agree that air circulating around a car and being ventilated will dry a car - as long as the source of moisture is finite, ie you are not putting more water on the car.

 

I think the problem we are faced with is that it is not practical to run an extractor fan all the time. So with Ians garage, as soon as the fans stop the continuing source of water will evapourate into the air until saturation point is reached for the temperature of the air and then proceed to condense onto cold surfaces, eg car or walls.

 

With respect to the sub-floor ventilation, the air bricks do assist in reducing wet-rot in floor timbers but they are still vulnerable at the joist ends where they are in contact with brickwork that is below the building damp proof line. The ideal then is that the timbers would be prevented from getting wet AND there is good ventialtion to aid drying and reduce condensation. On houses that have encountered this problem, the normal remedy is to splice in new joist ends that have been pre-treated with a waterproofing agent and to add more air-bricks. Preventative medicine is always the best.

 

Iam not certain that the work could not be taken on now if we are talking about digging out the floor and re-laying with a plastic memabrane. I agree it is not ideal but should be ok if you look at the weather forecast and pick your day. I might be inclined if it was me to try and get it done, particularly if the rest of the garage structure is sound and the alternative is a damp se7en all winter.

 

Ade

 

Make the world a better place, hug an estate agent

 

Edited by - Ade Ray on 11 Nov 2002 14:11:50

[pete east]

Just another comment on the damp garage theme. I still believe

the best way to avoid damp in an enclosed space is to ensure that

proper ventilation exists.If a car is put into a heated SEALED garage the humidity will rise to very high levels and corrosion will

be accelerated particularly in cavities/box sections in the vehicle.

It is actually better to leave a vehicle outside in all weathers than

to store it in a damp sealed garage,Another contributor touched

on this when he referred to his garage having an `invisible' door.

as I mentioned earlier because we live at the bottom of an ocean of air whatever air exists outside the garage will also occur inside

unless of course our garage is a hermetically sealed pressure chamber from which all moisture is mechanically extracted (nice

but unlikely).In the absence of continual and expensive heating or

de-humidifying systems the best you can do is have the car in a space protected from the rain but as open as possible,or use a Carcoon. this assumes that the car itself has had as much anti corrosion protection as you can afford/feel is appropriate.

[andytommo]

If the floor is damp,the floor slab has no Damp proof membrane.Putting a new slab in could force damp to travel sideways and up the (unDPC'ed) walls. Rather than trying to tackle this problem head on- in an expensive way, consider natural cross ventilation in the garage. -That is the insertion of 2 louvred windows or several air bricks at high level on opposite sides. When your car is driven wet into the garage the vents will allow the car to dry naturally and the floor to dry out too.

 

Andy (Allen Bell Architects, London)

 

 

[andytommo]

OOps- The above is only my oppinion -(Andy )

and not that of Allen Bell Architects.

Good luck with th garage

Andy

 

 

 

[Buda]

vent axia fan is cheaper than air bricks/louvers materials are less but bugeration is more - assumes your garage door isn't sealed though, I still think the retaining wall theory needs investigation though, if the ground is lower at the back then this may be retaining water. Anyway in the original post it says that the walls appear to have a dpc, I'd still expect to see white staining on the floor if it was water coming through the slab (only when its dry however).

 

Buda RICS (Quantity Surveyor) if we're going to get all professional about it

[fireblade]

Following this thread closely, as I have exactly the same problem. Caterham Fireblade coming next week, and my garage is too damp!

 

I think I'll go for the Carcoon. Question - what size?

 

Size 3: 400cm x 160cm (13'2" x 5'3")

Size 4: 470cm x 180cm (15'5" x 5'11")

 

According to Caterham specs for SLR:

 

Overall length: 3,100mm (122.0in)

Overall width: 1,575mm (62.0in), Height: 800mm (31.5in)

 

Seems the Size 3 will be only 1 inch wider than my car. Is this enough clearance?

 

John Latham

 

[alicat]

I see there is talk of ventilation fans.

 

Just fitted one in the bathroom which is controlled via a built in humidistat (switches on at when humidity reaches a set level - cost about £40 from City Electrical Factors.

 

Tony Leach MIOSH.RSP MIIRSM Dip2.OSH (just following the theme )

 

 

[Edzup Ezzer]

A Carcoon has to be the answer. I have a damp detached garage but the Carcoon (size 2 I think) certainly does the trick. Cheap to run as well. Don't waste time on all the other heating and ventilation ideas. Just one thing though, make sure you rig up a failsafe arrangement (light rope from the ceiling to the hanging loops) to hold the fans off the floor in the event of a powercut. The fans don't work well lying face down on the floor after a powercut. Carcoon keeps it clean as well. MOney well spent.

 

 

 

Cheers

Ezzer

[Luke Beaumont]

I too have this problem, and the main arse with a carcoon is that it does nothing to protect your tools. Even my Snap-On stuff has acquired a few pinpricks of rust through the chrome ☹️

 

Ban single wall detached garages.