Damp proofing ancient garage...

[RzB]

I am converting an ancient (1960s) garage to a store room for wood (for woodworking not fire wood) and tools. The size is 4.4M long, 2.45M wide and 2.2M High. I want to seal this room from damp.

The floor is a concrete slab, that does not have a damp proof membrane.

The walls are single skin concrete blocks that sit on the concrete slab. There is a strip of damp-proofing at floor level. There is half an inch of mortar on the floor, then the damp-proofing, then another half inch of mortar, then the first row of blocks.

The walls have been painted with white emulsion. As you can see from the staining there has been damp coming through the walls. Much of this has been because of debris build up outside - this has now been cleared.

See picture 001... at

would the experts recommend to hold the damp at bay.

Outside is all a bit tight. The wall at the far end has a retaining wall keeping a neighbours garden at bay see picy 003.

The left hand wall has a narrow gap to another neighbours property, which is at a much higher ground level. See picky 006.

The outside of these walls are "get-atable" but only just.

Roy

[Mary Fisher]

You call that ancient?

[Lobster]

Dry line it? - build a timber framework between floor and ceiling for attaching plasterboards, with a 1" air gap between timber and walls

David

[AlexW]

You may want to consider insulating the dry lining and including a vapour barrier / membrane (you can buy wall board with this on).

Ideally, for storing timber for woodworking the environmental conditions should be close to as possible to the environment that your work will live in other wise the wood will (generally) dry out following being placed in a, say, centrally heated house.

I have been caught out by this and experienced movement even with kiln dried timber, but worse with reclaimed stuff which was probably never dried properly.

Inroducing heating will help but some heaters such as gas heaters emit moisture as a by product, which does not help. I am thinking about a wood burning stove, for working but not long term storage, in my "shed".

Leaving you timber under the bed etc to acclimatise for a (quite) while before working might be one approach.

HTH,

Alex.

[RzB]

Alex,

Many thanks for you help. I do intend to have a dehumidifier running in this room.

I must admit I was not really considering a second skin. I was hoping to do some sort of tanking or whatever. Also a second skin is not going to stop damp coming through the floor....

Hmm..

Thanks, Roy

[Chris Bacon]

Paint it with bitumen emulsion, three coats at right angles, let each coat dry thoroughly before applying the next. Blind the last coat while still wet with dry sand (throw it on with a (hand) coal shovel). When it's completely dry, nail on a treated batten all around the bottom, and plaster.

[Stuart Noble]

Pliolite paint is easier, and probably more effective than bitumen, at least in emulsion form.

[Chris Bacon]

It's nowhere near as effective as bitumen emulsion (which is water proof), and it's a "breathable" paint - it will let moisture pass through from the wall, which is what the OP wants to avoid!

[RzB]

Chris/Stuart, Many thanks for your help.

Will it be OK to paint the bitumen over the white emulsion paint?

And can I do the same on the floor ?

Thanks, Roy

[Chris Bacon]

There's not much you can do about that, short of getting the inside sand-blasted... there should be a reasonable "key, I should think, and bitumen emulsion is very, very sticky.

Stuart: I've thought about my post about bitumen emulsion being waterproof - I am not trying to be nasty - have you used bitumen emulsion? It's a deep black-brown s**te, that smells faintly "off", and has no relation to "emulsion paint" as we know it. When it's dry, it is a film of waterproof bitumen - the idea of going three layers is of course to make sure there are no holes in the film! It can be used to paint over concrete flors which are then screeded - giving a damp-proof course. It's *very nasty* to clothes, brushes etc. - unless you are contemplating cleaning-up with petrol or something, chuck away things that are contaminated. Don't get it near paint, either, as it will discolour and bleed through.

(see "Keying Treatment" in last URL).

Similar, if it's clean-ish - screed it over.

[RzB]

Chris,

A bit of a google showed up this - I guess this is the sort of stuff you are talking about...

'll follow through on this - in fact they are not very far from me..

Many thanks for your help.. Roy

[Peter Taylor]

Roy, I'd like to chip in to add that however waterproof you make the walls and floor, you're always going to get condensation inside, particularly when the weather gets colder. Sealing the structure will not prevent this and actually will tend to seal it in, so without good ventilation the garage is going to become very musty - ideal conditions for rot. If you're storing timber it's very important to have plenty of fresh air circulating to prevent it rotting, just like you'd have for the void under a timber floor. So, as well as the window, I think I'd feel happier with several 9x9 airbricks in the walls.

Peter

[RzB]

Peter,

Many thanks for your help. Yes - very good thoughts. I do intend to run a dehumidifier in this room - constantly. Do you think I should add ventilation as well given that fact? The situation of the structure is that it is in a fairly enclosed space on all sides. As you can see from the pictures. Trees around and over. All in all a very damp area. Very little air movement even on a windy day.

I was considering airbricks but decided on the dehumidifier route because I felt the environment in that location was just too damp.

Still not sure what to do on this subject...

Many thanks, Roy

[Peter Taylor]

Sounds like my garage! :o) You'll probably find condensation dripping from the ceiling in the winter, especially when there's snow on the roof.

If it was a purpose-built timber store it would have fully open sides like a Dutch barn or be completely louvred to keep the rain out. You can't have too much ventilation, but too little will create really big problems. The sheltered situation makes this all the more important.

I don't honestly think the dehumidifier is a practical answer. It won't do any harm, but it will be very expensive to run and need constant emptying. This doesn't really add up when natural ventilation will do the same job for free without having to burn more fossilised trees.

If you're really worried about it, or if it's valuable hardwood, it's a good idea to invest in a moisture meter so you can make sure the moisture content in the timber doesn't go above 20%. Try to ensure that air can circulate to all surfaces (using spacers if necessary) and keep it well supported so it doesn't sag.

HTH Peter

[Stuart Noble]

Yes, I'm familiar with bitumen, and bitumen emulsion, the latter being widely used during WW2. The problem with all emulsions is that the surfactants used to make them water dispersible in the first place remain in the dried film, making them more water sensitive than the solvent based equivalent. If you apply it half an inch thick then this may not be an issue, but I think things have moved on in the coatings field. Pliolite resins are now widely used as masonry paints and, like most surface coatings, they are not a barrier to water *vapour*, only to water *droplets* i.e. rain. So they breathe, and although the air they breathe may be close to 100% moisture content on occasions, they don't drink and so usually prevent water reaching the inside of the building.

[Chris Bacon]

However, I've never seen bitumen emulsion wash off, once cured.

It's in wide use for tanking, DPCs, and all sorts of things.

Th OP was, I thought, looking for something to put *inside* his building, as the outside can't be accessed all around. Masonry paint would be OK on the outside, but not the inside, as it would "breathe" water into the building! Maybe I read it wrong.

[RzB]

Stuart, Many thanks for your thoughts on this. One of the things I have been considering is to run a dehumidifier in this room, after it's been "sealed". If I use the breathable stuff you are suggesting does this mean my dehumidifier will be pulling moisture in from the outside? Many thanks, Roy

[RzB]

Oh ? I was thinking this was for the inside ? Yes / No?

Roy

[Chris Bacon]

Not sure what you mean, but I thought you wanted to put something inside, as you can't get all around the outside, hence suggesting a coat of bitumen emulsion/sand blinding then a plaster coat. Did you mean the inside, or the outside?

[RzB]

Apols - Yes - I'm looking to put whatever on the inside...

What my post is saying, is that when I read Stuarts post I thought he was saying the Pliolite stuff was to be applied to the inside... Your post suggest that may not be the case...

Doh... crossing at talk purposes :-)

Roy