Concrete Garages - Damp Proofing

I have recently acquired a garage near my house which the Jag just fits
in (1" to spare) but it seems to be a bit damp and the car gets a fair
bit of condesation on it, especialy in the recent damp weather.

It's a standard 1950's pre-fab concrete construction, up and over door,
two external walls and a concrete floor. Corrugated asbestos type roof.
No power.

A couple of pictures:
http://www.sweller.dynalias.org/images/garage1.jpg
http://www.sweller.dynalias.org/images/garage2.jpg

The damp patch is in the far corner floor but the cold, concrete panels
aren't helping.

How best to seal the floor and wall panels?

Is there a concrete sealing product or is a tank membrane or plaster
board 'cavity wall' the answer? And for the floor?

Opinions?

 

Mum had a new Compton prefab garage installed in 2002. The original fitters
did not seal the base/wall interface properly. Compton sent a snagger who
fashioned some sort of bond on the inside using a wedge of sticky mortar.
I'm no expert but I'm guessing he used PVA or some other goo from the
Unibond range. googling suggests there are epoxy resin based products too.
This bond is still working now.

Other thoughts: is water running towards the rear/side of the garage? If
so, can you divert it? It might be a case of diverting the flow from a
downpipe.

 

sweller formulated on Saturday :

Assuming the roof is sound, the usual problem is water entering at
ground level between floor slab and vertical panel. The solution which
worked for me was a 2" triangular fillet of mortar all the way around
the sides - around the inside. Put a 3" strip of plastic material,
vertical along the base of the panels - to prevent the mortar from
sticking to the panels.

 

Not sure about the floor, but my garage was suffering badly from
condensation, to stop water entering by soaking through the concrete
block work (exposed external wall) I used Thompson's water seal which
worked well.

For the condensation from the roof I spoke to a couple of roofing supply
companies and the recommendations were either:
- Coat inside with UPVC foam (cost circa 600 quid for DIY!)
- Put new roof on with foam bonded to metal (cost around 500 quid)
- Put new roof on with felt bonded to metal to trap moisture (cost
around 400 quid)
- Put cheap second skin on roof with 4" of loft insulation between
skins.


Surpisingly I took the cheap approach. Especially as I managed to get
some free roofing material so the total cost was about 70 quid. Lots
better.

Other thing I've done is put a heater and extractor fan on a timer to
keep the air moving and to try to suck the damp air out.

 

Wouldn't it be better to put a fillet on the outside to stop it getting
under the panel in the first place?

--
Malc

Rusted and ropy.
Dog-eared old copy.
Vintage and classic,
or just plain Jurassic:
all words to describe me.

 

Google for "Tanking liquids". In fact, **** it, I did it for you

http://www.dampness-info.co.uk/tanking shop_google.htm?gclid=CJOCh6yB4J8CFaFi4wod3EjOHA

Used for exactly your situation. It's a rubber based compound which is
brushed on like paint, but "becomes" like a thin layer of rubber. I used it
to great effect on my own garage 20 years ago (so it should be even better
nowadays).


--
Beav

VN 750
Zed 1000
OMF# 19

 

malc brought next idea :

No, absolutely not. The fillet is bound to crack and pull away from one
surface or the other. Most likely it will pull away from the panels of
the garage as they expand and contract as the sun hits them much more
than the base - the result will be rain water running down the faces
and then funnelled inside by the fillet. On the inside and deliberately
made not to stick to the panels, it will form a dam forcing water which
comes under the panel back out.

 

formulated on Sunday :

That is the same problem which I currently have and it affects both the
garage and the joined on workshop. I only get the condensation when it
gets to below freezing. I'm planning to fit some 1.5" thick flame
retardant expanded polystyrene which comes as sheets of 8 x 4', just as
soon as I can get some delivered. That should work out at about £70 to
£100 to cover the entire roof area of both (24x12' and 12x16'). It will
also leave some space still, to store long material between the
rafters.

 

malc laid this down on his screen :

Another way would be to simply add an extra 1" or so of screed on top
of the inside only of your existing floor.