clairetoo
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 posted on 29/12/12 at 04:38 PM |
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Garage floor problem
I had a `builder' put down the base when I put up my concrete sectional garage to use as my machine shop , and I've had a major damp
problem ever since .
With all the heavy rain we've had the last few weeks its been flooded , with up to 2" of water over most of the floor (as well as damp ,
its not very flat either....)
So.......today I smashed a hole in the middle of the floor , to see what was going on . The `builder' had put polystyrene insulation under the
concrete (which seems to be 90% gravel) , but on top of the damp proof membrane !
That cant be right ?
I dug down about a foot , and dropped in a garden water feature pump , set on as low as it will go , and have been pumping water out all day - the
water is dripping off the top of the DPM...........
Any ideas how to fix this ? The layer of insulation (which I didnt want.....) is water-logged , and from what I can see of the edge of the slab , the
DPM is turned up at the edges , so what I have is a pond.......when what I need is a dry workshop.......
Its cuz I is blond , innit
Claire xx
Will weld for food......
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r1_pete
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| posted on 29/12/12 at 05:59 PM |
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Hi Claire.
It sounds as though the surface of your garage floor is below the surrounding ground level, or, you have a lip of floor around the outside of the
garage which is catching water and channeling it inside.
If it is the latter, you could try masticking up between the bottom of the walls and floor and between the panels, on the inside, then create a 30
degree plus ramp around the outside in concrete to channel the water away.
If it is the former, the only real solution is to start again and build the floor up higher than the surrounding ground, if you are not short of
headroom you could try building up the floor inside only, but the proper solution is too start again, and make sure any dpc is above surrounding
ground level, otherwise, as you say you are building a pond.
[Edited on 29/12/12 by r1_pete]
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samjc
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| posted on 29/12/12 at 06:26 PM |
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If you intend to use the garage often and keep it for a few years, I would first build a concretlip on inside and out of all walls (obviulsy avoiding
doors) to try seal the garage, and then I would try fitting some cheap drainage like the thin grating you put infront of the garage door. I myself
have the same issue and also have a small ramp inside both doors to seal it all once doors are closed, if picture are required u2u me your email
adress and ill send you pictures.
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macc man
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| posted on 29/12/12 at 06:41 PM |
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A freind of mine had the same problem with a garage installed by 'professional installers'. I went around the outside and inside walls
with silicone mastic. Best to use the type you can use under water. Then I haunched up inside and out around the walls with a fine concrete mix with
waterproofing added. This made a huge difference and kept the water out. Worth a try before starting again.
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JoelP
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| posted on 29/12/12 at 08:02 PM |
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Sounds like he's done the slab like you would for a house, but too low (obviously for a garage the finished level needs to be close to ground
level). He's not thought it through!
Now you have cut through the damp membrane, you will get water seeping up through it if you just fill the hole and concrete. You can dig round outside
and try to create some drainage to stop it coming in under the wall sections.
The floor insulation does seem pointless since the room will be largely unheated. FWIW, house builders are free to put the insulation over or under
the conrete at will. Having it under the slab means you have more thermal mass in the house so a more stable temp.
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SteveWalker
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| posted on 29/12/12 at 08:08 PM |
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quote:
Originally posted by clairetoo
So.......today I smashed a hole in the middle of the floor , to see what was going on . The `builder' had put polystyrene insulation under the
concrete (which seems to be 90% gravel) , but on top of the damp proof membrane !
That cant be right ?
It's perfectly normal to put polystyrene on top of the DPM - our conservatory floor is done this way. In fact, in this case the insulation had
to be above the DPM, as clips needed to be pushed into the insulation to hold underfloor heating pipes in place while the screed was poured on top.
The DPM being turned up at the edges is also correct, as the DPM is probably below ground level and so has to prevent water penetrating from the sides
as well as below. If you are getting damp problems it is likely that water is getting in around the edges, but above the DPM (possibly under the
walls) or that the DPM was damaged when it was put down (it should have been laid on top of a sand blinding to prevent the membrane being punctured by
the hardcore below).
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loggyboy
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| posted on 29/12/12 at 08:08 PM |
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It is unlikely to be insulation, more likely to be something like Claymaster: http://www.bbacerts.co.uk/CertificateFiles/25/2543ps1i1a18.08.2011.pdf
Mistral Motorsport
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clairetoo
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| posted on 29/12/12 at 08:32 PM |
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quote:
Originally posted by loggyboy
It is unlikely to be insulation, more likely to be something like Claymaster: http://www.bbacerts.co.uk/CertificateFiles/25/2543ps1i1a18.08.2011.pdf
Nope....its just ordinary polystyrene sheet......which is totally waterlogged
I've noticed for a long time that after rain , water literally rises up through the floor - so the concrete is allso permanently wet (in last
winters megga low temperatures several patches of the floor `exploded' as that water froze and expanded)
I've pretty much resigned myself to digging a soak-away drain across the rear of the garage where the garden is quite a bit higher , the hole in
the floor I will dig as deep as I can and just fill it with suitable gravel (pebbles ?) , then just make a grate to cover it .
I suppose long term I would be best to add a new membrane and 2" of fresh concrete on top - but theres two lathes , a small milling machine and
compressor in there........plus a bit of junk 
Its cuz I is blond , innit
Claire xx
Will weld for food......
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jossey
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| posted on 29/12/12 at 09:22 PM |
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Membrane from floor across to the walls n up a ft then concrete over the membrane put drainage under that though first.
Thanks
David Johnson
Building my tiger avon slowly but surely.
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JoelP
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| posted on 29/12/12 at 10:00 PM |
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My garage has the same problem, that the land at the back is far too high. I dug it out once but its difficult to get to and didnt really help, since
the sides are paved and i couldnt put drainage in! There is no substitute for doing it right first time.
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bi22le
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| posted on 30/12/12 at 03:30 AM |
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If dpm is in place your pond is being filled from the top. Either find where the ingress is and seal it or make a soak away.
Soak away can just be a 500mm X 500mm hole at the lowest point. Drive piles into the ground of any dia and side tubes down that are perforated. Fill
the lot with course sand or gravel.
Depending on garage size and knowing your skills i would do this.
I hope you live above the ground water level.
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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wylliezx9r
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| posted on 30/12/12 at 08:41 AM |
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iHi claire,
My garage has internal concrete edging as shown in the picture below. I often have water pooling around the outside perimeter but the floor inside
stays bone dry. If your garage doesnt already have this I would do this first before doing anything major (I dont know if it's a special type of
concrete ?). I would say that your base has been put down correctly althought I dont know what the purpose of the insulation is in a garage.
 
HTH Dan
[Edited on 30/12/12 by wylliezx9r]
[Edited on 30/12/12 by wylliezx9r]
I spent a lot of money on booze, birds and fast cars. The rest I just squandered.
George Best
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splitrivet
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| posted on 30/12/12 at 10:31 AM |
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How about digging a trench all the way round with a land drain covered with gravel brought round to a sump and pumped or led to the nearest drain.
Google French drain to see what I mean.
Cheers,
Bob
[Edited on 30/12/12 by splitrivet]
I used to be a Werewolf but I'm alright nowwoooooooooooooo
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