thesecondprize
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| posted on 30/8/11 at 08:49 PM |
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How do I make my garage waterproof?
Are there any builder-types out there who’d know how best to tackle the following?
My garage (on the left) has always leaked on one wall, where a sloped concrete path ran down the side of it, above the level of the garage floor.
Underneath the path was effectively ‘hollow’ as shown, creating an ‘overhang’ inside the garage.
As you can see from the first photo, I’ve removed the concrete path and I intend to revert back to a path with steps in it.
My question is:
[B]How should I proceed in order to prevent further leaks into the garage?[/B]
Should I:
a.) Use flat paving slabs to ‘bridge the gap,’ then pour a concrete path on top with a gentle downwards slope.
b.) Brick up the ‘gaps’ on the inside of the garage to create a continuous internal wall then fill the void (with what?) Create a concrete path as
above.
c.) Tackle it in some other way (please specify!)
Lastly, with any of these options, will I need to tank the inside of the garage in order to make it waterproof?
Thanks in advance.
Pete 
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JohnH
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| posted on 30/8/11 at 09:09 PM |
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Hi, What you need to do is build a new outer wall,leaving a 2" cavity between the walls.When you start to build the wall you need to put in a
verticle damproof membrain (roll of DPC polythene)The dpc needs to be in between the inner and outer leaf,then back out the outer leaf about 12"
above ground. Any problems leave me a u2u and i ll send you my number.
John (joiner &builder)
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coozer
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| posted on 30/8/11 at 09:21 PM |
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Can you not put a roof over the whole lot?
1972 V8 Jago
1980 Z750
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Guinness
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| posted on 31/8/11 at 06:20 AM |
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I'm not suprised it leaked. That was designed to be a water feature.
I'd do as John suggests, but with the addition of some tanking or waterproofing membrane / bitumen paint.
To my understanding, a cavity wall traps moisture, so that extreme rain that hits the outside skin, will soak through to the inner side of the outer
skin of bricks. It'll then run down to the bottom and out the weep vents. Or it'll just evapourate and out the top into the roof / facia
vents. Light rain will soak into the bricks and then evapourate from the surface due to sun / wind.
Your new cavity wall will not be vented at the top as it'll meet the existing and it'll not drain at the bottom as it'll be
underground. It'll also not be naturally dried by the action of sun / wind as you are putting back the slabs.
I'd be tempted to build the cavity wall under the line of the existing, then back fill the trench with a french drain, or even concrete and some
UPVC drain pipe with gulleys at ground level.
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MikeRJ
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| posted on 31/8/11 at 09:51 AM |
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quote:
Originally posted by JohnH
Hi, What you need to do is build a new outer wall,leaving a 2" cavity between the walls.When you start to build the wall you need to put in a
verticle damproof membrain (roll of DPC polythene)The dpc needs to be in between the inner and outer leaf,then back out the outer leaf about 12"
above ground. Any problems leave me a u2u and i ll send you my number.
John (joiner &builder)
If he does this then only stick insects will be able to use the path?
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jossey
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| posted on 31/8/11 at 02:49 PM |
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tank it first though if you use concrete. and cut the lining into the floor so any small moisture goes into the floor.
Thanks
David Johnson
Building my tiger avon slowly but surely.
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Bare
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| posted on 31/8/11 at 03:25 PM |
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Seriously?? To do it 'correctly' or as close to it as possible on the above??
Remove All those concrete blocks and Whatever? that cantilevered abomination might be...Necessary... get right down to the dirt the foundation rests
upon.
One then needs to install and extend waterproofing and redirecting methods right down to the bearing soil...no if ands or buts.
Dimpled Plastic Drain board is best, over a Tar painted ('waterproofing' emulsion  cast concrete foundation. Blocks/ bricks are a PITA
to deal with as they traditionally leak like sieves. Only double or triple applications of waterproofing paint ons seems to work on those as does an
EPDM membrane.. but it's pricey and tricky to attach competently. One also needs a drainage system (drain pipes) to channel any water, at
foundation bearing soil level, out and away from man made structures. Even a rudimentary one would be leagues better than what is currently in place
:-)
Possibly a bit onerous amount of effort for the condition in the photos..Which seems to have had Repeated Bodge efforts.
It only needs doing well..once :-)
PS: been an Architect for almost 30 years
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MikeRJ
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| posted on 31/8/11 at 04:01 PM |
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quote:
Originally posted by Bare
Seriously?? To do it 'correctly' or as close to it as possible on the above??
Remove All those concrete blocks and Whatever? that cantilevered abomination might b
PS: been an Architect for almost 30 years
I've been an architect for...well never, but I can see exactly what the cantilevered abomination is for just by reading the OP's post. It
used to be a sloping path, and hollow underneath, so those parts were supporting the path. Not a great bit of construction admittedly, and looks like
someone has picked up random bits of masonry and mortared them into place.
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thesecondprize
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| posted on 31/8/11 at 07:10 PM |
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A few questions if I may - I'm more confuddled than before I started!
1. Bare, firstly you say...
quote:
get right down to the dirt the foundation rests upon
and then...
quote:
Dimpled Plastic Drain board is best, over a cast concrete foundation.
So given I already have a cast concrete foundation in place already i.e. the garage floor, should I be looking to remove the section that extends
outside of the main garage 'footprint' ... or not? (Just seems like a lot of work if all I'm going to be doing is laying more
concrete down again...)
2. What's to stop me bricking up the 'arches' as seen in the second pic and laying Dimpled Plastic Drain board in the newly formed
"channel" outside the garage, over the existing concrete foundation? Is is simply a lack of a slope to channel water away? (If so, could I
lay one on top of the existing foundation in ''waterproofing' emulsion cast concrete'?)
3. Given I'm still a bit confused, maybe people could doodle something in MS Paint to show me exactly what they mean?
Here's the sort of thing I was thinking:
4. If following Bare's recommendation, how should I reinstate the path (required for access)?
Also, just to point out that I'm keen not to disturb the concrete block work on the right-hand side of the first pic if at all possible, for
fear of affecting the neighbour's property (i.e. THEIR garage). I'm not bothered about water being absorbed on that side to be honest, as
long as it doesn't end up getting into my garage.
Thanks guys - appreciate the help!! 
Pete
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Litemoth
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| posted on 31/8/11 at 08:02 PM |
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Where's the boundary?
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thesecondprize
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| posted on 31/8/11 at 09:37 PM |
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quote:
Originally posted by Litemoth
Where's the boundary?
On the right hand side of the breeze blocks as you looh at the diagram. If I remove them, I'll leave my neighbour with a half unrendered garage.
Not very friendly.
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