Hello

My garage is built of concrete blocks (cement rendered externally) which have been laid onto a concrete pad.

During heavy rain I find that some water seems to creep under the blocks and into the garage. It looks like the bottom mortar course is acting like a wick, drawing the water through from outside.

The amount isn't huge but it is annoying and I would like to stop it happening if possible.



Description


Description

Is there a readily available chemical treatment that I could apply to the bottom layer of blocks & mortar inside the garage which will repel water?

Any advice or ideas will be very welcome.

Thanks,
John.

Wheres the damp proof course? its looking as though the outside ground level it the same height as the interior level, which means the damp proof course is at ground level (which is bad)

If you trap the moisture behind a "treatment" its liable to creep up the wall.

Best would be to tank seal it from Outside, basically rubber membrane round at floor level so water cant come through.

It's all in the building regs book, if you want a scan of the picture...

Hi Ben

You are right, the exterior and interior levels are the same (built like that by the previous owner) meaning there is no effective damp proof course. The first layer of blocks have been laid on a piece of dpc material but this is largely ineffective because it is, of course, at the same level as the floor.

I was hoping that a chemical treatment might be absorbed into/through the blockwork and this would have a 'dual action' preventing any creep either up the wall or under it.

I agree that tanking from outside would definately be the most effective method but this would be pretty difficult due to access issues etc...............I was hoping for an easier fix

Thanks,
John

Simple answer ( and the right one), reduce the exterior ground level by 4inches to a width of 3 feet.

There are treatments, but i'm unsure how or if they'll work for this!

Is there no way of dropping the level of the ground from outside?

You could try Thompsons WaterSeal, it does seem to work pretty well on walls, but couldn't say if it will stop ground level damp like that. It's not that expensive though, so probably worth a go.

Would it be possible to cut a small channel in the concrete slab at the bottom of the wall to collect water? Or perhaps even put some flashing down to keep water away from the mortar joint at the bottom?

I remember seeing a Canadian programme on Sky where a bloke fixed peoples' house problems.

In cases where the water table was very high, and the damp-proof course too low (or missing), he would dig a trench around the building, part fill with gravel, then put a perforated drain pipe around that was linked to the rainwater drainage system, then back-filled with more gravel. I think that there was also some form of membrane involved too.

Probably overkill for your situation, but maybe a partial implementation would do it, e.g. dig a good-sized trench around and fill with gravel to a few inches below the line of the garage floor. This should give a bit of clearance to the DPC, plus it would stop water pooling on the outside of the wall.

look up tanking on ebay.

Hi.. Im a builder (ATbuilders) and I deal with this sort of thing all the time... as mentioned above the DPC is at the wrong level.. Dpc on a garage should be around 225mm higher that the garage door opening..

Obviously U cant cut into our block work and ad a dpc but what U could do with a small expense is.

1. Tank up the inside of ur garaghe about 200mm with black jack and DPM tanking... silver foil stuff that sticks like shit..
lap this on to ur floor about 150mm but DO NOT stick it your floor.

2. Get some Damp proof membrane like Visqueen or similar but a decent gauge.. lay this over your floor and over the top of the flaps of tanking..

this in theory makes the building Damp proof again.. then U would have the task of laying a screed (concrete floor) over the top of ur membrane again...U could get away with about a 50mm concrete covering in a garage

yeah this is the bit of a task.. but I'd say U could do it for around £150 if that would be ok with U ????

If a jobs worth doing.. Do it right !!!

Cheers Alan

Does the raft (concrete slab) that the walls are sitting on extend outside?...or does it stop flush with the ouside of the walls?

It's not ideal and certainly no substitute for a damp course bit I suggest putting a fillet at the bottom of the wall....use a water proofer in the cement (Everbuild 202 or SBR for example).#
In conjunction, ensure the render stops short of the floor and has a bell cast to throw the water clear of the bottom of the wall. I would render or paint a waterproofed slurry to the area inside and out before adding the fillet.

Not ideal but it'll give the water a much harder time getting in. (It seems that the water isn't rising through the raft, simply running down the wall and wicking actoss at floor level. Not the end of the world.

Ensure everything is sound, clean and not soaking wet before you start work.








[Edited on 2/8/11 by Litemoth]

I like your picture! Did you do that by hand and scan it in?

Thanks everyone for all the ideas and suggestions. I really appreciate you taking the time and trouble to assist

The concrete raft does extend outside the walls Litemoth, exactly as you describe, so your idea certainly looks workable. The water isn't rising up through the raft.......it collects on the exterior perimeter of the raft and then creeps through under the blockwork.

Equally good is what you describe Alan (tompat3463).............as you say, if a job is worth doing etc. etc...........and to be honest I can never really be comfortable with a bodge. This solution might actually be easier for me to do, simply because access to the exterior sides & rear gable wall is very awkward due to the very close proximity of my neighbours land & my own garden both of which are at a higher level than the concrete pad (always complications aren't there!). These issues make all the suggested exterior ideas difficult to implement (nothing wrong with the ideas btw, just I would struggle to put them into practice).

Many thanks again to everyone who made the effort to post. Very generous of you all try and help out

Cheers,
John

[Edited on 2/8/11 by RACER101]

Chemical solution

LINKY

Fillet compound:

LINKY

My thoughts, for what they're worth, on the screed option would be:

Would 50mm of screed, not bonded to the base, crack?; It's going to be driven on, parked and jacked on etc. Fine in a living room but in a garage? Maybe a waterproofing/bonding additive would be a better option?

Seems a lot of work for a small amount of water penetration; it's not like the raft is suffering rising damp....

Screeding isn't an amature's job....it needs to be mixed and handled in such a way that it sets as a whole to prevent cracks and mixed so that it doesn't break up or become dusty......much easier to achive with a wet concrete raft.

...Just trying to give the benefit of things i've learnt the hard way.

quote:

---

Originally posted by MikeRJ
I like your picture! Did you do that by hand and scan it in?

---

50mm of concrete is sufficient for a farage floor.

U could do a wet mix which would be Wat easier to lay and would give a similar finish !


Where u like by the way may be able to come an see.

Cheers alan

Dpc on a garage should be around 225mm higher that the garage door opening..

COMPLETE AND UTTER RUBBISH !!!!!!

quote:

---

Originally posted by Puzzled
Dpc on a garage should be around 225mm higher that the garage door opening..

COMPLETE AND UTTER RUBBISH !!!!!!

---

Racer 101,

Not sure if you have seen my posts of late, but to maybe give you an idea of what i have done, see the photo below:


Description

I actually did all the boarding out in a few months when the weather was dry and hot. Then to my horror i had a few leaks when the rain came.

So what i have done is painted the fillet that meets the wall and floor with two good coats of Bitumis paint. It rained really badly yesterday and not a single drop came in.

Quite pleased with the work so far - just ordered my sockets from screw fix, so tomorrow it should all be wired up.

Ps. Floor is going to be painted red with floor paint once i have built my work bench and cupboards.

Rob

Blimey!...nice job.


If mine was like that, i'd move in!

ermmmm......how that rubbish like U tit ??

are U a builder ???

Puzzled...U must be...

when building new house DPC would be at at floor level... correct ???

Now in the rule book says a garage floor should be 225mm below house floor level ??? Correct ???

Hense a continuos DPC around a house and attatched garage would make DPC at garage 225mm about garage door.

People are trying help people on here not trying to proove people wrong U retard..

if 225mm is incorrect that would would be the DPC height for a garage ????

Im spinning on my seat for this answer and explanation U tool !

[Edited on 3/8/11 by tompat3463]

Retard ---- Tit ----- Tool

Keep spinning, . What do you build with ?? Leggo???? I did"nt think they supplied DPC with Leggo !!!!!
You obviously have no idea about good building practices. I do however admire your gall, to call yourself a "Builder".
The world is full of people like you, a hammer ,saw and a shovel , then call yourself an "Expert". What I am ,is no
concern to you, but as can be seen by my posts, I"ve offered sound advice to other forum users in matters relating to
the construction industry. Its a field that I understand and feel qualified to have an opinion on. I, on the other hand
have gained knowledge of mechanics, electrics, and other car related matters by seeking advice from those in the know
, for this I"m very grateful. I think I will let others judge as to MY and YOUR understanding of DAMP PROOF LEVELS ETC

quote:

---

Originally posted by Puzzled
Retard ---- Tit ----- Tool

What I am ,is no concern to you

---

still waiting for ur explaination of of which height DPS should be at on a garage !!!!

heres my back up from a well know site !!


In a cavity wall, there is usually a DPC in both the outer and inner wall. In the outer wall it is normally 150-200mm above ground level (the height of 2-3 brick courses). This allows rain to form puddles and splash up off the ground, without saturating the wall above DPC level. The wall below the DPC may become saturated in rainy weather. The DPC in the inner wall is usually below floor level, (under a suspended timber floor structure), or, with a solid concrete floor, it is usually found immediately above the floor slab so that it can be linked to the DPM under the floor slab. This enables installation of skirting boards above floor level without fear of puncturing it. Alternatively, instead of fitting separate inner and outer DPCs, it is common in commercial housebuilding to use a one-piece length of rigid plastic, (albeit an angled section), which fits neatly across the cavity and slots into both walls (a cavity tray). This method requires the need for weep vents to enable rainwater ingress to drain from the cavities otherwise rising dampness could occur from above the DPC.


http://en.wikipedia.org/wiki/Damp_proofing


......I've been in the trade for 10 years... have a city & guild in level 3 site managment and an AQA advanced construction award....

Ill mail U the certificates if U like....

now...according to that write up on wikipedia..DPC should be 2-3 brick courses above (my 225mm was spot on by the way as 3x75mm is 225mm) ground level................Just so U've got my point id like to U to point out a garage that has a door opening higher that the garage floor.......

Thats why I called U a retard..Tool...Tit.....now go back U your cowboy builders with Dominic littlewood and study what he and Melinda Messenger say before U critisize my first hand experience in this matter....

PS.....please give me the dimention of what U would put ur DPC at in ur garage... Ill happilly point out where ur going wrong

By the way 'Leggo' is 1 G ....... LEGO.....its spelled like that so children can spell it

OK Tompat

I have decided , that should you wish to apolagise for calling me a "TIT ---- RETARD ----- and a TOOL" , to share
my vast knowledge with you and point out the error of your ways!!!!!.

Firstly , refer to Litemoths previous post where he agrees with MY comments, but not the manner in which they
were conveyed. I have a weakness, I just HATE to see people make statements of fact , when I know these statements
to be wrong. On reflection, I , will apolagise for making the said statement in such a fashion. This does however, not
detract from the fact that I WAS RIGHT. I would respect Litemoths status , and his obvious knowledge in construction
matters. Therefore I have decided on the above course. Now, you may be asking yourself --- "Why should I apolagise
To this twat????" Reason ----- If you want to learn something ---- there is always a price to pay. So do the right thing --
and become a wiser MAN !!!!!

look mate... im not wanting too hear another way of implementing a DPC from the way ive been doing mine for the past 10 years...my DPC's have always been passed by local building control and i've never had work condemned for any reason.

instead of making ur silly sarcastic remark in your first post why not share with us the propper way to build a DPC in a garage and elighten us all

By the way i've been making my living from the construction industry for the past 10 years. I'm yet to know what ur Job title reads.



Message to the OP....as U know DPC is missing from your garage and as U've mentioned.. the method I advised on getting around this was an elidgable option.

Glad U've got it sorted mate.. although the scale of ur problem probably would not have caused that many problems.

Cheers Alan

PS. UR above monolog makes absolutely NIL sense !!

Right Tompat,

Because you refer to me as "Mate" I will accept this as a form of apoligy and point out the following.



Previous Poster said there WAS a DPC under the blockwork at ground level. This IS IN FACT PLACED AT
THE CORRECT LEVEL. Where a wall is being built on an independant and seperate slab, for the purpose of
a garage , then the rising wall WILL ALWAYS BE BUILT ON A DPC. IT is usual and good practice to ensure that
the building should be started on the extremeties of the slab. Pathways should be poured afterwards, finishing a
min of 6 inches below the DPC level. As Litemoth pointed out, the problem here is, that because there was concrete
outside the rising wall with no fall away from the building, the water could not flow away ,and was coming back into
the building. Refer to my first post giving the solution.

" as mentioned above the DPC is at the wrong level.. Dpc on a garage should be around 225mm higher that the garage door opening.. "

You stated the above. Now picture this ----

Garage door ope,--- The bottom of the door usually closes onto the top of the slab --- agreed???/
If you follow YOUR logic and place the DPC 225mm higher than the slab, then damp will rise to the level of the
DPC, and will be evident insofar as the block/brickwork absorbs this damp.. Not So ????


When a garage is built as an integral part of a house, as you rightly point out, the floor level MUST be under
the floor level of the house.To ensure that rising damp is kept at bay THE DPC IS STEPPED WHERE THE GARAGE
AND HABITABLE AREA OF THE HOUSE ABUTT. This again is common and usual practice in structures that contain
different levels within. I enjoyed many years working in an industry that I loved, made money, lost money, but
the things I learned were ---- There is ALWAYS A BETTER WAY , AND SOMEONE ALWAYS KNOWS MORE THAN
ME.

Hope you have learned from me

Regards

Thanks for all the additional posts and for the useful linkies Litemoth.

This forum is a great place to get advice & opinions from people who generously share their knowledge and expertise and I am really grateful to all concerned.

I am not in a position to judge who is right or wrong in the "discussion" about correct techniques but, at the end of the day, the topic isn't important enough to fall out over.............chill guys please

With the useful advice I have now received I have at least 3 cheap and practical solutions to the problem (which is really only an irritation anyway rather than anything too serious).

Cheers,
John