damproofing

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ferg

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can anyone help. i waterproof rendered a couple of walls in a customers house after she had a damproof course injected. I then levelled them up as best I could with bonding and then skimmed them with multi finish. she has since had a guy from another damproofing firm in and he says I should not have used bonding and thats why the walls are still a dark colour and still containing moisture. I could be wrong but I think its because the moisture can only go one way now because the render is waterproof and if she put a dehumidifier in the room or opened a window it would dry out but like I said I could be wrong. please somebody give me some advice. cheers
 
unfortunately for you your damp proofer is correct...
waterproofer in render doesnt completely waterproof the wall, theres 'tanking' for that...
what it does is slow down / inhibit the passage of moisture through the wall... you should also have used a waterproofer with a salt inhibitor in it...
a damp wall can take up to a year to dry out completely... the injection just stops the moisture returning once its dried out, the wall should also be left paint free for as long as possible to avoid sealing the moisture in....
you may have problems here mate, bonding is as porous as talcum powder... expect it to end up like paper mache... the thats the reason they use sand / cement.. it isnt affected in the same way by moisture...
i's also be surprised if the d.p. company will have anything to do with the plastering now as you havent followed the guidelines every damp proofing company will lay down...
have a look in the 'new to plastering section' theres some more pointers in there..
 
Chris is right mate, Damproofering a bit of a minfield there is only certain products you can use when it comes to rendering/plastering after damp work has taken place, bonding is not one of them , I'm not sure why these company's will not get involved with the re- plastering after they have injected but I'm sure than have there reasons probably financial imo.
 
probably cos the moneys in the injecting church... pretty much an open cheque when your terms and conditions state your only guaranteeing the injection itself and there isnt the same profit margins in plastering...
and another reason could always be that if the damp patch doesnt go away - blame the plasterer for not following the spec to the letter and not using their chemicals... cant be sued then.. its all in the small print after all..
 
looks liked I messed up then. any tips on solutions? I'm thinking go back and knock all the finish and bonding off and start again?
 
best to get rid of the bonding coat mate , try to find out the spec from the damp firm regarding plastering so you get it right this time . Stick to it and get your money , best of luck .
 
the general spec for replastering after a dpc is this..
3:1 sand:cement scratch coat containing waterproofer/salt inhibitor/plasticiser (an all in one product usually supplied by the dpc company carrying out the injection for use by others carrying out the plastering work)
4 or 5:1 sand cement float coat..
top with finish...

the reason the salt inhibitor is there is to stop the water thats being drawn into the room as the wall dries bringing with it hygroscopic salts (found in the bricks naturally) and manifesting itself on the internal wall where it will destroy any painted finish... its like a white fluff when it appears...

if the existing render is pretty thin youll get away with 1 coat of render and float it but you didnt hear that from me...

you can buy salt repellant from the builders merchants so if youve got none in your render then knock the bonding off and replace it with a weaker render mix (assuming your render was well scratched), skim it, let it dry (day or two) then paint on the salt repellant (its a clear liquid that smells like battery acid)
that'll soak in...
then let it dry fully... it may take a while...

failing that knock the lot off and start again but if youve used a 3:1 mix and its cured youll need a good kango to get it off again.. messy...

if you absolutely must paint it then make SURE you use a breathable pain of some description, cheap matt should be ok but most vinyl silk paints aren't
 
I done some damp injection work when i was on a placement on the YTS scheme at 16 yo , the guy gave a machine and some chemical told me what to do apparently he gave the customer a 25 year grantee ::) i think he is a motorbike instructor now ... ;D
 
church said:
I done some damp injection work when i was on a placement on the YTS scheme at 16 yo , the guy gave a machine and some chemical told me what to do apparently he gave the customer a 25 year grantee ::) i think he is a motorbike instructor now ... ;D
;D ;D
 
I have been plastering on the books for different DPC firms for years now and take it from me if you haven't followed spec to the letter its all somehow your fault. If it was me I would bang it all off and replaster again with 3:1 s+c with the DPC firms own or reccommended additive. I was always told to use the same mix with the additive for both scratch and float coats, then skim with board finish. The spec does change with every DPC firm and chemical company. Basically just do as your told.
 
i fink chris w should make a 0845 number up.. people can call for any plastering related problems and get and answer there and then! £1 per min could be on 2 a winner
 
oasis said:
i fink chris w should make a 0845 number up.. people can call for any plastering related problems and get and answer there and then! £1 per min could be on 2 a winner
dont 118 118 already do that? ask us anything?...
someone should try it and see if we get a new member called 118118 ;D

terms and conditions apply..chris w accepts no responsibilty for the outcome of your project.. you dont wanna do that.. ooooo noooo
please read the small print before following advise
 
well ferg you fell for the big damp con, injectin dont work neither do any of the other fandango bullshit they use, you messed up with the bonding but whos to say they sorted the problem? you adding bonding to a waterproofed scratch which is a no no but the blame is always passed on and you were an ideal candidate, another misdiagnosed damp problem.
 
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