Advice on Plastering below dpc

[cornsack]

Went to look at a job yesterday to do 1 wall in a garage. The other 3 walls were done a long time ago and apparently received damp treatments, injection courses or something and then completed with s&c and a top coat of multi I believe.

The wall that needs doing now is the shared internal wall with the house. Don't believe this wall had any such treatment.

The dpc is quite high above the ground. I know that general rule is don't plaster below the dpc. But what options are there to get below it? Or none at all? I normally do a lot of domestic works and don't have a huge amount of experience with damp proofing other than knowing the basics of not bridging cavitys or going below dpc. But I believe there are options I just don't know much about (tanking? membranes?).

They are cavity walls (even in garage) and no damp present at the moment.

Pictures attached, one showing where the dpc is.

Thanks in advance!

 

[Danny]

@flynnyman @zolco @irish_spread @Arti

 

[zolco]

@flynnyman @zolco @irish_spread @Arti

I let the others compete on this, I'm busy with the tiler

 

[brimplas1]

2 coats of ka tanking then plaster away..

 

[zolco]

I'd just put thermacheck boards up, with a few mushrooms tbh and skim it, and would make sure that the garage door post is well sealed with mastic both sides before doing anything

 

[carlos]

Render in sika 1. And skim done.


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[cornsack]

The sika 1 render mortar? Never used the stuff but heard it's horrible to work with and hard to get finish to stick? Where do you get the stuff anyway? Do any of the big chains sell it or is an internet jobby?

Or did you just mean normal s&c render with the sika waterproofer in it?

 

[jamesthefirst]

@carlos

 

[carlos]

I meant 3-1 sand and cement render with the sika1 additive.

Travis stock it but it's generally cheaper in screw fix about £45 a gallon.

The prebagged mortars are just batched sand and cement. You still add the additive when mixing.



Or a 3mm meshed cavity drain membrane and dab or float with whatever you like.


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[cornsack]

Cheers @carlos. And I can just go straight down to floor level past the dpc as long as the sika 1 is in it?

I haven't done any s&c work since I was a labourer and even then I didn't do much. Do a lot of domestic work and pretty much never get asked to do any. Want to get some practice in so glad this has come up!

What's your mix? Just 3:1 plasterers sand and the sika 1? Do you add anything else? How much sika 1 to a bag of cement?

Thanks in advance.

 

[carlos]

Yeah pretty much all bang on. Sika 1 is a below ground waterproofing product.

It makes for a dead mix. Good sand is key.

Sika 1 @ 10:1 10 water to 1 sika 1

Or if the sands wet 0.75L per 25kg cement.


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[cornsack]

@carlos thanks a lot mate, really appreciate it!

I'll be sure to scratch a key into it then. Ready to skim a week later? Does it need any sort of priming before skimming (or rendering) first or just wet down on both?