# Forum Home Renovation Bathrooms  Waterproofing rendered shower walls - or just the junction

## renov8or

Just working out how much Davco K10 plus to buy and realised I probably don't need to waterproof shower walls other than corner junction - at least not to same degree as floor. Waterproofing Standard says to make "water resistant" to 1800mm above 150mm from floor. 
What is the usual go on rendered walls in shower - 1 coat, 2 coats? 2 will be used for floor. 
The whole bathroom is technically a wet area but the shower floor is the only area to regularly have water actually running over it. The rest of the floor may get the occasional splash or wash. 
The waterproofing stuff is not the cheapest and I never had any water leaking problems with old tiles with no waterproofing - rendered walls, concrete slab.

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## SilentButDeadly

Correct. Only floor and corners is required.  But in our case that proved to be most of the wall anyway... 
You can use Bondcrete on the wall render to enhance water resistance prior to tiling....

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## intertd6

Technically you only have to do the shower floor & walls to 1800mm. Above the bath & hand basin plus around the plumbing fixtures (taps).
In practice you would additionally do all the bathroom floor, plus all the wall & corner junctions up 150mm
regards inter

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## autogenous

I would paint any tiled area in the shower to the 1800mm high.  It will be the cheapest insurance you'll ever have. 
Taps leak, grout fails.. 
Its not just the cost. Its the time and effort to do it all again if a leak makes it way back to the wall peeling paint off on the opposite side etc.

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## Bloss

> I would paint any tiled area in the shower to the 1800mm high.  It will be the cheapest insurance you'll ever have. 
> Taps leak, grout fails.. 
> Its not just the cost. Its the time and effort to do it all again if a leak makes it way back to the wall peeling paint off on the opposite side etc.

   :What he said:  I assume by 'paint' he means the waterproofing compound. Might be expensive, but as he says cheap insurance and you can't do it after!

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## multiblade

Bostik do a decent 1 part solvent based polyeurothane waterproofing, about $150 for 15litres. its available in beige and grey. I'm having a mental blank but I think its called bostik ultraseal r.
Its a decent although not too cheap product that dries very strong and flexible, and it will cover probably your average bathroom floor, plus 150 or so up the wall as well as a normal shower area to a bit above the shower nozzle. 
Being a polyeurothene it laminates well with using a product like sikaflex pro as a chemical bond breaker at all your joins. 
For the little money it costs, i would seal the render first with something. 'Something' can be any number of products, from a polymer sealer to bondcrete to lanolatex. Dont quote me on the sealers, they are just what I have seen used. you can buy the recommended sealers from any waterproofing manufacturer / supplier. The bondcrete is used commonly but as it is a pva based product, it should not really be used in overly wet situations.  
The sealer helps reduce the moonpockets. If you dont seal it first you will likely have heaps. 
After sealing I would fill all joins and gaps and internal angles with a   bead of sika or equiv, including waste pipe penetrations etc. You   should leave it to cure for a bit then i would apply 1 coat of   ultraseal. in a day or two, i would apply a second coat, checking   carefully for moon pockets in the first and second coats. 
When you have finished you have an extremely water tight environment, with flexible bondbreakers to all the joins. being that both the bondbreakers and the waterproofing are solvent based polyeurothenes they are unlikely to de-laminate. 
If i was doing a wet area that was villaboard walls and scyon fc wetarea flooring, i would do the sika chemical bond breakers to all the joins in the floor sheet and to the nail heads before waterproofing, in escence making it damn near waterproof before the first coat of waterproofing is applied.
Sorry but I'm paranoid, having seen and dealt with too many waterproofing disasters.
err sorry for rant.
err check for yourself waterproofing techniques, i am not a waterproofer by trade, although i have done dozens.
cheers 
PS 
bostik arent the only manufacturer of this type of product, tremco and  many others do them and are probably cheaper. i just mention bostiks as i  have used that many times, and am familiar with it. Bostik also do a  version of sikaflex pro that is about half the sika cost. 
PSS the reason they make it in grey and beige is because if u are doing a  lot of area, you buy 1 tin of each, and do ur first coat in one colour  and the second in the other colour. this allows u to easily check your  cover is perfect.

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## barney118

I dont think you can buy a small qty of waterproofing material, costs about $130 for a bucket, so you may as well go stupid with it. As they above have said, cheap insurance. You will put more than one coat on anyway.

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## GeoffW1

> I dont think you can buy a small qty of waterproofing material, costs about $130 for a bucket, so you may as well go stupid with it. As they above have said, cheap insurance. You will put more than one coat on anyway.

  
Hi, 
Yeah, you can, Crommelin anyway. But yes, don't economise. 
Cheers

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## Oldsaltoz

for not much more you could get the waterproofing done professionally and have the advantage of a 5 to 7 year warranty. 
Also note, Insurance claims are often rejected if you have no waterproofing certificate as supplied by a Pro. 
Avagoodweekend...... :Biggrin:

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