Cement sheet, waterproofing, external tiling and other mysteries of the universe

some more info required - you say "outside of cottage" - does that mean cladding - ie vertical surfaces or horizontal.

how thick is the cement sheet, and whats it attached to and how.

water proofing is usually only concerned with not letting water through the sheet into whatever is behind - usually this requires the joints only to be waterproofed, and the rest to be primed before tile glue is used

ok,

yes outside of cottage ie external walls. The current cement sheet is 6ml nailed to a timber frame. I want to use a thin stone veneer to go over the cement sheet.

Doing some research on "blueboard" it seems to be listed as only WEATHERproof not WATERproof. that being the case what is the difference between using it and the cement sheet? Can I use silicone sealant for joints then prime and "tile" over with stone? I'll be grouting between the stones. Is this a weak link?

I'm so confused? What's wrong with the cement sheet we've used? How is blueboard different?


Sonja

hello,

silicone is no good because nothing sticks to it, you need to use sikaflex or bostix seal n flex which are polyurethane's

you have probably installed villa board (plain old compressed cement sheet),

i would look at using a high quality tile glue, something like Ultraflex, no pre-mixed jobs but the expensive bags from the tile shop,

grout is always porous but a vertical wall doesnt absorb that much water, only bottom is issue

thankyou

myla

thanks myla,

so is cement sheet more or less water resistant/proof than blueboard?

What is currently behind the cement sheet? Just the timber frames? If so, you'll have a really hard time making that waterproof.
Also don't forget that any cladding you add to the outside will affect the window and door architraves. Sounds like you might need some advice from a builder who can inspect the property.
And research the stone veneer products thoroughly - you can buy everything from cheap and nasty manufactured fake stone panels to hand split real natural granite.
Good luck.

Henlan,

The cement sheet is over timber studs but the research I'm seeing on the net says that cement sheet is no more or no less water resistant than blueboard. The stone veneer is real stone which actually works out cheaper than the manufactured stuff.

Sonja

the stones are 15-20mm and weight is approx 40kg per m2

This is the stuff here. http://slatediscounts.com.au/Product...s.asp?PID=1402


Sonja

The stone retailer is recommending blueboard at 7.5mm to hang the product. His argument for blueboard against cement sheet is a waterproofing issue not a weight issue.

I'll check with Hardie/CSR/BCG about the vertical weight load of their sheet.


Sonja

I have clad a few exterior walls with stone and slate very similiar to what you are trying to achieve (I think). I did some research about the technical aspects and used Blueboard screwed to studs set at 400 centres. Then over the blueboard I applied an exterior grade waterproof membrane (Gripset 2 P) over which I glued the slate using exterior grade cement based tile glue and finished with cement based grout. (cement based glues and grouts stick to the gripset like you wouldnt believe)

To date (5 years later) there have been no problems. I think the waterproofing membrane is the important aspect becuase water can get behind the slate and stones and needs to be kept out of the blueboard sheet becuase all uncompressed fibre cement sheeting will soften if left damp. This could lead to stones / tiles falling off and taking a few layers of blueboard with it.

DD,

where did you get the gripset? Approx price? Easy to apply?
so you did blueboard, gripset, tile adhesive. Did you have to prime it at any point? Am being told prime and glue. That wouldnt be necessary if you'd waterproofed would it?



Sonja

Sonja, you may have to check the yellow pages in Melbourne. Or maybe check website for stockists. http://www.gripset.com/construction/...hp?productid=9

It is 2 part membrane (1 part liquid 1 part powder and has a strong acrylic latex smell but not dangerous) - a 15 litre drum is about $120. It can be rolled or brushed or trowelled on.

I sealed the blueboard with a coat of Gripset sealer (one of those water white PVA type sealers). In the seams between the blueboard I simply used Gripset and a bit of reinforcing bandage.