Hi
For my renovation of my Victorian house we dug up the old quarry tiles in the kitchen and bathroom and laid a concrete slab. The slab was not quite thick enough and so we now have to lay a really thin screed (probably 15-25mm); it's not ideal but still it's going to be a hell of a lot better than what was there before and what would have been there had we left the tiles in place (which frankly were sitting on earth).
So to the point, my understanding is that the new screed needs to be bonded to the concrete slab; and also it needs to be strengthened because it's so thin. I'm not sure about waterproofing it as the concrete slab has a membrane underneath it already?
So, do I just add SBR to the screed mix, to both bond the screed to the concrete and strengthen the screed, or do I also need to put something like PVA on the concrete? And if so what type of PVA? I've got some waterproofing PVA; do I use that?
Thanks very much in advance for any advice.
EDIT
I just found this at http://www.irishcement.ie/download/Floor Screeds.pdf
"A bonded screed is generally 25-30mm thick. The concrete base slab on
which it is laid should be mechanically roughened and cleaned, soaked
overnight with water, then scrubbed with a 1:1 sand/cement grout.
The screed should be cast onto the freshly grouted surface within approximately 20 minutes (9 or 10 minutes in warm conditions). A bonding agent may be used to assist bonding to the base slab."
Regarding the 1:1 grout: is that just a dry mix of cement and sharp sand, or is it wetted?
For my renovation of my Victorian house we dug up the old quarry tiles in the kitchen and bathroom and laid a concrete slab. The slab was not quite thick enough and so we now have to lay a really thin screed (probably 15-25mm); it's not ideal but still it's going to be a hell of a lot better than what was there before and what would have been there had we left the tiles in place (which frankly were sitting on earth).
So to the point, my understanding is that the new screed needs to be bonded to the concrete slab; and also it needs to be strengthened because it's so thin. I'm not sure about waterproofing it as the concrete slab has a membrane underneath it already?
So, do I just add SBR to the screed mix, to both bond the screed to the concrete and strengthen the screed, or do I also need to put something like PVA on the concrete? And if so what type of PVA? I've got some waterproofing PVA; do I use that?
Thanks very much in advance for any advice.
EDIT
I just found this at http://www.irishcement.ie/download/Floor Screeds.pdf
"A bonded screed is generally 25-30mm thick. The concrete base slab on
which it is laid should be mechanically roughened and cleaned, soaked
overnight with water, then scrubbed with a 1:1 sand/cement grout.
The screed should be cast onto the freshly grouted surface within approximately 20 minutes (9 or 10 minutes in warm conditions). A bonding agent may be used to assist bonding to the base slab."
Regarding the 1:1 grout: is that just a dry mix of cement and sharp sand, or is it wetted?
