Quick question on bedding sand

chequers · Post: # 100859Post **chequers** Fri Sep 12, 2014 11:37 am

Hi All
Ok got the sub base sorted and can see that it is to be sharp sand 6 to 1 mix on the sub base but i have a lot of slabs to lay on steps which are constructed from blockwork so should i then change to buildling sand which would give better adhesion to the slab? (stickier)

Fri Sep 12, 2014 5:12 pm

no just knock the mix up wetter and add SBR to the mix
also prime the blocks with SBR
cheers LLL

chequers · Post: # 100867Post **chequers** Sat Sep 13, 2014 11:14 am

Hi
Okay our sharp sand is in fact building sand its all that is available in this area so i will have to go with it
What does the sbr do and should the underside of tbe slabs be treated with sbr when laying on the patio?
Thanks

mickg · Post: # 100870Post **mickg** Sat Sep 13, 2014 2:57 pm

yes we coat the back side of the paving with SBR as well as adding it to the mix

SBR stops the efflorescence from leeching through the paving and showing on the surface as white staining plus it acts as an adhesive, be very careful using the SBR and have a bucket of clean water and a brush to hand at all times because if it gets onto the surface of your paving you can't remove it

Sat Sep 13, 2014 11:41 pm

chequers wrote:Hi
Okay our sharp sand is in fact building sand its all that is available in this area

what area is that then?
sounds like someone is talking total bollox to you
sharp sand is available everywhere
LLL

chequers · Post: # 100877Post **chequers** Sun Sep 14, 2014 11:25 am

South west Wales
options are plastering /building sand or top coat finer sand , tried all the merchants and aggregate supplies
no choice but to go with plastering/ building sand

r896neo · Post: # 100878Post **r896neo** Sun Sep 14, 2014 6:36 pm

plastering sand and building sand are not the same, plastering is much coarser and would be better for laying your paving on.

chequers · Post: # 100880Post **chequers** Mon Sep 15, 2014 3:51 pm

I didnt think it would be this hard to order sand
I have found after phoning around one merchant who has what is described as coarse grit sand 6 to 8 mm used for concreting and floor screeding
I quoted the ref on this website re class m etc and he didnt have a clue what i was talking about
Guess this is the right one ?

Post: # 100881Post **msh paving** Mon Sep 15, 2014 7:24 pm

That will be fine...MSH

Mon Sep 15, 2014 7:25 pm

yes!
the sand used for floor screeding
AKA
grit sand
screeding sand
flooring sand
river wash sand
class M sand
sharp sand

every merchant calls it something different
ideally it has bits of grit in it,
6-8 mm sounds a very odd size

everywhere in the uk stocks screeding sand which is what you want
cheers LLL