The Brew Cabin

Posted: **Tue May 06, 2014 6:39 pm**

Started with a concrete sub base (ballast and cement). I let that dry for 2 weeks.

I used a mix of 6 shovels sharp sand and 1 shovel cement and added a little water to make a semi dry mix (just enough water for it to stick together if you squeeze by hand)

I used a screed type bedding method, so the bed water perfectly level and then laid the flag on top and gave it a gentle tap so it sits in nice.

It has been two weeks now and noticed nearly half of them are loose and can easily be lifted off the bed. Some of them are stuck on perfectly but the rest are loose.

Not sure what i am doing wrong?

Posted: **Tue May 06, 2014 6:50 pm**

The mix is not wet enough, and if you are laying sandstone, you need a bond bridge and sbr in the mix.

Posted: **Tue May 06, 2014 6:56 pm**

dig dug dan wrote:The mix is not wet enough, and if you are laying sandstone, you need a bond bridge and sbr in the mix.

Thanks, i am laying natural limestone.

I think i may buy SBR. I was told not to make it too wet just went enough so it hold together..

Posted: **Tue May 06, 2014 7:47 pm**

Just a little drier than bricklaying mortar is about right.
you will need a bond bridge, sbr and cement mixed as a slurry, painted on the back of the slabs prior to laying. A dry mix is no good

Posted: **Wed May 07, 2014 10:45 am**

In additions to Dans advice you also need to give the slabs a little bit more than a gentle tap. The mortar needs to be well compressed/compacted. The more compacted it is the harder it will be

Posted: **Wed May 07, 2014 7:55 pm**

Thanks, should i use a screed bed type method or just lay the mix loose?

Posted: **Wed May 07, 2014 8:58 pm**

I like it as wet as you like and do not have any issues with rockers or movement

roger has just jetwashed a patio i laid 7 years ago (75m2) and not 1 flag I laid is loose

LLL

Posted: **Wed May 07, 2014 9:13 pm**

Ive tried dry mix on indian sandstone, naff idea....wet mix with sbr is the way.

Posted: **Tue May 13, 2014 11:38 pm**

Yes, SBR in the bedding mortar AND SBR in the bonding primer. Put the primer on the base and on the underside of the flag. That's proper belt and braces.

See BnR SBR For Bedding

The Brew Cabin

Help! flags not stuck to bedding after two weeks