The Brew Cabin

Posted: **Tue Jul 17, 2007 1:45 pm**

Hi

I am about to lay a 24m2 sandstone patio as a DIY project, and have several specific questions wrt laying, which I am quite concerned about; I would appreciate your replies:

1) Buttering
a)when buttering, how far up the face of the flag are you buttering. Ie on a 25mm sandstone flag, surely there can be any buttering as the pointing depth needs to be (i believe) approx 25m thick

b)what purpose does buttering serve?

b)if the bedding mix is suitably wet could this be used as the butter mix, or does it need to be stonger

c)can the buttering process be ommitted and only use pointing

2) bedding mix
a)On another note if I decide to opt for a wetter mix to aid the laying process would a different mix than 10:1 be appropriate?

b)should PVA be added to aid with adhesion to the flags

c) I have seen other mixes down to 7:1 suggeted by other mebers. what are the advantages,disadvantages of stonger mixes?

d) I have also seen other people advocating a small amount of soft sand to aid workability ie 6:1:1, is this necessary?

e) I have read on this site that the bed depth should not exceed 50mm as this is the 2 "weakest" part, can this commnet be explained in a little more detail. what would I need to do differently for a 60-65mm bed....anything? stronger mix?

3) Paviours Maul
biggest slab size is approx 570 * 855 smallest 285*285 what is best option to use for 1 off job (small rubber hammer ?) do I really need a great big wooden hammer?

4) Fall
I am planning to have a fall running away from house 1:60, and across the house (left to right with much less slope)
is there any issues/tips I should bee aware of when laying to two falls.

5) Splash strip
I was going to accomdate one of these, then I read that it wasnt necessary, therefore can I lay the flags upaginst the brickwork (i will be >=150mm below DPC) can the flags actually touch the brickwork or should theier be a slight gap

6) Subbase has been laid with MOT Type1 approx 75mm depth.I have read that the subbase should be blinded over with sharp sand, to fill any voids, if so to what depth?, is it necessary?

Posted: **Tue Jul 17, 2007 9:22 pm**

1a 25mm
1b makes sure the joints are full
1c no
1d yes

2a i use about a 6:1 but AFAIK 10:1 is fine
2b i use pva, ronafix is better but more expensive
2c stronger mix is the way i have always done it,it allows a tolerance for the labourer making a mistake
2d i have done this in the past ,and it does improve workability a little but not really needed
2e not the end of the world,but 35-50 mm is ideal
3a no
4a it can look crap
5a 10-15 mm gap
6 100mm compacted type 1 is the recommended subbase ,use as little sand as possible for blinding
LLL

Posted: **Wed Jul 18, 2007 9:01 am**

Thanks for that, please excuse my noddy questions...but

I would appreciate a bit of clarification with the buttering issue. From what you tell me the butering is to ensure that the joint is full, and that buterring can be omitted and rely entirely on pointing. OK so I understand that, but when it come to buttering how far up the face of the flag are we going to go....??? You see if the flag is only 25 mm deep and the pointing needs to be 25 mm, then the pointing depth and flag depth are the same, so there is no available height above the bedding for the buttering.

If I use the PVA or ronafix, do I just add this to the mix? if so what is the suggested ratio?, or do you apply it to the back of the slab? futhermore should the back of the slab be wetted (with hose) prior to laying to aid with adhesion?

With regard to the paviours maul question you replied ..."no" , is that no to the rubber hammer, or no to the big wooden hammer.

thanks very much

Posted: **Wed Jul 18, 2007 10:34 pm**

do I really need a great big wooden hammer?

answer was no
if you butter ( i dont) then the 45 deg goes from the top/s of the adjoining flags/slabs
i add approximately 50 ml of pva to every barrowful i.e. 1 mix
cheers LLL

Posted: **Wed Jul 18, 2007 11:17 pm**

Hi

Many thanks for the reply. I think the light is slowly coming on

Please can you confirm that my understanding of buttering is correct

Buttering is used instead of pointing, so that when the two edges of the flags come together the butter mortar is squashed and comes all the way up the faces of the flags and can then be struck... i that correct??

Out of interest if you dont use the buttering technique then what do you use for the pointing. Furthermore what would you recommend for a novice, DIYER!!

many thanks for all your help and advice

cheers

Posted: **Thu Jul 19, 2007 12:27 am**

romex patio
or rompox easy
LLL

Posted: **Thu Jul 19, 2007 12:07 pm**

Buttering is used as a precursor to pointing. It's purpose is to create regularly-spaced and well-filled joints with no crap between the flags, and while sometimes the butter mortar will be 'squeezed up' to completely fill the joint, on other ocassions it only partly fills the joint and has to be 'topped up' with pointing mortar (same mix).

The Brew Cabin

Buttering and stuff - Several specific questions wrt laying