Limestone confusion over prep

[nmh]

Have just bought some natural limestone at quite an expense for the outside patio.

 

But I'm baffled by all the prep instructions from the company (Quorn Stone) - see below. We've some fantastic builders but the idea of them lovingly cleaning, drying and buffing each limestone slab just isn't going to happen. I've bought Lithofin Stain Stop W as a sealant but what's the best 'real world' way of applying this? How much prep does the stone really need? PH washes etc??! 

 

We also bought the Kerakoll grout on their advice https://www.tilingsuppliesdirect.co.uk/product/kerakoll-fugabella-color-grout 

 

Are we overthinking things? Any advise great appreciated!

 

COMPACTED HARDCORE BASE The sub-base must be made up of a well compacted layer of MOT type 1 to a minimum depth of 100mm. This should be compacted at 50mm intervals which will ensure maximum solidity and aid with achieving an even level. Following this, a thin layer of washed sharp sand can be compacted to the surface of the compacted MOT type 1. Ensure a fall of 1:60 has been accurately set within the subbase to allow for adequate drainage away from the building. The pavers must be installed onto a full bed of mortar made from 5 parts washed sharp sand and 1 part cement, mixed to a workable consistency. Prior to laying onto the mortar we advise coating the back of the paver with an SBR slurry mix made from 5 parts cement, 1 part SBR and 1 part water which will improve the bond strength to the mortar. It is best practice to gauge out the mortar bed and manoeuvre the paver into position rather than strike heavily with a mallet as this can lead to breakages, should there be any natural weak points. Pavers must be installed onto a full bed of mortar as per BS7533 – under no circumstances should they be spot or ribbon fixed. During the laying process it is advisable to clean away any spots of mortar or slurry as soon as possible as they can be difficult to clean when dry. After the pavers have been laid the area must not be walked on for at least 36 hours.

 

CONCRETE BASE Ensure a fall of 1:60 has been accurately set within the substrate to allow for adequate drainage away from the building. If installing onto a solid cement substrate the minimum curing time is 28 days before installation can commence. Please note this timeframe will vary depending on site conditions and thickness of concrete. The method for laying exterior pavers onto a concrete subbase is very similar to installing tiles internally. First the substrate must be clean and dust free as a this can impair the bond strength and could lead to failure. Please note the installation must be carried out in dry conditions. Pavers should be back buttered with a thin coat of exterior grade flexible white adhesive and laid onto a full bed of trowelled adhesive using a 10mm notched spreader. Ensure the paver is pushed into place to collapse the ridges from the notched trowel, this will provide full coverage beneath the paver and allow maximum strength for the finished patio. Under no circumstances should any of the pavers be spot fixed. Please note uncalibrated pavers should be graded prior to install and will require more adhesive in some areas

 

 

SEALANT - FIRST APPLICATION Sealant should only be applied once the tiles are clean, fully dry and released of all moisture. Please note the drying time of the adhesive does not indicate the floor is released of all moisture. This can take days and in some cases weeks - your professional installer will be able to guide you.

 

Prior to sealing, the pavers must be fully cleaned and dried so as not to seal in any contaminants from installation. We recommend using Lithofin Stain Stop. Apply generously using a sponge, whilst constantly moving the product around the area for 15 minutes, applying more product if necessary. It is always advisable to work in small sections to avoid application marks. Tilt the sponge at a 45-degree angle over the edge to protect the edges of the tile - take care to not flood the grout joints. Ensure all excess sealant is removed by buffing the stone touch dry with a white towel.

[nod]

Manufacturers tend to do this with instructions in case a five year old is reading them 

Base prep will be the same as your builders always do 

Full bed of mortar and don’t hit the to hard is common sense 

SBR slurry should be painted on to the back of anything that’s laid on to mortar 

Sealing them is very important 

They should be dry and clean 

Perhaps worth doing this yourself a day or two before 

Fill a bucket and wipe both side with a sponge 🧽 

Let them dry then repeat 

Limestone will bleed through if not sealed correctly 

We have a flat tray that we part fill and lie the slab or tile in for a few seconds 

[saveasteading]

My thoughts.

The bedding instructions look correct to me. I wouldn't reduce any of that, but you can expect your builder to say it is over the top.

 

I don't agree with varnishing. It is stone and should look like stone. It will go darker when wet anyway.

 

If you did varnish it, it will wear off with foot traffic or brushing.

 

I don't think there is any urgency in varnishing anyway, and you could do it next year.

How are the joints filled?

 

[nmh]

2 hours ago, nod said:

Manufacturers tend to do this with instructions in case a five year old is reading them 

Base prep will be the same as your builders always do 

Full bed of mortar and don’t hit the to hard is common sense 

SBR slurry should be painted on to the back of anything that’s laid on to mortar 

Sealing them is very important 

They should be dry and clean 

Perhaps worth doing this yourself a day or two before 

Fill a bucket and wipe both side with a sponge 🧽 

Let them dry then repeat 

Limestone will bleed through if not sealed correctly 

We have a flat tray that we part fill and lie the slab or tile in for a few seconds 

Thanks so much for this - their instructions say drying could take days or a few 'weeks'?! If we used a sponge to clean them, would a few days (esp in this heat) suffice? Do they dry to the touch/eye? 

[nmh]

2 hours ago, saveasteading said:

My thoughts.

The bedding instructions look correct to me. I wouldn't reduce any of that, but you can expect your builder to say it is over the top.

 

I don't agree with varnishing. It is stone and should look like stone. It will go darker when wet anyway.

 

If you did varnish it, it will wear off with foot traffic or brushing.

 

I don't think there is any urgency in varnishing anyway, and you could do it next year.

How are the joints filled?

 

Thanks - we have been told sealing them is helpful. Is this the same as varnishing? The Lithofin feels more like a sealant than varnish? 

[saveasteading]

I was being casual. I mean sealant. From my experience of concrete sealant/ hardener it either soaks in or sits on the surface. The latter, if the concrete is good, making it pointless.

 

We had to scrape it all off again once as it got slippy.

 

Presumably with stone  it likewise soaks into pores and otherwise sits on the top.

 

But you would think this stone, of all the stone in the world,  had been selected for  purpose rather than depending on additives.

 

If it's anything like what gets sold to seal stone tiles internally, you will need  several coats, and to renew regularly.

 

The people selling it of course say it's great.

I've not seen reviews. So it is just my instinct to ignore the optional extras....as with a car..

 

What would it cost? Is there any guarantee?

[ToughButterCup]

3 hours ago, nod said:

....

SBR slurry should be painted on to the back of anything that’s laid on to mortar . Sealing them is very important 

....

 

Why has it taken 70 years for someone to tell me that ......🤔

[joe90]

1 hour ago, ToughButterCup said:

 

Why has it taken 70 years for someone to tell me that ......🤔

Every day is a school day (even when you are my age 🥹)

[Temp]

1 hour ago, ToughButterCup said:

 

Why has it taken 70 years for someone to tell me that ......🤔

 

I've started using Ultra Scape Pro Prime to repair loose india stone originally stuck with unknown  slurry.

[saveasteading]

This need for an sbr primer on stone slabs is news to me. So I looked it up.

 

BAL Bond SBR is also useful as a primer before tile fixing, providing extra protection for peace of mind.

 

well, i don't  think that is good enough. Somebody needs to say why the stone needs it.

and what horrible things will happen if it isn't used.

 

I'd think It will keep water inside the stone, if porous, making it more liable to frost damage.

[Temp]

Mortar just doesn't seem to stick to some stone very well without it. Not a great example but..

 

[saveasteading]

Our team has been laying these slabs, so I asked.

 

Its my son in law, and he says he has used sbr as advised on 

https://www.pavingexpert.com/stain_reflective_01#:~:text=Why it happens%3A,the underside of each flag

 

He's done a great job, all by himself. To avoid rsi he has spread out the prep, then concretes and lays one slab.  Average production 1 slab per hour, all up.

He reads instructions too.

I basically font agree with bringing stone from India, then it isn't uk to the job. But sometimes I say nothing.

But we are NOT sealing the surface and are happy with the appearance.

Edited July 10, 2023 by saveasteading

[Temp]

This page on slurry bonding from the Paving Experts also worth a read..

 

https://www.pavingexpert.com/bond_bridge_01