Job - Sand stabiliser + sealant

pavingnightmare · Sun Sep 27, 2015 8:54 pm

Dear experts
I have had an expensive stone (Global Stone Serenity) installed on my 30sqm north facing patio only about 3 months ago. Unfortunately the maintenance required goes beyond my most conservative assumptions: the stone absorbes all sorts of dirt, and that's also quite visible due to the light colour. Also, algae, lichens and moss are starting to form. Note that the slabs are next to each other with very narrow gaps (less than 3mm) which have been left empty. We have treated the area with water and bleach, as recommended in this website, but it's very hard work and we won't be able to do it very frequently. I am concerned that with winter coming up, things can only get worse. Something must be done to make maintenance easier. Would one of you experts come to take a look (I am in London NW11), recommend a course of action and then do the job? Without knowing much about paving, I guess we need sand stabiliser between the slabs (no 815 as the gaps are too narrow), and a good sealant, but I do need your advise. In case I get more than one response, I will give priority to the more senior people from this forum. Thanks.

mickg · Post: # 106310Post **mickg** Sun Sep 27, 2015 9:35 pm

there are a couple of guys who work nationwide on this list

contractor list

hope this helps

Sun Sep 27, 2015 10:40 pm

Paving nightmare
all sawn sandstone seems to show the detritus more than riven
even if paving is sealed it wont stop leaves etc falling and the lack of sun on a north facing patio is always an issue (my own is north facing

a picture of the patio would help

what jointing material was used?

its the wrong end of the year to seal now for any kind of sealant, If you seal now you run the risk of sealing moisture in to the stone

cheers LLL

pavingnightmare · Mon Sep 28, 2015 7:05 am

Thanks Luton. It's sawn and I chose it as I thought it would be easier than riven for cleaning! In terms of jointing material, there is nothing between the slabs as the gaps are only 1 or 2mm; the contractor tried to put some sand in it but it has flown away at the first wash. Do you think this is an issue? Photo attached. http://i60.tinypic.com/2yvl2yf.jpg

Mon Sep 28, 2015 7:10 am

sand is not a jointing material
what will happen is that water will get down between the flags and freeze and then cause movement

however from your photo the job looks pretty good
I cannot understand why no proper joints were used?
more later

LLL

pavingnightmare · Mon Sep 28, 2015 8:30 am

The reason is that they were nice people but didn't have experience with that kind of stone. I only realised it when they started to work. So they basically didn't know what to put between the slabs and just put sand as they do with block paving. From what you say, this is an issue and needs to be fixed ASAP. Would you be able to help or recommend someone?

mickg · Post: # 106316Post **mickg** Mon Sep 28, 2015 10:58 am

Not quite correct there Tony, Marshalls recommend the Fairstone sawn king size paving is laid with a 2mm - 3mm gap and jointed using kiln dried sand

mickg · Post: # 106317Post **mickg** Mon Sep 28, 2015 10:59 am

I posted a link above with contractors who will cover your area

Mon Sep 28, 2015 5:06 pm

really mick? that is strange
You use 365 on yours dont you?

PN what are the flags laid on?

we are booked up till after xmas with building work so nothing can be done by us

but in truth not sure what can be done at all , as leaves weather etc are beyond anyone's control

Roger from R and A pressure washing might have some good ideas on maybe a topical sealant,

but its not cheap and its the wrong time of year

cheers LLL

pavingnightmare · Mon Sep 28, 2015 8:38 pm

Thank you all for your recommendations so far. I am reluctant to call in people at this stage as I see there is some disagreement amongst you on what needs to be done. I view you guys as the â€œGurus of pavingâ€� and it would be great if there was a solution most of you agreed on.

LLL, perhaps you can send me your website so I can contact you offline to discuss a sealing job for the summer.

As per the jointing, as Mickg mentioned Marshalls, I have called them directly to ask what they suggest as jointing for my type of paving (which looks very similar to the Marshalls Fairstone sawn, as you said earlier) and they have said that they only recommend kiln dried sand for block paving. I am not sure why what they have said to me is different to what was said to Mickg. For stone, they said jointing is needed both for protecting the edges of the stone and to avoid moisture getting trapped in, however the methods they suggested (mortar, weatherpoint 365) only work with relatively wide gaps. They had no recommendation for very narrow gaps. Now, in my case the slabs are laid next to each other, in most cases with nearly no gaps. See new photo. Is jointing required and what type of jointing? As per what's underneath, I am not sure.
http://tinypic.com/r/179uyv/8

mickg · Post: # 106341Post **mickg** Mon Sep 28, 2015 9:05 pm

when the fairstone king size was first launched it was recommended to lay on grit sand and to joint using kiln dried sand, I have never embraced that method as I feel a premium product should be bedded on sand and cement and jointed with a rigid product

I have tried to find the spec this evening but they have actually changed it to a rigid method hence why Marshalls technical department have advised you

Mon Sep 28, 2015 9:40 pm

effectively they are butt jointed
IMHO Mickg is the number1 man in the country for sawn paving but he is oop north

did you ask the contractor to lay them that tight or did they just do it off their own back?

myself and the gaffer (tony mcC) both believe that for a joint to be structural it should be 10mm wide and 25mm deep

I will PM you my number PN but every job I have ever looked at like this is a non-starter as the fix sometimes costs more than the initial job

cheers LLL

mickg · Post: # 106343Post **mickg** Mon Sep 28, 2015 9:47 pm

I agree there Tony but 10mm can easily become 12mm if the paving vary in size

we used to lay with a 4mm joint for a very clean looking finish but was advised using weatherpoint it needs to be wider, 6mm is the very minimum but better at 8mm to give the weather point the integrity it needs to bond the grains of sand

RAPressureWashing · Mon Sep 28, 2015 10:49 pm

Wouldn't go for a topical sealer on an outside paving as it is going to wear and look shite in time. If you use KDS then any impregnating sealer isn't going to work either as they are not designed to "seal" the sand so that's a no go as well. What you are wanting but it is the wrong product with this paving is something like Resiblock 22 to bind/seal the sand. I feel you have a bit of an issue here to be honest with what you have and what you can do with it. And as LLL stated you are pretty much coming up to the "to late to seal" time I'm afraid as the days get shorter and over night temperatures start to drop bringing in damp over night dew etc.

lemoncurd1702 · Tue Sep 29, 2015 7:35 am

Marshalls new product "Symphony Vitrified" is designed for narrow joints 4-6mm and comes with a jointing compound similar to the weatherpoint but with finer particles.
May work with 3mm joints but it sounds like some of the joints are less than this, maybe even touching.

Maybe worth a trial on a small area and see how it fares over the winter. Lots of water should help it work into joints.