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Posted: Sat Aug 09, 2014 12:18 am
by seneca
Hello,
I am currently having a patio and path laid with Marshalls Firedstone slabs and some of the slabs are getting damp stains on corners and a dot in the middle. The landscaper has told me he has laid the slabs on a full concrete base, as per his quote. I think he puts a layer of mix around the outer edge and then 5 dots. Is this common practice? What is a full concrete base?
It has been down for 3 days which have been dry and quite warm. They are not all stuck down yet and are yet to be pointed.
Can anymore advise me on what has happened? Should I wait longer to see if they dry out? Should I hold off having the others put down in the same way? Would the damp marks go if the slabs were pointed? He has suggested a sealant, but would that fix it? I am unsure what to do, as the job is half done. How should I proceed? I've attached some pictures and would value any opinions? Is there anyone else I could ask? Would Marshalls be worth a try, in case the slab is at fault? Don't know how to link my pictures to a webpage, they're on my laptop? please try this link
https://www.dropbox.com/sc/84kjqj8p9v99m75/AACxdjmUbklFMtOMhBCL7KKDa
Posted: Sun Aug 10, 2014 8:35 am
by Mikey_C
read about spot bedding here about half way down the page.
you already have one of the problems caused by spot bedding i imagine the others will follow.
how you want to sort this out with you contractor, is going to be the difficult bit.
Posted: Sun Aug 10, 2014 11:29 am
by lutonlagerlout
in the path picture i can see the dots and dabs
its no good
LLL
Posted: Sun Aug 10, 2014 11:32 am
by seneca
Thanks for the response.
Am I right in thinking moisture is rising from the ground, through the harcore base, through the mortared spots, through the slab and onto the surface? When the darker, mortared spots have dried, am I right in thinking it will recur again and again?
Will pointing the slabs make a difference? (They have not been pointed yet.) How can I prove the moisture is not just the slabs drying out and "it will eventually be ok" after the job has finished. Or that pointing will stop rain going into the base, so it won't be damp.
Is the remedy lifting all the slabs and relaying on full mortar base? Will that not mean the moisture from below will darken the whole of the slab, as it has mortar under all of it?
Any advice would be greatly appreciated. Thanks.
Posted: Sun Aug 10, 2014 2:50 pm
by r896neo
The moisture variation is not your problem.
However, the poor laying technique is. The dot and dab method is bad and will fail for a variety of reasons. pointing will not help and the pointing won't last if the slabs are laid on dabs. I had to lift and relay a large patio at considerable expense recently that was laid only 4 years ago on the dabs method as it was imposible to repoint.
Slabs laid on a full bed will dry out more evenly but there will always be a slight variation as its natural stone.
Posted: Sun Aug 10, 2014 3:35 pm
by seneca
thanks everyone for your replies. It really is appreciated, as I am very angry and upset by the way it has been laid, particularly as the quotes for both path and patio have "laid on full concrete base" written on them. When I first discussed it with him he told me this is what I would be getting. I have paid half in cash and the rest will be on completion of the job. He seems a nice guy and this is why I find it hard to understand why he is laying the slabs differently to what he said and quoted. The slabs are spot bedded and with no pointing, and approx. 2/3 are actually stuck down. How big a job is it to lift them all, clean them and then relay on a full bed - as originally quoted? Should I demand no less than that? What if he suggests just the ones with obvious spots? That obviously won't fix the whole problem will it? Has anyone any experience with Marshalls Firedstone? http://www.marshalls.co.uk/homeown....-paving
I'm not happy with how it has turned out and very angry and upset by the whole experience. I hope he agrees to lifting and relaying them, as I am already over my original budget and cannot afford additional costs.
Posted: Sun Aug 10, 2014 5:13 pm
by lutonlagerlout
if he has specified a full bed it should be that
it is as quick to lay on a full bed as spots and why some people still do it is beyond me
yes they do need to come up and be relaid
what pointing is he planning on using?
LLL
Posted: Sun Aug 10, 2014 6:11 pm
by seneca
I think he mentioned a wet cement based pointing, which is to be "pressed and ironed" according to the quote. Is that going to get rid of the whole wicking through mortar spots issue. It seems to me that it will stop water soaking in from above only if it is watertight, which is hard imagine any pointing being. Also, am I right in thinking that much of the moisture is in the ground beneath the hardcore ie. from underneath? That will want to rise and escape through the hardcore, dab of mortar and finally the slab. So I will still get the recurring damp patches.
At this moment, not having pointing means the slabs are easier to come up and be relayed. Not sure if pointing will be a good thing or not.
Posted: Sun Aug 10, 2014 9:04 pm
by lutonlagerlout
sadly I see this all the time
what happens is that the voids under the slabs become a home to ants,frogs and various other critters
they undermine the dabs and after a while it fails
also water can drip into the voids and when it freezes it expands
dislodging the slabs
all patios will get dark with rain,they are outdoors after all
LLL
Posted: Sun Aug 10, 2014 9:25 pm
by seneca
Yes the darkening does occur all over when wet, but the areas where the spots or dabs (not always round) seem to behave oddly. They dry out, come back, darken when cold (late evening when temp. drops) then fade when the sun comes out or when warm. I figure that if it's like this in Aug, what will it look like over winter. Dread to think. On top of that there are the structural issues you point out.
I can only foresee problems. I think my slabs are not natural stone, but concrete cast/moulded. Looking at a cut section, they are full of little stones and are of uniform thickness. Will lifting and cleaning these be especially difficult. I am hoping that not having been pointed, it will be easier.
Posted: Sun Aug 10, 2014 10:12 pm
by r896neo
It should not be that hard to lift them but a few here and there may break as the mortar is whacked off. The one good thing about dabs is its easy to clean off the slabs to relay.
Oh and a full concrete bed is unusal, a full mortar bed is more common.
Posted: Mon Aug 11, 2014 11:04 pm
by seneca
Hello,
When I asked the contractor about his method and how it was different to the quote and he has admitted he has spot bedded, but claimed he has always used this method and never had a problem. Regardless I insisted on a full mortar bed, though he originally offered to screed, which I declined as I was unsure about the procedure. He has said he will lift, clean and relay them at his own expense. I feel I have got a favorable outcome, so hope he goes through with it.
There are a few points I would like clarifying, before he relays:
1) Is there a good reference source I can follow to ensure it is being done correctly?
2) Anything specific I should look out for?
3) As I know I live in an area with a high water table and my patio has issues with drainage due to the entire garden sloping towards the house - is there anything that I could have done to alleviate this?
4) What should the correct mix for mortar be? ie. content and ratio? Should he include sharp sand? (He previously only used builders sand.
5) His hardcore base consists of recycled hardcore/rubble (looks like all the bricks and rubble crushed into smallish pieces) and he has compacted it down with a whacker plate. As this is down and in his quote it cannot be changed, but can I pay for something to improve it and any drainage issues?
Here's a picture of it
https://www.dropbox.com/lightbox/home/recycled%20hardcore%20base
6) He has told me he points the slabs after they have dried out and are fixed. As the slabs are grey, what is the correct mix to ensure I get grey pointing and it remains grey.
7) He never uses any additives in any of his mixes, should I suggest he does? (Don't mind paying for them if they will help.
Thanks in advance[IMG][IMG]
Posted: Tue Aug 12, 2014 11:06 pm
by seneca
Sorry to bother again, but need some advice-
My contractor has agreed to lift and relay them on a full bed, but insisted I give him details of the mix and it's content, as he will only do it once and exactly as I require. Therefore, could you please tell me the recommended ratio of sand to cement for the ideal mix and ratio for the full mortar bed and the kind of sand and cement that should be used. As the paving is a light grey colour should a different kind of sand and cement be used in order to prevent any future staining problems. ie. A white cement and silver sand? If so, could you please give examples/brand names. Is there also a specific mix (content and ratio) for the pointing that would not affect the light coloured paving.
Thanks.