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Posted: Mon Feb 20, 2012 5:30 pm
by Forestboy1978
I read on this site that for a mortar based patio you should use between 45 and 60mm. In the past I have often used 75+ and I know many professionals who use the same. I've been racking my brains and I can't figure out why using more than 60mm would be bad.
Would love to hear people views!
cheers
Posted: Mon Feb 20, 2012 5:52 pm
by lutonlagerlout
$$$
grit sand and cement are more expensive than type 1
you need roughly 40-60 mm to have a bit of give to knock the flag down
in rare cases I have gone 100mm but all you need is 40-60mm
LLL
Posted: Mon Feb 20, 2012 6:19 pm
by mickg
I agree with luton it could only be the additional cost of having a 4:1 mix instead of MOT type 1, I normally use 75mm deep bed but the reason being is most patio's I incorporate a border within the paving whats 50mm deep so you need the additional depth in the bed due to this thicker product
Posted: Mon Feb 20, 2012 8:00 pm
by Forestboy1978
lutonlagerlout wrote:$$$
grit sand and cement are more expensive than type 1
you need roughly 40-60 mm to have a bit of give to knock the flag down
in rare cases I have gone 100mm but all you need is 40-60mm
LLL
thanks:-)
That makes sense, if you can find no logical physical reason then it must be money!
Posted: Mon Feb 20, 2012 8:04 pm
by Forestboy1978
mickg wrote:I agree with luton it could only be the additional cost of having a 4:1 mix instead of MOT type 1, I normally use 75mm deep bed but the reason being is most patio's I incorporate a border within the paving whats 50mm deep so you need the additional depth in the bed due to this thicker product
Couldn't you just dig a lower chanel for the border and still use the same amount of mortar?
You use a 4:1 mix?
I was going to use a 7:1 with a 3:1 for the joints! I've not had any complaints from 7:1 jobs!?
Excuse all the questions, I'm new and I got the bug!
Posted: Mon Feb 20, 2012 8:14 pm
by mickg
by the time you have dug out the MOT in a 120 mm channel and undermined part of the bed what you have already laid the patio flags to get enough depth for the thicker border its easier in my opinion to keep the MOT lower over all the patio so you don't disturb anything
personally I am not a fan of these weaker mixes as they take longer to go totally hard, with a 4:1 you can normally guarantee that the bed will be rock hard the following morning and your able to walk over the paving knowing it will not be knocked out of line
ADDED
to stop the leeching of cement onto the surface of the paving you need to SBR the back side of every patio flag before they are laid
Posted: Mon Feb 20, 2012 8:20 pm
by Forestboy1978
Makes sense. I'm gonna stick to my 7:1 cos I've had no problems with it but I may use 4:1 here and there cos this is a bitch of a job and it would help to be able to walk on the patio now and then the next day!
Obviously I knew that the mix would be harder but I never knew that it dried quicker too
Cheers for the feedback
Posted: Mon Feb 20, 2012 8:22 pm
by Forestboy1978
SBR. Sealing of some sort? Due to the higher concentration of cement?
I have not experienced any staining yet but I am laying uncalibrated indian sand stone tomorrow and I am a bit nervous!
Posted: Mon Feb 20, 2012 8:26 pm
by mickg
not saying it dries quicker, its just harder the following morning than a weaker mix, never done any testing other than a visual when running the vibrating plate down the side of the edging only bedded the previous day and if you use a weaker mix the vibrating plate can knock them out of line as the haunching is not rock hard like it will be using a 4:1 mix
Posted: Mon Feb 20, 2012 8:32 pm
by Forestboy1978
ok thanks
sbr ronafix. Got it!
Posted: Mon Feb 20, 2012 8:57 pm
by lutonlagerlout
i agree with mick ^^
CBA with weak mixes
LLL
Posted: Mon Feb 20, 2012 8:59 pm
by Forestboy1978
What is it with all these acronyms!
CBA = Chief bodge artist lol?
Posted: Mon Feb 20, 2012 9:28 pm
by mickg
CBA = cant be arsed 
Posted: Mon Feb 20, 2012 9:37 pm
by Forestboy1978
Cheers you guys are great BTW 
Posted: Mon Feb 20, 2012 10:15 pm
by lutonlagerlout
as haggi would say "the time for yap yap has finished and the time for tap tap is approaching"
good luck
LLL