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Posted: Fri Apr 04, 2014 1:38 pm
by Ematt
Hi, I`ve dug up my old 23 square metre patio and prepared the ground to put in a 100 m sub base which i`ll wack down. The base i have dug out though is very sandy in parts and now boggy in parts after constant rain.
Is it ok to put my sub base over sand and should i wait for it to completely dry out?
Posted: Sat Apr 05, 2014 12:55 pm
by seanandruby
Isn't the sand from the old base? See how deep it goes, dig it out and any soft spots, fill soft spots and then start the formation
Posted: Sat Apr 05, 2014 4:27 pm
by Ematt
It seems too deep to be from the old base as I,ve dug out 6 inches and there is still another 6 inches of sand in parts, goes as deep as the pipes. If I wack the sand down can I then wack down the hard core?
Posted: Sun Apr 06, 2014 8:19 am
by Mikey_C
Ematt wrote:"as deep as the pipes"
what pipes? are they drainage pipes, is the sand pipe bedding?
If it is drainage pipes you may want to explore details on the site about when to encase them in concrete?
Posted: Sun Apr 06, 2014 8:30 am
by seanandruby
Maybe sand for sevices so be careful, could be gas or leccie. Are there tiles, or electric/gas warning tape in the trench?
Posted: Sun Apr 06, 2014 11:03 am
by Tony McC
Once you've resolved the issue with the mystery pipes, you could use a geo-textile (NOT a landscape fabric) to act as a separation membrane between sand and the overlying sub-base.
Posted: Sun Apr 06, 2014 9:00 pm
by Ematt
The pipe runs from outside the kitchen to a small manhole (inspection ?) about three feet away...can't see anything else but the pipe. Is it a case of putting plenty of the sand back around the pipe and hardcore on top?
Posted: Tue Apr 08, 2014 11:53 am
by Tony McC
Not "plenty of sand", just 60-100mm or so to act as a cushion. If you put too much, it moves and the sub-base descends into it which can cause settlement.
Posted: Tue Apr 08, 2014 7:34 pm
by Ematt
Cheers chaps, much appreciate the advice.
Posted: Wed Apr 09, 2014 7:28 pm
by Ematt
Oh and just one more question, is 4 sand to 1 cement for the full mortar bed ok? Seems to be a lot of conflicting advice on this subject online.
Posted: Wed Apr 09, 2014 8:55 pm
by Mikey_C
what slabs/flags/stone are you laying?
Posted: Thu Apr 10, 2014 11:45 am
by Tony McC
More than adequate. I usually suggest 10:1 for patio work
Posted: Thu Apr 10, 2014 5:39 pm
by Ematt
Will be using concrete riven slabs in three different sizes, with a 2 inch fall over 12 feet.
Posted: Wed Apr 16, 2014 4:44 pm
by Ematt
Hello again, i`ve got all my slabs down now a mix of 600x600, 450x450 and 300x300 and i have noticed a few of the 300x300 have not bonded with the mortar and one of them slightly rocks. Whats the best course of action to remedy this? Will this be taken care of when i point up the joints in a couple of days? Also what is the best mortar mix for pointing up? our slabs are buff so i want to keep the joint mortar light in colour so i will need to add a dye i presume.
many thanks for the help so far.
Posted: Wed Apr 23, 2014 11:06 am
by Tony McC
Loose flags need to be lifted and re-laid. Never rely on pointing to rectify rocking flags: it will fail, maybe not next week, but at some point, it *will* fail.
If you use a pale sand (silver sand, perhaps) you will get a pale mortar without the need to rely on dyes which fade.