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Posted: Fri Nov 14, 2008 6:22 pm
by privacy121
FANTASTIC SITE!!
Well impressed - been reading non-stop for two weeks now!
Already posted elsewhere in 2 other subject areas.....
However; in some cases detail may be too much for my simple mind............
Simplicity for all you experts; have taken up some flags from patio as doing extension and wife has kindly suggested using them in front of garden shed at bottom of garden as currently its earth. It will not be subject to heavy or excessive traffic. Good idea so my solution is/was to dig out earth so I can put in some scalpings I've got left over from the actual extension so 3-4" deep and use whacker plate on them so they'll end up being approx 2" deep.
I've then got one last concrete pour (for over-specified ground slab over 2.3 m deep foundations!) so I was going to put in approx 3 inches of concrete. Finally I bed the flags using a mortar mix.
Is all this ok, or overkill, or underkill?
Oh and do I need a layer of poly in it and if so at which layer?
Thanks & Cheers for any help
Dominic
NB I appreciate the info is contained within the site but just wanted some reassurance I'm approaching it from the right angle.
Posted: Fri Nov 14, 2008 7:03 pm
by msh paving
hi, no poly that method will be fine if the concrete is dryish you can bed the slabs straight onto it :;):
Posted: Sat Nov 15, 2008 8:51 pm
by privacy121
thanks for prompt reply - appreciated
wont have time to bed flags straight onto concrete as;
1) its a wet mix as need 8 cubic metres for the reinforced ground slab going over top of 2.3m foundations (building control eh!?!?!?) so will order the extra amount (once calculated from one of this sites awesome calculators) and barrow it down at same time as pouring slab - in other words will have a couple of volunteers to quickly do that and tamp it flattish as all my concentration will be on slab pour
2) because of above will not have time to lay them flat, etc
Posted: Sun Nov 16, 2008 6:40 am
by seanandruby
Dont under sell yourself p121. you and your wife have done well
to think it through and make good use of the surplus materials.
forward planning is the key to a good profit, well done. 
Posted: Sun Nov 16, 2008 7:08 pm
by lutonlagerlout
its overkill really IMO
but what you have described is absolutely fine,better over spec than under
i take it with your founds etc you have trees nearby
we have done 2 jobs this year with this type of detail due to trees
LLL
Posted: Mon Nov 17, 2008 9:50 am
by privacy121
ta for all responses and help
appreciate where you're coming from Mr LLL but as you say better over than under specify and at least I'm using up the scalpings (instead of having to hand-barrow them back all the way down the other side of the house
and as using pump for slab (had to for foundations once already) i know the driver/operator so he may even lay some extra tubing down the garden to shed for a "drink"
in response to LLL and brief summary of build thus far (& no doubt to bore you all);
1) we are knocking down old extension jutting out from back of building (must have previously been old garage/stabling that had been "joined" over time to main house by means of a flat roof) as it was cold, damp, single skin and basically poorly thought/laid out. Intention to replace with roughly same square footage but wider across back of house.
2) "THEORETICALLY planning said could do it under "permitted development" but then when we said completely demolishing old extension and not re-using any of it it was a "new extension" even though the site would be completely flat only for a day or so till we started on new founds, etc!!!!!!!! One wall is a boundary wall to next doors garden and the architect did suggest we leave it up, build a new inner wall skin and then "accidentally" damage/destroy old wall....................but we didn't, thinking we'd be open and above board.
2) architect said "no trees nearby" on original planning application but when the sh*t hit the fan with building control saying "xyz" cos of tress AND i in turn went berserk with architect for not clearly stating real situation from outset.........................he calmed me down by saying had he acknowledged nearby trees good chance the borough tree preservation officer may have got involved from outset and completely knock application back? So a method to the madness I guess from architect?
3) so build control say they want a structural engineers design as nearby trees and clay ground. so engineer knocks up a plan for 2.1m founds, 600mm wide with "claymaster" board lining inside walls all way round foundations. SO; get a digger and learn how to use it by first knocking up a much-needed garden soakaway and then official soakaway for new extension. I LOVED it; boys & toys eh??
Anyway when I get build inspector to come and "pass" the 1.5*1.5*2m deep soakaway (having gone thru clay cap) he says "ok". NB bloody big learning process with build control, etc doing your own build!!!!????
I then ask build inspector where is reference point for the 2.1m deep foundations i.e. damp proof course will be gnd level on extension as we are having big sliding doors that when opened allow a seamless "join" to outside i.e. no step up/down and threashold of door is flush to ground. To get this passed we are putting in a "tanked" french drain just in front of glass sliding doors. Build inspector agrees gnd level is exisiting floor level so off I go on the digger again!
4) then I come across an old disused oil well as house must have previously been oil fired heating right in line of one of trenchs! So I'm thinking as its approx 2.5m deep I use angle grinder/kango to make 600mm openings either side of hole in the same line of founds as its approx 1m wide/diameter and when I pour the foundations, they are as before but when it comes to oil well I obviously fill the whole of the hole (I know more expense of concrete but hey, hey sh*t happens) so it has a "bubble" in line of founds?? "No way" says build control - as oil well must have been dug out many moons ago the whole of the area around it is considered a "soft spot". So onto structural engineer again and his plan is to make foundations as thus; 500mm from each side of oil well there is to be a 1m square pad (same depth off 2.1m) and then put a bloody big steel across and encase in concrete. So off we go digging these 1m sqaure pads along with rest of founds........
5) Really, really hard work as clay so tough we have to hand-kango final half metre by hand and just use digger to scoop out. Done; call out build inspector - TOSSER!! He changes ALL the rules and contradicts himself saying gnd level is another 200mm down, blah, blah, blah, bloody blah. You can't argue with these guys as they are God it seems?? I've STILL never got to bottom of why/justification of changing "gnd level"??
As the digger has dug itself backwards to one side of house and alley btn both houses I can't get back in so we have to re-dig 20cm of clay by hand through all the founds - approaching 30 metres. So those in the know will appreciate where I'm coming from; kango 20-30cm of rock-hard clay, then spade or lift clumps into buckets, then hand buckets out. It took four of us four days - the most soul destroying part so far - I honestly nearly gave up.
6) build inspector comes back and passes the founds to FINALLY pour;
7) 26 blooming cubic metres to fill.................
(sorry for waffle but had to get it off my chest)