Can standard polystyrene sheet be used around reinforced groundbeams or does the special stuff aka claymaster and clayshield have 'magic properties' that do the job in a different way to say jablite floor insulation.
Compressible board under/alongside groundbeam
- Thread starter Deluks
- Start date
Duke, See no reason why you can not use Jablite Jabfloor 70 for the purpose that you want it for. The only problem every one thinks of it as insulation.
How ever we always use Clayshield or Claymaster as nine times out of ten, that is what is specified on drawings.
Me son will be in tomorrow, will have word with him, as he does all our heavy work now.
old un.
How ever we always use Clayshield or Claymaster as nine times out of ten, that is what is specified on drawings.
Me son will be in tomorrow, will have word with him, as he does all our heavy work now.
old un.
Duke , Had a word with my son and he is only using Clayshield now as he got pulled by a BCI a while ago on a 2.4 dig close to tree situation.
Personally I think that this work close to trees has gone way over the top.
If no BC involved , then use what ever you have providing it’s polystrene.
Hope your keeping busy and out of mischief.
old un.
Personally I think that this work close to trees has gone way over the top.
If no BC involved , then use what ever you have providing it’s polystrene.
Hope your keeping busy and out of mischief.
old un.
Was mulling this over earlier and the bleedin' obvious raised it's head. What's the compressive strength of concrete?
What's the compressive strength of polystyrene?
Blue polystyrene? Bloody snake oil, that's what it is!
What's the compressive strength of polystyrene?
Blue polystyrene? Bloody snake oil, that's what it is!
Claymaster etc leaves a definite void whereas jablite does not, if there is alot of movement jablite will not work.
You have answered your own question Duke. Snakes oil, Blue snakes oil. Give your nuts some exercise, go and buy the right gear.
By the way the only thing we mull over, when we drop the chute, has the driver got enough water on board, to make it run out like p**s, with a good head on it.
old un.
Not anticipating a lot of movement TBH, the ground is chalky, so good stuff. I'm just worried that the mature sycamore might get taken down by a future, (rather well off) neighbour and leave the ground a little too 'moist' although it is believed that the root system will have less growth under the existing large concrete slab, that's been down for 30 years.
Technically you could use the polystyrene on the sides of the ground beam IF you can prove it to be compressible to the amount required (by NHBC) for the type of soil.. normally 25-35mm min.. actual thickness of material can be 2-3x that..
Under the ground beam youll need to provide void of 100-150mm min which can also take the weight of wet concrete/rebar without compressing..
Under the ground beam youll need to provide void of 100-150mm min which can also take the weight of wet concrete/rebar without compressing..
Useful info, thanks. Only dug two of the holes for the pads so far, very little in the way of roots and as mentioned there is chalky soil, no clay. But the tree is only 5m away. I might just go with 100mm of eps under the beam and be done with. Or do all ground beams require a void regardless of soil type?
Also how deep should the beam sit, I was gonna go about half a block deep from top of beam to ground level.
Also how deep should the beam sit, I was gonna go about half a block deep from top of beam to ground level.
When you say chalky how chalky? You talking fragments in the clay?
What plasticity is the clay.. if its low then you wont need protection on the sides only the bottom of the ground beams..
You may also need protection on the pads.. if med/high plasticity..
Also the protection should go to all ground beams within the trees whole influence zone.. what type of tree is it?
What plasticity is the clay.. if its low then you wont need protection on the sides only the bottom of the ground beams..
You may also need protection on the pads.. if med/high plasticity..
Also the protection should go to all ground beams within the trees whole influence zone.. what type of tree is it?
No clay, which is why I'm only contemplating chucking some bog standard polystyrene in there for good measure. Soil/chalk/flint, I've only dug down 1m. but ground is very firm and below roots.
2 sycamores 50-60ft and about 6ft apart and 5m from pads, haven't been pruned for years (maybe never) so lots of growth up top and thick butts down below.
Got some A939 offcuts so they will be going in the pads which will be about 400 deep.
View media item 23223
2 sycamores 50-60ft and about 6ft apart and 5m from pads, haven't been pruned for years (maybe never) so lots of growth up top and thick butts down below.
Got some A939 offcuts so they will be going in the pads which will be about 400 deep.
View media item 23223
If there is no clay then no compressible to strictly required.. but shouldnt hurt so long as its not so weak that it compacts during the pour and deforms the beams too much..
Those sycamores can influence 17m at maturity so lucky its not clay..
I assume the pads will be 400mm depth of concrete and also guess your doing pad/ground beams cos of all that fill.. and that A939 really is A393..
Those sycamores can influence 17m at maturity so lucky its not clay..
I assume the pads will be 400mm depth of concrete and also guess your doing pad/ground beams cos of all that fill.. and that A939 really is A393..
Duke, Sycamore, mature height 22m. Water demand Moderate.
As no clay, take soil shrinkage as low, water demand moderate, distance from tree, 5 metres, traditional foundation depth to be 1.350mm.
Take soil shrinkage as medium, ditto, ditto, traditional foundation depth to be 1.700mm.
Regard to pads and ring beam, could tell you what |I would do and what voids I would leave, but I may not be 100% technically correct.
Possibly Static will point you in right direction.
Bless yer. old un.
As no clay, take soil shrinkage as low, water demand moderate, distance from tree, 5 metres, traditional foundation depth to be 1.350mm.
Take soil shrinkage as medium, ditto, ditto, traditional foundation depth to be 1.700mm.
Regard to pads and ring beam, could tell you what |I would do and what voids I would leave, but I may not be 100% technically correct.
Possibly Static will point you in right direction.
Bless yer. old un.
Static: A*** I know what I mean!!!! (typo) 
The pad n beam idea was primarily because of trees but doing away with all that potential spoil is a bonus. Doing this over a period of time so can self mix and pour one pad at a time, plus having a skip sat outside for months not really an option, I can easily bag it all and stick it in the boot, council tip is only 5 mins away. 3 trips per hole I'm working to, plus a few sack of concrete which I'll keep and use for fill elsewhere.
Pads 1m down, 400 deep, blockwork off that, beams cast onto blocks.
Not keen to go down more than 1m for a single skin blockwork garage
Oldie: Don't keep your thoughts to yourself on this one (that's not like you at all is it?) Throw some ideas in, nothing I ever do is 100% technically correct anyway!
The pad n beam idea was primarily because of trees but doing away with all that potential spoil is a bonus. Doing this over a period of time so can self mix and pour one pad at a time, plus having a skip sat outside for months not really an option, I can easily bag it all and stick it in the boot, council tip is only 5 mins away. 3 trips per hole I'm working to, plus a few sack of concrete which I'll keep and use for fill elsewhere.
Pads 1m down, 400 deep, blockwork off that, beams cast onto blocks.
Not keen to go down more than 1m for a single skin blockwork garage
Oldie: Don't keep your thoughts to yourself on this one (that's not like you at all is it?) Throw some ideas in, nothing I ever do is 100% technically correct anyway!
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