Trying to cut down the overall thickness of my solid floor
construction (for various reasons).
Does this seem OK :-

65mm screed (no reinforcement)
100mm concrete (was 150 - will 100 need reinforcement ?)
DPM
75mm celotex (was 100mm polystyrene on old regs)
25mm sand (was 50mm but whats the point)
100mm MOT (was 150mm, but BCO has just said 100mm OK for domestic
floor)

Thanks,
Simon.

sm_jamieson wrote:
Trying to cut down the overall thickness of my solid floor
construction (for various reasons).
Does this seem OK :-

65mm screed (no reinforcement)

Thats OK
100mm concrete (was 150 - will 100 need reinforcement ?)
Mm. I would reinforce.

DPM
75mm celotex (was 100mm polystyrene on old regs)

Thats good, but put them ABOVE the concrete not below.


25mm sand (was 50mm but whats the point)

I afree,

100mm MOT (was 150mm, but BCO has just said 100mm OK for domestic
floor)

If he says OK, go fer it.


Thanks,
Simon.

On May 13, 4:53 pm, sm_jamieson wrote:
Trying to cut down the overall thickness of my solid floor
construction (for various reasons).
Does this seem OK :-

65mm screed (no reinforcement)
100mm concrete (was 150 - will 100 need reinforcement ?)
DPM
75mm celotex (was 100mm polystyrene on old regs)
25mm sand (was 50mm but whats the point)
100mm MOT (was 150mm, but BCO has just said 100mm OK for domestic
floor)


If you use Maxit LWA instead of the MOT, it contributes to the
required insulation, so you can reduce the thickness of celotex.

A

On 13 May, 19:23, "
wrote:
On May 13, 4:53 pm, sm_jamieson wrote:

Trying to cut down the overall thickness of my solid floor
construction (for various reasons).
Does this seem OK :-

65mm screed (no reinforcement)
100mm concrete (was 150 - will 100 need reinforcement ?)
DPM
75mm celotex (was 100mm polystyrene on old regs)
25mm sand (was 50mm but whats the point)
100mm MOT (was 150mm, but BCO has just said 100mm OK for domestic
floor)

If you use Maxit LWA instead of the MOT, it contributes to the
required insulation, so you can reduce the thickness of celotex.

A

Really. What price is it ? Can it be delivered in 1 tonne bulk bags ?

Celotex 75mm to cover my 20m^2 would be around 170 quid.
Also, I guess it would support the slab better than celotex if the
slab is going
over the insulation.
Simon.

On 13 May, 17:58, The Natural Philosopher wrote:
sm_jamieson wrote:
Trying to cut down the overall thickness of my solid floor
construction (for various reasons).
Does this seem OK :-

65mm screed (no reinforcement)

Thats OK 100mm concrete (was 150 - will 100 need reinforcement ?)

Mm. I would reinforce.


What is the trick here ? prop up some of that steel grid on bricks and
pour the concrete around it ?
Simon.

On May 13, 8:10 pm, sm_jamieson wrote:
On 13 May, 19:23, "



wrote:
On May 13, 4:53 pm, sm_jamieson wrote:

Trying to cut down the overall thickness of my solid floor
construction (for various reasons).
Does this seem OK :-

65mm screed (no reinforcement)
100mm concrete (was 150 - will 100 need reinforcement ?)
DPM
75mm celotex (was 100mm polystyrene on old regs)
25mm sand (was 50mm but whats the point)
100mm MOT (was 150mm, but BCO has just said 100mm OK for domestic
floor)

If you use Maxit LWA instead of the MOT, it contributes to the
required insulation, so you can reduce the thickness of celotex.

A

Really. What price is it ? Can it be delivered in 1 tonne bulk bags ?

Celotex 75mm to cover my 20m^2 would be around 170 quid.
Also, I guess it would support the slab better than celotex if the
slab is going
over the insulation.
Simon.

http://www.maxit-uk.co.uk/2557
It's about £7 per 50l bag - you need about 3 per m2 for 150mm
thickness, so it's not the cheapest option. It's incredibly quick and
easy though, and replaces the MOT, sand and celotex, and doesn't need
compacting. They do bulk deliveries, but I think just for larger
quantities.

A

On 13 May, 21:37, "
wrote:
On May 13, 8:10 pm, sm_jamieson wrote:



On 13 May, 19:23, "

wrote:
On May 13, 4:53 pm, sm_jamieson wrote:

Trying to cut down the overall thickness of my solid floor
construction (for various reasons).
Does this seem OK :-

65mm screed (no reinforcement)
100mm concrete (was 150 - will 100 need reinforcement ?)
DPM
75mm celotex (was 100mm polystyrene on old regs)
25mm sand (was 50mm but whats the point)
100mm MOT (was 150mm, but BCO has just said 100mm OK for domestic
floor)

If you use Maxit LWA instead of the MOT, it contributes to the
required insulation, so you can reduce the thickness of celotex.

A

Really. What price is it ? Can it be delivered in 1 tonne bulk bags ?

Celotex 75mm to cover my 20m^2 would be around 170 quid.
Also, I guess it would support the slab better than celotex if the
slab is going
over the insulation.
Simon.

http://www.maxit-uk.co.uk/2557
It's about £7 per 50l bag - you need about 3 per m2 for 150mm
thickness, so it's not the cheapest option. It's incredibly quick and
easy though, and replaces the MOT, sand and celotex, and doesn't need
compacting. They do bulk deliveries, but I think just for larger
quantities.

A

My floor 20m^2.
Quick calc based on bulk bag prices:
for 100mm MOT, 2m^3 = 4 tonnes MOT = 5 bulk bags (850kg) = 5 x 30 =
150 quid
1 tonne sand = 1 bulk bag = 30 quid.
celotex = 180 quid.
Total trad method = 360 quid.

maxit 150mm for 20m^2 = 20 x 3 = 60 bags.
60 x 7 = 420 quid.

Factor in the hire of whacker plate for trad method,
and there is not a lot in it, save time.

Does my quid calc seem about right ?
I may well have a good think about this.

Simon.

On 13 May, 22:13, sm_jamieson wrote:
On 13 May, 21:37, "



wrote:
On May 13, 8:10 pm, sm_jamieson wrote:

On 13 May, 19:23, "

wrote:
On May 13, 4:53 pm, sm_jamieson wrote:

Trying to cut down the overall thickness of my solid floor
construction (for various reasons).
Does this seem OK :-

65mm screed (no reinforcement)
100mm concrete (was 150 - will 100 need reinforcement ?)
DPM
75mm celotex (was 100mm polystyrene on old regs)
25mm sand (was 50mm but whats the point)
100mm MOT (was 150mm, but BCO has just said 100mm OK for domestic
floor)

If you use Maxit LWA instead of the MOT, it contributes to the
required insulation, so you can reduce the thickness of celotex.

A

Really. What price is it ? Can it be delivered in 1 tonne bulk bags ?

Celotex 75mm to cover my 20m^2 would be around 170 quid.
Also, I guess it would support the slab better than celotex if the
slab is going
over the insulation.
Simon.

http://www.maxit-uk.co.uk/2557
It's about £7 per 50l bag - you need about 3 per m2 for 150mm
thickness, so it's not the cheapest option. It's incredibly quick and
easy though, and replaces the MOT, sand and celotex, and doesn't need
compacting. They do bulk deliveries, but I think just for larger
quantities.

A

My floor 20m^2.
Quick calc based on bulk bag prices:
for 100mm MOT, 2m^3 = 4 tonnes MOT = 5 bulk bags (850kg) = 5 x 30 =
150 quid
1 tonne sand = 1 bulk bag = 30 quid.
celotex = 180 quid.
Total trad method = 360 quid.

maxit 150mm for 20m^2 = 20 x 3 = 60 bags.
60 x 7 = 420 quid.

Factor in the hire of whacker plate for trad method,
and there is not a lot in it, save time.

Does my quid calc seem about right ?
I may well have a good think about this.

Simon.

Only snag now is, the level under my slab is too low for just 150mm
max, 150mm concrete + screed. I guess I could just shovel back 2
inches of soil soak it and walk all over it for a few days. If I had
to build up with MOT, thats taking me back where I started !
Simon.

sm_jamieson wrote:
On 13 May, 17:58, The Natural Philosopher wrote:
sm_jamieson wrote:
Trying to cut down the overall thickness of my solid floor
construction (for various reasons).
Does this seem OK :-
65mm screed (no reinforcement)
Thats OK 100mm concrete (was 150 - will 100 need reinforcement ?)

Mm. I would reinforce.


What is the trick here ? prop up some of that steel grid on bricks and
pour the concrete around it ?
Simon.

Mmm. Not sure you would even need to prop it much..the loose stuff under
ins more likley to compact, so you want the steel underneath really.

I must say I would be tempted to whack the MOT down, lay a grid, forget
the sand and pour concrete..

On 13 May, 16:53, sm_jamieson wrote:
Trying to cut down the overall thickness of my solid floor
construction (for various reasons).
Does this seem OK :-

65mm screed (no reinforcement)
100mm concrete (was 150 - will 100 need reinforcement ?)
DPM
75mm celotex (was 100mm polystyrene on old regs)
25mm sand (was 50mm but whats the point)
100mm MOT (was 150mm, but BCO has just said 100mm OK for domestic
floor)

Thanks,
Simon.

Sorry guys - what's MOT ? Can cope with most TLA's but his one I
don't know.

Rob

On May 13, 10:35 pm, sm_jamieson wrote:
On 13 May, 22:13, sm_jamieson wrote:



On 13 May, 21:37, "

wrote:
On May 13, 8:10 pm, sm_jamieson wrote:

On 13 May, 19:23, "

wrote:
On May 13, 4:53 pm, sm_jamieson wrote:

Trying to cut down the overall thickness of my solid floor
construction (for various reasons).
Does this seem OK :-

65mm screed (no reinforcement)
100mm concrete (was 150 - will 100 need reinforcement ?)
DPM
75mm celotex (was 100mm polystyrene on old regs)
25mm sand (was 50mm but whats the point)
100mm MOT (was 150mm, but BCO has just said 100mm OK for domestic
floor)

If you use Maxit LWA instead of the MOT, it contributes to the
required insulation, so you can reduce the thickness of celotex.

A

Really. What price is it ? Can it be delivered in 1 tonne bulk bags ?

Celotex 75mm to cover my 20m^2 would be around 170 quid.
Also, I guess it would support the slab better than celotex if the
slab is going
over the insulation.
Simon.

http://www.maxit-uk.co.uk/2557
It's about £7 per 50l bag - you need about 3 per m2 for 150mm
thickness, so it's not the cheapest option. It's incredibly quick and
easy though, and replaces the MOT, sand and celotex, and doesn't need
compacting. They do bulk deliveries, but I think just for larger
quantities.

A

My floor 20m^2.
Quick calc based on bulk bag prices:
for 100mm MOT, 2m^3 = 4 tonnes MOT = 5 bulk bags (850kg) = 5 x 30 =
150 quid
1 tonne sand = 1 bulk bag = 30 quid.
celotex = 180 quid.
Total trad method = 360 quid.

maxit 150mm for 20m^2 = 20 x 3 = 60 bags.
60 x 7 = 420 quid.

Factor in the hire of whacker plate for trad method,
and there is not a lot in it, save time.

Does my quid calc seem about right ?
I may well have a good think about this.

Simon.

Only snag now is, the level under my slab is too low for just 150mm
max, 150mm concrete + screed. I guess I could just shovel back 2
inches of soil soak it and walk all over it for a few days. If I had
to build up with MOT, thats taking me back where I started !
Simon.

The LWA can be laid up to 3m thick without compacting, so you could
just use more. Would put the price up, but improves the insulation
performance.
5 bags per m2 does 250mm deep.

A

On 14 May, 08:36, robgraham wrote:
On 13 May, 16:53, sm_jamieson wrote:

Trying to cut down the overall thickness of my solid floor
construction (for various reasons).
Does this seem OK :-

65mm screed (no reinforcement)
100mm concrete (was 150 - will 100 need reinforcement ?)
DPM
75mm celotex (was 100mm polystyrene on old regs)
25mm sand (was 50mm but whats the point)
100mm MOT (was 150mm, but BCO has just said 100mm OK for domestic
floor)

Thanks,
Simon.

Sorry guys - what's MOT ? Can cope with most TLA's but his one I
don't know.

Rob

It was Ministry of Transport type 1 sub-base I think. Basically
crushed stone, you know the grey stuff used as a base for everything
(roads, drives, floor slabs). Its one bit of jargon I learnt. Umm,
jargon is GOOD ...
Simon.

On 14 May, 09:19, "
wrote:
On May 13, 10:35 pm, sm_jamieson wrote:



On 13 May, 22:13, sm_jamieson wrote:

On 13 May, 21:37, "

wrote:
On May 13, 8:10 pm, sm_jamieson wrote:

On 13 May, 19:23, "

wrote:
On May 13, 4:53 pm, sm_jamieson wrote:

Trying to cut down the overall thickness of my solid floor
construction (for various reasons).
Does this seem OK :-

65mm screed (no reinforcement)
100mm concrete (was 150 - will 100 need reinforcement ?)
DPM
75mm celotex (was 100mm polystyrene on old regs)
25mm sand (was 50mm but whats the point)
100mm MOT (was 150mm, but BCO has just said 100mm OK for domestic
floor)

If you use Maxit LWA instead of the MOT, it contributes to the
required insulation, so you can reduce the thickness of celotex.

A

Really. What price is it ? Can it be delivered in 1 tonne bulk bags ?

Celotex 75mm to cover my 20m^2 would be around 170 quid.
Also, I guess it would support the slab better than celotex if the
slab is going
over the insulation.
Simon.

http://www.maxit-uk.co.uk/2557
It's about £7 per 50l bag - you need about 3 per m2 for 150mm
thickness, so it's not the cheapest option. It's incredibly quick and
easy though, and replaces the MOT, sand and celotex, and doesn't need
compacting. They do bulk deliveries, but I think just for larger
quantities.

A

My floor 20m^2.
Quick calc based on bulk bag prices:
for 100mm MOT, 2m^3 = 4 tonnes MOT = 5 bulk bags (850kg) = 5 x 30 =
150 quid
1 tonne sand = 1 bulk bag = 30 quid.
celotex = 180 quid.
Total trad method = 360 quid.

maxit 150mm for 20m^2 = 20 x 3 = 60 bags.
60 x 7 = 420 quid.

Factor in the hire of whacker plate for trad method,
and there is not a lot in it, save time.

Does my quid calc seem about right ?
I may well have a good think about this.

Simon.

Only snag now is, the level under my slab is too low for just 150mm
max, 150mm concrete + screed. I guess I could just shovel back 2
inches of soil soak it and walk all over it for a few days. If I had
to build up with MOT, thats taking me back where I started !
Simon.

The LWA can be laid up to 3m thick without compacting, so you could
just use more. Would put the price up, but improves the insulation
performance.
5 bags per m2 does 250mm deep.

A

Starts to get rather pricey then. Interestingly, since it self-
compacts (basically round stuff), I gues it could in theory be used to
bed drains, thus insulating the drains. They are still a heat leakage
route in floor slabs (especially an internal inspection chamber).

Does the LWA settle a bit when the concrete is poured though ?
You'd want to account for that in ordering your concrete.
Simon.

robgraham wrote:
On 13 May, 16:53, sm_jamieson wrote:
Trying to cut down the overall thickness of my solid floor
construction (for various reasons).
Does this seem OK :-

65mm screed (no reinforcement)
100mm concrete (was 150 - will 100 need reinforcement ?)
DPM
75mm celotex (was 100mm polystyrene on old regs)
25mm sand (was 50mm but whats the point)
100mm MOT (was 150mm, but BCO has just said 100mm OK for domestic
floor)

Thanks,
Simon.

Sorry guys - what's MOT ? Can cope with most TLA's but his one I
don't know.

Rob
MOT type A. Ministry of transport TYPE A road base.

Crushed limestone to the rest of us. Its lime 'gravel' that you whack
down to provide a permeable and stable and load spreading base for other
work above.

On 13 May, 16:53, sm_jamieson wrote:
Trying to cut down the overall thickness of my solid floor
construction (for various reasons).
Does this seem OK :-

65mm screed (no reinforcement)
100mm concrete (was 150 - will 100 need reinforcement ?)
DPM
75mm celotex (was 100mm polystyrene on old regs)
25mm sand (was 50mm but whats the point)
100mm MOT (was 150mm, but BCO has just said 100mm OK for domestic
floor)

Thanks,
Simon.

Simon
I agree with the posters that say
a) you must reinforce the 100 mm concrete
b) put the concrete below the insulation
c) additionally, I would increase insulation to celotex 100mm
d) use MOT no 1
e) additionally use Fibrogel or similar in the screed preferably
premixed and supplied in a lorry
There is the option of a pumped screed which is much thinner but I
don't like gypsum

No mention of UFH but I would not be without mine in the screed....
Chris

On 14 May, 09:30, sm_jamieson wrote:
On 14 May, 09:19, "



wrote:
On May 13, 10:35 pm, sm_jamieson wrote:

On 13 May, 22:13, sm_jamieson wrote:

On 13 May, 21:37, "

wrote:
On May 13, 8:10 pm, sm_jamieson wrote:

On 13 May, 19:23, "

wrote:
On May 13, 4:53 pm, sm_jamieson wrote:

Trying to cut down the overall thickness of my solid floor
construction (for various reasons).
Does this seem OK :-

65mm screed (no reinforcement)
100mm concrete (was 150 - will 100 need reinforcement ?)
DPM
75mm celotex (was 100mm polystyrene on old regs)
25mm sand (was 50mm but whats the point)
100mm MOT (was 150mm, but BCO has just said 100mm OK for domestic
floor)

If you use Maxit LWA instead of the MOT, it contributes to the
required insulation, so you can reduce the thickness of celotex.

On 14 May, 11:11, wrote:
On 13 May, 16:53, sm_jamieson wrote:

Trying to cut down the overall thickness of my solid floor
construction (for various reasons).
Does this seem OK :-

65mm screed (no reinforcement)
100mm concrete (was 150 - will 100 need reinforcement ?)
DPM
75mm celotex (was 100mm polystyrene on old regs)
25mm sand (was 50mm but whats the point)
100mm MOT (was 150mm, but BCO has just said 100mm OK for domestic
floor)

Thanks,
Simon.

Simon
I agree with the posters that say
a) you must reinforce the 100 mm concrete
b) put the concrete below the insulation
c) additionally, I would increase insulation to celotex 100mm
d) use MOT no 1
e) additionally use Fibrogel or similar in the screed preferably
premixed and supplied in a lorry
There is the option of a pumped screed which is much thinner but I
don't like gypsum

No mention of UFH but I would not be without mine in the screed....
Chris

I hate UFH (especially wet, the amount of leakage stories you hear),
and hate the idea of reinforced screed over insulation. My insulation
is going under the slab.
I agree though, if UFH, you would certainly want the insulation above
the main slab.
But, all seem to say 100mm concrete should be reinforced, especially
over insulation. I wonder about 5" concrete (!)
Simon.

On Tue, 13 May 2008 08:53:45 -0700 (PDT), a particular chimpanzee,
sm_jamieson randomly hit the keyboard and
produced:

Trying to cut down the overall thickness of my solid floor
construction (for various reasons).
Does this seem OK :-

65mm screed (no reinforcement)
100mm concrete (was 150 - will 100 need reinforcement ?)
DPM
75mm celotex (was 100mm polystyrene on old regs)
25mm sand (was 50mm but whats the point)
100mm MOT (was 150mm, but BCO has just said 100mm OK for domestic
floor)

The screed is there to provide a level, smooth surface. If it's laid
directly on top of the concrete it can be reduced (usually about
50mm). If you really, really want to reduce thickness, you could
power-float the concrete to the kind of surface one sees in B & Q and
Ikea, etc.

100mm concrete should be OK over a well compacted base without
reinforcement, but with a thin or non-existent screed over, I'd look
at an admixture to the concrete of fibres (can't remember exactly what
they're called) which act as an anti-crack mesh.

If your plans were deposited prior to April 2006, then the 'old' Part
L applies, so you may be able to use 50mm-65mm Celotex.

Again, a 100mm well compacted hard-core base should be OK, provided
that what's below it is firm, uniform and contains no organic matter.
--
Hugo Nebula
"If no-one on the internet wants a piece of this,
just how far from the pack have you strayed?"

On 14 May, 13:56, Hugo Nebula abuse@localhost wrote:
On Tue, 13 May 2008 08:53:45 -0700 (PDT), a particular chimpanzee,
sm_jamieson randomly hit the keyboard and
produced:

Trying to cut down the overall thickness of my solid floor
construction (for various reasons).
Does this seem OK :-

65mm screed (no reinforcement)
100mm concrete (was 150 - will 100 need reinforcement ?)
DPM
75mm celotex (was 100mm polystyrene on old regs)
25mm sand (was 50mm but whats the point)
100mm MOT (was 150mm, but BCO has just said 100mm OK for domestic
floor)

The screed is there to provide a level, smooth surface. If it's laid
directly on top of the concrete it can be reduced (usually about
50mm). If you really, really want to reduce thickness, you could
power-float the concrete to the kind of surface one sees in B & Q and
Ikea, etc.

That always seemed like a skilled job to me - I could be wrong. Also,
I am doing an ajoining slab as another job and screeding the whole lot
(job i 2 parts so I can live there at the same time !), and also
meeting another floor level, so the screen may need to be slightly
sloped to align the various floors. I think screeding to 65mm / 75mm
is common due to alignment with the brick courses and DPC etc.


100mm concrete should be OK over a well compacted base without
reinforcement, but with a thin or non-existent screed over, I'd look
at an admixture to the concrete of fibres (can't remember exactly what
they're called) which act as an anti-crack mesh.

I've actually got a big bag of glass-fibre (alkali-resist) that I used
on a previous reinforced concrete project. Also, did you mean the
fibres in the concrete, or in the thinner screed ?


If your plans were deposited prior to April 2006, then the 'old' Part
L applies, so you may be able to use 50mm-65mm Celotex.


Yep, thats my situation, the plans had 100mm polystyrene, although
insulation is a good thing ! I did wonder if changing from the plans
that were passed on the old regs meant I had to comply with the new
ones.
If I had taken out a building notice rather than full plans, is it the
regs when the notice is taken out, or when the job is done ?

Again, a 100mm well compacted hard-core base should be OK, provided
that what's below it is firm, uniform and contains no organic matter.

Yep, I wonder it its worth dosing the ground under with strong weed-
killer before the job. Couldn't hurt I suppose.

Also, I've realised I've got an extra inch to play with (oo-er), would
this be better in the hard-core or in the slab ?

Thanks for the info, my knowledge bank is on the up !
Simon.

On Wed, 14 May 2008 06:38:01 -0700 (PDT), a particular chimpanzee,
sm_jamieson randomly hit the keyboard and
produced:

Yep, thats my situation, the plans had 100mm polystyrene, although
insulation is a good thing ! I did wonder if changing from the plans
that were passed on the old regs meant I had to comply with the new
ones.
If I had taken out a building notice rather than full plans, is it the
regs when the notice is taken out, or when the job is done ?

Provided that the application is for substantially the same work (ie,
not doubling the size of the extension or moving it from one side of
the house to the other), then any changes to the design or materials
are treated as minor alterations. IME it's rare for an extension to
be built as per the plans anyway.

In most cases, work must comply with the Regulations in force on the
day the full plans application or Building Notice were 'deposited'
(ie, physically received by the Council with the correct fee, etc.).
In the last decade there have sometimes been 'transitional
arrangements' for some changes; these have usually taken the form of:

-for full plans, if the plans were fully approved (without conditions
or all conditions discharged) before the change to the Regulations; or

-for either BN or FP, the work had commenced before the change;

then the 'old' Regs applied.
--
Hugo Nebula
"If no-one on the internet wants a piece of this,
just how far from the pack have you strayed?"