Green Building Forum - 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? Wed, 03 Jun 2026 07:47:27 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=17882#Comment_17882 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=17882#Comment_17882 Fri, 04 Apr 2008 12:28:39 +0100 Pingy
Going down the path of more is better than less approach can anyone advise whether it would be possible to have a 100mm concrete slab on top of 300mm of flooring grade EPS?

Is the concrete too thin?
Does the concrete need steel reinforcement?
Can underfloor heating pipes be cast into the concrete?]]> 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=17884#Comment_17884 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=17884#Comment_17884 Fri, 04 Apr 2008 12:36:09 +0100 Mike George 2. Probably not but see 1.
3. Sorry don't know

I'm in the not necessary camp but it isn't always black and white. If you need to excavate 300mm then I would not do it. On the other hand, if you need to infil 300mm then I would.]]> 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=17892#Comment_17892 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=17892#Comment_17892 Fri, 04 Apr 2008 13:18:03 +0100 Pingy 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=17907#Comment_17907 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=17907#Comment_17907 Fri, 04 Apr 2008 16:47:18 +0100 joe.e 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=17911#Comment_17911 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=17911#Comment_17911 Fri, 04 Apr 2008 18:43:19 +0100 Ben 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=17913#Comment_17913 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=17913#Comment_17913 Fri, 04 Apr 2008 18:54:00 +0100 James Norton Posted By: Benthe mysterious U value

What's mysterious about it...?

:confused:

J]]> 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=17918#Comment_17918 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=17918#Comment_17918 Fri, 04 Apr 2008 19:14:09 +0100 tony 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=17923#Comment_17923 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=17923#Comment_17923 Fri, 04 Apr 2008 19:23:39 +0100 Mike George Posted By: James Norton
Posted By: Benthe mysterious U value


What's mysterious about it...?

:confused:" start="fileopen" height="15" alt=":confused:" ismap="false" hspace="0" loop="1" src="http://www.greenbuildingforum.co.uk/newforum/extensions/Vanillacons/smilies/standard/confused.gif" width="15" vspace="0" >

J

Misused more like:bigsmile:]]> 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=17946#Comment_17946 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=17946#Comment_17946 Sat, 05 Apr 2008 00:51:28 +0100 Terry Why not screed it rather than use concrete. This is quite standard with UFH, although as I understand it you have to inform the screed suppliers about the UFH.]]> 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=17996#Comment_17996 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=17996#Comment_17996 Sun, 06 Apr 2008 01:58:55 +0100 ali.gill 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=17997#Comment_17997 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=17997#Comment_17997 Sun, 06 Apr 2008 08:47:46 +0100 tony
It is OK to concrete on top of the insulation that you suggest. It would be better in terms of maintenance/accessibility to have a screed too.

Size of the slab will to some extent determines thickness.

I would use an anticracking mesh (A142) as well it is nice to tie the pipes to apart from anything else.

I once saw specifier ban the use of 100mm sheets and made them use 50mm sheets in that case x4 scared of air pockets and sagging!]]> 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18001#Comment_18001 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18001#Comment_18001 Sun, 06 Apr 2008 09:29:16 +0100 Mike George
Seems sensisble to use 2 x 50mm layers instead but even then is this a worry? Perhaps insulation under solid floors should only be allowed under the concrete? and not between the concrete and screed which is also allowed at present]]> 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18114#Comment_18114 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18114#Comment_18114 Mon, 07 Apr 2008 21:29:13 +0100 jamesingram then DPM
then slab with mesh and UFH as the finished floor
got to be time/material saving

whats the easiest way to get a decent finish
never tried power floating or rolling ,
how about getting it a good a possible then level tex

Any good ideas for a simple builder who doesn't want to get a ( I presume) expensive specialist team in

thanks

Jim]]> 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18119#Comment_18119 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18119#Comment_18119 Mon, 07 Apr 2008 22:12:23 +0100 Jeff Norton (NZ) 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18120#Comment_18120 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18120#Comment_18120 Mon, 07 Apr 2008 22:14:47 +0100 Mike George
I use a 'Part 1' concrete mix, which sets in a few hours. This allows you to tamp level when wet, Float up when tacky, and polish up to a final finish in a similar manner to finishing gypsum plaster.

It is easier to do if you are very fussy with levelling the blockwork/ shuttering]]> 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18122#Comment_18122 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18122#Comment_18122 Mon, 07 Apr 2008 22:25:48 +0100 jamesingram
Mike, your right I should of said blinded hardcore
i'll look into that part 1 mix, I guess one of those long handled, wide broom like trowels would be used for finishing

cheers Jim]]> 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18123#Comment_18123 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18123#Comment_18123 Mon, 07 Apr 2008 22:26:03 +0100 biffvernon 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18124#Comment_18124 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18124#Comment_18124 Mon, 07 Apr 2008 22:30:27 +0100 jamesingram
What your best solution to a heated ground bearing floor without concrete?]]> 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18135#Comment_18135 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18135#Comment_18135 Tue, 08 Apr 2008 07:26:59 +0100 Mike George 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18140#Comment_18140 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18140#Comment_18140 Tue, 08 Apr 2008 08:34:56 +0100 biffvernon 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18142#Comment_18142 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18142#Comment_18142 Tue, 08 Apr 2008 09:11:45 +0100 Mike George
I have often broached the possibility of using more 'green' materials with clients. As soon as they find out the cost they lose interest very quickly.]]> 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18171#Comment_18171 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18171#Comment_18171 Tue, 08 Apr 2008 19:47:49 +0100 jamesingram
What are we after once we have a low energy consumption building

The longer it lasts ( achieving its purpose, doing its job )the more sustainable it its
or is it,
The ease with which it can be created and returned to its original state without a negative impact on the enviroment

Hay, I dont know the answer to that one

any thoughts]]> 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18174#Comment_18174 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18174#Comment_18174 Tue, 08 Apr 2008 19:55:19 +0100 Mike George Posted By: jamesingramwhat did the romans do , they were pretty good builders, built things to last



Didn't they invent concrete?]]> 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18181#Comment_18181 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18181#Comment_18181 Tue, 08 Apr 2008 20:46:50 +0100 stemack http://eastcambusmoon.blogspot.com for pics (around last October).]]> 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18202#Comment_18202 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18202#Comment_18202 Wed, 09 Apr 2008 07:33:53 +0100 biffvernon Posted By: Mike George
Posted By: jamesingramwhat did the romans do , they were pretty good builders, built things to last



Didn't they invent concrete?
Yes, but as you well know, they used a naturally hydraulic lime not Ordinary Portland Cement. They didn't burn very much of the world's fossil fuel resources or cause global warming, yet some of their buildings have lasted for two millenia and more would have survived if they had not cocked up their socio-political relationships.

There are still too many people claiming to be hanging round the Green Building Movement who have not yet read Jim Hansen's paper, Target Atmospheric CO2: Where Should Humanity Aim?
http://www.columbia.edu/~jeh1/2008/TargetCO2_20080407.pdf

(Ok, so it was only published yesterday, but do try to catch up, this is urgent, we've a planet to save.)]]> 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18203#Comment_18203 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18203#Comment_18203 Wed, 09 Apr 2008 07:58:06 +0100 Mike George
Would you care to name names?

You're right about the Romans of course , but I think James knows that as well. I just looked at a site which discusses their use of pozzalans and came across a claim that the Egyptians may have use 'Burnt Gypsum' as a cementitious material at Giza. http://nabataea.net/cement.html

But then if you've read Graham Hancock's books you may think that the Egyptians did not build the so called pyramid of Khufu, but that it supersedes the Egyptians by thousands of years. Now hasn't that lasted a long time.

There's more to green building than cement v lime. It is not the be all and end all. It would be even better if those promoting and selling such materials would bring the prices within reach of the majority of the population.

You will be pleased to hear that I am about to undertake a job using sheepswool -I finally found someone who is willing to pay 3 times the cost of the alternative glasswool.]]> 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18272#Comment_18272 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18272#Comment_18272 Thu, 10 Apr 2008 07:50:08 +0100 Mike George Posted By: Mike GeorgeBiff, Re "There are still too many people claiming to be hanging round the Green Building Movement"

Would you care to name names?

That's a 'no comment' then?]]> 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18281#Comment_18281 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18281#Comment_18281 Thu, 10 Apr 2008 14:01:58 +0100 stephendv 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18282#Comment_18282 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18282#Comment_18282 Thu, 10 Apr 2008 14:09:03 +0100 agu 100mm Concrete Slab on 300mm Thick EPS Floor Insulation - Good or Bad? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18284#Comment_18284 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1533&Focus=18284#Comment_18284 Thu, 10 Apr 2008 14:46:04 +0100 biffvernon Posted By: Mike George
Posted By: Mike GeorgeBiff, Re "There are still too many people claiming to be hanging round the Green Building Movement"

Would you care to name names?


That's a 'no comment' then?

Not at all - I just don't read every thread every day on this forum (I have a life, I think).

Of course it would be invidious to name names so let's just stick with anyone who has suggested using something made of petroleum derivatives or involves CO2 emission in its production and use. (That should include most of us.) We could then put folk into a rank order, with OPC enthusiast near the top of the list.]]>