Lightweight insulated concrete block

Brave Harvey

Can anyone please recommend a lightweight insulated concrete block to start an inner leaf block wall for first three rows from the foundations up to the floor finish and so to reduce the thermal bridge that the wall would impose using standard medium density blocks. I am aware of only on manufacturer of these blocks am told not to use them underground. Any help on this would be great.

Poor Uncle Tom

There are no insulated concrete blocks. There are insulated concrete forms (for ICF builds), foam glass blocks or low density concrete blocks.

Brave Harvey

Yeah i seen the spec on "http://passivedesign.org/integrated-energy" as lightweight insulated concrete blocks. Would low density concrete blocks be a good thermal break and also have good compressible strength, and what blocks do you use in this area where you want to provide a thermal break. foamglass is very expensive.

sydthebeat

some blocks have polystyrene beads included in the mix which makes them a bit more insulative than a standard dense concrete block.
These are usually specif as light weight blocks for use on concrete slabs to reduce loadings


Not to be confused with AAC blocks.

Brave Harvey

Ok probably getting somewhere now, can you recommend aac blocks that i could use for thermal break. pm please if you dont want to disclose manufacturer details...

sydthebeat

Brave Harvey wrote: »

Ok probably getting somewhere now, can you recommend aac blocks that i could use for thermal break. pm please if you dont want to disclose manufacturer details...

no problem mentioning quinnlite aac blocks

Brave Harvey

Just a quick question, what considerations would need to be considered when detailing the protection of these blocks underground?

hexosan

sydthebeat wrote: »

no problem mentioning quinnlite aac blocks

Apart from Quinnlites are there any other recommended AAC blocks.

Brave Harvey

Apart from Quinnlites are there any other recommended AAC blocks.

There are schock novoumer, thermoblock, and perinsul foamglass, i think i heard on the boards that foamglass is 42 times more expensive than a normal block, schok are 30 times more expensive, i haven't any information on thermoblock. Thats all i know a.t.m.

BryanF

Brave Harvey wrote: »

Just a quick question, what considerations would need to be considered when detailing the protection of these blocks underground?

There are sub dpc type Quinn lite blocks available

Brave Harvey

There are sub dpc type Quinn lite blocks available

Yes but their thermal conductivity elevates when in contact with water to 0.25 W/mk. Therefore are there certain measures to waterproof these blocks when they've been installed..

Carbonnet

The PSI values achieved using ACC/insulated block (0.15ish conductivity) Med Dense Block (0.52 ish) and Dense block (1.15) does differ significantly in the same construction expecially at the ground floor junction, but generally the resultant total Y-value you'll need to record in the DEAP to reach current Part L standards of 0.05 will be achieved with all of them. (UK has set a Y-value of 0.05 as Zero Carbon Standard)

What is probably more critical is whether the f Factor achieved by the same modelling is above 0.75 to avoid condensation build up - it generally is with all the blocks following half decent detailing (In design and actually on site!)

Be carefull with just the first few rows being of one block then changing to a different type - differential drying will cause cracking in plaster. And then what do you do a sills/heads/gable junctions etc? - change back again?

Look at the Average Y-value rather than concentrating on just the floor junction.

Easier and cheaper to improve other junctions - that will improve the over all Y.

Carbonnet

Brave Harvey wrote: »

Yes but their thermal conductivity elevates when in contact with water to 0.25 W/mk. Therefore are there certain measures to waterproof these blocks when they've been installed..

The difference between 0.12 ans 0.35 will make no difference to the PSI value.

sinnerboy

Carbonnet wrote: »

The difference between 0.12 ans 0.35 will make no difference to the PSI value.

Very interesting , have you modelled this for yourself ?

Carbonnet

sinnerboy wrote: »

Very interesting , have you modelled this for yourself ?

No - but I know a man who has.

Eoghan Barra

Brave Harvey wrote: »

Can anyone please recommend a lightweight insulated concrete block to start an inner leaf block wall for first three rows from the foundations up to the floor finish and so to reduce the thermal bridge that the wall would impose using standard medium density blocks. I am aware of only on manufacturer of these blocks am told not to use them underground. Any help on this would be great.

You should look at Alphatherm blocks, which are made out of pumice aggregate by Acheson & Glover in the north. The same strength as standard blocks but a third of the thermal conductivity. They are also quite reasonably priced. We used them for the inner leaf of our new build for better decrement delay (we used an insulated foundation, so eliminating thermal bridging wasn't such an issue for us), but we only moved in a month ago, so a bit early to comment on how they perform.

I have no connection with the company, by the way.

Carbonnet

Eoghan Barra wrote: »

You should look at Alphatherm blocks, which are mad out of pumice aggregate by Acheson & Glover in the north. The same strength as standard blocks but a third of the thermal conductivity. They are also quite reasonably priced. We used them for the inner leaf of our new build for better decrement delay (we used an insulated foundation, so eliminating thermal bridging wasn't such an issue for us), but we only moved in a month ago, so a bit early to comment on how they perform.

I have no connection with the company, by the way.

As we're talking about actual performances using all the differing block - what PSI value did you get for your specification? (I know you said you eliminated the thermal bridge - but I don't think you'll ever get an answer of zero)

Eoghan Barra

Carbonnet wrote: »

As we're talking about actual performances using all the differing block - what PSI value did you get for your specification? (I know you said you eliminated the thermal bridge - but I don't think you'll ever get an answer of zero)

PSI - pounds per square inch? :rolleyes:

sinnerboy

Eoghan Barra wrote: »

PSI - pounds per square inch? :rolleyes:

No . Ψ.

Don't you know.

Eoghan Barra

I didn't calculate any Ψ value for the junction between the inner leaf and foundation. I used my bonce to arrive at the conclusion that by combining an insulated foundation (Supergrund) with low thermal conductivity blocks on the inner leaf the result would be acceptable to me and to the building regs.

sinnerboy

Eoghan Barra wrote: »

I didn't calculate any Ψ value for the junction between the inner leaf and foundation.

Is all you needed to say.

Eoghan Barra wrote: »

I used my bonce to arrive at the conclusion that by combining an insulated foundation (Supergrund) with low thermal conductivity blocks on the inner leaf the result would be acceptable to me and to the building regs.

This reflects badly on you as does this .

Eoghan Barra wrote: »

PSI - pounds per square inch? :rolleyes:

Moderator warning - lose the attitude.

Carbonnet

Eoghan Barra wrote: »

I didn't calculate any Ψ value for the junction between the inner leaf and foundation. I used my bonce to arrive at the conclusion that by combining an insulated foundation (Supergrund) with low thermal conductivity blocks on the inner leaf the result would be acceptable to me and to the building regs.

Like most things in construction there are ways and methods of measurement, set normally in EN standards - thermal bridging is no different. The are many theories out there that claim extraordinary performances - without giving evidence. I once spoke to a technical guy at an exhibition in Munich who was selling insulated type spacers that replaced a brick size section of wall at the wall/floor junction, he couldn't explain the figures in their own literature!

We in Ireland are heading for a goal of around Y=0.05/0.04, UK are now quoting Y=0.05 for their Zero Carbon 2016 standard, this level can be achieved with half decent detailing on the 'easily treated' junctions such as reveals/corners and lintels - and reasonable detailing at the difficult junctions - wall/floor - even with the use of a dense block.

The results are readily calculated following PSI values from published Acceptable/Details - and the determining the Y-values for each of your designs (Party walls can be difficult tough - but then if you only achieve 0.06/07 - improve other parameters such as permeability etc)

hexosan

Carbonnet wrote: »

As we're talking about actual performances using all the differing block - what PSI value did you get for your specification? (I know you said you eliminated the thermal bridge - but I don't think you'll ever get an answer of zero)

How exactly do you calculate the PSI value ??

sinnerboy

You must use a software program

hexosan

sinnerboy wrote: »

You must use a software program

Had a sneaking suspicion it wasn't a pencil & paper job

sinnerboy

Or,if you build using details based on DOE Acceptable Construction Details then Appendix D of TGDL 11 gives calculated Ψ values for those detailed junctions for a limited range of elemental U Values .

Carbonnet

hexosan wrote: »

How exactly do you calculate the PSI value ??

It s VERY long and complicated modelling process completed on thermal bridging specific software. The is an on going debate as to whether modelling should be completed on 3D or 2D software. On reading the standard BR497 and following the conventions for measurement in IP 1/06 I understand that in all cases the ability to look at the model in 3d is obligatory ~ on the junction in question wall/floor it is impossible to calculated the f factor along with the psi that will indicate the possibility of surface condensation forming. And let's face it that is the important factor.

2d software is available foc from the web. All professionals use program's such as physibel - which is very expensive. Traing on it - even more expensive.

There are standard details out there from passive hauls, from DOE and uk planning portal that are applicable in Ireland that quote usable psi values (Scotland details might be more applicable to us in Ireland as window positioning is more in tune with what we do)

I'd recommend sticking to std detailing where possible - to do something out side the 'norm' would cost a fortune to model (€300/ junction?)

BarneyMc

BryanF wrote: »

There are sub dpc type Quinn lite blocks available

Yes indeed, this is explained here. Why then are some people concerned with these blocks absorbing moisture?

Carbonnet

BarneyMc wrote: »

Yes indeed, this is explained here. Why then are some people concerned with these blocks absorbing moisture?

Because the principals are completely mis understood. claims of super performances in low energy builds - without measurement - are just claims.

Reasonable claims and reasonable performances make a lot more sense.

BarneyMc

Perhaps then it makes more sense to just use the top 2 layers of AAC blocks at http://passivedesign.org/integrated-energy

sydthebeat

barney, put a quinnlite block into a bucket of water and see what happens.

BarneyMc

This is disappointing. I'd imagine there are a significant number of strip foundations with Quinn Lites in them out there.

sydthebeat

BarneyMc wrote: »

This is disappointing. I'd imagine there are a significant number of strip foundations with Quinn Lites in them out there.

if design measures have been taken to reduce the risk of moisture ingress, then they should work fine.

however, if that hasnt been a consideration in the detail, then the risk increases.

Carbonnet

BarneyMc wrote: »

Perhaps then it makes more sense to just use the top 2 layers of AAC blocks at http://passivedesign.org/integrated-energy

They're really nice - what PSI value do they achieve?

BarneyMc

Sorry, haven't a clue Carbonnet.

Carbonnet

BarneyMc wrote: »

Sorry, haven't a clue Carbonnet.

It would be interesting to find out just what the difference is between their system and a standard type construction - they are obviously aiming to achieve Passive Haus Standards. If you can find it out I'll do a calc for the Y value - just on a typical house - to see the benefit over all.

I can't see the point in promoting any such details to improve bridging if they don't quote a performance.

Eg. ???? mpg in an advertised eco-car - why would you bother?

Brave Harvey

if design measures have been taken to reduce the risk of moisture ingress, then they should work fine.

however, if that hasnt been a consideration in the detail, then the risk increases.

By design measures do you mean putting a drainage pipe at foundation level around the house? Or do you paint the blocks with a type of waterproofer, which i heard somewhere before but haven't seen done?

Brave Harvey

Carbonnet I can't see the point in promoting any such details to improve bridging if they don't quote a performance.

Yes carbonnet this is what i would like to know how to calculate, its all well and good to tell someone to fork out on materials that will decrease cold bridges bringing up the cost but why should you bother if you dont really know what your returns will be from this measure in the long run. I am very interested in this side scientific side of building because you need to back up these details with evidence

Carbonnet

Brave Harvey wrote: »

By design measures do you mean putting a drainage pipe at foundation level around the house? Or do you paint the blocks with a type of waterproofer, which i heard somewhere before but haven't seen done?

All block manufacturers quote lambda values for their blocks above and below ground - that take into account the moisture content in situ - use the wet one in foundation situations - simples

check out Celcon or Thermalite foundation block web sites 9Perhaps the local blocks don't do the same? - but a default penalty should be added if not - this deafult can be found in CIBSE guide)

fclauson

So - I have (as you can guess) took a very good look at this before approving it for my build and I tried to work out how wet these blocks would actually get when installed.

Firstly remember you radon sump is at the same level as the lower layer - hence if these blocks are sitting in water then so is your radon sump which is not a good thing - and for reference mine is bone dry

we then need to look to see if moisture will wick in to these blocks from the surrounding materials - if installed as per the approval cert then this can be minimised

then we need to look at what happens under a building over time - unless you are in a flooding area etc then under your build will be dry and get drier over time
a) as the building heats up and hence the soil directly under it takes in a little of that heart plus the fact its getting no rain on it
b) moisture pressure.

So all in all from the research I have done these blocks will general perform very well

Coming back to the difference between using a regular block vs AAC - I do (somewhere) have the maths on this - if you fail to minimise the thermal bridge at the junction of an internal wall to floor then there is a probability (all be it small) of getting a very think line of condensation along this junction (probably behind the skirting where its hidden from view) and this will lead to mould

fclauson

BarneyMc wrote: »

Perhaps then it makes more sense to just use the top 2 layers of AAC blocks at http://passivedesign.org/integrated-energy

This is a actually the spec of my foundation - and I know this works - €2 to €3 per day heating evening during the colds months last winter

BarneyMc

Thanks fclauson. So what prevents the lite block from getting wet from the soil (brown) on the left hand side of the diagram or even the hardcore on the right?

fclauson

on the left there is a land drain around the whole house (not shown) - plus your concrete path will stop rain coming down on them - so the soil might be damp but not wet - and will continue to dry out over time

and as I say - the bit under the house should not be wet (if it is you have other issues to work through not just thermal bridging) as you radon sump will be full of water

fclauson

oh - and I am not an engineer or professional - and you will need them to approve/sign off on what ever you choose to do

BarneyMc

fclauson wrote: »

oh - and I am not an engineer or professional - and you will need them to approve/sign off on what ever you choose to do

Have a man on the job, thanks fclauson!

BarneyMc

Just looking at the main diagram showing the external wall at http://passivedesign.org/integrated-energy and it seems like there are a lot of lite blocks used all the way round (5). Do the bottom 3 (2 on their flat and 1 on it's edge) really make a thermal difference?

Brave Harvey

fclauson if you fail to minimize the thermal bridge at the junction of an internal wall to floor then there is a probability (all be it small) of getting a very think line of condensation along this junction (probably behind the skirting where its hidden from view) and this will lead to mould

If you have a highly insulated house it is my inclination that as well as some transmission heat losses though the block wall which has the higher conductivity you will also run a strong risk of a build up of condensation along this junction. If you imagine a super insulated, very airtight house (no exfiltration heat losses) and combine this with no work done on minimizing thermal bridges the heat will pour to these cold edges like water through a hole in a bucket, i think its if the temperature goes below 12.6 degrees celsius water will condense and if there are areas receiving frequent condensation you will discover mold growth which will lead to other nasty problems health wise and structural.

I don't know the likelihood of blocks at this point going as low as 12.6 degrees celsius? I just have a feeling that they may during sustained cold periods with persistently low external temperatures.

fclauson

Another way of visualising this is like when you played with iron fillings at school on a piece of paper

people think that as a house is well insulated there will be no condensation - the opposite is true - any condensation will get concentrated or attracted to the coldest point - and this will be at a cold bridge junction

if you want to research then Google "Psychometric Charts" - you can actually chart at what temp and what RH you will get mould build up

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Carbonnet

fclauson wrote: »

Another way of visualising this is like when you played with iron fillings at school on a piece of paper

people think that as a house is well insulated there will be no condensation - the opposite is true - any condensation will get concentrated or attracted to the coldest point - and this will be at a cold bridge junction

if you want to research then Google "Psychometric Charts" - you can actually chart at what temp and what RH you will get mould build up

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Sorry Gents - 'Like a hole in a bucket' or 'Iron filings' can not be input into DEAP.

There is a method of measurement and unit of input given within our building regulations for inclusion in the energy performance calculation to account for thermal bridging. When this modelling is done in accordance with EN standards an f-value is also determined - THIS ensures the detailing will be free of condensation and mould - on paper.

In practice there is a set of acceptable details that must be followed, signed off, and ALSO SCORED IN DEAP, to ensure the calculations are followed through in site.

It is NOT theoretical, we have been asked to do this under our regulations for years.

fclauson

totally agree - my "iron fillings" example was to try and explain to people that in a highly insulated building there are stills risks - and they are more concentrated at certain points

BarneyMc

I contacted the technical team in Quinn and they sent me these 2 attachments.