Lightweight insulated concrete block

Brave Harvey · 17-05-2013 10:10AM #1

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 · 17-05-2013 10:25AM

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

Brave Harvey · 17-05-2013 10:54AM

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 · 17-05-2013 11:00AM

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 · 17-05-2013 11:05AM

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 · 17-05-2013 11:10AM

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 · 17-05-2013 11:29AM

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

hexosan · 17-05-2013 11:46AM

sydthebeat wrote: »

no problem mentioning quinnlite aac blocks

Apart from Quinnlites are there any other recommended AAC blocks.

Brave Harvey · 17-05-2013 11:57AM

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 · 17-05-2013 12:11PM

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 · 17-05-2013 12:17PM

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 · 17-05-2013 01:35PM

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 · 17-05-2013 01:36PM

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 · 17-05-2013 01:52PM

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 · 17-05-2013 04:19PM

sinnerboy wrote: »

Very interesting , have you modelled this for yourself ?

No - but I know a man who has.

Eoghan Barra · 19-05-2013 08:40PM

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 · 19-05-2013 08:48PM

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 · 19-05-2013 09:07PM

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 · 19-05-2013 11:24PM

Eoghan Barra wrote: »

PSI - pounds per square inch? :rolleyes:

No . Ψ.

Don't you know.

Eoghan Barra · 20-05-2013 07:50AM

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 · 20-05-2013 08:56AM

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 · 20-05-2013 10:24PM

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 · 21-05-2013 06:33AM

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 · 21-05-2013 06:38AM

You must use a software program

hexosan · 21-05-2013 06:43AM

sinnerboy wrote: »

You must use a software program

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

sinnerboy · 21-05-2013 06:46AM

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 · 21-05-2013 07:04AM

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 · 24-05-2013 08:29AM

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 · 24-05-2013 08:41AM

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 · 24-05-2013 09:02AM

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

sydthebeat · 24-05-2013 09:38AM

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

Lightweight insulated concrete block

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