# Insulated Poroton single leaf build



## Brigid (27 Feb 2010)

Hi, does anyone have experience of using the above Insulated single leaf clay blocks as sold by FBT or NBT- tradenames seem to be Poroton or Thermoplan 

Is it cost effective? when you take into consideration all the different factors that go into the normal cavity block method.
Is it difficult to use to construct with - I remember reading that if not used exactly correctly it can leak etc. 
Is it true that it gives a very good u-value which is definite and not at the mercy of insultation being inserted correctly? and there are no thermal bridges etc?
Is the Irish weather up to it - are we too damp a climate?

Can you stone front these clay blocks or does that affect their breathability?

When I first heard of it a couple of years ago I thought it sounded brilliant but not many people seem to know about it. Any engineer/architect I spoke to either hadn't heard of it or if they had heard of it didnt know anything about it. 

What are the 2010 Part L regulations that may make the usual cavity wall build a thing of the past that I just read about on another thread? and would the Poroton Blocks as described fulfil these regulations?

So many questions - I am sorry but I hope someone will be able to guide me... thank you.


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## Brigid (28 Feb 2010)

Well ... since no one has made any comment on the above does that mean that no-one knows about it or that it is such a bad idea no one wants to go near the subject???

I thought that these blocks could be the answer to all the problems associated with cavity build and insulation but maybe I am wrong...


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## forgotten (1 Mar 2010)

worked with them in germany back in the late 90's. we used very thin bed mortar-almost glue like-to bond them together. then used paroc insulation on the outside or just plaster in some cases. very quick build time .
came back to this country and irish builders still build cavity walls with badly fitted insulation because they know no other way and then install underfloor heating and solar panels and then wonder why the houses are still cold and expensive to heat.
you would find it cheaper to import a lorry load of them yourself from an european manufacturer (germany,poland etc all use them} than go through a dealer here.
quinn lite blocks would be the closest thing to them here i guess.


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## onq (1 Mar 2010)

Yes  Brigid I have very little knowledge about them and was hoping someone else would post.
I would be interested to learn how the standard wall makes opes, in particular, the blocks are lightweight with thin walls, so:


 How are the walls weatrherproofed?
 How are ope reveals weatherproofed?
 How are lintols supported and weathered?
 What is the fire resistence of the structural wall?
 What is the weight and strength of the wall -vs- wind?
  I say what looked like a wall made of these block apparently blown over in the news last evening about that storm that swept up through Europe recently.
I've seen many cure-all details that work fine as a solid wall but fail at the details or else need additional stuff on the outside to weather them.
Those are interesting Links DBK100,but as with any material claiming intrinsic values the devil is in the details.

I suppose I'm asking about the kind of thing that a good 1:20 section addresses. 

And it would be great to know how the OP got on in that thread.

ONQ.

[broken link removed]


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## forgotten (1 Mar 2010)

from my memory which is not what it should be.
 the blocks were not thin they were 8 inchs wide and some were 12inchs wide.
1 the walls were weather proofed with paroc on the outside and then plastered ,sometimes just plastered. with plaster that was sprayed on and smoothed with trowels
2 the reveals were built with L shaped blocks or blocks which were cut and shaped on site with a wetsaw
3 the lentols for opes came pre-made of u shaped blocks which had concrete in the center.for longer openings we used u shaped blocks which we filled with rebar and concrete.all opes were surported with timber frames which were left in place for a good while
4 not sure about the fire resistence but think they blocks were kilm fired as part of the manufacting process
5 all external walls were ring beamed with u blocks filled with concrete and rebar in a continuous pour. for wind force i guess they would at least be as good as all the high garden walls built around estates with 8 inch cavity blocks which seem to stand up to irish winds.
like i said this was about 12 years ago so i am open to correction.


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## onq (2 Mar 2010)

Thanks forgotten, that's what I was looking for.
I presume this was a bungalow, or do you have the intermediate floor support detail?

ONQ.


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## John1957 (2 Mar 2010)

the poroton block is a standard building system through out europe. I know of one large property built with the poroton block. This is stone clad exterior directly onto the poroton.

Not an expert but the poroton block is  'breathing' system and is usually used ith specialist plaster. I know there have been damp issues with the poroton block/ stone walls. House owner is having to repoint walls to try and resole the problem.

Suggest if you want to use the poroton block go and look at some actual house builds!!!!!!!


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## forgotten (2 Mar 2010)

ong
worked mainly on large blocks of flats and one off houses now and again.the floors were usually ducon slabs that rested on the ring beam on the top course, sitting about halfways onto the 8 inch or 12 inch block, we then ran a course of narrower blocks-4 0r 6 inch blocks- outside this. concrete then poured on ducon slab up to level of ouside block. then started next floor with the 8 or 12 inchs blocks which rested half on ouside block and half on the poured concrete. the internal load bearing walls were built with u blocks on the last course which were rebarred and filled with concrete tied into the external ring beam,usually all poured together for strength.


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## onq (2 Mar 2010)

forgotten said:


> ong
> worked mainly on large blocks of flats and one off houses now and again.the floors were usually ducon slabs that rested on the ring beam on the top course, sitting about halfways onto the 8 inch or 12 inch block, we then ran a course of narrower blocks-4 0r 6 inch blocks- outside this. concrete then poured on ducon slab up to level of ouside block. then started next floor with the 8 or 12 inchs blocks which rested half on ouside block and half on the poured concrete. the internal load bearing walls were built with u blocks on the last course which were rebarred and filled with concrete tied into the external ring beam,usually all poured together for strength.



Thanks forgotten for that info.

Did you experience cracks at the floor levels and at the ring beam level due to the differing construction or was that not an issue?

ONQ


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## onq (2 Mar 2010)

John1957 said:


> the poroton block is a standard building system through out europe. I know of one large property built with the poroton block. This is stone clad exterior directly onto the poroton.
> 
> Not an expert but the poroton block is  'breathing' system and is usually used ith specialist plaster. I know there have been damp issues with the poroton block/ stone walls. House owner is having to repoint walls to try and resole the problem.
> 
> Suggest if you want to use the poroton block go and look at some actual house builds!!!!!!!



Thanks John 1957 for that info.

I think the problem with the stone walls is that the poroton block is a breathing system as you say and stone doesn't breath.

Air borne moisture may try to migrate as normal through the poroton construction, only to meet the impervious stonework.

I used to have a link to difficulties with stone houses in Scotland -ah!

[broken link removed]

You have to think a bit to get your head around the principles.

If you build or point with cement mortar this may make the problem worse, as it doesn't breath, whereas lime mortar does.

FWIW

ONQ.

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon as a defence or support - in and of itself - should legal action be taken.
Competent legal and building professionals should be asked to advise in Real Life with rights to inspect and issue reports on the matters at hand.


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## forgotten (2 Mar 2010)

never saw any settlement cracks or otherwise on german sites.
noticed that a lot of celtic tiger blocklayers lay on the mortar beds incredibly big which might contibute to water ingress in that poroton build john 1957 mentioned.
who kmows?


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## onq (6 Mar 2010)

forgotten said:


> never saw any settlement cracks or otherwise on german sites.
> noticed that a lot of celtic tiger blocklayers lay on the mortar beds incredibly big which might contibute to water ingress in that poroton build john 1957 mentioned.
> who kmows?



Thanks forgotten.

I was thinking that the joint itself might end up opening up a little because it wasn't supported on an inner leaf - the floor loads will tend to cause a bit of deflection, even in a concrete plank system.

Joints that are too thick in a lime-mortar system aren't clever. Striking the right balance between mortar and what the mortar is jointing is the key. The mansonry elements are what throw off the bulk of the incident rain. Reduce the argument to absurdity and think of a whole wall made out of lime-mortar - what would it be like at keeping out the rain?

ONQ.


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## Superman (6 Mar 2010)

Brigid said:


> Is it cost effective? when you take into consideration all the different factors that go into the normal cavity block method.
> Is it difficult to use to construct with - I remember reading that if not used exactly correctly it can leak etc.


I've only done preliminary investigations on this as a build method.
So stuff I've come across:

A big issue would be that it is a single leaf system - and so would be inherently more likely to have air tightness problems, unless you are going to stick in air tightness membranes etc.
Also unless you are going to employ some specialist builders, local builders will be unfamiliar with the construction method. 

One particular difficulty is about chasing for electrical cables etc. internally - which is a bit of a mess.  Best to keep electrics to internal walls only, or to run a service cavity along the external elevations.  
Also you will have difficulty putting up curtains and kitchen units.  You'll need to ensure that timber dowels are "rammed" into the external wall early to take curtain poles.



> Is it true that it gives a very good u-value which is definite and not at the mercy of insultation being inserted correctly? and there are no thermal bridges etc?


There are thermal bridges - esp. at lintols etc..  It is better than some forms of construction regarding "claimed" U value compared to "actual" U value - with the caveats about air tightness.

It does also appear to be a more expensive construction method - though it does lend itself to building something yourself.  

I personally am not convinced that it is a superior system to a good quality timber frame in an Irish building environment.


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## forgotten (7 Mar 2010)

its a single leaf construction about 8inchs to 14 inchs wide depending on the poroton block you use. the blocks key into each other on the vertical joint and you use thin bed mortar or glue along the beds.  the blocks are laid very tight together which should help airtightness. local builders might be  unfamiliar with it -but if i know irish builders it wont stop them building it for you!!
surprised you throw in the curtain and kitchen problem as they seem to have solved that technological problem already in europe
cutting chases for electrical cables etc is easier with poroton than with concrete block.
not sure about thermal bridging at lintols. 
 it is more expensive, but i read somewhere that all houses are to be built to passive house standard by 2016.
agree that a well built timber frame is an alternative.


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## onq (7 Mar 2010)

forgotten said:


> <snip>
> it is more expensive, but i read somewhere that all houses are to be built to passive house standard by 2016.
> agree that a well built timber frame is an alternative.



Its Carbon Neutral by 2013.

Discussion of several issues here:
http://www.askaboutmoney.com/showthread.php?p=969979

I've started another thread on this matter and given my opinion - please feel free to contribute.

ONQ.


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