Fibolite Blocks

[MortarThePoint]

I'm thinking of swapping to Fibolite blocks. When I first heard of them they sounded a bit 'high tech' for my reasonably traditional approach to the superstructure. I was also wary of cracking concerns having heard of it associated with other thermally performant blocks. Whilst Fibolite blocks help with U-values, the absolute requirement in my mind for the blocks to perform their structural role and I'm not wanting to make any sacrifices there. I'm sure like all self builders, I want my house to still be standing in a couple of century's time ?.

 

What do people think, does anyone have anything to say against Fibolite blocks?

[PeterW]

What are you trying to achieve..? They are only an AAC block using clay bead not fly ash or shale or something similar. AAC blocks are much of a muchness - 7N or 10N are fine, 3.6N for non load bearing walls, all the manufacturers are pretty much the same. 

[MortarThePoint]

  On 01/06/2020 at 20:59, PeterW said:

What are you trying to achieve..? They are only an AAC block using clay bead not fly ash or shale or something similar. AAC blocks are much of a muchness - 7N or 10N are fine, 3.6N for non load bearing walls, all the manufacturers are pretty much the same. 

Expand  

 

Are you sure they count as an AAC block? They aren't foamed concrete, but are an aggregate block. The aggregate is foamed/aerated though:

    "Expanded clay nodules are produced by sophisticated pyrogenic technology whereby geochemically specific clay is expanded in a rotary kiln at high temperature."

but it claims to be "Class 1 aggregate as defined in BS 5628 -3"

[PeterW]

Yep - they are clay beads cement bonded

 

 

Ultra-lightweight and lightweight blocks are manufactured from cement together with one of a variety of natural or man-made expanded aggregates including: granulated/foamed blast-furnace slag, expanded clay or shale, furnace bottom ash (FBA) and fly ash (FA). The density of the aggregate is generally proportional to the strength of the block.

 

 https://www.modernmasonry.co.uk/mma/Resources/Aggregate-Blocks.aspx

[MortarThePoint]

Can anyone recommend a good alternative for 10.4N blocks as Fibolites only go up to 7.3N? Aglite Ultima also made by Plasmor aren't as good thermally and they can have some odd constituents that I wouldn't want in the living space.

 

Fibolite   7.3N   k=0.28W/mK

Aglite (special order)   10.4N   k=0.36W/mK

Stranlite   10.4N   k=0.43W/mK

[PeterW]

What are you building that needs 10.4N blocks..?

 

3.6N are good to 3 storey, 10's are used for significant point loading or high stress situations

[MortarThePoint]

  On 11/06/2020 at 15:21, PeterW said:

What are you building that needs 10.4N blocks..?

 

3.6N are good to 3 storey, 10's are used for significant point loading or high stress situations

Expand  

 

Specified by the Structural Engineer as we have some long runs without perpendicular walls or bracing and concrete first floor

[Mr Punter]

I have never had 10 newton blocks specified.  They often spec wind posts to add strength / support.

[MortarThePoint]

  On 11/06/2020 at 15:28, Mr Punter said:

I have never had 10 newton blocks specified.  They often spec wind posts to add strength / support.

Expand  

 

Yes got some windposts as well ?

[PeterW]

Strong blocks won't help you with a long wall - only bracing or wind posts as per @Mr Punter will help with that.

[MortarThePoint]

Must be the hollowcore concrete flooring then

[epsilonGreedy]

3.7N fibolites are the default choice for inner block walls in my part of the world. I would classify them as belonging to the light end of medium weight blocks at 8.9Kg per block from memory. When I enquired about ordering 7N Fibolites my BM said that would be a special order though I did notice packs of blue-stripe 7N fibolites onsite at an upmarket millionaire type private build in Boston the other day.

 

Fibolites are quite distinct from the typical light weight blocks which have the consistency of a Cadburys whisper bar. My brickie likes them because when laying courses above chest height he can lower an 8.9 kg  block onto a bed of mortar with one hand, that said my simple masonry property does not have the engineering challenges that you mention.

[epsilonGreedy]

  On 11/06/2020 at 15:44, PeterW said:

Strong blocks won't help you with a long wall - only bracing or wind posts as per @Mr Punter will help with that.

 

Expand  

 

Can metal mesh roll laid on mortar beds provide an alternative reinforcement against wind pressure on large masonry panels?

[PeterW]

  On 11/06/2020 at 15:53, epsilonGreedy said:

 

Can metal mesh roll laid on mortar beds provide an alternative reinforcement against wind pressure on large masonry panels?

Expand  

 

No - the point of a windpost is it resists buckling and transfers the load to the floor structure. Most houses don't need them as there are perpendicular walls (don't need to be load bearing) that do the job anyway.

[MortarThePoint]

I'm ordering the blocks (ouch) and made a decision I thought I'd gauge people's thoughts on [over-analysing hat on again]. I decided to stick with a single 7.3N block type, rather than using 7.3N Fibolite for the inner leaf of exterior walls and 7.3N Stranlite for the load bearing partitions. So Fibolites for both wall types. I saw the pros and cons as:

 

Pro's to using Fibolite internally:

• single block type for brickies
• order simplicity

Con's

• cost (51.4m2 @ £1.52/m2 difference --> £78.18)
• acoustics?
• lower thermal mass (950 vs 1350)

Bit worried about the acoustic side of it. Does anyone have any experience of how well Fibolite blocks damp sound?

[MortarThePoint]

Fibolites seem to have 3dB less attenuation than Stranlites. I think that means the transmitted sound energy is double in the case of Fibolite. I don't know what a stud wall looks like in terms of sound attenuation though for comparison.

 

Fibolite 100mm (850 kg/m³) :

https://www.plasmor.co.uk/uploads/files/Technical_Library/Technical_Data_&_Reports/Acoustic Test Certificates/100mm_Fibolite_-_Plastered.pdf

 

Stranlite 100mm (1400 kg/m³) :

https://www.plasmor.co.uk/uploads/files/Technical_Library/Technical_Data_&_Reports/Acoustic Test Certificates/100mm_Stranlite_-_Plastered.pdf

 

Edited June 25, 2020 by MortarThePoint

[Wagas]

  On 01/06/2020 at 20:59, PeterW said:

What are you trying to achieve..? They are only an AAC block using clay bead not fly ash or shale or something similar. AAC blocks are much of a muchness - 7N or 10N are fine, 3.6N for non load bearing walls, all the manufacturers are pretty much the same. 

Expand  

 

Just resurrecting this... I was planning on using 3.6N Fibolite's for all walls including load bearing. From the Plasmoor web site I think this seems to be fine. Do you think otherwise? Thanks

[PeterW]

What has the engineer specified ..?

[MortarThePoint]

  On 26/04/2021 at 19:06, Wagas said:

 

Just resurrecting this... I was planning on using 3.6N Fibolite's for all walls including load bearing. From the Plasmoor web site I think this seems to be fine. Do you think otherwise? Thanks

Expand  

 

3.6N feels a bit on the low side to me for load bearing. Has the Structural Engineer specified 3.6N? There may not be much of a price difference between 7.3N and 3.6N. There was a point in time when I had 4 types of 100mm block on site (7.3N Stranlite, 7.3N Stranlite paint grade, 7.3N Fibolite, and 10.4N Stranlite). I wouldn't do it again that way. Structural Engineer hadn't called for anything more than 7.3N for 100mm blocks so wasn't critical.

Edited April 26, 2021 by MortarThePoint

[MortarThePoint]

  On 26/04/2021 at 20:13, MortarThePoint said:

There may not be much of a price difference between 7.3N and 3.6N.

Expand  

 

As an example, my copy of SPON's has 7.0N Hemelite @15.51/m2 and 3.5N Hemelite @ 15.76/m2, so 7.0N cheaper than 3.5N.

[Critical Path]

Wagas - Had same quandary myself, ended up with Plasmore Stranlte 7 Newton. light enough and barley affected u value, 

currently paying 73 p. each. in Manchester. 

[MortarThePoint]

  On 29/04/2021 at 12:22, Critical Path said:

Wagas - Had same quandary myself, ended up with Plasmore Stranlte 7 Newton. light enough and barley affected u value, 

currently paying 73 p. each. in Manchester. 

Expand  

 

That's a great price. I was paying £1.153 each in June last year down near Cambridge. As soon as I had a quote from one BM, the job was known and I got the same price form others.

[MortarThePoint]

For reference, I have had some cracking of blocks under 1.8m wide windows (near middle of window). Hopefully this is just shrinkage, but I thought I would share it on this thread as it was one of the Fibolite considerations. I suspect if we had used a layer of bed joint reinforcement in the bed just under the window this wouldn't have happened, but ultimately the shrinkage has to be accommodated somewhere and arguably under a window is the best place (?). This photo shows the worst of it (so far, but 6 months after being laid).

[epsilonGreedy]

  On 17/05/2021 at 08:06, MortarThePoint said:

For reference, I have had some cracking of blocks under 1.8m wide windows (near middle of window). Hopefully this is just shrinkage

 

Expand  

 

Is this on the first floor above wooden joists embedded within the blockwork??

 

 

[MortarThePoint]

  On 17/05/2021 at 09:18, epsilonGreedy said:

Is this on the first floor above wooden joists embedded within the blockwork??

Expand  

 

It's on the first floor but above concrete (HCF) floor planks that rest on the inner leaf.

 

Edited May 17, 2021 by MortarThePoint