Concrete Block Options - Fibolites?

[VDubDan]

So, the time has come to start above the DPC so I need to finalise the specification of the wall.

Here's what I do know:

External Finish: Traditional sand/cement render w/ pebbledash to match existing house
Internal Finish: Dot & Dab and/or studded out
Caivty: 100mm, partial fill*

*The NHBC reckon full fill insulation can have issues with rendered walls

Right now I'm having analysis paralysis over the number of different types of block. I'll be honest, I'm not loving thermalites/celcon and I gather they're near enough a no-no for rendering. And as a it's a utility there may be some heavy stuff to hang such as kitchen cabinets.

On the other hand, I'm not excited about the prospect of laying 500 odd dense blocks.

Right now I'm pondering on fibolites - they seem to be the best of all worlds? Or maybe play it a bit safer with a Hemelite Medium Dense 3.6 block? (I realise I need to do my U Value calcs before finalising)

Would love to hear peoples general opinions and favourites

Also, can anyone confirm that 3.6N blocks are okay for a single storey?

 

[cdbe]

Sorry I can't really help you but I'd love to be laying heavy blocks. I'm using thermalite turbo blocks (2.9N) with a 75mm full fill cavity and it's a PIA!. The blocks are so light the insulation batts keep pushing the blocks outwards, especially on the DPC course where there's no real adhesion at the bottom. I had to prop them up till they went off:

If you can sort out the u values I'd use heavy blocks throughout - and think of the muscles you'll have at the end!!

 

[garyo]

I used fibolites on the outer leaf and light weight blocks on the inner. Makes your purchasing and wastage a bit more challenging obviously.

 

[VDubDan]

I used fibolites on the outer leaf and light weight blocks on the inner. Makes your purchasing and wastage a bit more challenging obviously.

Cheers! I certainly don't mind a mix and match approach. How did you find rendering the fibolites?

What do you mean by "lightweight blocks", sorry?

 

[acurachris]

Also, can anyone confirm that 3.6N blocks are okay for a single storey?

They should be fine. I'm using 2.9N Celcon Solar blocks on the inner leaf of a two storey extension (the 2.9N good up to 2 storeys). I've found the blocks super absorbent, drawing the moisture from the mortar very quickly, so I'd imagine rendering to such a block would be a PITA.

 

[noseall]

We used a 7n fibloite on the outside (3.5's internally) of this job....

Garage1

• noseall
• 15 Mar 2019

 

[VDubDan]

We used a 7n fibloite on the outside (3.5's internally) of this job....

Garage1

• noseall
• 15 Mar 2019

Looks amazing - what are you up to next weekend

Do you mean 3.5 Fibolite inside, or 3.5 normal block?

Presume you find them to be decent?

Why 7's on the outside, if the inside is the load bearing wall? Just denser for rendering etc?

 

[noseall]

Why 7's on the outside, if the inside is the load bearing wall? Just denser for rendering etc?

Correct.

 

[garyo]

How did you find rendering the fibolites?

No complains from the rendering chaps, and it's all good 18 months later.

What do you mean by "lightweight blocks", sorry?

Just the usual fare... 3.5N aerated concrete such as celcons/thermalites.

 

[VDubDan]

Fibolites or Aglites it is, then. Now I just need to source the buggers!