Blocks for inner skin

[Nickfromwales]

On 27/04/2025 at 20:41, Iceverge said:

 

Are you not worried about using excessive amounts of the aero barrier caulk? 

 

Keep us posted. 

I spoke to a rep(?) at AB about a woodcrete ICF job for a member on here and they say it’s just done on m2 vs the substrate so it should matter with block tbh. 
 

They just asked that you prep it as well as possible, carry out 1st fix, and they state that they will then make a ‘good’ job ‘great’. 

[SBMS]

4 hours ago, Nickfromwales said:

I spoke to a rep(?) at AB about a woodcrete ICF job for a member on here and they say it’s just done on m2 vs the substrate so it should matter with block tbh. 
 

They just asked that you prep it as well as possible, carry out 1st fix, and they state that they will then make a ‘good’ job ‘great’. 

Do you know any jobs that have had it done?

[Nickfromwales]

1 hour ago, SBMS said:

Do you know any jobs that have had it done?

Their website has projects & testimonials iirc.

I’m really becoming a fan of this idea, as the cost of tape and the time and labour to do that, plus trying to (find and) fill the nooks and crannies is a major ballache.

 

When you get the job done please do come back and let us know the results, warts ‘n all! 🙏

[SBMS]

2 minutes ago, Nickfromwales said:

Their website has projects & testimonials iirc.

I’m really becoming a fan of this idea, as the cost of tape and the time and labour to do that, plus trying to (find and) fill the nooks and crannies is a major ballache.

 

When you get the job done please do come back and let us know the results, warts ‘n all! 🙏

My thinking too. I’ll put up a post with info and photos when they arrive!

[BTC Builder]

I've got 0.17 u value, thomas armstrong 7.3n lightweight concrete blocks inner and outer skin, 100mm unilin PIR partial cavity fill.

 

Blocks 97p each, 6.48 each for the unilin.

 

[Ben1984]

48 minutes ago, BTC Builder said:

I've got 0.17 u value, thomas armstrong 7.3n lightweight concrete blocks inner and outer skin, 100mm unilin PIR partial cavity fill.

 

Blocks 97p each, 6.48 each for the unilin.

 

Interesting - what size cavity? I'm reluctant to use PIR in the cavity, but those blocks look like a good alternative to 'standard' dense concrete blocks. 

[BTC Builder]

8 hours ago, Ben1984 said:

Interesting - what size cavity? I'm reluctant to use PIR in the cavity, but those blocks look like a good alternative to 'standard' dense concrete blocks. 

 

150mm. I find pir as easy to use as dritherm, which is difficult and itchy to cut, but I don't like it getting wet and soaking through so prefer pir 

[Jane W]

On 27/04/2025 at 09:13, Ben1984 said:

My current thinking is that it can't be done.

I've also arrived at the same conclusion. I'd like wet plaster so probably going with 375 cavity. Going to check out prices of dritherm 32 vs 36 as I've been told you get much better deals on dritherm 36, which brings medium density blocks + brick outer in with u value of 0.18. Dritherm 32 would give 0.16 iirc.

[Ben1984]

9 hours ago, Jane W said:

I've also arrived at the same conclusion. I'd like wet plaster so probably going with 375 cavity. Going to check out prices of dritherm 32 vs 36 as I've been told you get much better deals on dritherm 36, which brings medium density blocks + brick outer in with u value of 0.18. Dritherm 32 would give 0.16 iirc.

375 cavity? I presume you mean 375mm wall with 175mm cavity. The price difference between 32 and 36 dritherm is significant! This thread has convinced me that a wider cavity is the way forward for my project. If internal space really was a priority I might even consider PIR over 32 dritherm.

[SBMS]

6 minutes ago, Ben1984 said:

375 cavity? I presume you mean 375mm wall with 175mm cavity. The price difference between 32 and 36 dritherm is significant! This thread has convinced me that a wider cavity is the way forward for my project. If internal space really was a priority I might even consider PIR over 32 dritherm.

Why not fill with EPS beads? Similar to 32 dritherm in thermal resistance (0.033) and cheaper when I priced ours up. FYI we are a 200mm cavity brick and block with beads and are at around 0.14 u value. 

[Ben1984]

11 hours ago, SBMS said:

Why not fill with EPS beads? Similar to 32 dritherm in thermal resistance (0.033) and cheaper when I priced ours up. FYI we are a 200mm cavity brick and block with beads and are at around 0.14 u value. 

I'm doing the blockwork (along with everything else) on our build which means there are no installation costs for the dritherml, just my time. I would have to pay a contractor to blow in the EPS beads so in my circumstances I suspect it would add to the overall cost of the structure.

I have used cavity batts many times before and I know that I can install them well. I have no personal experience with EPS beads and while they could perform slightly better I perceive them as a risk so i'm reluctant to use them.

[SBMS]

12 hours ago, Ben1984 said:

I'm doing the blockwork (along with everything else) on our build which means there are no installation costs for the dritherml, just my time. I would have to pay a contractor to blow in the EPS beads so in my circumstances I suspect it would add to the overall cost of the structure.

I have used cavity batts many times before and I know that I can install them well. I have no personal experience with EPS beads and while they could perform slightly better I perceive them as a risk so i'm reluctant to use them.

Fair enough however pumped beads installed for me was less per sqm than I could get dritherm at. I think a pumped installation will get every nook and cranny that is tricky to do by hand, but each to their own 👍

[Jane W]

On 03/05/2025 at 21:04, Ben1984 said:

On 03/05/2025 at 11:57, Jane W said:

I've also arrived at the same conclusion. I'd like wet plaster so probably going with 375 cavity. Going to check out prices of dritherm 32 vs 36 as I've been told you get much better deals on dritherm 36, which brings medium density blocks + brick outer in with u value of 0.18. Dritherm 32 would give 0.16 iirc.

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375 cavity

Yes meant to say 375 cavity wall!