Barn conversion Cheshire

[Lessip]

Looking for answers related to Sips, mvhr, underfloor heating and best flooring

[IanR]

30 minutes ago, Lessip said:

Looking for answers related to Sips, mvhr, underfloor heating and best flooring

Hi and Welcome.

SIPs = don't do it, go for a twin wall or I Joist structure and cellulose blown insulation
MVHR = great benefits, but only if combined with a < 1.5m³/m².h @ 50Pa infiltration rate.
UFH = no regrets
Best Flooring = Hmm, subjective one, but combined with UFH I'd suggest PU poured Resin.

Good Luck!

[sgt_woulds]

I agree, using SIPs was the worst decision I ever made!  If I could do it again, I would use Kithurst NIPPS or Ecocon panels or other similar products, that not have nasty PIR and have better structural flexibility than PU SIPs.   Also better for the environment and internal healthy air. 

 

Also, consider accoustics - SIPs are awful for noises resonating through the drum-like skins.  If you live under a flight path you'll regret SIPs.  

 

Also consider decrement delay - SIPs are good at keeping internal heat in, but are rubbish at keeping external heat out.  I used woodfibre externally to counter this to some extent, but a build-up with decrement delay is probably going to be more important than ultimate u-values for the short winter months in the coming decades.

 

MVHR - great, but expensive for what it is.  Best with passiv house levels of airtightness.  If you are self-building, you should always aim for Passivhouse, even if you don't plan to have it certified.  Pick your builders and specifiers well to achieve this.  

 

UFH - wet underfloor any day. But if my house was passivhouse, it probably wouldn't need it except in bathrooms where it works a treat

 

I wouldn't have PU resin in any house that I intended to breath in.  Too many VoCs - especially when heated by UFH.

 

 

 

 

[IanR]

13 minutes ago, sgt_woulds said:

II wouldn't have PU resin in any house that I intended to breath in.  Too many VoCs - especially when heated by UFH.

That's a complete misunderstanding of the product.

[sgt_woulds]

I'll bow to your knowledge with suitable evidence.

 

PU resins (at least those I've had experience with in industrial cement repairs) generally contain solvents to liquify them to allow pouring and shaping.  The solvents off-gas as it hardens.  Adding warmth generally speeds up this process.  

 

Do the resins used in modern flooring use a different process?

 

 

 

 

 

[Nickfromwales]

16 minutes ago, sgt_woulds said:

I'll bow to your knowledge with suitable evidence.

 

PU resins (at least those I've had experience with in industrial cement repairs) generally contain solvents to liquify them to allow pouring and shaping.  The solvents off-gas as it hardens.  Adding warmth generally speeds up this process.  

 

Do the resins used in modern flooring use a different process?

 

 

 

 

 

If these are outside your airtight envelope and you have MVHR then the subject is almost entirely moot, is it not?

 

You can choose EPS in the floor, or PIR + additional membrane, so as to minimise / eradicate the effects of such off-gassing.

 

4 hours ago, Lessip said:

Looking for answers related to Sips

Go twin wall and pump the voids with Warmcell (cellulose) insulation. If you do go SIPs then check the spec as you may find additional PIR has to be installed to meet b regs minimum requirements, which is more time / money / complexity, and often omitted by the frame erector so they can get in and out and on the road to the next one. 😕

[IanR]

4 minutes ago, sgt_woulds said:

The solvents off-gas as it hardens. 

For some PU resins, voc's would be released during the curing process, once cured there is no further off-gassing whether or not heat is applied. That statement doesn't cover all PU foams where a foaming agent is used. Good ventilation is recommended during the 5 days of curing. There are also low-voc and zero-voc options that reduce off-gassing during the curing phase.

 

15 minutes ago, sgt_woulds said:

(at least those I've had experience with in industrial cement repairs) 

 

Wouldn't that be epoxy based for cement repairs, or are you referring to a PU sealant to fill cracks? Epoxy resins do continue to off-gas after curing, although at a much lower rate than during curing.

[Nickfromwales]

4 hours ago, Lessip said:

mvhr, underfloor heating and best flooring

You don’t mention airtightness? That’s # 1 on the list, and imo more important than the insulation solution(s). 

[Nickfromwales]

4 hours ago, sgt_woulds said:

Also, consider accoustics - SIPs are awful for noises resonating through the drum-like skins.  If you live under a flight path you'll regret SIPs.  

 

Also consider decrement delay - SIPs are good at keeping internal heat in, but are rubbish at keeping external heat out. 

I’ve been saying this for years…. Ideal for commercial or affordable etc, but not for a dream / forever home.

 

Lots who have chosen SIPs still try to defend the choice, but it’s crap. Take that person to a cellulose blown TF house (walls and roof) and they’ll shut their mouths in a millisecond. Graveyard silent vs you thinking a window has been left open somewhere.

 

Ive had to specify cooling for other such instances, and I get questions on “will I really need to spend out on cooling?”…..”yes you will”.