Timber framed VS SIP build.

[joe90]

4 hours ago, Thorfun said:

did any Rockwool get installed between floors? interested to know as we've put 100mm of Rockwool between our posi-joists and I'm hoping that will sufficiently reduce the noise transfer.

 

EPS of a structural engineered calculated compression rating will

Ditto, I was disappointed in sound transfer between floors despite sound insulation between pozi joists, i wish I had double boarded with sound bars.

 

Sorry I meant PIR / EPS “type” rather than rockwall “type”

Edited August 12, 2023 by joe90

[Elton]

I have a kingspan timber frame house. Sound transfer and a solid feeling floor was a priority for me so I had the pozijoists at 300mm centers and put 50mm of cemflow screed upstairs. There is 100mm rockwall between joists.

We haven't moved in yet but all tests show low noise transfer between up and downstairs and there are still carpets to go down. The extra cost for the joists was around £1500 and the cemflow £2500

[Iceverge]

250mm cavity here in South West Ireland. 

 

Full fill with EPS beads, wet plastered both sides of the blocked. No issues with full fill. Infact it's the standard method for cavity walls here and believe me, we get our share of rain. 

[IanR]

12 hours ago, LA3222 said:

probably the single most important thing to take into consideration....the method of build is irrelevant,

 

That suggests all insulation is equal and it's just a matter of choosing your product and appropriate thickness to meet your performance target. If that were the case then PIR/PUR insulation would be very competitive as few cost-effective insulations can achieve its U value within a given thickness.

 

While I was investigating SIPs for my own build there were just too many unanswered questions with regards both PIR/PUR insulation and the SIPS themselves. I have a timber cladding rain screen and an Aluminium roof, so was  concerned about decrement delay of the insulation and acoustic performance. I also had the experience of my existing home that had dormers with building regs levels of PIR insulation between the rafters and suffered from large temperature swings and very poor acoustics, even with a traditional tiled roof.

 

When I got further into the detail of the build and started to spec for PassivHaus levels of performance, the real levels of performance for the "as-designed" SIP panels didn't meet marketing due to timber fraction and cold bridging, especially for the roof. Additional layers of board insulation were then required to mitigate these inherent shortfalls in the product.

 

You also need to be comfortable with any potential toxicity and performance degradation related to off-gassing. While I was researching there was little definitive information and the distributors just dismissed any concern. One comment was "oh that was in the 80's", products are different now". Sick Building Syndrome is a real thing (although not only related to insulations), off-gassing, shrinkage and aging is a real thing and is to some extents accounted for with some performance specs.

 

The choice I went with in the end was a blown cellulose fibre as its longer decrement delay is better suited to my choice of a lightweight rain screen, and good acoustic performance is a better choice for a vaulted ceiling, with the added benefit that its inclusion improves airtightness rather than needing additional actions to mitigate its short-comings. The reduced insulating properties though do mean I've had to give a away a bit of floor area for a bit of extra wall thickness to achieve the same U value.

[MikeSharp01]

13 minutes ago, IanR said:

The choice I went with in the end was a blown cellulose fibre as its longer decrement delay is better suited to my choice of a lightweight rain screen, and good acoustic performance is a better choice for a vaulted ceiling, with the added benefit that its inclusion improves airtightness rather than needing additional actions to mitigate its short-comings. The reduced insulating properties though do mean I've had to give a away a bit of floor area for a bit of extra wall thickness to achieve the same U value.

Our architect gave us the idea of a composite insulation scheme so as to get the great decrement delay of blown Cellulose and the effective insulation properties of PIR as well. So we went stick (using engineered 300mm I-Beams) with an outer sheathing of OSB. Outside the OSB we have a layer of PIR (varies between 40 and 75mm thick) and between the I-beams we have blown cellulose. So we now have the best of both worlds thinner walls than would have been needed to achieve our U value using just the blown cellulose and still great U value of (generally)  0.099 W/(m²K)

[Iceverge]

2 hours ago, MikeSharp01 said:

Our architect gave us the idea of a composite insulation scheme so as to get the great decrement delay of blown Cellulose and the effective insulation properties of PIR as well. So we went stick (using engineered 300mm I-Beams) with an outer sheathing of OSB. Outside the OSB we have a layer of PIR (varies between 40 and 75mm thick) and between the I-beams we have blown cellulose. So we now have the best of both worlds thinner walls than would have been needed to achieve our U value using just the blown cellulose and still great U value of (generally)  0.099 W/(m²K)

 

A layer of board insulation outside a frame makes a lot of sense. It keeps the sheathing warm and really mitigates the effects of any thermal bridging around openings. 

 

What is inboard of the cellulose in your case? A variable membrane or just plasterboard? 

[LA3222]

6 hours ago, IanR said:

 

That suggests all insulation is equal and it's just a matter of choosing your product and appropriate thickness to meet your performance target. If that were the case then PIR/PUR insulation would be very competitive as few cost-effective insulations can achieve its U value within a given thickness.

 

While I was investigating SIPs for my own build there were just too many unanswered questions with regards both PIR/PUR insulation and the SIPS themselves. I have a timber cladding rain screen and an Aluminium roof, so was  concerned about decrement delay of the insulation and acoustic performance. I also had the experience of my existing home that had dormers with building regs levels of PIR insulation between the rafters and suffered from large temperature swings and very poor acoustics, even with a traditional tiled roof.

 

When I got further into the detail of the build and started to spec for PassivHaus levels of performance, the real levels of performance for the "as-designed" SIP panels didn't meet marketing due to timber fraction and cold bridging, especially for the roof. Additional layers of board insulation were then required to mitigate these inherent shortfalls in the product.

 

You also need to be comfortable with any potential toxicity and performance degradation related to off-gassing. While I was researching there was little definitive information and the distributors just dismissed any concern. One comment was "oh that was in the 80's", products are different now". Sick Building Syndrome is a real thing (although not only related to insulations), off-gassing, shrinkage and aging is a real thing and is to some extents accounted for with some performance specs.

 

The choice I went with in the end was a blown cellulose fibre as its longer decrement delay is better suited to my choice of a lightweight rain screen, and good acoustic performance is a better choice for a vaulted ceiling, with the added benefit that its inclusion improves airtightness rather than needing additional actions to mitigate its short-comings. The reduced insulating properties though do mean I've had to give a away a bit of floor area for a bit of extra wall thickness to achieve the same U value.

I didn't suggest all insulation is equal, my point was/is that once you decide what airtightness and u value you want to achieve etc then any build method can achieve those values. The key factor in any build is the quality of workmanship and not the method of build. You can champion a particular build method if you like bit a crap tradesman can still make a hash of it. 

 

There is a fabled blown cellulose company championed on here and I recall early in the days of buildhub there were a few on here having some not insignificant issues. The 'best' build method can be cocked up, equally you cam lump for brick and block and achieve a great build given quality tradesmen and the right method.

 

Timbre fraction.and cold bridging...whatever. The vast majority of timber frame construction will be your standard 140mm stud and not larson Truss. SIP has far less timber coldbridging than standard timber frame.

 

Decrement delay is another load of nonsense championed on here. I did all the calcs with my build early on ref Dec delay etc and iirc my build was 14hrs plus....means feck all because eventually the heat will get in and guess what, all that insulation now works against you by trapping the heat in.

 

My build is something like 0.4ach, 0.1 for u values and triple glazed windows.

 

My top tip for future self builders, get the air tightness and u values as low as you can, put plenty of solar on the roof and stick air con in the house - I considered it and wish I had....the solar would mean it costs nothing.

 

My house is significantly cooler than outside but like I say, with windows etc eventually the heat will get in and then you're no better off than a normal house.

Edited August 12, 2023 by LA3222

[MikeSharp01]

15 hours ago, Iceverge said:

A variable membrane or just plasterboard? 

Intello plus membrane, 50mm service void finally fire rated plasterboard (dry lined).

[eandg]

On 11/08/2023 at 23:23, LA3222 said:

I have a SIP build, I am not sure why folks who don't have one are dismissive. The one thing I have learned through doing a self build is probably the single most important thing to take into consideration....the method of build is irrelevant, you'd be splitting hairs and if you standardise the ask I.e insulation/airtightness then king becomes cost; it is the application of the chosen method which is key. A supposedly great system can be Total shite if cobbled together by a bloke with one eye and three digits missing off each hand.p

 

You can achieve really tight specs with whatever method, it's the effort in monitoring that is essential.

Agreed. Plus our vaulted ceilings are great and our SIPs roof with a metal covering is noise free, can only hear the rain off the rooflights, with no traffic noise at all unless a window is opened. 

[SteamyTea]

16 hours ago, LA3222 said:

Decrement delay is another load of nonsense championed on here

I have to agree with that.

Should really be called thermal inertia. Thermal inertia assumes all the wall/roof buildup plays an equally important part, which it does not.

Then stick in an oversized SW facing window and all the calculations go, literally, out the window.

 

Cellulose is good for sound damping, but I don't know where adding an extra 50mm stops being of real benefit.

[joe90]

9 minutes ago, SteamyTea said:

I don't know where adding an extra 50mm stops being of real benefit.

True fir all insulation, diminishing  returns springs to mind.

[SteamyTea]

3 minutes ago, joe90 said:

True fir all insulation, diminishing  returns springs to mind.

Yes, but at least we can calculate the conductivity.

Thermal insulation is really down to how little energy you want to leave the building, if you start to base decisions on diminishing returns, it rather misses the point.

All nonsense really as there is no difference in cleanliness between a £100 shower and a £500 shower. Same as a kitchen top makes no difference to the taste of the food. 

[MikeSharp01]

46 minutes ago, SteamyTea said:

Should really be called thermal inertia.

Probably and

 

47 minutes ago, SteamyTea said:

Thermal inertia assumes all the wall/roof buildup plays an equally important part, which it does not.

so does decrement delay as a concept.

 

16 hours ago, LA3222 said:

Decrement delay is another load of nonsense championed on here.

Not sure that is correct - they are / it is an example of 'porridge words' Edward De Bono framed the term I believe and since then the idea has somewhat grown into a Gestalt! EG:

 

Porridge words

 

Porridge words are rather meaningless words.

It is precisely because they are meaningless that they are so immensely useful in thinking.

They act as link words to keep thought moving from one idea to another.

If there were no such words then thinking would come to a dead end when there was no direct step to another specific idea.

The various uses are listed below:

1. Porridge words allow one to set up vague questions when one has not enough information to ask a specific question.
2. Porridge words offer usable explanations when one cannot provide any more detail.
3. Porridge words act as cross-links for movement from one idea to another.
4. Porridge words can act as black boxes to enable one to leap-frog over an area of ignorance and carry on.
5. Porridge words prevent too early a commitment to a specific idea and so keep options open as long as possible.

The paradox is that porridge words arise from ignorance and yet they become immensely useful thinking tools in their own right.

 (From: https://bobembry.blogspot.com/2012/03/porridge-words.html 13.08.2023)

 

I sort of favour 5 as the option here but we can discuss / disagree as needed.

[SteamyTea]

26 minutes ago, MikeSharp01 said:

porridge

An old American girlfriend of mine used the word Porridge for semen. 

Could that, once anglicize, become 6 on the list 'load of bollocks'?

[Iceverge]

7 hours ago, MikeSharp01 said:

Intello plus membrane, 50mm service void finally fire rated plasterboard (dry lined).

 

Insulated service cavity?

[joe90]

5 hours ago, SteamyTea said:

if you start to base decisions on diminishing returns, it rather misses the point.

 

I disagree, it’s always been said the first inch of insulation is the most valuable and added Inches add diminishing returns. With mine I decided that a 200mm cavity filled with insulation was worth the money/efficiency but any more and the payback would be beyond my lifetime.

[SteamyTea]

1 minute ago, joe90 said:

but any more and the payback would be beyond my lifetime.

But not the planet.

 

If I had told you a decade ago that energy prices would tripled, almost over night, you would have laughed. Could have reduced your heating times by a third, and your peak heating times by 3.

 

[joe90]

1 minute ago, SteamyTea said:

But not the planet.

 

If I had told you a decade ago that energy prices would tripled, almost over night, you would have laughed

 

No, I would have not been surprised. but I built my house to my current and ongoing income AND the planet as I knew energy would not come down in price and fossil fuels were bad for the planet.

 

9 minutes ago, SteamyTea said:

Could have reduced your heating times by a third, and your peak heating times by 3.

please explain how deciding on how I could have done this by not deciding on the level of insulation I have?. Currently it only needs heating a couple of months a year and very little at that (4Kw ASHP).

 

[SteamyTea]

4 minutes ago, joe90 said:

16 minutes ago, SteamyTea said:

Could have reduced your heating times by a third, and your peak heating times by 3.

please explain how deciding on how I could have done this by not deciding on the level of insulation I have?

Your heating times were similar to mine, that was more to do with the being in the SW.

I would have to model your old house and increase the insulation levels, then see what the marginal cost would have been.

7 minutes ago, joe90 said:

18 minutes ago, SteamyTea said:

If I had told you a decade ago that energy prices would tripled, almost over night, you would have laughed

 

No, I would have not been surprised

I would have been.  Domestic energy prices had risen by less than inflation for 2 decades, but oddly stayed at about 5% of median household earnings (more to do with falling real wages).  They will gradually go back to that 5%, but the nominal price will have increased.

 

This same argument about diminishing returns has been going on since the 1970s and can be proved to be true.

You can by a large family tent, or 4, and stick a fan heater in them.  Would cost about about £110 per tent, including the tent.

The heat load will be about 1.5 kW, so £15/day for 8 months of the year (£3,500/year).

But you save the price of building a house, say £300,000, so if you had 4 family tents with fan heaters, that is:

Price of House - Price of tents and heaters = 300000 - (4 x 110) = 299,560

299,560 / 3500 = 85.6 years.

So one can argue that insulation, of any sort, is totally pointless from a financial viewpoint (it is the argument that the building trade still uses).

 

The alternative is to think about thermal loads and the associated CO_2e emissions.

Is it not better to reduce both as much as we can?

I am not saying that we need to put a metre thickness on all walls (would make my house 2 metres wide inside), but reducing, at the time of building, from the 0.25 W.m^-2.K^-1 to 0.125 W.m^-2.K^-1 would only have reduced my floor area by 8%, and as it is only about 25 metres of wall to insulate, the marginal cost would have been pretty small.

Same with floor insulation.  The one thing that building regs has improved upon.

[joe90]

5 minutes ago, SteamyTea said:

This same argument about diminishing returns has been going on since the 1970s and can be proved to be true.

👍

7 minutes ago, SteamyTea said:

You can by a large family tent, or 4, and stick a fan heater in them.  Would cost about about £110 per tent, including the tent.

The heat load will be about 1.5 kW, so £15/day for 8 months of the year (£3,500/year).

But you save the price of building a house, say £300,000, so if you had 4 family tents with fan heaters, that is:

Price of House - Price of tents and heaters = 300000 - (4 x 110) = 299,560

299,560 / 3500 = 85.6 years.

You may be comfortable living in a tent but I think most would not. If we did not insulate and invest in building houses our energy costs would be higher along with CO2 emissions .

 

10 minutes ago, SteamyTea said:

The alternative is to think about thermal loads and the associated CO_2e emissions.

Is it not better to reduce both as much as we can?

Yes by building better with more insulation spending the money once not monthly on energy.

 

11 minutes ago, SteamyTea said:

I am not saying that we need to put a metre thickness on all walls (would make my house 2 metres wide inside),

A common misconception even with new builds, everyone told me my rooms would be smaller however I decided on the room sizes then added the insulation afterwards (I know this is not possible with retro fit).

13 minutes ago, SteamyTea said:

So one can argue that insulation, of any sort, is totally pointless from a financial viewpoint

I think that many here and elsewhere would disagree with you on that 🤔

[SteamyTea]

32 minutes ago, joe90 said:

think that many here and elsewhere would disagree with you on that

I was making the point that insulation does not give a financial return, so best not to think about it that way.

Add as much as can be practically done, then up the spec to get a lower U-Value.

The problem is that people value the wrong things most if the time. A thermally comfortable house is of greater benefit than a deeper bathtub.

[joe90]

1 hour ago, SteamyTea said:

I was making the point that insulation does not give a financial return,

Yet you said….

2 hours ago, SteamyTea said:

But not the planet.

Which is why insulating is cutting energy usage which is good for the planet, and a personal investment cutting future costs to the user and giving a more comfortable living space (including a deeper bathtub if that’s what they want 🤷‍♂️)

1 hour ago, SteamyTea said:

Add as much as can be practically done, then up the spec to get a lower U-Value.

Which is what I did, (and most here) BUT working on diminishing returns limited that amount of insulation as value for money/comfort. Win win IMO.

 

Edited August 13, 2023 by joe90

[joe90]

1 hour ago, SteamyTea said:

The problem is that people value the wrong things most if the time.

Oh do we??? Anybody else want to jump in here 🤷‍♂️

[gustyturbine]

On 11/08/2023 at 18:19, ADLIan said:

Depends upon what’s in their BBA Cert. May be limited to max ‘severe’ exposure zone with masonry inner and outer. 50mm cavity still applies with sip and framed construction.

Agreed, that is what I was told during my last build.

[gustyturbine]

On 12/08/2023 at 08:00, Thorfun said:

did any Rockwool get installed between floors? interested to know as we've put 100mm of Rockwool between our posi-joists and I'm hoping that will sufficiently reduce the noise transfer.

 

EPS of a structural engineered calculated compression rating will

I went 100mm Rockwool and I was extremely disappointed. Maybe I just expected too much but you can hear conversation between floors even if you can't make out the words.