T stud

[scottishjohn]

this  looks is very interesting development in TF construction --

[ProDave]

A sort of SIP stud?

[Simplysimon]

progress, they'll get there in the end......  just use an i beam ?

[Russell griffiths]

I did watch that the other night and thought that the yanks had gone about this in a strange way, i joist and celotex would do exactly the same. 

[Ed Davies]

10 hours ago, Simplysimon said:

progress, they'll get there in the end......  just use an i beam

 

With a lot of labour and some thermal bridging for the blocking which I-beams need.

[PeterW]

I did wonder about the strength in the dowel system that they used as it seemed a bit “rustic”.... 

[Ferdinand]

Need help here.

 

Can someone convert an R20 wall into European for me? It seems to be a US terminology that is rarely explained. I have never made the calculations quite work as straight R values.

 

2.25 inches of foam insulation does not seem like a lot, and he suggested that that removed the need for anything else.

 

Thanks

 

Ferdinand

Edited June 8, 2019 by Ferdinand

[andyscotland]

R is 1/u and vice versa. So R20 is a u value of 0.05 (against 0.13 for standard timber).

 

I don't think he was saying that's all you need, you still have e.g. wool between studs at 0.039 but the studs form much less of a thermal bridge. So you can get a good overall wall u-value without having a secondary continuous layer of insulation in front of / behind the studs.

 

Edit: this post is nonsense but I'm leaving it as an example of what happens if you come on here before your morning coffee.

Edited June 8, 2019 by andyscotland
Incorrect information

[Jeremy Harris]

23 minutes ago, andyscotland said:

R is 1/u and vice versa. So R20 is a u value of 0.05 (against 0.13 for standard timber).

 

I don't think he was saying that's all you need, you still have e.g. wool between studs at 0.039 but the studs form much less of a thermal bridge. So you can get a good overall wall u-value without having a secondary continuous layer of insulation in front of / behind the studs.

 

 

Bear in mind that video is from the USA, so the R value is in US units, not metric.  The U value is definitely not 0.05 W/m².K, it's more like 0.24 W/m².K.

[andyscotland]

@JSHarris ahhhh thanks - I had no idea the US R values were different! Though of course it makes total sense that they are...?‍♂️

[Ferdinand]

43 minutes ago, andyscotland said:

R is 1/u and vice versa. So R20 is a u value of 0.05 (against 0.13 for standard timber).

 

I don't think he was saying that's all you need, you still have e.g. wool between studs at 0.039 but the studs form much less of a thermal bridge. So you can get a good overall wall u-value without having a secondary continuous layer of insulation in front of / behind the studs.

 

Was working on this.

 

There is no way his wall with 55mm of foam has a u value of 0.05, which is half of the u value of one of our walls with 150mm  of celotex, and about twice as good as required by passive. And he was talking about R30, nevermind R20.

 

When I renovate a solid 9” brick wall I roughly need 75mm of PIR to get under 0.25 for the u-value.

 

So .. is there a rule of thumb for getting to grips with these USA units?

 

Cheers

 

Ferdinand

Edited June 8, 2019 by Ferdinand

[Jeremy Harris]

15 minutes ago, andyscotland said:

@JSHarris ahhhh thanks - I had no idea the US R values were different! Though of course it makes total sense that they are...?‍♂️

 

 

The US use °F·ft²·h/BTU  for R values, whereas we use K·m²/W .

[andyscotland]

1 minute ago, JSHarris said:

 

 

The US use °F·ft²·h/BTU  for R values, whereas we use K·m²/W .

 

That's basically an entire sequence of units I have no concept of apart from the hours! And perhaps the ft² if I picture it as a ruler by a ruler ?

[Ferdinand]

1 minute ago, JSHarris said:

 

 

The US use °F·ft²·h/BTU  for R values, whereas we use K·m²/W .

 

If I wear a stove pipe hat like Mr Brunel, will it teleport be far enough back in time to do an appropriate Mindwarp?

 

Let’s do the mind warp again...

[andyscotland]

6 minutes ago, Ferdinand said:

 

Was working on this.

 

There is no way his wall with 55mm of foam has a u value of 0.05, which is half of one of our walls with 125mm of celotex, and about twice as good as required by passive. And he was talking about R30, nevermind R20.

 

When I renovate a solid 9” brick wall I roughly need 75mm of PIR to get under 0.25 for the u-value.

 

So .. is there a rule of thumb for getting to grips with these USA units?

 

Cheers

 

Ferdinand

 

Indeed. My post was mince from start to finish, with the possible exception of the bit that it just makes the timber good enough to avoid it being a thermal bridge through the surrounding wool.

[Ferdinand]

 

 

8 minutes ago, JSHarris said:

 

 

The US use °F·ft²·h/BTU  for R values, whereas we use K·m²/W .

 

So based on 9/5 F = 1 C, 10.74 square feet = 1 square metre, and 1W = 3.5 BTU/hr, my fiddle factor for converting a USA R value into a European R Value is about 5.5 as a ratio with no dimensions.

 

Which means that his R20 wall has an R Value of around 3.6, or a U-Value of around 0.28.

 

If I call 5.5 to be 5 to within an engineering approximation, that is 4 and 0.25 for those numbers.

 

And that is near enough for me to think with on the fly, so I am happy.

 

Cheers

 

Ferdinand

 

[scottishjohn]

2 hours ago, Russell griffiths said:

I did watch that the other night and thought that the yanks had gone about this in a strange way, i joist and celotex would do exactly the same. 

not convinced you will ever get celotex packed in an i-joist or anything as well as this integrated stud.

you could of course use your I-joist and spray foam them ,but a different way and no metal in wall 

 

 

[A_L]

31 minutes ago, Ferdinand said:

So based on 9/5 F = 1 C, 10.74 square feet = 1 square metre, and 1W = 3.5 BTU/hr, my fiddle factor for converting a USA R value into a European R Value is about 5.5 as a ratio with no dimensions.

 

Which means that his R20 wall has an R Value of around 3.6, or a U-Value of around 0.28.

 

If I call 5.5 to be 5 to within an engineering approximation, that is 4 and 0.25 for those numbers.

 

And that is near enough for me to think with on the fly, so I am happy.

 

@Ferdinand , you would be better using 6 rather than 5 as the correct value is 5.678.

[Ferdinand]

15 minutes ago, A_L said:

 

@Ferdinand , you would be better using 6 rather than 5 as the correct value is 5.678.

 

Yes, but for intermediate calcs when doing approximations I tend to work in 5s and 10s then adjust by multiples of 10% at the end. And here I am just after something better than a guesstimate. That is growing up with Countdown.

 

So 6 would be 5 plus 10% twice. But thanks. 5.678 is a nice one to remember. 

 

No idea how other people do this. I have a mate who counts indetermine numbers of ‘things’ by mentally arranging them into dominoes.

 

And this is also why I will personally put out a contract on any politician who sets VAT to a Prime Number.

 

Do people who grew up with LSD work in 12s and 6s? Which does actually fit with dice and dominoes.

 

F

Edited June 8, 2019 by Ferdinand

[Jeremy Harris]

5 hours ago, Ferdinand said:

Do people who grew up with LSD work in 12s and 6s? Which does actually fit with dice and dominoes.

 

 

Not really, I just think of psychedelic patterns and things moving when they shouldn't...

[Simplysimon]

5 hours ago, Ferdinand said:

 

Do people who grew up with LSD work in 12s and 6s? Which does actually fit with dice and dominoes.

 

F

can't remember, i keep getting flashbacks