Cold lost attics = good or bad insulation?

[Christophe]

Do cold roofs mean poor insulation? Yes a priori but no if we think about it more closely ...

It is a little "trap" question, a priori paradoxical, that I asked myself during our work onimproving the insulation of our lost roof spaces.

I deduced 3 possibilities:

- They are fairly well insulated BEFORE (insulation between the room and the attic) since the heat does not rise.

- They are poorly insulated AFTER (ie at the level of the roof) since the heat (there is always) does not manage to raise the temperature of the roof space.

- That they are not well insulated neither BEFORE nor AFTER: all the heat is screwing up ...

[jean63]

Do cold roofs mean poor insulation? Yes a priori but no if we think about it more closely ...

It is a little "trap" question, a priori paradoxical, that I asked myself during our work onimproving the insulation of our lost roof spaces.

I deduced 3 possibilities:

- They are fairly well insulated BEFORE (insulation between the room and the attic) since the heat does not rise.

- They are poorly insulated AFTER (ie at the level of the roof) since the heat (there is always) does not manage to raise the temperature of the roof space.

- That they are not well insulated neither BEFORE nor AFTER: all the heat is screwing up ...

1 - it bothered me from the start, there I went to watch the dictionary, and this although I thought: the word roof is masculine (Wikipedia):

In the vocabulary of construction, the roof is the space located under the frame. It can only be accessed by a hatch for visits..

2- I have an attic roof (above the garage attached to the house) not insulated. On the other hand, I isolated the unheated garage from the attic (roof space) and I can tell you that there is a huge difference between the garage and the attic (tonight -10 ° C ext; the garage facing north fell at 10 ° and in the attic it should be the same temperature as outside). Moreover in hot weather, the attic (roof) is untenable, even hotter than outside because confined, while the garage is cooler given the orientation to the North.

So I think your roof is badly insulated or not at all; it is therefore normal that it is always cold before and after the insulation of the slab. The losses through the roof are greater than the contributions through the slab.

But it could also be that the existing insulation (paneling + polystirene) was sufficient, because your real loss would be through the thermal bridge of the slab mentioned yesterday.

It's hard to know, but it's no wonder it's cold after and before your insulation in the attic. Under the roofs it is always very hot or cold depending on the outside temperature. The tiles act as thermal inertia and amplify the temperature one way or the other. In your case, the thinness of the sensors allows cold or hot to "pass" more easily.

The best solution would have been to over-insulate your ceiling on the housing side, but you had to reverse engineer all the paneling, lower it and there you went into carpenter's work.

All the habitable parts of the floor + mezzanine living room are anise with me. All laid by bibi: insulation 2 layers of rock wool of 10 cms + stapled vapor barrier + wide paneling - in the living room the paneling is replaced by cladding in red cedar varnish, blades 6 meters long by 20 cms wide and 2 cm thick which adds additional insulation). it represents a 6m X 4m panel under the roof + another living room with beamed ceiling + parquet + 4 cm of cork + floating parquet in the bedrooms / corridor / all heated by the heated floor including mezzanine.

I would not heat it with electric convectors! because the highest part is 6 meters minimum (at the ridge level).

This aprem, I opened the picture window which separates the veranda from the living room and the heat enters the living room (passive solar). The heating is stopped. I think I have 22 to 23 ° in the room tonight because the weather is very nice today.

Barometer at the top (the highest pressure since Dec 2005 - I had set a benchmark) = 1038 millibars.

Good Sunday.

[Christophe]

Ah shit for the male ... I also had a doubt seeing "lost" attic on some sites on the net ...

But wouldn't that be one of those words which is tunable to both feminine and masculine? Like "afternoon"?

To return to the subject,:

a) it was not a special case I asked the question to get an answer in general.

In our case the repair of cracks and various joints (which had been done with conventional mortar not special Ytong !! therefore normal that they broke) allowed to already gain a few ° C: inevitably, it was almost like a door opened !!

b) otherwise our slabs are 14 cm (and therefore not 30 like the walls like I supposed) I just managed to measure one, so for ytong from 400 to 500 kg / m3 it makes a Roof R less than 1 ! So largely insufficient on its own and improving the roof space was not a luxury ...

At the moment it's not cold enough to feel a big difference in the behavior of the house, but the next time I go up I will measure the 3 temperatures: room, slab and roof space.

ps:

the unheated attic garage (attic)

Attic garage? Kézako?

[jean63]

Attic is a noun not an adjective, it does not agree with anything.

He is masculine:

http://fr.wikipedia.org/wiki/Comble_(architecture)

Well, I'm going for a walk: beautiful sun with (chem?) Trails

jean63 wrote:
the unheated attic garage (attic)

Attic garage? Kézako?

did I write that? ..

In fact on the north side, the roof of the house extends above the garage but since there was a great height, I took the opportunity to make a ceiling in the garage and therefore it makes me a roof attic above the garage. roof is not lost because I have a pile of bazaar in between other wood remains of construction + spare parts for cars + ...... etc ..). I access it by a miller's staircase and a hatch from the garage.

[Christophe]

Jean when is it possible to see photos of your home? It makes you want your description !!

[bham]

Do cold roofs mean poor insulation? Yes a priori but no if we think about it more closely ...
I deduced 3 possibilities:

- They are fairly well insulated BEFORE (insulation between the room and the attic) since the heat does not rise.

- They are poorly insulated AFTER (ie at the level of the roof) since the heat (there is always) does not manage to raise the temperature of the roof space.

- That they are not well insulated neither BEFORE nor AFTER: all the heat is screwing up ...

Just question, whether you ask yourself BEFORE the cotton wool or AFTER?

It would be better if the 1st solution is the right one.
If I understood everything scattered pieces of information beyond, the slab of your attic is in Ytong slabs and the roof is insulated with polystyrene panels X cm thick. A priori, no large sources of thermal bridge.
There remain IPNs which are very good conductors of cold and heat but if a thermal bridge cut has been made ...
The 30 cm Ytong gables have an R of around 2,50.

No insulation was inserted between the ceiling paneling and the attic slab?

[Christophe]

Just question, whether you ask yourself BEFORE the cotton wool or AFTER?

Before obviously ...but it is not important because my question concerns all the roof spaces... not just ours ...

If I understood everything scattered pieces of information beyond, the slab of your attic is in Ytong slabs and the roof is insulated with polystyrene panels X cm thick. A priori, no large sources of thermal bridge.

Not at all...

a) the slab of the attic floor is in "classic" cellular concrete
b) the slabs (roof rempants) are 14 cm aerated concrete (measured this morning)
c) the gables are 30 cm aerated concrete
d) the extruded polystyrene is located UNDER the floor of the attic floors and after the paneling ...

The 30 cm Ytong gables have an R of around 2,50.

No from 1.6 to 1.7 only because it is 450 or 500 kg / m3 ytong (mass / volume estimate made with a few trailing ends).
https://www.econologie.com/isolation-pou ... -3474.html

No insulation was inserted between the ceiling paneling and the attic slab?

If 4 cm polystyrene ... I never talked about a polystyrene plate on the crawling roofs ...

[bham]

a) the slab of the attic floor is in "classic" cellular concrete ...

Ah okay, but do you still have a 6/7 cm concrete slab on the slabs?

b) the slabs (roof rempants) are 14 cm aerated concrete (measured this morning).

Ah original! You could have answered my question before

d) the extruded polystyrene is located UNDER the floor of the attic floors and after the paneling ...

Which is more logical to eliminate thermal bridges and avoid heating a slab that does not need to be.

The 30 cm Ytong gables have an R of around 2,50.

No from 1.6 to 1.7 only because it is 450 or 500 kg / m3 ytong (mass / volume estimate made with a few trailing ends).
https://www.econologie.com/isolation-pou ... -3474.html .

Ah, I did my calculation based on a lambda = 0,12

[Christophe]

a) no it is direct cellular concrete for the roof slabs

b) I know I was mean but I wanted to reserve the surprise for you via the video or I try to explain how it is wanked

c) you still assume, maybe wrongly, that the roof slab makes a thermal bridge, or nobody, for the moment, knows anything about it ... when I would make the measurements of T ° (room, slab and roofs ) we will have a clue ... but not before!

[bham]

a) no it is direct cellular concrete for the roof slabs

I was not talking about the floor slabs but the floor slabs (it's also called that). In general, when we make a slab with slabs and beams (concrete or IPN), we always cover the whole with a concrete slab which takes up everything and stiffens it.

c) you still assume, maybe wrongly, that the roof slab makes a thermal bridge, or nobody, for the moment, knows anything about it ... when I would make the measurements of T ° (room, slab and roofs ) we will have a clue ... but not before!

No, don't get mad, I don't have a priori, I just want to say that it's better if you don't have to heat the ceiling tile.