roof insulation of choice: glass wool, wood fiber?

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LNA216
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roof insulation of choice: glass wool, wood fiber?




by LNA216 » 28/12/14, 14:22

Hello,
I live in a house in 1958 in false joint ownership (double wall) on the gable, it is located south of the Landes and 1,5 km from the Ocean, so in a humid area during the inter-seasons and hot in summer. The attic is inhabited and the roof needs to be redone, two large Vélux windows will be changed on this occasion. I would like to gain both summer and winter comfort. I live there alone with my daughter and have brought in several professionals; we must straighten the frame which is curled and too much insulation would require raising the roof when due to the shared ridge, this is not possible. In addition, a HYGRO B CMV will be installed.
In the lot, two craftsmen seem to offer something interesting but I am afraid of being rolled in the flour:
the first offers wood fiber in 1 mm sheets (R 10) + on the other hand battening a thin heat-reflective insulation (BIPS-2,78 ?? certification) with R0115 we still arrive at 5,25 € for 14.000m² of roof. Hence my fears.
The second offers glass wool with the same thin insulation, but I don't have the quote yet because of the holidays.
What do you think please? Were there other possibilities that met my needs?
Thank you

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by djo59 » 29/12/14, 01:54

Hello,
What is the maximum height of insulation you can put?
I understand that the attic is arranged, but can not you push up to twenty cm?

Personally, in the current state of what you tell us, I would prefer the 10cm of wood wool to glass wool (if equivalent price). Wood wool will bring you a little more inertia for the summer, then it varies according to the density of the wool (the heavier, the more inertia)
As for the thin insulation in R = 5.25 : Mrgreen: : Mrgreen: : Mrgreen:
0.5 can be ....

On 10 cm of thickness one will remain on the same order of thermal resistance namely 2.5-3 except polyurethane ù where one will turn to 4.5 approximately but no inertia.
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by Obamot » 29/12/14, 04:02

True, but what would it be for?

Wood wool (and wood for that matter) are far too light to constitute a sufficient thermal balloon as inertial materials, and if they intervene in terms of comfort, it is in such restricted and irregular time slots that you can hardly count on that, right? So it increases the heating time (since their purpose is to isolate ...)

On the other hand, a concrete wall about 50cm thick (reinforced if load-bearing) and offering itself all day in the sun behind a large picture window facing south ...

Small calculation, with an air volume of 500m3 in the room (x1005 J / kg / k) and a wall in full sun 5m long and 45cm thick by 2,5m high (5,6m3 = 12 '375 kg x 880 J / kg / k etc). If the latter is heated by the rays to 24 "C, it would theoretically take more than 3 hours to cool down and fall below the comfort T °. Except that if the building is very well insulated, it can last until late in the day. at night, which becomes very interesting since the inertia then makes it possible to pass the course of the diurnal cycle). I do not guarantee the above formulas, it is just as an example ...

But for that you have to really isolate, "passivate ...!"
So nothing like that with wood wool and amha ...

Here a site which gives orders of magnitude, tables and calculation methods, to get an idea:
http://www.ideesmaison.com/Construction ... lculs.html

Then you have to see, it's case-by-case ...

LNA216: this amount seems excessive to me.
However you hardly give enough elements to give a clear opinion ... Anyway, if you opt for glass wool, it is imperative to ask for a solution with an airtight partitioning (otherwise wool dust from glass in the lungs, and there ... not good, not good at all ... So when I say "hermetic"...)

I think indeed that in your case, it would be either panels of extruded polystyrene (for example with lambda 0.034 and 10 € per m2 for 8cm thick, without the installation, although this is not sufficient) hunted panels / forced between the beams and without daylight between them to absolutely avoid any air circulation (it requires a careful and meticulous work, but it is easy to install and without danger), and of the greatest possible thickness / allowed. + polyurethane foam in any cavities, if applicable. Since indeed, the entire roof must be insulated in one piece so as to offer perfect airtightness edge-to-edge. Otherwise, it's not even worth it to start the work ...

Or to pose oneself (or to hire a workman) that would make € 1'250.— + € 400.— for the installation (well paid ...). It's easy to install and can "stick" to the polyurethane foam ... (which can be used to fill in the gaps if needed ...)
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by Obamot » 29/12/14, 05:10

Besides, as long as the security of the structure is not in danger, I don't see why you should redo everything.

It is normal for a roof to buckle over time. The idea would rather be to determine the causes. Because if you don't know why, you're going to redo your entire roof and it will surely happen again ....

Besides, if these causes exist and the problem can be fixed (installation of reinforcement / s, supports, metal stirrups or what do I know) there may not be any need to start all over again ... 'say that, I say nothing I haven't seen the house, maybe you could post some photos!)
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thank you for these answers even if I did not understand everything ...




by LNA216 » 29/12/14, 09:43

Bjr everyone,

Thank you for the time spent thinking about the situation, late in your nights if I judge the response times.
For Djo59, the possible thickness does not seem to be able to reach 20 cm since the fiber is proposed to me in thickness 10 but it is a question of 55 FX in the name of the product, I suppose that it is the density the R is of 2,78, 6). For the thermo-reflector of seems to "wince", it is not reassuring for my business. However, I remember that the craftsman told me that for a roof you need a total of 7 or 5,25 depending on the type of roof, and that each time he used this product, there was no problem with the R and the tax credit for its clients. I looked for some information, this product does exist with an RXNUMX certification and seems to be unleashed by passions. He provided it for me in addition to the insulation on the other hand as recommended.
For the warped roof, I assumed it was because of the age of the house. Each past craftsman told me that it was normal, but without going into detail. We are in a sandy and humid area in the fall and these last spring and hot in the summer, it is perhaps for that too, the old frames are certainly made of pine.
For the photos, I am not persuaded to arrive there: to take them it is necessary that I cross the avenue so that it is visible while zooming perhaps. I will try but I do not guarantee the result.

for Obamot, I did not understand everything about the beginning of the message which was undoubtedly addressed to Djo59 and on the passage relating to the wall, but on the other hand thank you for the information site which I will go to explore just after.
The estimate at 14000 includes the 2 Velux, the resumption of the frame, the cover (removal of the old and change) I forgot to say, sorry and therefore the installation of the thermo reflector and fiber panels. I don't know anything more about the quote.
If I opt for GR32 glass wool (density and higher R perhaps?) What should I ask? what is an airtight partitioning?
Nobody offered me extruded polystyrene, the only thing that looked like this is the Icynéne product that I had never heard of before, it's Canadian.
I would not take the risk of bringing in someone unofficially, the roof is too high, and I will be too afraid of an injury, in addition, we must redo the ridge that is common with the neighbor and suddenly , it must be done well.
If you see other food for thought, don't hesitate and thank you again.
Good day to you both
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by Obamot » 29/12/14, 13:35

You are right, you have to take your time, do not go too fast at work ...

The description lacked elements, but it is not because there are certain technical constraints that it wouldn't be worth it to determine the causes of the deformation of your roof!

The lcynene is well of the type of what I proposed, since it would be a foam of urethane – polyisocyanurate, and I spoke to you about poly-urethane (having cyanide compounds).
- so if the origin of the product is "Canada", it is a mark that you will pay more expensive than any other polyurethane foam of any kind (you pay the mark and the pompous label "Canada" which does not is not one. It just proves to you that I directed you to a good product ...)
- but I don't see how we can apply this between beams, since it swells until it reaches the maximum of its expansion coef, so we need a partitioning, and this we have to pay for;
- it is impossible that it is a “sound insulator” (as the advertisement would claim), no thermal insulator can act as sound insulator (this is a classic error, er I mean deception, intentional or not);
- it is true that it cannot burn, if the origin of the product comes from Europe, but in the event of very high temperature (when one must be already quite dead) that releases toxic gases;
- pay attention to the fact that during installation and until all polyurethane foam has "stabilized", you must not stay in the premises (there is still cyanide in there ... after that it is volatile , so it goes).

If it was my roof, I would prefer to put extruded polystyrene panels, for the following reasons:

- It sticks easily with polyurethane foam (in case of irregular beams);
- It acts as a partition, so well laid it is airtight.
- There is therefore no need to pay for the installation of heavy and costly partitioning;
- It is light and therefore does not add by its weight, constraints to a roof already tired by time;
- It doesn't rot;
- It doesn't burn;
- It is cheap;
- You can remove them to intervene and make a roof repair (and even very locally with a hole made in the cutter), then put them back, reseal / (re-stick) and / or replace very easily;
- The gray energy to produce them is very low;
- The insulation coefficient is one of the highest (... among the highest) you can find (you only have a small thickness, so you need the most efficient product possible);

And it should be remembered that with only 10cm of thickness available (which you may not understand in my answer above) it is illusory to put wood wool to hope to benefit from a certain inertia. Besides, if you put a CMV, you will not need it.

The partitioning consists of insulating in a hermetic way, with a film or a wall which avoids any circulation of air between outside and inside - and in the insulator itself - which is imperative if you put a CMV. And what is very difficult to guarantee in the long term with glass wool (it settles and disintegrates over time, savings at the start, but replacement in 15 or 20 years to be expected eventually);

I understand that you lack the technical mastery to hire a worker and give him instructions, but of course you have to hire people who know how to climb ladders and attach themselves when necessary, and you must make sure that they have accident insurance (which should be compulsory.)

Pay attention to the Velux, if they are installed incorrectly and air circulation is observed, you will lose all the benefit of the roof insulation.

Take a separate company to check the pressurization of the premises once the work is completed, or in any case let it be known that you will do it to the contracted company, so that it follows the work of laying the cleat (a pressurization makes it possible to know if the job has been done well and if it corresponds to the expected objectives ...)
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by djo59 » 29/12/14, 15:35

Sorry I was getting tired (look at the time of my post : Cheesy: )
Wood wool will bring a little PHASE and not inertia. The phase difference is the time it takes for the heat to enter the house
http://www.btci-traitement-charpente-isolation.com/isolation-naturelle-gard-herault-montpellier-nimes.html
Criterion to take into account for the comfort of summer, even more for you than for me (North)


Wood wool: lambda 0.038 R = 2.6 (best for phase shift (summer comfort)
Extruded polystyrene: lambda 0.035 R = 2.9
Polyurethane: lambda 0.025 R = 4
Glass wool: Lambda 0.038 R = 2.6 or lambda 0.032 R = 3.1 (inexpensive, but better to partition so as not to breathe particles. Very poor durability; settles over time)


As for thin insulation, CSTB classifies them as additional insulation but assigns them an R between 0.36 and 1.5, using 2 non-ventilated air spaces of 3cm. Apparently not the case here. All this for a total height of 65mm. Or the same thing in the end with around (depending on the insulation) 5cm of "classic" insulation. At best, wood wool + thin insulation, we get R = 4.1
http://www.cstb.fr/actualites/webzine/editions/juin-2005/premiers-avis-techniques-pour-procedes-a-base-de-produits-minces-reflechissants.html
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by LNA216 » 29/12/14, 16:28

It is really nice to take heart to respond to the ignorant. So I have to start reading again and digest everything a bit. After that I may still be in time to take the one that seemed the most serious and professional and impose the product that suits me. You seem to be saying that the installation of polyurethane seems easy and the product efficient, so I have to reread with a rested head and that I see if it also fits with the conditions imposed for Tax Credits.
Thank you for your help, it is also interesting to see the different opinions and the various experiences.
bye,
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by Obamot » 29/12/14, 19:50

djo59 wrote:Sorry I was getting tired (look at the time of my post : Cheesy: )
Wood wool will bring a little PHASE and not inertia. The phase difference is the time it takes for the heat to enter the house
http://www.btci-traitement-charpente-isolation.com/isolation-naturelle-gard-herault-montpellier-nimes.html
Criterion to take into account for the comfort of summer, even more for you than for me (North)

Wood wool: lambda 0.038 R = 2.6 (best for phase shift (summer comfort)
Extruded polystyrene: lambda 0.035 R = 2.9
Polyurethane: lambda 0.025 R = 4
Glass wool: Lambda 0.038 R = 2.6 or lambda 0.032 R = 3.1 (inexpensive, but better to partition so as not to breathe particles. Very poor durability; settles over time)

As for thin insulation, CSTB classifies them as additional insulation but assigns them an R between 0.36 and 1.5, using 2 non-ventilated air spaces of 3cm. Apparently not the case here. All this for a total height of 65mm. Or the same thing in the end with around (depending on the insulation) 5cm of "classic" insulation. At best, wood wool + thin insulation, we get R = 4.1
http://www.cstb.fr/actualites/webzine/editions/juin-2005/premiers-avis-techniques-pour-procedes-a-base-de-produits-minces-reflechissants.html

No, it's good inertia of the materials I was talking about! Because upstream, it would be well to learn about this point (as well as the different coefs and their relationships with each other ...) BEFORE thinking about the phase shift they can bring.

And no, the critical season is winter and not summer! With extruded polystyrene panels, no problem in hot weather, but where would be the problem? I do not see. On the other hand in winter with wood wool if it is not "dry" ... Do not forget that the roof is curled, therefore strong presumptions of wood properties / water expansion which led to this.

As for the phase shift (I come to it), it is fine to give the lambda (and again, it depends on the density of the wood wool expected ... so), but still must we calculate the set in the place provided and according to its specific criteria [Phase shift (h) = 0,023 X thickness (10 cm) X square root of (Density in Kg / m3) X Specific heat (J / Kg.K) X Thermal conductivity (0.042 w / m²K)], to determine whether it will be meaningful at first. But in my opinion...

I think that the wood wool, on only 10cm thick and in this case, there is a significant risk that it will fill with float since it is in a humid area (as the original post describes it ) so it is not improbable that depending on the circumstances - and depending on the fluctuating dew point - it will be soaked quickly (to be seen again by providing a rain screen + vapor barrier, which I would highly recommend (but very much doubt that this is sufficient)! Besides the recommendation of the use of a CMV is a precious clue which goes in this direction, since the "wood wool" - it is good when everything is dry - that there is has no cold bridge, etc (but there 10cm it does not really smell good ...). Here we are talking about the ambient humidity of a room which would condense on contact with the insulation (wood wool) what about the coldest winter days?

..afterwards, everyone does what they please ...! : Lol:
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