Choosing a roof insulation ... Difficult! :)

[morpheus666en]

Hello,

I am currently building an attic. The roof was redone 2 - 3 years ago.

Currently, so I have mechanical tiles, so with my battens and my battens which fixes the tarpaulin (it lets the frame breathe (that's what I was told at the time)). My rafters are 75mm thick.

I insulate my floor with loose cellulose wadding (thermofloc).

So I want to attack my roof insulation.

Question n ° 1: Which insulator is the best for a roof space?
I did several forum and salons and I noticed that wood wool and duck feather stand out among ecological products.

Question n ° 2: I made a comparison on wood wool (Steico, Pavatherm, Homatherm, Actis and Buitex) and I noticed that (supposedly) only Buitex had no chemical type product (poly. ..) because I had someone who insulated with poly products (I don't know what) didn't let the frame breathe. So who are the ones who let the frame breathe and who are really ecological?

Question n ° 3: Having a frame which is a little old (maybe 80 - 100 years old) I am hesitant to make a wooden frame ... In addition, having a somewhat limited budget the metal frame seems to me interesting. But I was told that wood wool is very heavy ... so what do you think?

Question n ° 4: I wanted to know the thickness that I have to put as insulation and how I will put it? Because I have chevrons 75 thick and so I wanted to put 100 and then put 100 or 120 in the other direction. But I discussed with a pro who explained to me that I had to put 60 between my rafters or see 80 maximum ... so I would really like to know what I should ask .. ??

Thank you in advance for all those who can enlighten me.

[Obamot]

Difficult as you say, but maybe not for the reasons you think ...

I see a relative contradiction with what you have already done and what you intend to undertake. You shouldn't put the cart before the horse (I'm not saying it is, but it sounds like you read it).

I put you a link in connection with your questions, on the mishap that happened in Eisenheim:
https://www.econologie.com/forums/travaux-d- ... t8236.html

You will find in this thread examples of errors accumulated when one does not pay attention to the basic rules, and especially when one takes the risk of being inspired by ideas taken here and there without real comprehensive strategy and sometimes even with course changes during the works or during their modification / planning.

It is often difficult to answer questions categorically to threads of this kind and with so few elements (in your case no one here knows your house in detail except through what you say, but not in real, nor its complete history)

In addition, we do not know the professional background of those who improvise (or not) "site manager" (with regard to their real skills in the field)
Do not see it as an excitement but just a little pragmatism based on lived experiences.

[Obamot]

After this foreword, I try to reflect on what you are telling us (if that can enlighten you):

Hello,

I am currently building an attic. The roof was redone 2 - 3 years ago.

Currently, so I have mechanical tiles, so with my battens and my battens which fixes the tarpaulin (it lets the frame breathe (that's what I was told at the time)).

It is not a tarpaulin which can act as a vapor barrier.

I insulate my floor with loose cellulose wadding (thermofloc).

Why insulated your floor, the way you did, if you are not clear about whether your house is breathing properly or not?

So I want to attack my roof insulation.

Question n ° 1: Which insulator is the best for a roof space?
I did several forum and salons and I noticed that wood wool and duck feather stand out among ecological products.

Question n ° 2: I made a comparison on wood wool (Steico, Pavatherm, Homatherm, Actis and Buitex) and I noticed that (supposedly) only Buitex had no chemical type product (poly. ..) because I had someone who insulated with poly products (I don't know what) didn't let the frame breathe. So who are the ones who let the frame breathe and who are really ecological?

Question n ° 3: Having a frame which is a little old (maybe 80 - 100 years old) I am hesitant to make a wooden frame ... In addition, having a somewhat limited budget the metal frame seems to me interesting. But I was told that wood wool is very heavy ... so what do you think?

Question n ° 4: I wanted to know the thickness that I have to put as insulation and how I will put it? Because I have chevrons 75 thick and so I wanted to put 100 and then put 100 or 120 in the other direction. But I discussed with a pro who explained to me that I had to put 60 between my rafters or see 80 maximum ... so I would really like to know what I should ask .. ??

Thank you in advance for all those who can enlighten me.

How would you expect someone to give you the right "coefs" in relation to your questions, without having answered the two preceding points? And with so little information on your house, its heating, its geographical location ... its orientation, etc. etc.

A priori it would fail to put things in their right place and an overall strategy of the entire insulation of the house taking into account all that it is (and / or is not). Amha. @ +

[morpheus666en]

To answer you precisely, it is an old house which has been inhabited and which is no longer inhabited. The ground floor will be inhabit but a little heat. This is why I used cellulose wadding, special flooring, to limit heat loss. The roof has one side facing north and the other facing south.

I want to clarify that I am not improvising site manager. I have a professional who helps me. He is not a specialist in all that is ecological insulation. He got into it because I asked him.

I try to choose a quality insulator to have maximum living comfort.

The house is terraced. the walls are brick with lime between the bricks. On one side, the wall is reinforced by a 40 cm thick gauge wall.

I was planning to put on a hemp vapor lock after having made my insulation, the tarpaulin being put as a rain shield.

If you wish I can provide photos.

Since the beginning of my work I have not changed course and for the insulation, I more starting on an insulation in Wood wool with metal framework if possible (I saw that this was doing) ...

Again thank you for your response.

[Obamot]

I hope I have been careful enough in my remarks to prevent this from relating to you. Whether this is the case or not, it is you who know! But the awareness might not be useless if there were

I will stay in the generalities:
If you want to do something that works with your house, and you don't particularly want to keep the exterior appearance of the facade as it is now, I would strongly advise you to insulate by the exterior, making a kind of insulation shell with your house inside.
Apart from that, no salvation with this type of house, there is not much to do given the massiveness of cold bridges - in general - it will remain energy-consuming, so do not count on a hypothetical "comfort" even after doing your insulation work. You will just have a decrease in the unpleasant feeling of cold.

I want to make a prognosis by starting in a metaphor (like horse racing, because that's often how it happens) You leave with a big handicap. You will arrive at a certain result (achieving maximum living comfort, it's vague) especially if you ride a draft horse. Then you will always want to do more, here and there and always go further, but you will notice that the price of bran and oats will increase a lot (hear the heating fuel) and a draft horse eats more than a racehorse. You will then want to gallop but you will always have a draft horse. This is when you will put double windows in the stables and change the heating to improve the comfort of the animals by thinking that they will eat less ... But nothing will change. Then there will come a point when the cost of fitting out the stable will exceed the price of a new one ...

So I advise you to think carefully about the question, otherwise you will think that insulating from the outside is expensive. But when you have calculated everything you are going to do inside. You will quickly realize that it was better to do things right from the start. But it's just a personal opinion based on the little information I have. Good luck to you anyway.

[swift2540]

Currently, so I have mechanical tiles, so with my battens and my battens which fixes the tarpaulin (it lets the frame breathe (that's what I was told at the time)). My rafters are 75mm thick.

Hi,
i guess the tarpaulin is a fell-x or similar?
Old generation of roofing (rain barrier) which is breathable ONLY by coverings. The tar is waterproof and non-breathable.
You MUST therefore leave an air gap between the insulation and the roofing (opinions differ from what I read, about 2cm).

Which insulator is the best for an attic?

There is no better, there is an acceptable compromise depending on what you are looking for and the price to pay. Otherwise we would only make one insulator ...

I had that insulators that had poly products (I don't know what) don't let the frame breathe. So who are the ones who let the frame breathe and who are really ecological?

Polytrucs (pse, pu, ...) are waterproof and therefore do not allow breathing, not a low% of "polytruct glue" in a material.
The pb of polytruct is VOCs. But since we are on the roof (ie outside) it is not a pb (for the interior).

Question n ° 3: Having a frame which is a little old (maybe 80 - 100 years old) I am hesitant to make a wooden frame ... In addition, having a somewhat limited budget the metal frame seems to me interesting. But I was told that wood wool is very heavy ... so what do you think?

Why would wood be a problem?
The metal frame is possible, if it can support AND ESPECIALLY if it does not create a thermal bridge (steel is good conductor, wood rather insulating).

Question n ° 4: I wanted to know the thickness that I have to put as insulation and how I will put it? Because I have chevrons 75 thick and so I wanted to put 100 and then put 100 or 120 in the other direction. But I discussed with a pro who explained to me that I had to put 60 between my rafters or see 80 maximum ... so I would really like to know what I should ask .. ??

Thickness = technically as much as possible. The passive house will tell you 40cm, elsewhere you will be told 6cm is better than nothing
6cm between rafters is the max (maybe even 5cm would be better?), Then it's a question of interior height and budget.
With these few generalities:
The use of a vapor retarder is essential
Air tightness is essential (vapor barrier / walls connection, ...)
It is better 15cm well placed than 40cm badly placed (thermal bridge)
PS: for the insulation of a roof, sarking is a very good process, but I suppose that the removal of the roof is not on the agenda ...
@+