Notice lime-hemp insulation inside

[Pere]

Hello,

I started to make the interior plaster of an old and small house:

THE HOUSE: This house is over 100 years old. It was built with lime (made in situ) and small and medium stones, all well mixed into a sort of argamasse / conglomerate well packed in chests. The interior has been whitewashed.
The walls are about 30cm thick (a bit thin!).
One of the peculiarities of this house is that it was built in front of a huge rock taking advantage of the rock as a back wall:

Climate: The climate is dry, very hot in summer (up to 40ºC) and cold in winter (it freezes, it sometimes snows, -10ºC minimum). It doesn't rain often.

This last summer I took advantage to make the roof and the exterior plaster based on hydraulic lime (St Astier) and sand. At that time I did not at all think of insulating the house from the outside. From what I read in the forum, I should certainly have thought about it!

Today I start to make the interior plaster and I thought that it might be time to insulate the house a little.

The choice is very basic:
- either I make the plaster based on hydraulic lime and fine sand, all by hand
- either I make it with hydraulic lime and hemp, by hand the same
- either I first make a layer of lime-sand and after another layer of lime-hemp (hydraulic in any case), all by hand.

My worries about using hemp are that there are potential humidities. I have read that hemp does not like humidity (mushrooms).
Humidity can come from the ground itself (the house does not really have foundations) or also, and more easily, from the rock behind the house:

Between the wall and the rock, on the outside, there is a channel to divert the water and prevent it from rising between the rock and the wall, but I have already seen drops of water inside the house that slide by the rock.

Suddenly I hesitate to put hemp for fear that it takes humor and rots.
Also, the masons I work with have never used hemp, so I don't know if "we can miss it".

Of course, I will try to prevent water from sneaking between the rock and the wall, but you never know. Besides, if you have ideas ... I have heard of paintings with which I could paint the rock outside to prevent water from entering.

At some point I will have to do the slab too ... and there, the same problem: lime-hemp or lime-sand ??

It must be said that hemp would be easier for me to transport: the house is isolated, I have to cross a lake with a boat then put on a trailer and pull with a mini tractor. But hey, we've been doing everything in the sand for now, so this doesn't worry me, it's just a small detail.

I am taking all your opinions, and I hope you will be indulgent with my spelling (I am not French).

Thank you in advance to all.

more and good coating!

Pere

[raymon]

Very nice job you did there. I have never done interior insulation with hemp coating I have done it with sawdust or with lavender straw crushed in bulk with 10cm plasterboard. But I think hemp lime is a very good solution that will make something very nice and rustic. remains the rock wall or humidity is likely to be a problem and there actually it would be better to make a brick partition against ur polystyrene insulation on this wall would be preferable but good not very ecological.
For transport any insulation will pose a transport problem the volume will be identical.
In fact what will be the use of the main house or second home?

[Pere]

Thank you raymon for your response.
Even if it will sound crazy, but I want to keep the rock inside . In addition I would lose a lot of space if I mount a partition to hide it. I thought of digging it out and making small built-in cupboards to keep cold cuts, cheeses, and alcohols.
For transport, it is rather the weight and size that could cause problems.
Another solution would be to make a lime-sand plaster inside to standardize the walls and redo a hemp lime plaster outside to insulate ... except that this requires me to touch up the exterior.
For now it would be to enjoy the house in my spare time, but I plan to set up an agricultural project in the area and go there to live permanently.

[izentrop]

Hello,
On the inside of damp walls, I put a vapor barrier on the wall, a smooth and smooth back partition separated from the wall and rigid rock wool panels.
Interesting link on hemp methods: http://www.parcduluberon.fr/Un-Parc-a-v ... Le-chanvre

[raymon]

It is true that the aesthetics of a rock in a house is high class. Good insulation like dip waterproof tar is not bad. Perhaps prevent the runoff water from getting too close to the house by making a 2nd channel protection a few meters away.
By the way, what region are you in?

[Pere]

Thank you izantrop, I looked at the documents to make the plaster and the lime-hemp slab. Apparently you need a skill ... that the masons and I don't have.
So I hesitate to make the plaster in hydraulic lime + sand and too bad for the insulation.
But I have other questions that come at once: since the exterior coating is also in hydraulic lime, it poses problems that I make the interior coating also in hydraulic lime? Should I use weakly hydraulic lime or does this have no influence on the insulation / perspiration of the walls?
raymon, the house is in Catalonia. For the painting I will look, thank you!