Ivanka Annot

Thanks for the replies!

@Aaron, with your pier&beam floor insulation setup, are you not worried about moisture getting trapped in your rockwool and joists? Or do you have a vapourbarrier between your joists and decking?

The rigid rockwool board is a great idea, there's one available here called "RockFloor Solid".
Any second layer insulation on the underside of the joists I will pair with anti-mice mesh, the dutch mice love even rockwool I can tell you.
The difference then would be rigid rock wool being more dampopen, than the XPS
I did some calculations on dampdiffusion, and think I'll go for a damp-open setup. Since my dampbarrier on the warm side is just the 18mm multiplex, that means no XPS for me since it would lock moisture in.

So I think I'll go for:
- rockwool between joists
- rigid rockwool on underside joist
- damp open climate foil
- anti-mice mesh

Hi permies,

I want to insulate the floor of my self-built small straw&loam house, but I'm having a hard time figuring out what materials to use best.
Would love some experienced advise!

The specifics:
--> The house is in a cold & wet climate (The Netherlands).
--> The first layer of ground is 5 cm gravel and about 30 cm of sand - no concrete anywhere and no foundation going into the ground.
--> The house is built on scribed poles, standing on big pieces of rock, see photo 1 that I took during construction. (there's a whole house on top now)
--> There's a 35 cm crawlspace, completely open on all sides. This means full ventilation ánd that rodents have full access if they want - enclosing is not an option.
--> The floorjoist are burned and oiled for extra durability.
--> The floor itself is buildup of 18mm underlayment, flax underfloor and 20mm planks. (it's been here about 7 years and no moisture problems on the exposed underlayment)
--> I'm ok with using XPS/PIR/rockwool stuff - as long as it is recycable. So sprayfoam is not an option for me.

I'm debating between these options:

Option 1: 15cm rockwool insulation between the joists, dampfoil and mice mesh on the bottom of the joists. My worry here is that the dampfoil encloses moisture..
Option 2: 15cm rockwool insulation between the joists, 3cm XPS board with foil on bottom of joists. For airtighness and makes batting inaccessible for mice. Plus mice mesh. Same worry as option 1.
Option 3: 15cm XPS between the joists. Will have gaps, for which I could use purfoam but I'd hate that so I'd take my losses. With or without: dampfoil / mice-mesh.

What would you recommend?