Suspended ceiling board

[Tovin]

At first, I was considering placing rough tongue and groove boards or subfloor boards at the bottom between the floor joists of the Attefall house. This was to protect the floor insulation. But now I've acquired polystyrene for the floor instead, which is more moisture-resistant.

I've seen that some people only attach, for example, chicken wire at the bottom and let the insulation rest on that.
Would that work well? Are there any disadvantages?

 

[Derbyboy]

The downside is that mice and rats love styrofoam.

 

[Tovin]

Okay, how do you usually protect Styrofoam against mice?

 

[Derbyboy]

I protected my insulation (not Styrofoam but regular insulation) in the crawl space with fiber cement board.

https://www.byggmax.se/trossbottens...LwiDwlwCHiIeBnWSsJh0jEaAml2EALw_wcB#267=33049

 

[Tovin]

So chicken wire is out of the question? The mice eat it then?

 

[ClasseClas]

Follow the recommendations from Träguiden instead of making things up yourself.
https://www.traguiden.se/konstruktion/konstruktionsexempel/bjalklag/

You should have a bottom board as wind protection and to prevent regular stone wool from becoming damp. Also to avoid attacks from pests.

Chicken wire will rust away, sooner or later.

What kind of polystyrene have you got? Loose boards or some floor system? The boards must fit perfectly. A gap of a few mm creates thermal bridges. That's why glass or stone wool is used.

 

[ClasseClas]

A bonus picture of my 15m2 friggebod with a plinth foundation built in 2013. These are waxed trossbottenskivor in what appears to be perfect condition.

 

[Derbyboy]

I think you should describe how you envision the floor from top to bottom.

Replacing the trossbottenskiva or e.g. råspont, asfaboard, or oljehärdad board with polystyrene just sounds strange.

 

[Nickesågen]

Initially, I considered placing raw plank hatches or alternately subfloor boards at the bottom between the floor joists for the Attefall house. This was to protect the floor insulation. But now I've acquired Styrofoam for the floor instead, which is more moisture-resistant.

I've seen that some only attach, for example, chicken wire at the bottom and let the insulation rest on it. Would that work well? Are there any drawbacks?

Are you planning to fill the compartments with just Styrofoam instead of insulation? Keep in mind that you'll never get that board completely tight against the joists. Over the years, new gaps will arise as the timber moves slightly.

 

[Tovin]

I thought styrofoam was common for floor insulation?

I'm using floor chipboard, 170 mm joists, styrofoam between the joists, wind barrier fabric, and possibly subfloor boards.

 

[useless]

Polystyrene is commonly used under concrete floors. Otherwise, I haven't heard it's particularly common in floors. There are solutions where additional insulation and moisture protection are applied to the existing floor structure by gluing a layer of polystyrene to the underside of the subfloor.

The biggest problem with polystyrene in the floor structure is, as mentioned, that the sheets are rigid, making it difficult to achieve a completely airtight seal.