How should I do?

[Nygge72]

Hello, I have a toilet/shower building at the cabin that needs some renovation. Since it will be removed later, I don't want to spend a lot of money or effort on it. However, I need to replace the paneling as the current one has dried so much that it is starting to gap.

I want to do all the work from the outside, i.e., not touching the interior.

What I want to do is add some insulation both to protect the water during winter and to keep the heat out during summer since it always turns into a sauna.

I can see through the gaps that it currently only consists of interior panel - Studs - Exterior paneling. That is, no insulation or weather barrier, etc.

This also means that, currently, moisture is escaping. The shower out, because it is not airtight, so my work must preserve this function so moisture is not trapped inside the building and begins to mold.

So how do I best, simplest, and cheapest way to add some insulation and new paneling? That is, the different layers.

Thanks in advance

 

[Oldboy]

Depends somewhat on how long it should stand, but in principle, it's just a matter of placing asfapapp against the inside, then filling with insulation, then asfapapp, and then panel.
If there isn't one, it is appropriate to make a hole and install a vent in the wall.

Assuming the wall/insulation will not be thicker than 95 mm. Then moisture can travel relatively easily in both directions without being trapped for too long, preventing mold formation.
Further assuming that no showering/splashing water on the inside wall occurs.

 

[Nygge72]

Depends a bit on how long it will stand, but in principle, it's just a matter of placing roofing felt against the inside, then filling with insulation, then roofing felt and finally panel.
If it's not present, it's advisable to make an opening and install a vent in the wall.


Assuming the wall/insulation will not be thicker than 95 mm. Then moisture can migrate relatively easily in both directions without being trapped for too long, preventing mold formation.
Furthermore, assuming that no shower water is splashed on the inside wall.

No, it won't be more than 95mm. What function does the roofing felt serve, and do you just staple it to the existing studs?

The water from the shower is in a cabin, so no water from there, and I can place the vents as I wish.

I was thinking of Hunton Nativo for insulation possibly since it's supposed to allow moisture through. But then you can put regular Bison wind barrier outside the insulation with furring strips as an air gap, right?

 

[Oldboy]

What purpose does the "asfapapp" serve then, and do you just staple it to existing studs?

It makes the insulation effective by being windproof. It allows moisture through, but not wind/drafts. Stapling it up works just fine.
Weather-resistant fabric does the same job as "asfapapp," so it's much of a muchness. (The insulation needs to be windproofed on both sides since neither side is windproof by itself.)

You can use hygroscopic cellulose insulation, but ordinary fiberglass is cheaper, even if it's less pleasant to work with.

 

[Nygge72]

It stops the wind so that the insulation is of some use. It allows moisture through, but not wind/drafts. It's fine to staple it up.
Windproof fabric does the same job as tar paper, so it's essentially the same thing. (The insulation needs to be windproofed on both sides since neither side is windproof on its own.)

You can use hygroscopic cellulose insulation, but regular fiberglass is cheaper, albeit more unpleasant to work with.

But does regular fiberglass allow moisture to pass through?

 

[Oldboy]

Yes.
The only difference is that fiberglass does not absorb any moisture. Hygroscopic insulation like cellulose-based does. But moisture can move freely right through.

 

[Nygge72]

Yes. The only difference is that glass wool does not absorb any moisture itself. Hygroscopic insulation such as cellulose-based does. But moisture can freely pass right through.

Yes. The only difference is that glass wool does not absorb any moisture itself. Hygroscopic insulation such as cellulose-based does. But moisture can freely pass right through.

Aha, I didn't know that. I thought it was only the "natural" ones that let moisture through.

 

[Barriospurer58]

Aha, I didn't know that. I thought it was only the “natural” ones that let moisture through.

Mineral wool is hardly airtight, which is why houses built with mineral wool also have an internal vapor barrier (plastic) to prevent moisture from penetrating the wall and condensing when it cools down.

Hygroscopic means the ability to absorb and release moisture. It should give a similar ability as the wood in the structure and panel to handle moisture; if it gets damp, it should be able to dry out again. Mineral wool has poorer properties for drying out once it becomes damp (which, as mentioned, is avoided with the help of plastic).

That said, it is entirely possible that mineral wool will work in your case. Especially as a short-term, cheaper solution. Ventilation will likely be important regardless, a shower area without waterproofing sounds like a high risk for moisture problems.

 

[Nygge72]

I'm considering whether to reframe the small house. Since it's built with smaller studs and not the standard center-to-center measurements typically used today, and I'll also be replacing the old windows currently in place, I'm thinking about possibly using new, thicker studs. Can I then screw them in with angle brackets/toe-nail them and just cut the old ones once the new ones are in place, or is there any risk with that?

 

[Oldboy]

In principle, it should work well, but make sure that the roof rafters/trusses are placed on top of the studs and not between them, unless there is a thick standing stud acting as a wall plate. (The same goes for the foundation if it is a pier foundation.)

 

[Nygge72]

Principally it should be fine, but make sure that the rafters/trusses are placed on top of the studs and not between, unless there's a thick standing stud as a wall plate. (Same thing applies to the foundation if it's a pier foundation.

This is just a small "cube" of about 2x3.5m or similar with very little slope on the roof. Supported by 6 piers (3 on each side)

 

[Oldboy]

Depends on how the hammarband and sill/bärlina are constructed/dimensioned. But sure, it's a small (light?) roof that even with Dalarna's snow zone shouldn't become too heavy. However, one becomes a bit skeptical of the construction when you want to reinforce the wall due to sparse and weak wall studs?

 

[Nygge72]

Still depends on how the hammarband and sill/bearing beam are executed/dimensioned. But sure, it's a small (light?) roof that even with Dalarna's snow zone shouldn't become too heavy. However, you get a bit skeptical about the construction when you want to improve the wall due to sparse and weak wall studs?

It's more because I want the current standard. It has stood steadily for the 15 years I've had it despite sometimes large amounts of snow. So really money down the drain if I replace the studs probably. But insulation and new paneling are needed.

 

[Nygge72]

How important is the wind barrier on the inside of this? I've examined the studs behind a bit and the house is built with double studs that have no more than 5-10 cm spacing, meaning there's no opportunity to staple the barrier to these, then there’s a gap of about 50 cm, and then these double studs appear again.

Feels like either you skip the barrier if it's not that important, or you re-stud if it must be there.

 

[Oldboy]

You cut your 5-10 cm insulation strips, clip 15-20 cm wide strips of asfapapp which you fold around the "front edge" of the insulation and then press the strips between the studs. With existing houses, you have to do the best possible based on what is practically possible/reasonable.