Wind barrier behind asphalt board?

[Tovin]

I am building an Attefallshus. The foundation is on slabs above the ground. I have screwed decking boards under the floor joists, on which I then placed asphalt board. The bottom between the joists is board in between.

The question is whether the asphalt board is sufficient protection against moisture/wind. Can I lay the insulation directly on the asphalt board or should I place wind barrier paper between the asphalt board and the insulation?

 

[GEHA]

Remove ddm and instead place a slice of fibercement, otherwise you'll have problems with growth on the underside later.

 

[Tovin]

Now I have bought asfaltsboard and it cannot be returned. But if growth is a problem, maybe you can place the wind barrier under the asfaltsboard?

 

[Jan_G]

Yes, asfaboard is enough. No need for wind barrier or anything else.
And it grows no more on asfaboard than on fiber cement.
Just make sure the smooth black side is facing down.

 

[saltet]

We have removed our asphalt board as it started to bulge, which made the insulation visible and became a haven for mice. Use fiber cement. The asphalt board in our case was about 15 years old.

 

[MagHam]

We have removed our asphalt board as it started to bulge...

Yes, asphalt board is not particularly dimensionally stable. However, it sounded like the OP had built a blind bottom with decking underneath ? so it might work. Laying large horizontal sheets of asphalt board without support doesn't work in the long run.

 

[saltet]

Yes, asphalt board is not particularly dimensionally stable. However, it sounded like TS had built a subfloor of decking underneath? In that case, it might work. Laying large horizontal sheets of asphalt board without support doesn't work in the long run.

That's exactly what happened in our summer house. That's why we tore everything up.

 

[Eribe]

Asfaboard, mounted with the correct side down, should not risk more growth than other suitable boards. Or? The problem is shape stability, as someone writes. I think TS should be able to lay some supports between the sections to prevent the Asfaboard from sagging?

 

[multix]

With plenty of support, asphalt board should be good. I had placed släkt kalk in the insulation against rats.

https://www.byggahus.se/forum/threads/slaeckt-eller-oslaeckt-kalk-mot-moess-i-trossbotten.177010/

 

[Tovin]

With plenty of support, asphalt board should be fine. Släkt kalk I would have put in the insulation against rats.

[link]

Is it that kind of kalk?
https://www.granngarden.se/slackt-t...3veEU9gKG8QIFFsWqfid2ga5keFbyuaRoCpo0QAvD_BwE

 

[ClasseClas]

Use trossbottenskiva instead of asfaboard. Strong recommendation!
Favorite in reprise
https://www.byggahus.se/forum/threads/trossbottenskiva.423990/#post-4320859