Filling crawl space with foam glass / cellular glass / hasopor?

[BirHan]

Hello everyone!

I am renovating a log house with a crawl space and am considering the best solution. Initially, I was planning to just redo the subfloor and insulate it, but I've encountered people who have used hasopor to fill the foundation. As I understand, you can do it like this (see picture): [image]

But I'm also wondering what happens to ground moisture in such a construction?

The biggest advantage is that you don't have to build subfloors throughout the house. The material, foam glass, is also durable and nothing for mice to build in.

I'm also wondering if I need to remove the current support beams to reduce the risk of moisture problems? And I'm also wondering if it's possible to remove them at all considering the construction. They are notched into the house's walls, which may indicate that they hold the house together in some way? My feeling is that they should remain. I still need something to nail the floors to, right?

Feedback on this model is greatly appreciated!

Hello,

I have received a proposal from a construction company to insulate my house with this material.
Did you do it?
Has it worked well - poorly?

 

[Zebula]

Hello,

I received a proposal from a construction company to insulate my house with this material.
Did you do it?
Has it worked well - poorly?

Worked well in our brew house.

 

[MJ6321]

Hello!

I'm bringing up this interesting thread again. I've read through everything in the thread and I plan to use Hasopor in my crawl space. I want to add an aspect, which is that at some point a "modern" ventilation grille was installed in the house foundation, presumably in the 1950s (standard grid model), but only in one place, and that’s where I plan to build a floor with Hasopor. The foundation is dry-stacked stone on the ground, as was done in the old cottages and longhouses in Skåne.

There has been some discussion here about ventilation and I've concluded that there doesn't need to be ventilation in the foundation when you're going to fill a space with Hasopor, which should insulate and keep itself dry. In the rest of the house, there's an old earthen bank, and I'm just going on logic that it seems completely unnecessary to let in a lot of air that forms condensation under the floor when warm air meets cold. With the vent in the foundation, there would likely be quite a draft under the floor as well.

So my thought is actually to completely close off the ventilation before I fill with Hasopor. Does that sound reasonable?

 

[Jochi]

Hello!

I'm bringing up this interesting thread again. I've read through everything in the thread and I plan to use Hasopor in my crawl space. I want to add an aspect, which is that at some point a "modern" ventilation valve was installed in the foundation, presumably in the 50s (common grid model), but only in one place, and that's where I intend to build a floor with Hasopor. The foundation is dry-laid stone on ground as was done in old Skåne cottages and farmhouses.

There has been some discussion here about ventilation, and I've concluded that there doesn't need to be ventilation in the foundation when filling a space with Hasopor, which should insulate and keep itself dry. In the rest of the house, there's an old mullbänk, and I'm just following logic that it seems completely unnecessary to let in a lot of air that would form condensation under the floor when warm air meets cold. With the valve in the foundation, there should also be quite a bit of draft through the floor.

So my thought is actually to seal off the ventilation completely before filling with Hasopor. Does that sound reasonable?

Or fill the foundation by blowing in loose fill??

 

[Sommartorparn]

Hi!

I'm bringing up this interesting thread again. I've read everything in the thread and I will use Hasopor in my torpargrund. I want to add an aspect that at some point a "modern" ventilation vent was installed in the house foundation, probably in the 50s (usual grid model), but only in one place and it's where I plan to build a floor with hasopor. The foundation is dry-stone on ground as they used to do in old Skåne cottages and longhouses.

There has been some discussion here about ventilation and I have concluded that there is no need for ventilation in the foundation when you plan to fill a space with hasopor, which is supposed to insulate and stay dry by itself. In the rest of the house, it's an old soil bench and I'm just going by logic, that it feels completely unnecessary to let in a lot of air that forms condensation under the floor when warm air meets cold. With the vent in the foundation, there should also be quite a bit of floor draft.

So my thought is actually to seal the vent completely before filling with hasopor. Does that sound reasonable?

It sounds reasonable that there is no need for ventilation if you plan to fill the foundation with hasopor. Rather, you want it completely sealed to avoid floor drafts.

I recently did a similar project and several complications arose during the project. In my case, it turned out that despite excavation with machinery, the depth was just a little over 30 cm, which is the bare minimum needed for hasopor to be capillary-breaking. Additionally, the foundation walls appeared very unstable when the floor filling was excavated. If it's a masonry house without a sill beam, you don't want the foundation stones to start moving because the wall will crack! So it ended with me allowing the casting of support walls of leca/cement to keep the foundation in place and then I chose perlite instead of hasopor as a filling. Geotextile at the bottom! New floor joists rested on the support walls and a cast knee wall in the middle of the room. Then a layer of clay between perlite and wooden floor to stop drafts and buffer moisture (geotextile between perlite and clay). In summary, it all became more extensive than I initially thought, so the rest of the house I might just fill with some fresh sand and then with a new wooden floor.....

What specific problem are you trying to solve when redoing the foundation?

 

[Träkåk]

Or fill the foundation by blowing in loose wool? The thread is about foam glass.

Hello!

I'm bringing up this interesting thread again. I've read through everything in the thread, and I'm going to use Hasopor in my crawlspace foundation. I want to add an aspect, which is that at some point a "modern" ventilation vent was installed in the house foundation, presumably in the 1950s (model common grid), but only in one place, and it is where I plan to build a floor with Hasopor. The foundation is dry-stacked stones on the ground as was done in old Scanian cottages and houses.

There has been some discussion here about ventilation, and I've concluded that there doesn't need to be ventilation in the foundation when you're going to fill a space with Hasopor, which should insulate and keep itself dry. In the rest of the house, there's an old soil bench, and I'm just using logic, that it seems completely unnecessary to let in a lot of air that creates condensation under the floor when warm air meets cold. With the vent in the foundation, there should also be quite a bit of floor draft.

So my idea is to actually block the ventilation completely before I fill with Hasopor. Does that sound reasonable?

A bit OT but close; when I had a new foundation built on a rounded rock outcrop, with masonry, plastered Leca stone as foundation walls, completely filled with Leca balls (I advocated for foam glass), the builder wanted to install a couple of vents at low points as extra security IF the rock unexpectedly started to release water through cracks. On the Leca, a concrete slab was poured, and then tiles were laid. Both the foundation wall and the floor are made of diffusion-open materials (mortar, grout, paint). I thought the vents were unnecessary as the entire construction can breathe and that the vents would only cool in winter. Perhaps the vents should be blocked in winter. I know several who have filled old foundations with Leca who have put in vents with humidity-controlled fans with pipes running through the Leca, but there has never been a need to ventilate the Leca. I would have skipped vents in your case, without being an expert in the field.

 

[Microkatten]

Hello!

I'm bringing up this interesting thread again. I've gone through everything in the thread and I plan to use Hasopor in my crawl space. I want to add an aspect and that is that at some point a "modern" ventilation vent was installed in the foundation of the house, presumably in the 1950s (model common grid), but only in one place and that's where I intend to build a floor with Hasopor. The foundation is dry-stacked stone on soil as was done in old Skåne cottages and farmhouses.

There has been some discussion here regarding ventilation and I have concluded that there doesn't need to be ventilation in the foundation when filling a space with Hasopor, which is supposed to insulate and keep itself dry. In the rest of the house, there's old "mullbänk," and I'm just going by logic that it feels completely unnecessary to let in a ton of air that forms condensation under the floor when warm air meets cold. With the vent in the foundation, there should also be quite a bit of floor draft.

So my thought is actually to close off the ventilation completely before filling with Hasopor. Does that sound reasonable?

Hasopor is also meant to insulate, which it does not do if ventilated. Just remember to allow moisture to migrate up through the foundation and floor and then be ventilated out in the room.

We have used perlite, same construction as @Sommartorparn with clay on top just under the wooden floor.

 

[MJ6321]

Hasopor is supposed to insulate as well, which it doesn't do if ventilated. Just remember to allow moisture to migrate up through the foundation and floor, and then be ventilated away in the room.

We have used perlite, same construction as @Sommartorparn with clay on top just below the wooden floor.

Thanks, then we're thinking the same. How do the floors feel now when there are sub-zero temperatures and the cold wind? I was planning to lay pipes in the uppermost clay for underfloor heating. How have you/you considered underfloor heating?

 

[Microkatten]

We have only created one space so far, so I can't say much about how it feels. Regarding underfloor heating, as you say, it should be possible to lay pipes in the clay layer. I saw the construction for this in a course, but I have no practical experience with it.