Can I just replace the sawdust with insulation?

[downup]

Need to replace the insulation in the attic. Right now there's just a thin layer of sawdust. The house was built in 1920 and it's in good condition, but the heat is lost during the winter.

Can I just buy insulation at Byggmax and put it in instead of the sawdust?

The beams are about 90cm deep/high. It's a crawl space attic.

 

[b8q]

Need to replace the insulation in the attic. Right now there's just a thin layer of sawdust. The house was built in 1920 and is in good condition, but the heat escapes during the winter.

Can I just buy insulation at Byggmax and put it in instead of the sawdust?

The joists are about 90cm deep/high. It's a crawl space attic.

You can, but the risk is that you might get mold growth in the attic instead! Sawdust can buffer moisture (i.e., get moist and then dry again), which regular insulation cannot.

And if you insulate too much, it might get colder in the attic, and moisture could condense on the wood (typically on the sheathing), which then starts to mold.

So you have to ask yourself - how much heating cost is it worth to avoid mold in the attic?

 

[LaT]

In that case, replace the sawdust with cellulose wool, it has the same ability to absorb/emit moisture.

 

[fribygg]

Why do you need to change the sawdust, isn't it enough to just refill so you avoid a lot of work and get better insulation ability with a material that suits the house?

 

[Finndjävel]

As fribygg says. If the sawdust is fresh, just top it with spray insulation. Use some hygroscopic material that fits well with the sawdust, cellulose or similar.

You can start with quite a little, around 100mm or so, to see how it affects the climate in the attic. You can always add more later.

 

[downup]

Why do you need to replace the sawdust, isn't it enough to just refill it to avoid a lot of work and get better insulation ability with a material that suits the house.

Can you buy sawdust somewhere?

 

[Screew]

Can you buy spån somewhere?

I bought a sack of kutterspån at Byggmax when I needed to refill at my place. 100l was about a hundred or something.

 

[Rickard.]

One of the local sawmills here sells their by-products at almost cost price (loaded loosely with a loader) but they don't advertise it directly and you have to make a bit of an effort to buy. With a bit of luck, you have something similar nearby.

 

[Mattias Andreasson]

Can you buy shavings somewhere?

I bought a pallet of wood shavings at Granngården, chose a coarser "dust-free" variant to make it more pleasant to work with, which I laid on top of the old, first fluffing up the old material. Used 13 bales, sold the rest to a horse girl https://www.granngarden.se/kutterspan-grov

The previous owner had placed a layer of yellow fiber boards on top of the old shavings and then rolled out insulation with paper. I bought and added an additional layer of boards. It only cost a couple of thousand and almost doubled the thickness of both the shavings and the insulation.

This happened in conjunction with a lot of new electricity being run through the attic, so much of the insulation was thrown aside up there, so it wasn't much extra work when it had to be restored anyway.

 

[Aunty]

I generally think the recommendations in the thread to TS are quite poor. Recommending topping up with wood shavings must be the worst solution for TS.

Wood shavings have several negative aspects such as pest damage, mold damage, and high fire risk. But above all, it is a poor insulation in terms of U-value compared to the alternatives. For example, Cellulose fiber insulation insulates about twice as well as wood shavings.

So, of course, remove all wood shavings and replace them with Cellulose fiber insulation, which has the good moisture buffering properties of wood shavings but not the negatives.

 

[fribygg]

I think the recommendations in the thread for TS are generally quite poor. Recommending adding more wood shavings must be the worst solution for TS.

Wood shavings have several negative aspects such as susceptibility to damage, mold attacks, and a high fire risk. But most importantly, it is a poor insulator regarding U-value compared to the alternatives. For example, cellulose fiber insulation insulates about twice as well as wood shavings.

So, of course, remove all the wood shavings and replace them with cellulose fiber insulation, which has the good moisture-buffering properties of wood shavings but not the negatives.

What is the benefit of removing the existing shavings?

 

[Aunty]

What is the benefit of removing the existing shavings?

takes up unnecessary space when you're planning to blow in new cellulose fiber insulation, a few extra centimeters in the attic make a huge difference, especially when you replace it with such a much more effective insulation.

then sawdust has several bad properties as I mentioned earlier that you then avoid, such as fire risk and pests.

 

[fribygg]

takes up unnecessary space when you're going to blow in new cellulose fiber insulation anyway; a couple of extra cm in the attic makes a huge difference, especially when you're replacing it with insulation that is much more efficient.

Furthermore, wood shavings have several bad properties, as I mentioned earlier, which you then avoid, such as fire risk and pests.

But the OP has sawdust and has no problem with it except that there is too little.
It is entirely possible to add more sawdust, cellulose fiber, or wood shavings on top of the existing sawdust, and as far as I understand, there is plenty of space.

 

[Davion]

takes up unnecessary space when you're going to blow in new Cellulose fiber insulation anyway, a few extra cm in the attic makes an incredible difference, especially when you replace it with insulation that is so much more efficient.

then shavings have several bad properties, as I said earlier, which you avoid, such as fire risk and pests.

It's not bad at all to suggest a bit more shavings, given that the only problem for TS currently is that there's a bit too much waste. It's a minor issue compared to what might happen if other solutions are attempted, and you can partially solve it just by increasing the amount of shavings.

 

[Mattias_Jo1]

In that case, replace the sawdust with cellulose wool, it has the same ability to absorb/release moisture.

One can lay cellulose directly on the sawdust. I will do so. Had a company here and they said it was the easiest if you already have sawdust.