Attefall house with concrete blocks

[HannesH]

I have plans for a attefallshus where I am planning a split-level floor. As I need to use concrete on the lower level, I am likely thinking of using the same material throughout and not mixing concrete + wood. However, I don't know which blocks one should use. I need someone to point me in the right direction. Am I on the right track by not mixing concrete + wood? Which blocks should I use and of what thickness? Perhaps a sandwich construction for good insulation? Are there risks with building a house in concrete blocks compared to a wood house? Thinking about problems with weight. It will be a concrete slab on the ground.

Thanks in advance

 

[huggan]

Not mixing wood and concrete is preferable even though it is still quite common.

What you should use for masonry is some form of Isblock with a core of cellular plastic.

Regarding the weight, you need to know what material is in the ground.

 

[HannesH]

Are there any specific blocks to look at? I've seen that there are different types of blocks, like Ytong, Leca etc.
How thick should they be to get reasonably good insulation?

 

[yonna]

It becomes very heavy if you have more than 30 cm in such a small house like an attefallare. My whole house (in Skåne) has this thinner and it works well. It's the windows/doors that are the culprits for heat loss.

 

[HannesH]

Yes, if you use blocks thicker than 300mm it feels like too much floor space is lost.
Is it possible to use thinner blocks perhaps?

 

[HannesH]

On the side that is below ground, it is recommended to use regular blocks (not isoblocks). Therefore, you also need to insulate with cellplast. Will the insulation count towards the building area? Are there any tips on what thickness and type of insulation should be used?

 

[Jonatan79]

Why not use isoblock for the entire house? 300mm is a bit excessive, go down a size if you plan to have it all the way to the ceiling? Isn't it much more expensive than wood studs & regular insulation?

 

[b8q]

Why not use isoblock throughout the house?

...because the manufacturer says you should not use isoblock below ground, perhaps?
https://www.weber.se/leca-registred...stemlosning/yttervaggar-leca-reg-stenhus.html

 

[Jonatan79]

ajf_n, I had missed that.

 

[haavard]

The majority of all single-family homes indeed mix concrete and wood. The most common is a concrete slab with a wooden superstructure, but there are also many hillside/basement floors with a wooden superstructure.

 

[HannesH]

Still considering what thickness the blocks should be. Now the idea is to build everything that will be underground and construct the rest in a wooden structure.

Looked here:
https://www.weber.se/fileadmin/user_upload/pdf/leca/arbanv/leca-block-arbetsanv.pdf
Can one go down to 200 or even 150 blocks? How do you insulate on the inside? What U-value can be expected?

 

[vanpire]

I would opt for 150 mm leca and then insulate with Kingspansheets which have a high U-value. It does cost a bit more than regular insulation, but an Attefallshus isn't that big...

 

[HannesH]

Do you mean low U-value? Is there a specific Kingspan board you're thinking of or PIR insulation in general?

 

[vanpire]

Sure, low U-value of course 🙈
I don't know what type it is.

 

[vanpire]

Checked
It's Cooltherm K12 that bro has used on his Attefallshus built in Leca.