Ok to move the sill from the edge of the slab with external horizontal insulation?

[Anders_Nilsson]

I have designed my vacation home with an exterior wall of 195mm vertical studs and 45mm horizontal on the inside as an installation layer. I'm considering if I should instead have 45+145+45, i.e., a horizontal insulation layer on the outside.

In that case, is it OK to move the sill and the 145-studs 45 mm inward to maintain the exterior dimensions (I have already submitted the building permit)? This way, the panel won't hang far outside.

Then I'm wondering about the rigidity, I initially planned to use outdoor gypsum on the 195s to stiffen it up. Should I then apply the outdoor gypsum on the 145s and then add horizontal 45mm insulation, but settle with windproof paper and then nail studs and horizontal paneling on the outside?

How do you then handle the support for the roof trusses? I plan to use the roof truss book's program, I thought you could specify 190 mm as the support even if the trusses only rest on the innermost 145mm, right or wrong?

/Anders

 

[Ola78]

If it's okay depends on whether your foundation can handle the load coming further in. But if that's not an issue, I don't see why you couldn't do so. Regarding the stiffness of the wall, follow this principle you can find here http://www.traguiden.se/TGtemplates/popup2spalt.aspx?id=4552&contextPage=5947

 

[Matti_75]

Instead of 45mm regular insulation on the outside, you use västkustskiva on the exterior gypsum. This gives you a complete insulation layer without thermal bridges, and the insulation also has wind protection.

 

[Anders_Nilsson]

Instead of 45mm regular insulation on the outside, you use west coast board on the exterior plasterboard. That gives you a complete insulation layer without thermal bridges, and the insulation also has wind protection.

Is it one of those complete ones where you attach the battens with plastic spacers? I think I've seen it somewhere.

The foundation: it should be a slab on grade with L-beams so moving the sill inward should move the load further from the edge beams and increase load-bearing capacity.

/Anders

 

[Ola78]

Is it one of those comprehensive ones where you put nail battens on plastic spacers? I think I've seen it somewhere. /Anders

It's that kind of board Matti_75 means, Isover's equivalent is called facade board but is a similar product.

 

[Matti_75]

If you are going to use L-elements, you should not place the sill right at the edge, as you will have no load-bearing capacity. In that case, it would be only the insulation foam supporting the entire house.

 

[b8q]

When it comes to the stiffness of the wall, according to this principle which you can find here [link]

Probably a good site when it comes to wood, but I notice that they have a drawing ("Connection to foundation wall") where the foundation wall has internal insulation...

 

[Mikael_L]

I have designed my holiday home with an outer wall of 195mm vertical studs and 45mm horizontal on the inside as an installation layer. I'm considering if one should instead have 45+145+45, i.e., a horizontal insulation layer on the outside.

Is it OK in that case to move the sill and the 145 studs 45 mm inwards to maintain the external dimensions?

Yes.

Then I'm wondering about the stiffness. I initially thought of attaching exterior gypsum to the 195s for rigidity. Should I then attach the exterior gypsum to the 145s and just add horizontal 45mm insulation, settling for wind protection paper, and then nail battens and horizontal cladding on the outside?

I would have attached the exterior gypsum to the 45s. Everything else seems a bit tricky, even though it certainly works. If you place the gypsum in between, it might be best to use a wind barrier fabric on the outside instead of windproof paper, as the fabric is more breathable.

How do you then handle the supports for the roof trusses? I'm planning to use the roof truss program from the handbook, so I thought of specifying 190mm as the support even if the trusses only rest on the innermost 145mm, right or wrong?

No, it is not correct to specify a longer support length than the actual one since the program calculates based on the compression load. Design and draw plans as if the trusses are on a house with only a 145mm frame and corresponding top plates. Set the span for this frame exactly as it will be in your finished house. Design truss ends that are 4.5 cm longer than what you envision for the final result.

Then build a house with a 145mm frame and roof trusses suitable for this, and then "retrofit" with 45mm of insulation on both the inside and outside. It's also better not to lock the spacing measurement for the outer insulation to a top plate but rather to run full panels past and up to the truss.

Or use west coast panels. They provide better wall insulation but are more expensive.

 

[Mikael_L]

The foundation: it should be slab on grade with L-beams so moving in the sill beam should move the load further from the edge beams and increase the load-bearing capacity.

Not further from the edge beams, that's not good ... :O
But you might mean the edge, and then you're right.
You have the best load-bearing capacity if the load is centered on the edge beam. And centered on the edge beam is often inside the outer wall when building with L-elements. So your idea of moving the framework inward (and narrower sill beam) is just good, and beneficial.

 

[Ola78]

Probably a good site when it comes to wood, but I note that they have a drawing ("Connection to foundation wall") where the foundation wall has interior insulation...

It doesn't have to be wrong, there are several variants of outdoor ventilated crawl spaces. Here you can read about these http://www.traguiden.se/TGtemplates/popup1spalt.aspx?id=1188 and here you find an example of a construction on an outdoor air-ventilated foundation that also has insulation on the inside http://www.traguiden.se/TGtemplates/popup2spalt.aspx?id=4421&contextPage=5945

 

[Anders_Nilsson]

Not further from the edge beams, that's not good ... :O
But you might mean the edge, and then you are right.
You have the best load-bearing capacity if the load comes in the middle of the edge beam. And the middle of the edge beam is often inside the outer wall when building with L-elements. So your idea of moving the frame inward (and narrower sill) is only good and beneficial.

The idea of placing the gypsum on standing studs (the 145s) was that it feels stiffer sideways because you get more edge area that is directly connected to the wood. You can then attach to both the standing stud and the sill/rafters. But maybe it will be stiff enough anyway? Otherwise, there is the recipe with the Västkustskiva.

The edge beams are thus the frame (approx. 200mm) of thicker concrete (you remove a layer of styrofoam?) where you place the cages with rebar, like 3 twelves at the bottom and 2 twelves on top and wire brackets around? I meant further from the thin styrofoam/plaster edge on the L-element that constitutes the outside of the foundation and more onto the rebar-reinforced edge beam.

Yes, it sounds reasonable that the center of the sill should stand on top of the center of the edge beam (concrete frame). I have read in assembly instructions for L-elements that they warn against loading near the edge, apparently, facing bricks are not recommended.

Roof trusses: I understand what you mean. My thought was to get more clearance to the top chord. However, the roof trusses in the truss book almost have the top chord directly on top of the bottom chord (only a few centimeters cut at an angle on the bottom chord), so there is space in height anyway, otherwise I was afraid that the uppermost lying stud would be difficult to fit, some trusses I have seen have cut the bottom chord with the roof angle all the way. Then you immediately hit the top chord with the uppermost stud.

/Anders