ᐅ Is the construction of the basement wall and floor like this acceptable?
Created on: 24 Oct 2023 11:21
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Narnulf1368N
Narnulf136824 Oct 2023 11:21Hello everyone,
We are in the final stages of our house planning (which has now been ongoing for two years...), but we are about to submit the building permit / planning permission application!
I have now received detailed plans from the architect and am uncertain about the construction of the basement walls and floor. Specifically, I notice that the insulation is on the outside of the walls, followed by the concrete, whereas for the floor, the concrete slab comes first and then the insulation. Although insulated blocks are planned, doesn’t that create a thermal bridge directly into the basement?
I’ve attached a picture.
Is that a type of waterproofing tank / cavity waterproofing?
Even though this is the basement subforum, is the roof structure okay as shown?
Thank you in advance!
We are in the final stages of our house planning (which has now been ongoing for two years...), but we are about to submit the building permit / planning permission application!
I have now received detailed plans from the architect and am uncertain about the construction of the basement walls and floor. Specifically, I notice that the insulation is on the outside of the walls, followed by the concrete, whereas for the floor, the concrete slab comes first and then the insulation. Although insulated blocks are planned, doesn’t that create a thermal bridge directly into the basement?
I’ve attached a picture.
Is that a type of waterproofing tank / cavity waterproofing?
Even though this is the basement subforum, is the roof structure okay as shown?
Thank you in advance!
H
hanghaus202324 Oct 2023 11:42The roof can be designed like that. However, it’s difficult to say whether 28mm (1.1 inch) rafters are structurally necessary. That seems quite large to me.
Why is the support span on the ground floor so wide? Using 30mm (1.2 inch) joists is quite expensive. This can be done much more cheaply with something like this.
A ceiling height of 2.36m (7 ft 9 in) is a no-go.
Why is the support span on the ground floor so wide? Using 30mm (1.2 inch) joists is quite expensive. This can be done much more cheaply with something like this.
A ceiling height of 2.36m (7 ft 9 in) is a no-go.
Narnulf1368 schrieb:
Now I have received detailed plans from the architect and am uncertain about the construction of the basement walls and floor. Specifically, my concern is that for the walls, the insulation is applied on the outside and then the concrete, whereas for the floor, the concrete slab comes first and then the insulation. Although insulating blocks are planned, doesn’t this create a thermal bridge directly into the basement?According to the textual description, 6 cm (2½ inches) of "pressure-resistant insulation" is to be installed under the slab. This is not immediately problematic, but the thickness is quite small – a minimum of 14 cm (5½ inches) should be planned, depending on energy efficiency goals, even more. I hope the note about "lean concrete" between the slab and insulation is a typo – it should be placed beneath the insulation.
Make sure that the edges of the slab are properly insulated as well. According to the drawing, they are currently not insulated (although the slab is shown in a rather unusual way) – meaning the insulation must be applied to the slab edges and also extended on top (possibly tapered) to connect with the wall insulation.
For this, the rigid foam insulation (PUR) above the slab could be installed a bit thinner (e.g., 60 mm (2⅜ inches), if installations allow) – this could save about 4 cm (1½ inches) of room height.
I also find the 12 cm (4¾ inches) wall insulation quite minimal – more would be better.
As mentioned, insulation is also planned under the concrete slab. 12 cm (5 inches) of polyurethane (PU) against the basement floor plus 6 cm (2.5 inches) of extruded polystyrene (XPS) underneath is a good combination. 12 cm (5 inches) of PU has a thermal conductivity of 0.022 W/mK and is absolutely sufficient against the ground.
The 10 to 12 cm (4 to 5 inches) of insulation against the ground on the basement wall is also sufficient according to the building energy code if it is 0.036 W/mK XPS. Better performance at the same thickness can be achieved with 0.027 W/mK rigid phenolic foam (resol foam), but this is more expensive.
The roof should be constructed with 28 cm (11 inches) beams and appropriately thick insulation for good thermal protection, as should the stud walls.
The 10 to 12 cm (4 to 5 inches) of insulation against the ground on the basement wall is also sufficient according to the building energy code if it is 0.036 W/mK XPS. Better performance at the same thickness can be achieved with 0.027 W/mK rigid phenolic foam (resol foam), but this is more expensive.
The roof should be constructed with 28 cm (11 inches) beams and appropriately thick insulation for good thermal protection, as should the stud walls.
Narnulf1368 schrieb:
We are in the final stages of our house planning (which has now been ongoing for two years...), and we are just about to finally submit the building permit application! All the more unfortunate that you haven’t kept us updated along the way, especially since your concept has obviously changed significantly since https://www.hausbau-forum.de/threads/wie-viel-dachueberstand-bei-holzhaus.45138/ ... and now you only focus on one problem area instead of showing the entire house :-(
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