ᐅ Single-family house without a basement – creating additional usable space elsewhere
Created on: 26 Mar 2018 14:43
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EnnoBecker
Hello everyone,
We are building our single-family house without a basement with the following specifications:
Gable roof with a 45° pitch
Knee wall 1m (3.3 ft)
Living area: 148 m² (1,593 sq ft)
House dimensions: 8.95m x 11.32m (29.4 ft x 37.2 ft)
We want to compensate for the lack of storage space from the missing basement through the following measures:
I have questions regarding the following points:
1 - Attic:
This is a cold roof, meaning the floor between the upper floor and attic is insulated with mineral wool and has a vapor barrier in between.
The goal is to create more storage space. The attic is not intended to be used as living space.
For this purpose, I want to use tongue-and-groove boards, as these are vapor permeable compared to OSB panels and therefore prevent issues with rising moisture from the upper floor.
Questions:
The attached picture is provided as an example.
2 - Garage
The garage is planned to be 3.45m (11.3 ft) wide and 9m (29.5 ft) long. Inside the garage, a partition wall will be installed to separate the parking space from a storage area. Do you have recommendations for manufacturers or personal experience with this?
Thank you for your help.
Best regards,
Enno
We are building our single-family house without a basement with the following specifications:
Gable roof with a 45° pitch
Knee wall 1m (3.3 ft)
Living area: 148 m² (1,593 sq ft)
House dimensions: 8.95m x 11.32m (29.4 ft x 37.2 ft)
We want to compensate for the lack of storage space from the missing basement through the following measures:
- Make the attic accessible
- Build an extended single garage
- Build a spacious garden shed
I have questions regarding the following points:
1 - Attic:
This is a cold roof, meaning the floor between the upper floor and attic is insulated with mineral wool and has a vapor barrier in between.
The goal is to create more storage space. The attic is not intended to be used as living space.
For this purpose, I want to use tongue-and-groove boards, as these are vapor permeable compared to OSB panels and therefore prevent issues with rising moisture from the upper floor.
Questions:
- So far, a pull-down attic ladder is planned. My wife prefers a fixed space-saving staircase with a railing for easier access. In my view, this should be no problem as long as the access hatch to the attic remains insulated. Are there suitable solutions for this?
- We would also like to dry wet laundry in the attic. In our case, is this unproblematic? I believe the evaporated moisture could easily escape.
- What do you think, how much effectively usable floor area would this create?
- Do you have any personal experience with this?
The attached picture is provided as an example.
2 - Garage
The garage is planned to be 3.45m (11.3 ft) wide and 9m (29.5 ft) long. Inside the garage, a partition wall will be installed to separate the parking space from a storage area. Do you have recommendations for manufacturers or personal experience with this?
Thank you for your help.
Best regards,
Enno
K
Knallkörper28 Mar 2018 23:29After airing out under these outdoor conditions, I measure 20°C (68°F) and 30% humidity. The dew point is then 1.9°C (35.4°F). This means that water will condense if I open the attic ladder in these conditions. If the hatch remains open, the humidity in the attic rises to 99%....
For a cold floor, even the typical indoor humidity during winter can become a problem. Your living spaces at 20 degrees Celsius (68°F) and 40% relative humidity hold more moisture than an attic at 1 degree Celsius (34°F) and 99% relative humidity.
This means that if the attic is left open for too long in winter and the room air warms the attic, the air has a high absolute humidity, which is not initially a problem at 20 degrees Celsius (68°F). However, once the hatch is closed and the temperature drops, the maximum amount of moisture the air can hold decreases. When 100% relative humidity is reached, water condenses... and then we end up with mold in the insulation.
This means that if the attic is left open for too long in winter and the room air warms the attic, the air has a high absolute humidity, which is not initially a problem at 20 degrees Celsius (68°F). However, once the hatch is closed and the temperature drops, the maximum amount of moisture the air can hold decreases. When 100% relative humidity is reached, water condenses... and then we end up with mold in the insulation.
H
hemali200329 Mar 2018 08:33So opening the roof hatch is rather counterproductive...? Otherwise, we wouldn’t be able to ventilate at all.
But good to know that if you need to get something, you should keep it as brief as possible to avoid having the hatch open for too long.
But good to know that if you need to get something, you should keep it as brief as possible to avoid having the hatch open for too long.
C
Caspar202029 Mar 2018 08:40In the next life
In summary, it can be said:
- A warm attic (insulated ceiling and insulation between rafters) must be connected to a controlled mechanical ventilation system and requires heating?
- A cold attic (only ceiling insulated) does not require either?
We need a warm attic because the controlled mechanical ventilation system and heating will be installed there. We have a concrete ceiling slab. The energy consultant recommends: 18cm (7 inches) of styrofoam insulation (flat EPS 035 insulation board) + 315mm (12.4 inches) OSB. Insulation between rafters with friction-fit mineral wool, vapor retarder, and gypsum fiberboard (alternatively gypsum plasterboard). The consultant even denied that a vapor barrier is necessary. However, I would use one as a precaution.
Now to the question: Can we safely use OSB? Could it warp due to moisture? I would rather use tongue-and-groove boards, but according to the energy consultant, that requires a complicated substructure. Or is this easy to install? And with this insulation method, do we still need heating and connection to the controlled mechanical ventilation system?
A second option suggested by a supplier would be wood fiber insulation boards (100mm (4 inches) Pavatex Isolair WLF 0.043 + 80mm (3 inches) Pavatex Isolair WLF 0.046) + 22mm (0.9 inch) OSB. The insulation between rafters is the same as in the first variant. According to the supplier, OSB should no longer warp with this setup. Is that true? Is heating and connection to controlled mechanical ventilation still necessary with the second option?
- A warm attic (insulated ceiling and insulation between rafters) must be connected to a controlled mechanical ventilation system and requires heating?
- A cold attic (only ceiling insulated) does not require either?
We need a warm attic because the controlled mechanical ventilation system and heating will be installed there. We have a concrete ceiling slab. The energy consultant recommends: 18cm (7 inches) of styrofoam insulation (flat EPS 035 insulation board) + 315mm (12.4 inches) OSB. Insulation between rafters with friction-fit mineral wool, vapor retarder, and gypsum fiberboard (alternatively gypsum plasterboard). The consultant even denied that a vapor barrier is necessary. However, I would use one as a precaution.
Now to the question: Can we safely use OSB? Could it warp due to moisture? I would rather use tongue-and-groove boards, but according to the energy consultant, that requires a complicated substructure. Or is this easy to install? And with this insulation method, do we still need heating and connection to the controlled mechanical ventilation system?
A second option suggested by a supplier would be wood fiber insulation boards (100mm (4 inches) Pavatex Isolair WLF 0.043 + 80mm (3 inches) Pavatex Isolair WLF 0.046) + 22mm (0.9 inch) OSB. The insulation between rafters is the same as in the first variant. According to the supplier, OSB should no longer warp with this setup. Is that true? Is heating and connection to controlled mechanical ventilation still necessary with the second option?
Experience after one winter.
Cold attic with stair access, separated from the living area by an insulated hallway upstairs plus a patio door. A patio door, because it can handle the large temperature difference between the attic floor and the living space without warping and because it is well insulated.
The attic is ventilated through a Velux window. Stored there are cushions, a boat and garden equipment, blankets, suitcases, tools, miscellaneous items, chairs, and much more. Everything intact, no mold, everything dry. There is no need for additional insulation. Really not. Karsten
Cold attic with stair access, separated from the living area by an insulated hallway upstairs plus a patio door. A patio door, because it can handle the large temperature difference between the attic floor and the living space without warping and because it is well insulated.
The attic is ventilated through a Velux window. Stored there are cushions, a boat and garden equipment, blankets, suitcases, tools, miscellaneous items, chairs, and much more. Everything intact, no mold, everything dry. There is no need for additional insulation. Really not. Karsten
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