flowschi
2020-01-03 20:40:23
- #1
Hello,
Happy New Year!
And my first post here.
We have been struggling for a while with the decision between the two remaining construction companies. To come to a decision, I would like to gather some opinions.
From the beginning, only the timber construction method was an option for us, with ecological and healthy building being important. We obtained offers from 6 companies and have now reduced them to two. What is offered is a shell house: same floor plan, wooden windows, planning for controlled residential ventilation and underfloor heating. Heating, sanitary, and electrical work are not considered at this point – these will be assigned separately or done by ourselves.
Here is a brief summary of our options:
Offer A - Massive Wood Wall (MHM)
- Exterior walls: 100 mm wood fiber + 205 mm massive wood wall
- Interior walls: 115 or 160 mm massive wood wall
- Sheathing then done with gypsum plasterboards
Advantages:
- Ecological, no chemical treatment of the MHM
- Good summer thermal protection
- The company seems a bit more reliable and professional than Offer B. Offer B would not still be in the running if we had doubts here.
Disadvantages:
- About 8-10% more expensive than Offer B
- Not KFW40 as standard, since the exterior wall has a U-value of 0.22. Exact calculation only after order placement, with additional costs KFW40 possibly feasible (controlled residential ventilation and photovoltaics are planned). However, I am skeptical about this U-value since I have studied it in more detail ("effective U-value", phase shift…).
My main concern is the funding: Our financier could not tell us yet whether the KFW subsidy is worthwhile for us without a concrete calculation.
- Especially in the electrical trade (DIY): a precise, prior planning is necessary here. Later deviations during installation mean more effort to get them into the walls.
Regarding the massive, foil-free, and chemical-free walls (as far as I can judge, possibly excluding the wood fiber board outside), this is our favorite. As for the winter insulation properties, I am not quite clear about it. The simple U-value initially represents the wall rather badly, but various studies conclude that reality is different and the actual energy costs are significantly below the calculated ones.
Offer B - Timber Frame Construction
- Exterior wall: 60 mm wood fiber board, 60/260 KVH studs with Isocell, 15 mm OSB board, 12.5 mm gypsum fiberboard
- Interior walls: 12.5 mm Fermacell, 120 mm KVH Duo or 160 mm, 12.5 mm Fermacell. Insulation done in DIY with jute.
Advantages:
- Very ecological, no foil/vapor barrier, no polystyrene insulation
- U-value 0.14. KFW40 "as standard," with controlled residential ventilation and photovoltaics + storage also KFW40 plus.
- Continuous cable duct (no separate installation layer), DIY "electrical" probably somewhat more flexible than with massive wood
- About 8-10% cheaper, without considering possible KFW subsidy
Disadvantages:
- Insulation materials jute and cellulose: Not necessarily as ecological and healthy as often marketed. Borate salts, polyethylene terephthalate, ...
- Walls for hanging objects naturally not quite as easy to use as with massive wood
---
We have already discussed this among acquaintances and have received very different opinions, such as:
1) MHM: Poor U-value, not even KFW40, and more expensive? No way!
2) MHM: Only 10% more expensive? That healthy and ecological building method is definitely worth that to me!
My opinion is somehow in between: If prices were equal, I would choose MHM and also forgo KFW40. For our financing, these 10% are not insignificant, but somehow feasible.
Now I look forward to your assessment and also subjective opinions.
Is there anything missing in my information that interests you?
Thank you very much!
Happy New Year!
And my first post here.
We have been struggling for a while with the decision between the two remaining construction companies. To come to a decision, I would like to gather some opinions.
From the beginning, only the timber construction method was an option for us, with ecological and healthy building being important. We obtained offers from 6 companies and have now reduced them to two. What is offered is a shell house: same floor plan, wooden windows, planning for controlled residential ventilation and underfloor heating. Heating, sanitary, and electrical work are not considered at this point – these will be assigned separately or done by ourselves.
Here is a brief summary of our options:
Offer A - Massive Wood Wall (MHM)
- Exterior walls: 100 mm wood fiber + 205 mm massive wood wall
- Interior walls: 115 or 160 mm massive wood wall
- Sheathing then done with gypsum plasterboards
Advantages:
- Ecological, no chemical treatment of the MHM
- Good summer thermal protection
- The company seems a bit more reliable and professional than Offer B. Offer B would not still be in the running if we had doubts here.
Disadvantages:
- About 8-10% more expensive than Offer B
- Not KFW40 as standard, since the exterior wall has a U-value of 0.22. Exact calculation only after order placement, with additional costs KFW40 possibly feasible (controlled residential ventilation and photovoltaics are planned). However, I am skeptical about this U-value since I have studied it in more detail ("effective U-value", phase shift…).
My main concern is the funding: Our financier could not tell us yet whether the KFW subsidy is worthwhile for us without a concrete calculation.
- Especially in the electrical trade (DIY): a precise, prior planning is necessary here. Later deviations during installation mean more effort to get them into the walls.
Regarding the massive, foil-free, and chemical-free walls (as far as I can judge, possibly excluding the wood fiber board outside), this is our favorite. As for the winter insulation properties, I am not quite clear about it. The simple U-value initially represents the wall rather badly, but various studies conclude that reality is different and the actual energy costs are significantly below the calculated ones.
Offer B - Timber Frame Construction
- Exterior wall: 60 mm wood fiber board, 60/260 KVH studs with Isocell, 15 mm OSB board, 12.5 mm gypsum fiberboard
- Interior walls: 12.5 mm Fermacell, 120 mm KVH Duo or 160 mm, 12.5 mm Fermacell. Insulation done in DIY with jute.
Advantages:
- Very ecological, no foil/vapor barrier, no polystyrene insulation
- U-value 0.14. KFW40 "as standard," with controlled residential ventilation and photovoltaics + storage also KFW40 plus.
- Continuous cable duct (no separate installation layer), DIY "electrical" probably somewhat more flexible than with massive wood
- About 8-10% cheaper, without considering possible KFW subsidy
Disadvantages:
- Insulation materials jute and cellulose: Not necessarily as ecological and healthy as often marketed. Borate salts, polyethylene terephthalate, ...
- Walls for hanging objects naturally not quite as easy to use as with massive wood
---
We have already discussed this among acquaintances and have received very different opinions, such as:
1) MHM: Poor U-value, not even KFW40, and more expensive? No way!
2) MHM: Only 10% more expensive? That healthy and ecological building method is definitely worth that to me!
My opinion is somehow in between: If prices were equal, I would choose MHM and also forgo KFW40. For our financing, these 10% are not insignificant, but somehow feasible.
Now I look forward to your assessment and also subjective opinions.
Is there anything missing in my information that interests you?
Thank you very much!