ᐅ House built with solid construction and a gable made of timber frame?
Created on: 26 Jan 2016 17:17
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elVincentE
elVincent26 Jan 2016 17:17Hello,
the planning for our construction project is progressing rapidly. We just received the following proposal from the carpentry company responsible for the roof: From their perspective, it would be advisable to build the gable sides of our staggered shed roof as a timber frame structure, because this would
a) be structurally simpler overall, and
b) offer advantages in terms of thermal bridge prevention.
The house is otherwise planned as a solid masonry building with 36.5cm (14 inches) walls. According to the current plans and calculations by the energy consultant, we will achieve KfW55 standards. Nevertheless, we are naturally open to anything that could provide additional energy efficiency benefits. The simpler construction might also mean it could ultimately be more cost-effective.
My main concern is the risk of cracking in the facade due to different thermal expansion of the materials used. While this will always be somewhat the case, I imagine the effect would be more noticeable if everything above the upper floor ceiling is made of wood.
It might be important to mention that the space between the upper floor ceiling and the roof is intended only as a storage room. Insulation is still provided through the roof surfaces, so the room is within the insulated building envelope.
Does anyone have experience with this topic or any reasons for or against such a design?
Thank you very much and best regards
Holger
the planning for our construction project is progressing rapidly. We just received the following proposal from the carpentry company responsible for the roof: From their perspective, it would be advisable to build the gable sides of our staggered shed roof as a timber frame structure, because this would
a) be structurally simpler overall, and
b) offer advantages in terms of thermal bridge prevention.
The house is otherwise planned as a solid masonry building with 36.5cm (14 inches) walls. According to the current plans and calculations by the energy consultant, we will achieve KfW55 standards. Nevertheless, we are naturally open to anything that could provide additional energy efficiency benefits. The simpler construction might also mean it could ultimately be more cost-effective.
My main concern is the risk of cracking in the facade due to different thermal expansion of the materials used. While this will always be somewhat the case, I imagine the effect would be more noticeable if everything above the upper floor ceiling is made of wood.
It might be important to mention that the space between the upper floor ceiling and the roof is intended only as a storage room. Insulation is still provided through the roof surfaces, so the room is within the insulated building envelope.
Does anyone have experience with this topic or any reasons for or against such a design?
Thank you very much and best regards
Holger
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Doc.Schnaggls27 Jan 2016 08:27Hello Holger,
we recently looked at a so-called "hybrid house" that was for sale.
We actually noticed almost continuous and clearly visible cracks at the junctions between the masonry and the timber frame sections, both inside and outside.
The house was only three years old at the time of the inspection.
However, I am not an expert in building defects – I’m sure others will chime in here.
Best regards,
Dirk
we recently looked at a so-called "hybrid house" that was for sale.
We actually noticed almost continuous and clearly visible cracks at the junctions between the masonry and the timber frame sections, both inside and outside.
The house was only three years old at the time of the inspection.
However, I am not an expert in building defects – I’m sure others will chime in here.
Best regards,
Dirk
Hi,
I have never seen gable ends constructed solely with timber frame construction. I can well imagine that what Doc Schnaggels says is correct and supports your concerns: whether this is really the best solution is certainly open to question at first.
In the immediate neighborhood, a house was built with a solid ground floor and a timber frame upper floor. My father and I have a similar house in Hesse, with a masonry ground floor and a Swedish log house upper floor. However, that’s somewhat different from just the gables.
If this proposal came up afterwards, then the issue of thermal bridges must have already been successfully calculated in relation to solidly built gables. So where exactly is the advantage, since the house is already planned to meet KfW-55 standard.
Best regards
Thorsten
I have never seen gable ends constructed solely with timber frame construction. I can well imagine that what Doc Schnaggels says is correct and supports your concerns: whether this is really the best solution is certainly open to question at first.
In the immediate neighborhood, a house was built with a solid ground floor and a timber frame upper floor. My father and I have a similar house in Hesse, with a masonry ground floor and a Swedish log house upper floor. However, that’s somewhat different from just the gables.
If this proposal came up afterwards, then the issue of thermal bridges must have already been successfully calculated in relation to solidly built gables. So where exactly is the advantage, since the house is already planned to meet KfW-55 standard.
Best regards
Thorsten
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Bauexperte27 Jan 2016 11:50Hello Holger,
I tend to think that this mainly benefits the carpenter’s scope of work.
I know two contractors who work like this or similarly; the purpose of this hybrid masonry has not yet become clear to me. One generally builds the gable walls in the attic fully solid, the other only the inner leaf (including the knee wall) in lightweight construction; the ground floor and any additional full stories are always built solid.
So why are you considering spending money again for structural engineering and, almost certainly, thermal performance verification?
Best regards, Bauexperte
elVincent schrieb:
Now there is the following suggestion from the carpentry company responsible for the roof: From their point of view, it would be advisable to construct the gable ends of our staggered shed roof as timber frame walls, because overall this would
a) be structurally simpler and
b) offer advantages regarding thermal bridge reduction.
I tend to think that this mainly benefits the carpenter’s scope of work.
I know two contractors who work like this or similarly; the purpose of this hybrid masonry has not yet become clear to me. One generally builds the gable walls in the attic fully solid, the other only the inner leaf (including the knee wall) in lightweight construction; the ground floor and any additional full stories are always built solid.
elVincent schrieb:
According to the current plans and calculations by the energy consultant, we will achieve KfW55.
So why are you considering spending money again for structural engineering and, almost certainly, thermal performance verification?
Best regards, Bauexperte
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elVincent27 Jan 2016 13:24Thank you for the responses.
I have also been considering the possible advantages and am still unsure. The short vertical section between the two shed roofs will definitely be constructed in timber, so theoretically, this could even mean one less material change.
The energy consultant has confirmed that this measure would have a positive effect on transmission heat losses. However, since we can achieve our goal without it, the question of necessity is naturally justified.
The structural engineer has also commented: if built with a timber frame, the ring beam can be omitted. So there are indeed structural advantages.
The remaining question is whether such a construction might be more prone to cracking from the plasterer’s perspective (whom we unfortunately do not have yet).
The best approach is probably to compare the expected costs of both options, and if there is no cost benefit to the hybrid construction method, to stick with the tried and tested solution. I will definitely get back to you once the costs are clear.
Thank you very much and best regards
I have also been considering the possible advantages and am still unsure. The short vertical section between the two shed roofs will definitely be constructed in timber, so theoretically, this could even mean one less material change.
The energy consultant has confirmed that this measure would have a positive effect on transmission heat losses. However, since we can achieve our goal without it, the question of necessity is naturally justified.
The structural engineer has also commented: if built with a timber frame, the ring beam can be omitted. So there are indeed structural advantages.
The remaining question is whether such a construction might be more prone to cracking from the plasterer’s perspective (whom we unfortunately do not have yet).
The best approach is probably to compare the expected costs of both options, and if there is no cost benefit to the hybrid construction method, to stick with the tried and tested solution. I will definitely get back to you once the costs are clear.
Thank you very much and best regards
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