ᐅ Exterior wall brick + interior walls calcium silicate blocks
Created on: 15 Sep 2013 16:10
A
Augustus
Hello,
Our detached house is being built monolithically with exterior walls made of brick. It was originally agreed that the interior walls would also be made of brick, as it seems that certain disadvantages can occur with the "red-white" combination. However, the interior walls have been constructed with calcium silicate blocks instead.
I am now wondering whether this supposed rule—that one should use either "red-red" (brick-brick) or "white-white" (aerated concrete-calcium silicate) combinations, but not mix "red-white"—is actually a common misconception, or if there are indeed real disadvantages and medium- to long-term issues (such as cracks) to be expected.
We are still at the shell construction stage, so in principle, significant changes could still be made with considerable effort. However, the ceilings have already been poured with concrete, which makes replacing the interior walls quite difficult.
Thank you for your assessments.
Augustus
Our detached house is being built monolithically with exterior walls made of brick. It was originally agreed that the interior walls would also be made of brick, as it seems that certain disadvantages can occur with the "red-white" combination. However, the interior walls have been constructed with calcium silicate blocks instead.
I am now wondering whether this supposed rule—that one should use either "red-red" (brick-brick) or "white-white" (aerated concrete-calcium silicate) combinations, but not mix "red-white"—is actually a common misconception, or if there are indeed real disadvantages and medium- to long-term issues (such as cracks) to be expected.
We are still at the shell construction stage, so in principle, significant changes could still be made with considerable effort. However, the ceilings have already been poured with concrete, which makes replacing the interior walls quite difficult.
Thank you for your assessments.
Augustus
A
AallRounder19 Sep 2013 20:04Addition:
A sliding joint only applies if the described anchors can move vertically along an anchor rail. In your case, it seems to involve fixed anchors. Whether this is sufficient given the different building materials and the expected shrinkage/creep values should be assessed by a professional who specializes in resolving such issues.
I would not take the construction defect with the calcium silicate brick lightly. Obtain a copy of DIN 1053-1, especially section 6.7.
What do the architect and, if applicable, the structural engineer say?
A sliding joint only applies if the described anchors can move vertically along an anchor rail. In your case, it seems to involve fixed anchors. Whether this is sufficient given the different building materials and the expected shrinkage/creep values should be assessed by a professional who specializes in resolving such issues.
I would not take the construction defect with the calcium silicate brick lightly. Obtain a copy of DIN 1053-1, especially section 6.7.
What do the architect and, if applicable, the structural engineer say?
Hello Allrounder,
thank you very much for your explanations.
Question: What would you do in my position if you actually find an exterior wall made of brick and load-bearing interior walls made of calcium silicate brick?
With the additional condition that an expansion joint is present and a groove cut is made.
Would you have them removed?
Best regards, Augustus
thank you very much for your explanations.
Question: What would you do in my position if you actually find an exterior wall made of brick and load-bearing interior walls made of calcium silicate brick?
With the additional condition that an expansion joint is present and a groove cut is made.
Would you have them removed?
Best regards, Augustus
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AallRounder20 Sep 2013 08:23Hello Augustus,
I would first have a clarifying conversation with the architect and construction manager to understand how the contract violation occurred and already hint that the drastic solution—demolition—is definitely an option. Have them explain exactly how the mistake can be corrected.
For proper compensation and the professional connection of the interior walls to the exterior walls (for this, get the above-mentioned DIN standard, which in section 6.7 fits your case exactly), you might consider agreeing to refrain from demolition. The company will have to accept that first. After all, they did not adhere to the contract and created unnecessary problems.
Simply cutting the joint will not solve the general issues caused by the different shrinkage/creep/moisture behavior of the two building materials: a thick Poroton wall with high moisture exposure (because it’s an exterior wall) versus a thinner calcium silicate wall, which as an interior wall will always be drier. This always poses a risk of cracking, which must be addressed with additional structural measures; unlike the originally planned homogeneous construction with a single building material.
Regards,
AallRounder
PS:
Based on your description of the anchors, this is probably not a slip joint, unless the anchors are vertically movable within an anchor channel!
I would first have a clarifying conversation with the architect and construction manager to understand how the contract violation occurred and already hint that the drastic solution—demolition—is definitely an option. Have them explain exactly how the mistake can be corrected.
For proper compensation and the professional connection of the interior walls to the exterior walls (for this, get the above-mentioned DIN standard, which in section 6.7 fits your case exactly), you might consider agreeing to refrain from demolition. The company will have to accept that first. After all, they did not adhere to the contract and created unnecessary problems.
Simply cutting the joint will not solve the general issues caused by the different shrinkage/creep/moisture behavior of the two building materials: a thick Poroton wall with high moisture exposure (because it’s an exterior wall) versus a thinner calcium silicate wall, which as an interior wall will always be drier. This always poses a risk of cracking, which must be addressed with additional structural measures; unlike the originally planned homogeneous construction with a single building material.
Regards,
AallRounder
PS:
Based on your description of the anchors, this is probably not a slip joint, unless the anchors are vertically movable within an anchor channel!
B
Bauexperte20 Sep 2013 10:48Hello Allrounder,
Your commitment to the forum is commendable, but in this thread, you are using "a sledgehammer to crack a nut."
That is correct and advisable; deviations from the building specifications (BB) should not be made without compelling reasons (geology, structural engineering, or local regulations) and “should” not be done without consulting the client. In most contracts, however, the construction manager (BU) is authorized by the client to act in this regard.
This will probably do more harm than good for the original poster, as there is—if the relevant standards (DIN) are properly followed—no reason to remove the interior walls made of sand-lime brick. The sand-lime brick industry has been offering tested products for years that help prevent cracks caused by different drying behaviors between hollow bricks and sand-lime bricks.
Provided the plasterer does their job properly, there is nothing against constructing interior walls with sand-lime brick; on the contrary, this is common practice and respects the homeowner’s wish for peace within their own four walls. Fundamentally, I agree with you that mixing masonry materials should, if possible, remain an exception.
In my opinion, those are not anchors but the usual metal strips commonly found in any shell construction.
Regards, Bauexperte
Your commitment to the forum is commendable, but in this thread, you are using "a sledgehammer to crack a nut."
Allrounder schrieb:
I would first have a clarifying discussion with the architect and construction manager to understand how the contract breach occurred.
That is correct and advisable; deviations from the building specifications (BB) should not be made without compelling reasons (geology, structural engineering, or local regulations) and “should” not be done without consulting the client. In most contracts, however, the construction manager (BU) is authorized by the client to act in this regard.
Allrounder schrieb:
And already hint that the radical solution = tearing everything out is definitely an option. They should explain exactly how the error can be fixed.
This will probably do more harm than good for the original poster, as there is—if the relevant standards (DIN) are properly followed—no reason to remove the interior walls made of sand-lime brick. The sand-lime brick industry has been offering tested products for years that help prevent cracks caused by different drying behaviors between hollow bricks and sand-lime bricks.
Provided the plasterer does their job properly, there is nothing against constructing interior walls with sand-lime brick; on the contrary, this is common practice and respects the homeowner’s wish for peace within their own four walls. Fundamentally, I agree with you that mixing masonry materials should, if possible, remain an exception.
Allrounder schrieb:
The anchors you described are probably not a movement joint unless the anchors are vertically movable in an anchor rail!
In my opinion, those are not anchors but the usual metal strips commonly found in any shell construction.
Regards, Bauexperte
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AallRounder20 Sep 2013 12:57Hello Building Expert,
nice to hear from you! I really appreciate your posts because of your balanced and competent approach.
I only mentioned demolition as a noteworthy option compared to renovation, not as a recommendation. From my experience, it can sometimes provide a stronger negotiating position if you don’t rule out the worst-case scenario from the start.
The builder should just be fully aware of what they are getting into and be able to at least roughly understand the technical requirements. A skillful plasterer alone would not meet the standard. It already depends on the structural wall connection with the “anchors made of stainless flat steel” (as the term used by the masonry industry known to me). Whether anchors, straps, or anchor modifications, we seem to be talking about the same element.
The builder should carefully coordinate this with the structural engineer and architect and always know exactly what they are committing to.
Regards
AallRounder
nice to hear from you! I really appreciate your posts because of your balanced and competent approach.
I only mentioned demolition as a noteworthy option compared to renovation, not as a recommendation. From my experience, it can sometimes provide a stronger negotiating position if you don’t rule out the worst-case scenario from the start.
The builder should just be fully aware of what they are getting into and be able to at least roughly understand the technical requirements. A skillful plasterer alone would not meet the standard. It already depends on the structural wall connection with the “anchors made of stainless flat steel” (as the term used by the masonry industry known to me). Whether anchors, straps, or anchor modifications, we seem to be talking about the same element.
The builder should carefully coordinate this with the structural engineer and architect and always know exactly what they are committing to.
Regards
AallRounder
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