ᐅ Is it still possible to install the concrete slab this year?
Created on: 31 Oct 2013 23:47
M
Milambar
Hello and HELP!!!
We are currently very anxious and worried.
How long does a concrete slab typically need to cure before construction can start on it (timber frame prefab house)?
And is "frost" really such a big problem?
If yes (I can imagine due to the water content), does this apply to a prolonged frost period,
or also to, for example, just a few hours during the night or early morning?
We have to hope that we can finish our slab somehow this year,
otherwise our house installation appointment in March/April will be seriously at risk.
We are supposed to get a "Thermo concrete slab KfW-55" (without heating).
Best regards
We are currently very anxious and worried.
How long does a concrete slab typically need to cure before construction can start on it (timber frame prefab house)?
And is "frost" really such a big problem?
If yes (I can imagine due to the water content), does this apply to a prolonged frost period,
or also to, for example, just a few hours during the night or early morning?
We have to hope that we can finish our slab somehow this year,
otherwise our house installation appointment in March/April will be seriously at risk.
We are supposed to get a "Thermo concrete slab KfW-55" (without heating).
Best regards
This topic also concerns me...
Thanks to an exemption we applied for, we have now been waiting for almost 3 months for the building permit / planning permission. Yesterday, I learned by phone that all authorities have now approved it, and we will most likely receive the permit by mail next week.
After that, the construction kickoff meeting with the developer company must take place, and only then can construction actually begin. The only question is: Will it still be possible to start at that point? In the best case, construction could probably start in calendar week 48.
Is it still possible to begin with the foundation slab by then????
Thanks to an exemption we applied for, we have now been waiting for almost 3 months for the building permit / planning permission. Yesterday, I learned by phone that all authorities have now approved it, and we will most likely receive the permit by mail next week.
After that, the construction kickoff meeting with the developer company must take place, and only then can construction actually begin. The only question is: Will it still be possible to start at that point? In the best case, construction could probably start in calendar week 48.
Is it still possible to begin with the foundation slab by then????
B
Bauexperte7 Nov 2013 11:42Hello,
I assume that it took you some time to decide on a provider and sign the contract. An exemption request for "something" usually ends up turning the dream of a simplified approval process into a regular building application. That process can take—in some cases—up to 6 months; you should have been informed about this.
Now it’s November—assuming you really have the unconditional building permit/planning permission on your desk next week, the soil report—if not already available—and the detailed construction plans/structural engineering calculations still need to be prepared. I would estimate this will take another good 3-4 weeks, including the necessary detailed plan review meeting, since you have to approve all plans. That puts us into December, likely with rather low temperatures—not ideal already. On top of that, there are the companies’ Christmas holidays, so no reasonable conditions for construction are possible before January anyway. If—and that’s a big if—the weather cooperates, but since recent years have taught us otherwise, I expect construction to begin in March or April 2014.
What good is a foundation slab exposed to the elements—if, contrary to expectations, it could still be poured this year—if all work then has to be stopped until the end of winter?
Hopefully, you plan to live in your new single-family house for many years—so a few extra months before construction begins should not be the deciding factor for you.
Best regards,
Bauexperte
aytex schrieb:It’s always interesting...
This topic concerns me as well...
Thanks to an exemption we applied for, we have now been waiting for almost 3 months for the building permit/planning permission. I found out by phone yesterday that all authorities have now approved it, and we will most likely receive the permit by mail next week.
After that, the construction kick-off meeting with the developer must take place, and only then can construction begin. The question is: can construction even start then? At best, it could start in calendar week 48.
Is it still possible to begin with the foundation slab by then????
I assume that it took you some time to decide on a provider and sign the contract. An exemption request for "something" usually ends up turning the dream of a simplified approval process into a regular building application. That process can take—in some cases—up to 6 months; you should have been informed about this.
Now it’s November—assuming you really have the unconditional building permit/planning permission on your desk next week, the soil report—if not already available—and the detailed construction plans/structural engineering calculations still need to be prepared. I would estimate this will take another good 3-4 weeks, including the necessary detailed plan review meeting, since you have to approve all plans. That puts us into December, likely with rather low temperatures—not ideal already. On top of that, there are the companies’ Christmas holidays, so no reasonable conditions for construction are possible before January anyway. If—and that’s a big if—the weather cooperates, but since recent years have taught us otherwise, I expect construction to begin in March or April 2014.
What good is a foundation slab exposed to the elements—if, contrary to expectations, it could still be poured this year—if all work then has to be stopped until the end of winter?
Hopefully, you plan to live in your new single-family house for many years—so a few extra months before construction begins should not be the deciding factor for you.
Best regards,
Bauexperte
Sorry Bauexperte, but you are quite wrong with nearly all your assessments.
From the beginning, we knew we could not expect a simplified building permit process, as we already knew when purchasing the plot that at least one exemption according to § 67 para. 1 BremLBO would have to be applied for. We just hoped that the approval would not take so long. In addition, the deadline for the building authority in Bremen is 3 months, not 6.
Next point: According to a phone call with the local office management (yesterday morning) and a prior email notification (with me as CC) to the building authority, the permit without conditions has been announced, so the building authority should now finally issue the building permit.
Another point: Soil survey and structural calculations are available.
One more point: In order to start as soon as possible, we have already scheduled the kick-off meeting with the developer next Thursday, expecting the permit to arrive in the mailbox during the week. At the latest, work can start in calendar week 48.
And regarding your point about why I am trying to start the work at short notice (if it makes sense):
I come from the mechanical engineering industry. Similar to construction, order books are more than full. In other words, if you don’t try to get into the companies’ production process and secure a slot for yourself so you don’t keep losing time waiting for supplies, you can wait a long time and throw your schedules out the window. If the checkbox “construction project xy started” is not ticked, they will almost certainly push you further and faster down the schedule than if it is a site where work has already begun. The financial aspect (for the developer) would of course also come into play.
So, once again the question: How critical is it to expose the foundation slab to weather conditions? Shouldn’t the frost protection insulation around the footing actually make this unproblematic?
From the beginning, we knew we could not expect a simplified building permit process, as we already knew when purchasing the plot that at least one exemption according to § 67 para. 1 BremLBO would have to be applied for. We just hoped that the approval would not take so long. In addition, the deadline for the building authority in Bremen is 3 months, not 6.
Next point: According to a phone call with the local office management (yesterday morning) and a prior email notification (with me as CC) to the building authority, the permit without conditions has been announced, so the building authority should now finally issue the building permit.
Another point: Soil survey and structural calculations are available.
One more point: In order to start as soon as possible, we have already scheduled the kick-off meeting with the developer next Thursday, expecting the permit to arrive in the mailbox during the week. At the latest, work can start in calendar week 48.
And regarding your point about why I am trying to start the work at short notice (if it makes sense):
I come from the mechanical engineering industry. Similar to construction, order books are more than full. In other words, if you don’t try to get into the companies’ production process and secure a slot for yourself so you don’t keep losing time waiting for supplies, you can wait a long time and throw your schedules out the window. If the checkbox “construction project xy started” is not ticked, they will almost certainly push you further and faster down the schedule than if it is a site where work has already begun. The financial aspect (for the developer) would of course also come into play.
So, once again the question: How critical is it to expose the foundation slab to weather conditions? Shouldn’t the frost protection insulation around the footing actually make this unproblematic?
B
Bauexperte7 Nov 2013 13:17Hello,
What should be considered when pouring the foundation slab in winter at low temperatures?
Pouring concrete in cold winter conditions requires special measures and careful planning, similar to concreting in hot weather.
Delayed strength development:
Low temperatures slow down or prevent the setting process and thus delay the hardening and strength gain of the concrete. For this reason, concrete must be adequately protected from frost damage in time.
Young concrete can suffer frost damage:
When water inside the concrete freezes, its volume increases, which weakens or destroys the already formed microstructure.
Concrete can withstand a one-time freeze without damage once it has reached a certain compressive strength (about 5 N/mm2).
Cracking:
Tensile stresses develop between the edge and core zones during setting. Depending on strength development, these stresses can cause cracks when they exceed the tensile strength of the structure.
Efflorescence:
Due to delayed hydration, calcium hydroxide can be transported to the surface with the mixing water and appear as a white powdery deposit.
Effective measures for concreting in winter:
- Use cement with rapid strength gain and high heat generation
- Increase the cement content
- Avoid long waiting times on site
- The site manager should ensure that the fresh concrete has a minimum temperature appropriate to the air temperature (e.g., for up to -3°C, fresh concrete must have a minimum temperature of +10°C when placed and maintain it for at least 3 days; therefore, additional warming measures are necessary)
- The temperature of fresh concrete can be easily and cost-effectively increased by preheating the mixing water
Also keep in mind:
- Formwork and reinforcement must be free of snow and ice
- Do not pour concrete on frozen ground
- Concrete should not be poured onto frozen structural elements
- Frost-damaged concrete must be removed before continuing concreting
- After placement, good thermal insulation of young concrete is essential to minimize heat loss, for example by covering
Frost-proof foundation in winter
To prevent surface water from running beneath the building and causing frost damage in winter, the foundation must be frost-resistant.
This can be achieved by installing a frost skirt around the foundation slab, which extends at least 80 cm (31 inches) below ground level and is usually made of concrete.
Alternatively, frost protection can be achieved by a gravel layer under the slab, known as frost protection gravel. The bottom of this gravel layer must also be at least 80 cm (31 inches) below ground level. The advantage of this method is that the slab can be fully insulated on all sides and underneath without interruption.
In summary, pouring the foundation slab during winter conditions is generally not recommended or should only be carried out by companies with experience in this field. You should also expect additional costs, as working on the foundation slab at low temperatures is more time-consuming and requires extra effort.
Source: my website
Best regards, Bauexperte
aytex schrieb:I know why I ask my clients if any of them studied mechanical engineering
So, once again the question: How critical is it to expose the foundation slab to weather conditions? Shouldn't the frost protection around the foundation slab make this unproblematic?
What should be considered when pouring the foundation slab in winter at low temperatures?
Pouring concrete in cold winter conditions requires special measures and careful planning, similar to concreting in hot weather.
Delayed strength development:
Low temperatures slow down or prevent the setting process and thus delay the hardening and strength gain of the concrete. For this reason, concrete must be adequately protected from frost damage in time.
Young concrete can suffer frost damage:
When water inside the concrete freezes, its volume increases, which weakens or destroys the already formed microstructure.
Concrete can withstand a one-time freeze without damage once it has reached a certain compressive strength (about 5 N/mm2).
Cracking:
Tensile stresses develop between the edge and core zones during setting. Depending on strength development, these stresses can cause cracks when they exceed the tensile strength of the structure.
Efflorescence:
Due to delayed hydration, calcium hydroxide can be transported to the surface with the mixing water and appear as a white powdery deposit.
Effective measures for concreting in winter:
- Use cement with rapid strength gain and high heat generation
- Increase the cement content
- Avoid long waiting times on site
- The site manager should ensure that the fresh concrete has a minimum temperature appropriate to the air temperature (e.g., for up to -3°C, fresh concrete must have a minimum temperature of +10°C when placed and maintain it for at least 3 days; therefore, additional warming measures are necessary)
- The temperature of fresh concrete can be easily and cost-effectively increased by preheating the mixing water
Also keep in mind:
- Formwork and reinforcement must be free of snow and ice
- Do not pour concrete on frozen ground
- Concrete should not be poured onto frozen structural elements
- Frost-damaged concrete must be removed before continuing concreting
- After placement, good thermal insulation of young concrete is essential to minimize heat loss, for example by covering
Frost-proof foundation in winter
To prevent surface water from running beneath the building and causing frost damage in winter, the foundation must be frost-resistant.
This can be achieved by installing a frost skirt around the foundation slab, which extends at least 80 cm (31 inches) below ground level and is usually made of concrete.
Alternatively, frost protection can be achieved by a gravel layer under the slab, known as frost protection gravel. The bottom of this gravel layer must also be at least 80 cm (31 inches) below ground level. The advantage of this method is that the slab can be fully insulated on all sides and underneath without interruption.
In summary, pouring the foundation slab during winter conditions is generally not recommended or should only be carried out by companies with experience in this field. You should also expect additional costs, as working on the foundation slab at low temperatures is more time-consuming and requires extra effort.
Source: my website
Best regards, Bauexperte
The sluggishness of my builder is driving me crazy. The building permit / planning permission has been approved for two weeks now, and we're practically begging for a pre-construction meeting, but the days just slip by. We're already in week 47, and there’s still no scheduled meeting or any indication of when the foundation slab will be poured. Given the temperatures, I seriously doubt it will happen this year... Grr....... ###!!***zzz$$
Or??
:-(
Or??
:-(
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