Is the floor slab still possible this year?

  • Erstellt am 2013-10-31 23:47:47

aytex

2013-11-07 11:21:04
  • #1
This topic also concerns me...

Thanks to an applied exemption, we have now been waiting for the building permit for almost 3 months. I learned yesterday by phone in advance that all authorities have now granted approval and we will most likely have the permit in the mail next week.

After this, the construction kickoff meeting with the developer must take place and only then could it start. The only question, of course, is: can it even start then? In the best case, it could probably start in week 48.

Is it still possible to begin with the foundation slab then????
 

Bauexperte

2013-11-07 11:42:03
  • #2
Hello,


It is always interesting...

I assume that it also took you a while to commit to a provider and sign the contract for work. An application for exemption from "something" generally results in the dream of a simplified approval process turning into a regular building application. This can take— in some cases up to 6 months; you should actually have been informed about this.

Now it is November— assuming you really have the exemption-free building permit on your desk next week, the soil survey— if not already available— as well as the execution plans/structural analysis still have to be created. I would estimate that—with the required work plan discussion— this will take another good 3-4 weeks, since you have to approve all the plans. Then we would be looking at December calendar-wise with probably modest temperatures; which are already not great. Added to this are the companies' Christmas holidays, so that no reasonable conditions for construction can be created before January anyway. If—the weather cooperates— but since the last few years have taught us otherwise, I rather expect a start of construction in March/April 2014.

What good is a foundation slab exposed to the weather— if it can still be poured this year against expectations— when all work has to be stopped until the end of winter?

You will hopefully live for many years in your new single-family house— so a few months more or less until the start of construction really shouldn’t be the deciding factor for you

Rhenish greetings
 

aytex

2013-11-07 12:16:35
  • #3
Sorry construction expert but you are pretty much wrong with all your assessments

From the beginning, we knew that we could not expect a simplified approval process, since we already knew when purchasing the property that at least one exemption according to § 67 paragraph 1 BremLBO had to be applied for. We just hoped that the approval would not take that long. In addition, the deadline for the building authority in Bremen is 3 months and not 6

Next point: According to a phone call with the local office management (yesterday morning) and a prior info by email (with me as CC) to the building authority, the approval without conditions is announced, so that the building authority should now please issue the building permit after all.

Another point: Soil survey, structural analysis are available

One more point: In order to start at short notice, we have already planned the construction startup meeting with the developer company for next Thursday in the expectation that the approval will be in the mailbox during the week. At the latest, work can begin KW48.

And regarding your point 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, the order books are more than full. In other words: If you don’t try to get into the companies’ production process, i.e., buy yourself a slot so that you don’t lose more time until you are supplied, you can wait a long time and might as well throw your schedule into the trash. If the tick is not set "construction project xy started," they will surely push you back more easily and faster on the construction plan than if it is a site where work has also begun. The financial aspect (for the developer) would naturally come in addition

So again the question: How critical is it to expose the base plate to the weather conditions? Shouldn’t the frost skirt make this exactly uncritical especially for the base plate??
 

Bauexperte

2013-11-07 13:17:37
  • #4
Hello,


I already know why I ask my interested parties if any of them have studied mechanical engineering

What should be considered when pouring the foundation slab in winter at low temperatures?

Pouring concrete at low winter temperatures requires – similar to pouring concrete at summer temperatures – special measures and forward planning.

Delayed strength development:

The cold temperatures prevent or delay the setting and thus the hardening and strength development of the concrete. For this reason, concrete must be protected from frost damage in time.

Young concrete can suffer frost damage:

Due to the volume expansion of water present in the concrete when freezing, the already formed framework structure is weakened or destroyed.
A harmless one-time freeze-thaw of young concrete is possible if the concrete has reached a certain strength (compressive strength of about 5 N/mm2).

Crack formation:

During the setting process, internal stresses arise between the edge and core zones.
Depending on the strength development, these stresses cause cracks if the tensile strength of the structure is exceeded.

Efflorescence:

Due to delayed hydration, calcium hydroxide can be transported with the mixing water to the concrete surface and precipitate there as a white film.

Effective measures for concreting in winter are:


    [*]Use of cements with fast strength gain and high heat development
    [*]Increase of the cement content
    [*]Avoid long waiting times on the construction site
    [*]The construction manager should ensure that the fresh concrete has a certain minimum temperature according to the air temperature (e.g. up to -3°C the fresh concrete must have a minimum temperature of +10°C when placed and maintain this for at least 3 days; thus additional heat retention measures are necessary)
    [*]The temperature of the fresh concrete can be simply and economically increased by warming the mixing water.


To be observed:


    [*]The formwork and reinforcement must be free of snow and ice
    [*]No concreting is allowed on frozen ground.
    No concrete may be placed against frozen components
    [*]Concrete damaged by frost must be removed before further concreting
    [*]After placement, good thermal protection of the young concrete is necessary to minimize heat loss, e.g. by covering.


Frost-free foundation in winter

To prevent surface water from flowing under the structure and causing frost damage in winter, a structure must be frost-proof founded.
For this purpose, the foundation slab can be provided all around with a frost skirt, which reaches at least 80 cm below the ground surface edge and is usually made of concrete.

Alternatively, frost safety can also be achieved by installing a gravel layer under the foundation slab, called frost protection gravel. The bottom edge of this gravel layer must also reach at least 80 cm below the ground surface edge. The advantage of this variant is that the foundation slab can be wrapped all around and without interruptions, also from underneath, with thermal insulation.

Overall, it should be noted that pouring the foundation slab at winter temperatures is not recommended or should exclusively be carried out by companies with experience in this area. Furthermore, you can certainly expect a surcharge because the work on the foundation slab at low temperatures is more time-consuming and also requires more effort.

Source: my homepage

Rhineland greetings
 

aytex

2013-11-07 13:52:50
  • #5
cool, thanks for the info
 

aytex

2013-11-20 15:09:10
  • #6
The inertia of my developer is driving me crazy.. The building permit has been here for 2 weeks, we are practically begging for a kick-off meeting but the days are slipping by. We are already in week 47 and still no meeting appointment, let alone a date for when the foundation slab is supposed to be done. Temperature-wise, I seriously doubt now that it will happen this year... Grr....... ###!!***zzz$$

Or??

:-(
 

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