Shell construction still this year

Hello,

Now it is the case that we are trying to submit the building application in October. We discussed it with our neighbor. He said that his application was approved within 3 days.

I can hardly imagine that, the exemption procedure usually takes 4 weeks; if it really went that fast for him, there was surely some "connections" involved...

Could it then not work to get the house "sealed" before the frost? So that only the interior work needs to be done in January-spring. If the windows are in, that wouldn't be so bad, right? Of course, I would be reluctant to just leave the floor slab exposed over the frost. Then one should probably really only start next year.

Assuming you really get the building permit at the beginning of October, it depends on the order books of your supplier; he also needs a certain lead time.

As soon as the shell is closed, the weather no longer matters. But when pushing for the start of construction, you should remember that you will probably live in this house for the rest of your life—does it really matter a few weeks more or less?

Kind regards

Provided the weather conditions allow it, the base slab can still be laid after the Christmas holidays. Then you have to wait out the frost period .... not good for the base slab

Hello Bauexperte,

thank you very much for your reply.

Our schedule has also shifted by now. We do not need a building permit (only a building start notification must be submitted), but the surveying work for the plot is still ongoing. That means our plan to have the shell built this year is off the table. However, we had considered at least finishing the base slab (we are building without a basement). The reason for this consideration is that a couple of friends, who built about 100 meters away from our plot in our small new development area about 2 years ago, actually wanted to start building directly in spring but then had to wait many weeks until they could lay the base slab because there was a lot of water in the "excavation area." We thought about avoiding this problem by completing the base slab this year. Now I read in your post that this is not good for the base slab. Can you explain why? You could possibly cover it with a tarp!

Oh, one more question. You write that once the shell is closed, the weather no longer matters. Isn’t it the case that the shell was intentionally left open over the winter before so it could dry (because the air is drier in winter than in summer)? Why should this be a problem today?

Thank you in advance!

Best regards Tatze

Hello Tatze,

Now I read in your post that this is not good for the base slab. Can you explain why? One could possibly cover it with a tarp!

I found an understandable explanation on the internet, which I am posting here so I don't have to start from scratch

Concrete requires certain curing times to achieve freeze resistance, as it sustains permanent damage if it freezes during curing. Concrete is considered freeze resistant upon reaching a compressive strength of 5 N/mm². Crucial in this context are the type of cement and the water/cement ratio.
At air temperatures between +5 and -3 °C, the temperature of the concrete at placement must not fall below +5 °C. With a cement content below 240 kg/m³, it must not fall below 10° C. The same applies to cement with low hydration heat. At air temperatures below -3 °C, the concrete temperature at placement must be at least 10 °C. It should then be maintained at at least 10 °C for at least 3 days.
However, the fresh concrete temperature must not exceed +30 °C.
The concreted surfaces can be kept at temperature by covering with thermal insulating materials.
Certain rules must be followed when making the concrete, including those concerning the temperature of the water, etc. In extreme situations (heat supply), care must be taken not to remove from the concrete the water required for curing.
Or in other words: Frost damage is caused by the fact that concrete, mortar, and plaster cannot generate sufficient heat of hydration during freezing. Incomplete curing causes cracks and joint leaks, into which water penetrates and can cause spalling when frozen. Therefore, concrete, mortar, and plaster work must be performed in winter only above 5° C.

Oh, one more question. You write that as soon as the shell is closed, the weather no longer matters. Is it not the case that the shell used to be intentionally left open over the winter to dry (because the air is drier in winter than in summer)? Why should this be a problem today?

It's less about the shell itself and more about the start of the finishing trades; you have to ventilate anyway. As a rule, these trades only begin once the shell is closed, because the risk of theft of equipment and materials is many times lower then.

Kind regards

I also have a question for the construction expert. This week we started with the preparatory measures for the base slab, namely batter boards, formwork, etc. That means next week the work on the base slab is supposed to begin. The weather looks quite good here so far, with temperatures up to 12 degrees forecasted and it should remain dry next week. However, at night it already gets quite chilly and it can certainly drop to 0 degrees. I think the risk of it being generally cold at night now is very high. How long does the concrete normally have to cure so that frost can no longer harm it? If this takes a few days, we would have a problem either way, right?

Hello,

How long does concrete normally have to cure so that frost can no longer damage it? If this takes a few days, we would have a problem anyway, right?

Correct, a concrete slab has to "cure." For curing, it even needs to be moist (which is why the current weather conditions are again somewhat good; unfortunately unpredictable). Concrete only becomes really hard after weeks or months – that is why concrete ceilings remain shuttered or supported for a long time. After pouring the foundation slab, masonry of the walls usually starts after 3 to 4 days.

It is important that there is no ground frost for a period of at least 4 days; if there are subzero temperatures, masonry will not proceed!

Kind regards

Our foundation slab was poured today. I will diligently measure and record the concrete temperature regularly over the weekend.