ᐅ Drying time for a completed basement before assembling the prefabricated house

Hello everyone,
we have received very different statements regarding the drying time of a precast basement during planning for a prefabricated house:

- Extreme 1: A precast basement can be built on two days after installation. Although the concrete only reaches its full strength after 28 days, the main load-bearing parts are already dried and have their design strength beforehand. The residual moisture in the cast transitions can continue to dry out.
Claim: Those who want to allow a long drying time do so only to bridge the long delivery times of the prefabricated house.

- Extreme 2: A precast basement should dry for at least 8-12 weeks to reliably achieve sufficient drying.
Claim: A shorter drying time is only a means to attract customers with shorter construction schedules.

Does anyone have any insights on this?

Thanks!

I would quickly remove the 2-day timeframe from my project. Even though concrete is usually sufficiently hard after 7 days (as a rule – outdoor temperature can have a significant impact here!), and the remaining 3 weeks mostly contribute the last 10%, you definitely don’t want to put live loads on it after just one week.

Normally, the ceiling supports for the slab need to stay in place for the full 28 days – you might remove most of them after 7 days, but as mentioned, only to bear the dead load until it is fully cured.

Extreme option 1 is at least feasible, although uncommon. First of all, concrete does not dry; it cures. Excess water escapes through the basement walls – and the basement ceiling couldn’t care less about that.

So yes. You can continue building on a prefabricated basement just as quickly as on a concrete slab or ground slab without a basement. Construction there also proceeds almost seamlessly.

Just make sure the basement is properly ventilated.

Thanks in advance for your answers!
In our opinion, the provider of "Extrem 1" is reliable. That’s why we are a bit surprised.
Additional information: The basement is planned to be built and poured during winter. According to provider 1, this is beneficial for curing as long as temperatures do not drop significantly below 0°C (32°F).

I’m now assuming that around 28 days of drying time is more reasonable, even for prefabricated basements.

I agree with @nordanney. When you are in a hurry.

DachDrueber schrieb:

I assume now that about 28 days of drying time is more reasonable, even for prefabricated basements.

That may be reasonable, but it is unrealistic in practice.
As with all concrete work in new construction, you don’t wait four weeks for every floor slab. Work continues a few days after the concrete is poured.