ᐅ Which type of screed do you prefer?

Hello,

We were originally supposed to use a calcium sulfate screed (Maxit). According to the technical data sheet, it has a thermal conductivity of about 1.83 W/mK.

The construction company now wants to use a product from Hasit instead: Hasit cement sulfate screed. According to its data sheet, it has a thermal conductivity of about 1.4 W/mK.

Our contract specifies calcium sulfate screed. Should we insist on that since it has better thermal conductivity?

Thank you.

It’s up to you what you decide to do. However, if the construction site is delayed by 1–2 months as a result, you haven’t gained anything. That said, it would of course be reasonable to request some form of compensation, such as discounts or additional work.

There is still some distance to the screed stage, so I do not expect any delays...

Will I notice the different screed type in the operating costs?
What should I consider here?

Hello,
since the building envelope is insulated, the heat will preferably go into the rooms rather than escaping outside. The heat might take a little longer to reach the rooms, but you probably won’t notice any significant difference in operating costs. There are certainly other characteristics where the two types of screed differ more noticeably than in the later operating or heating costs.
That is my laid-back opinion.
Regards

Because of the calcium sulfate screed, the underfloor heating system is not quite as slow to respond as with cement screed. We were told that the heat reaches the room faster. But perhaps that is just subjective in the end. Nevertheless, we had it installed on the ground floor and upper floor (except for wet areas) 10 days ago. In the basement, however, we consciously chose cement screed because it is said to be less susceptible to moisture-related damage. As you know, our house is located in the groundwater area. We had to pay an additional cost of around 500€ for the cement screed because the original quote was based on calcium sulfate screed. The calcium sulfate screed as a flow screed was applied very quickly (just over 2 hours for 2 floors) and only needed to be troweled since it is mostly self-leveling. The cement screed requires a bit more work, which is probably why it costs more.

Ask specifically why the change is being made now. If something is explicitly stated in the contract, it cannot be changed unilaterally unless there is a deviation clause, for example, in case of material unavailability.

Whether one screed is better or worse than the other is probably a matter of opinion. Cement screed has proven itself consistently over many decades, but I haven’t read any horror stories about calcium sulfate screed either.

According to the contract, cement screed will be used in the bathroom, while calcium sulfate screed will be applied in all other rooms.

As far as I know, the construction company generally switched from Maxit to Hasit in 2023 (Maxit increased equity requirements too much).

Specifically, calcium sulfate screed is mentioned.