ᐅ Insulating the Attic: Before or After the Screed?

Hello everyone!

Would you insulate the attic BEFORE or AFTER the screed is applied?

I’m concerned that moisture might get trapped in the insulation and be difficult to remove...

Of course, I will try to seal the vapor barrier as tightly as possible. However, I can’t guarantee a 100% airtight result. We are insulating the attic in addition to the top floor ceiling (this will be done by the general contractor’s drywall specialists and thus hopefully professionally). However, the ceiling insulation will only be installed AFTER the screed.

How would you handle this?

I have time now to take care of the attic... The screed will be applied in 3 weeks...

In our case, the opening to the attic is sealed before the screed for exactly that reason.

Place an electric dehumidifier in the attic; a device costing around €200 (approximately $220) should be sufficient, and run it as needed. This way, you’ll be on the safe side. Otherwise, you might need to ventilate constantly—if that’s even possible there. Closing off the opening also makes sense, since warm, moist air rises and will condense in the roof space.

You might be putting more effort into the vapor barrier than the general contractor. If possible, perform the blower door test before the interior cladding is installed.

Unfortunately, there is no option for ventilation up there.

However, I plan to set up two dehumidifiers inside the house anyway (rented).

Sealing the hatch would of course also be an option!

But since it is covered with regular tongue-and-groove paneling, quite a bit of moisture can probably still pass through, right?

Normally not, since you still have the vapor barrier. Moisture can come through the tongue-and-groove boards if the vapor barrier underneath is not intact, which in this case would actually be fine. But since you don’t have a window, I would still place a small, inexpensive dehumidifier at the top and run it as needed.