ᐅ Installing Windows Flush with the Exterior Wall (ETICS)

Hello,

I am currently renovating an old building where all the windows will be replaced and external thermal insulation composite system (ETICS) will be installed.

I would like to have the new windows installed flush with the exterior wall. My question is whether the old plaster on the reveal should be left in place, which would make the window slightly smaller, or if the plaster should be removed. The masonry is made of aerated concrete.

Good luck

breezer schrieb:

I am currently renovating an older building where all the windows will be replaced and an external thermal insulation composite system (ETICS) will be installed.

Since the building is made of aerated concrete blocks, it’s more of an existing building than a traditional older building. Aerated concrete only became popular around 1980, certainly not before the Adenauer era.

breezer schrieb:

I want the new windows to be installed flush with the exterior wall. My question is whether the old plaster on the reveal should be left in place, which would make the window slightly smaller, or if the plaster should be removed. The masonry consists of aerated concrete blocks.

After the removal of the old window, the reveal will have three distinct sections: old interior plaster – a breakout area all around at the installation plane of the old window – and the exterior plaster. Your question really only becomes relevant then, since at this stage it is difficult to realistically predict the extent of the damage. I would not recommend deliberately chipping off any plaster initially. Hopefully, you have an experienced window installer who is preferably also the supplier and will be removing the old windows. I say this based on my background as a former window manufacturer and later dealer. The key is the sequence: the installer should remove the old window first, then take measurements and proceed accordingly – is this ideally possible, or is the property occupied during the work?

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Thank you for your response. Yes, the building dates back to 1978, so it’s not very old. I have a contact who professionally installs windows, but I would order the windows myself online. Removing all the windows before ordering is not an option, even though the house is currently unoccupied. Otherwise, I would have to remove the exterior reveal plaster completely and then measure directly on the masonry, or, as mentioned, leave the old exterior plaster on the reveals and order smaller windows. I find the first option more straightforward, though—who knows how stable the old plaster still is.

Just to put this into perspective: We are having the windows replaced in our older building (built in 1930). Our window installer handles measuring, removing, delivering, and installing. For measuring alone, he needed a full day for 17 windows, 1 patio door, and 2 regular doors. He measured almost everything that can be measured before placing the order.

Measuring a window is definitely not something you can do quickly and casually.

My friend will assist me with the measurements. Do you remove all the windows and leave the house open for weeks until the ordered windows arrive, or how does that usually work? I thought the measurements could be taken with the old windows still installed.

As you prefer.

breezer schrieb:

Do you all remove all windows and leave the house open for weeks until the ordered windows arrive, or how should I imagine this? I thought the measurements were possible with the old windows still installed.

The standard practice is actually to take measurements with the windows installed. Measuring after removal is only done if you can leave the house open for about three months.
It doesn’t offer any real advantage and isn’t any more accurate either.