Reduce door opening, lightweight concrete

[KimLarsson]

Hello!

I have removed an old door frame in the basement, the opening is now 88cm and our plan is to install an 8*20 frame.

How should I fill the gaps for the frame from the aerated concrete wall?

1. Remove the half blocks in the existing wall and replace them with split blocks to get the correct width? The problem is that there is 15mm mortar in between, and it doesn't seem to exist for aerated concrete today?
Can I use any mortar?

2. Stack 70mm lightweight concrete blocks and glue them with PU700 to the aerated concrete?

3. Tear down the remaining wall and rebuild everything with lightweight concrete blocks?
(Most work)

Grateful for your help 😊

 

[Henkan Sundberg]

In an 88 cm wide hole, you can almost fit a 9*20 frame. Could that be an option? It might be easier to remove a couple more cm instead of building up, I think.

 

[Johan456]

So, you'll have a 40mm gap on each side of the frame. I would have made blocks as deep as the frame and 30-35mm wide. Glued and screwed these where I intended to attach with frame screws. Then drilled 14mm holes straight through and secured the frame with 140mm frame screws. 4 on each side. Then I would have put 69mm trim around, filled in on one side if needed. Of course, you need to drill into the lightweight concrete and set plugs. 8mm is probably suitable.

 

[KimLarsson]

Thank you! I just figured it out now when I took another look at how to do it. I have doorways on both sides, so I'll tear down the partition wall and use leca to get the right doorway with the right width without the risk of the lightweight concrete cracking with screws that are too long.

Thanks for the input!

 

[BSOD]

https://www.bauhaus.se/lattbetong-plattor-75x400x600mm

Saw along to get 75mm wide blocks which you glue to the existing wall with suitable construction adhesive. Or low-alkaline mortar if you want to be precise and follow the manufacturer's recommendations. Then you place it on one side, and the door opening is suddenly about 80cm.

I would have used really long screws to fasten the frame, it's important to have the right screw and long screws in lättbetong is my experience.

 

[MathiasS]

Make the hole a bit larger, insert a 90-door, do a casting so you have something to screw the frame into. A bit more work, much more stable.

 

[KimLarsson]

Make the hole a little bigger, install a 90-door, make a casting so you have something to screw the frame into. A bit more work, much more stable.

[bild]

Thanks, how do you fill the form, expanding concrete?

 

[prototypen]

I was "just" going to widen a doorway a bit, but it turned out that just outside there was a general joint in the brick after some renovation, so the opening became much wider. But a reasonably thick plank was screwed in, then it was easy to put in the door.
Protte

 

[MathiasS]

Thank you, how do you fill the mold, expansion concrete?

Using regular coarse concrete. The sides of the mold are in place, but build what's "next to the frame" in the door opening as you fill. Poke and tap on the mold so it flows nicely.

 

[KimLarsson]

Using regular coarse concrete. Have the sides of the form in place but build what is "next to the frame" in the door opening as you fill it up. Poke and tap the form so it flows out nicely.

Good tip, I'll go with this, so I can avoid the problem with crumbly concrete.
Thanks everyone!