Fixing metal door frames in Autoclaved aerated concrete.

[Mrdjc]

Has anyone got any obvious suggestions as to how this is done?

1. physically cut each block so that a lip fits into the doorframe, then seal with mortar to stop it moving.

2. Drill holes through the frame and anchor it in place using rawl bolts (But you would always see the heads of the bolts.)

3. Loosely fit it with wedges and fill the gap with mortar alone.

4. Expanding foam.

5. Some form of metal bracket which goes between the block work and locks into place in the frame itself?

 

[gregers]

if you just use mortar it will fail,once the door has been slammed a few times it will start moving,i would use screws/plugs/bolts whatever you can hide into the blocks then use expanding foam,then plaster/decorate as necessary.

 

[tony1851]

AAC blocks are not that good, so as gregers suggested use a few screws to locate the frame, and then fill the gap with foam. That way any vibration load from the frame is spread out over the whole of the contact area with the blockwork, rather than at just a few points.

 

[Mrdjc]

That would mean:
A. Need to drill a hole for the screws/bolts through the metal door frame.
B. The screws/bolts would be visible
C. The screws/bolts would protrude from the frame as it will be very hard to recess them.

That is far from ideal as it will be ugly as hell and every time you walk through the door frame you stand the risk of hitting one of the screw heads.

There must be another way of securing them securely without having the heads of whatever fixture sticking out.

Also fire safety and expanding foam don't really go hand in hand, the stuff burns like crazy.

From what I can tell from google translated discussion forums in Slovakia they cut out a lip that sits inside the "U" of the frame and then add expanding foam for the last bit, think that's the route I will go too.. Just hope I can cut a straight enough line!

 

[gregers]

you can drill and countsink for frame fixing screws,then use fire retardant foam.jobs a good en.

 

[^woody^]

Are these the type of steel frame that wrap around the block, or are they just the same as a timber liner?

 

[Mrdjc]

They wrap around the blockwork Woody, and they have a welded on flexible tie halfway up which is supposed to be tied into the blockwork next to it, but offers bugger all in terms of fixing as they are right in the middle of the frame creating a nice position for the doorframe to rotate around if not properly secured at the top and bottom.

The metal is plate steel, probably 2-3mm thick, recessing into this would require tools which the average DIY'er does not have access too, the recessed holes would require pressed in as there is insufficient material to simply drill a recessed hole into.

 

[^woody^]

The ones I have seen have a plate at the bottom to hole the base of the frame and like yours, a plate in the middle which is built into a joint. The blockwork is just slotted in and a bit of mortar holds the frame via friction

If need be a discrete screw or pin can be put through the section of frame which wraps round the face of the wall