Removing upstairs wall - running into problems!!!

[mfarrow]

Hi

I'm trying to move an alcove from the rear bedroom to the front bedroom. My plan was to remove the existing wall (between airing cupboard and chimney) and build a new stud wall to form the back of the new alcove.

Here is the plan:

View media item 101185
The upstairs is constructed of 2.5" interlocked blocks (blue = existing; green = to be removed on the plan) sitting on floorboard/joists with open space underneath. The existing alcove has had it's carcass and doorway removed as has the original bathroom, which forms a corridor now and part of a new stud wall (in red).

Half-way down the demolition, I've noticed some cracks in the ceiling plasterboard (at the joints) and in the wall. The front bedroom wall (bottom in plan) will not close now, and there's cracks above each doorway. Large cracks are present: a) at the bottom where the old wall meets airing cupboard; b) at the point where old wall is tied to the chimney breast.

The question is, what's causing this and am I safe to continue? The house has a standard gable and no water tanks any more. Floor joists are parallel to the wall I'm removing and ceiling joists are perpendicular to it.

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Many thanks

Mike

 

[TicTac]

If the ceiling joists are running parallel to the wall you're removing, then it's very likely just vibrations causing the crack.

 

[^woody^]

The big problem with those thin blocks, is that each bit of wall relies on the other for support, and when you remove one section the rest of it is loosened and can wobble all over the place. The ceiling joists were probably resting on the wall too.

 

[mfarrow]

Sorry the ceiling joists are perpendicular - now corrected.

 

[mfarrow]

Is the thin blocks thing a problem though woody? I was hoping that the box shaped cupboard ould keep steady. Is it a structural issue?

 

[TicTac]

If the ceiling joist are perpendicular, then in taking out the wall, you've removed the support for them. Depending what's in the loft, you either need a wooden lintel to support the joists, or a concrete rsj.

 

[mfarrow]

Hi, the loft construction is 3x2 joists with cross-bracing of 4x2 and chipboard on top. There are no water tanks these days.

A new stud wall will be constructed where the old alcove opening was removed previously (further towards mid span). Would this provide the support needed? There are 2 joists which are now unsupported.

There is plasterboard between the walls and the roof joists.

 

[noseall]

Empty the vacuum then see what happens.

Would this provide the support needed

Yes.
Fit a double header of two 2" x 4"'s on their side. No dramas. Try not to overly stress everything by making your uprights too tight. Nice and snug will do.

Sometimes it is better to bite the bullet and remove a complete wall rather than try and cobble together the remains of a doorway knock-out. I guess it all depends on the collateral damage. We have a re-cip' attachment that will cut through blocks once they have been stitch drilled. Rarely 100% successful though.

 

[mfarrow]

Thanks TicTac/noseall. When the snow clears I'll be able to get to wickes hopefully.

Opening other side is long gone, so it will be double header straight up against the ceiling.

View from bed this morning:

 

[^woody^]

Is the thin blocks thing a problem though woody? I was hoping that the box shaped cupboard ould keep steady. Is it a structural issue?

It's not that simple with these. These walls tend to be built off the timber floor and form a rigid panel which acts as one. Also when built between two external walls there are added factors of the panel being wedged so there is some inherent self support, and the wall load and wedging controls flex in the floor.

Taking a section out loses the rigidity so walls can move, plus floor movement can make them move. And it's very difficult/ impossible to stop.

That's not too say they become unstable, but it can be just enough instability to cause cracking at the usual stress points.

 

[mfarrow]

Thanks woody, I'm beginning to get a sense of what these walls are all about now.

I think the wall around the doorframe to the bedroom has historically uncoupled itself from the "rigid panel" at some point in the past, as the frame and plasterboard above are quite wonky.

There is some historic movement in the floor which I think the airing cupboard is now trying to settle itself back down on - I'm sure there's a gap under there which I'll try and fill. Any recommendations of fill medium?

Is the cupboard safe to stay there do you think? I'm thinking 14kg per standard-equivalent block (with plaster), that's about 11 blocks high and 3 wide, giving 462kg per flank cupboard wall.

 

[John D v2.0]

We had almost exactly that situation however the middle panel was a chimney that was demolished too far. Over 2 floors. Both floors the wall built on the floor boards. In the end the only issue was the roof was partly supported of it so we needed 4 steel channels t stabilise the wall. The didn't seem to be any concern about settlement, it was all about whether the thin block wall would crumple due to being too narrow.
Not sure how much that applies to your case.

 

[23vc]

I’ve had similar, the remaining wall could be rocked by touching it with your finger at the top, bit scary. After putting stud work in it was rock solid.

 

[noseall]

Believe it or not, adding dabbed plasterboard to a fragile block wall (both sides) will stiffen it massively.

 

[TicTac]

There is some historic movement in the floor which I think the airing cupboard is now trying to settle itself back down on - I'm sure there's a gap under there which I'll try and fill. Any recommendations of fill medium?

That would depend on the way the gap is forming. It may just require wedging, or may need a noggin under the floorboards. Can't advise further just from a vague description I'm afraid.

Looking at the last picture you posted, you need to clean out the old plaster, and first place a wooden fillet to level down to the ceiling heights. The you can put in Nosealls suggestion of a double header. Once you've built a stud wall in the other bedroom, I see no reason why the airing cupboard shouldn't be okay.