ceiling - structural support

[Pford75]

Sorry for the second post in quick succession....been away and now catching up with the never-ending list of jobs at home ;-)

The drawing room ceiling (l & p) has a crack running in a straight line across the entire length of the room (40ft). Upon further inspection, it is directly beneath an internal wall between two bedrooms on the 1st floor.

It appears that the wall was built off the floor (and not above a supporting wall on the ground floor). It's also noticeable that on the first floor, the floor has sagged over time with the weight of this wall (which I believe is blockwork and not just a stud).

So, some questions......

1. Do I just leave the wall and repair the crack...hoping that it won't move any further?

2. Is there any form of structural support I can insert without major works to the first floor and the ground floor ceiling?

3. If the wall is unsupported (and recent..ie. 1930's not 1700's), what are the chances of LBC to replace it with a stud? Would this be desireable?

 

[NT]

How much sag is there on the ceiling over what length of joist?

NT

 

[middi]

Having a masonary constructed partition wall above an unsupported ceiling it is not a very good idea, sooner or later it will be trouble.

I dont think the CO is going to complain if you replace it with a stud wall, especially if it is built in blockwork.

As contraddictive as it may sound, the thing that would concern me more would be the amount of stresses released and the distabilising effect this wall may have in an old building if you remove it.

I presume that you do not intend to " spoil" the existing aspect of the drawing room by inserting supports etc...., if that is the case you should engage the services of structural surveyor/engineer used to dealing with these building to evaluate how to overcome the problem, as applicable in your circumstance.

 

[Gervase]

Middi's right - this is where you need a surveyor's eye cast over the wall/floor problem. Thirty years of compression by several tonnes of blockwork on the floor joists may have 'set' them, but you need to be prepared for some sort of movement when you take the wall down and replace with studwork.

 

[Lime]

I echo what has been said.
I presume you know rather than believe the wall is constructed of blockwork.
Is the wall an addition or a replacement?
I ask because I wondered if it did any supporting itself such as roof joists or similar.

It is a compliment to the construction of your drawing room ceiling that it has done so well carrying the extra load.

 

[Pford75]

Thanks for the responses - really helpful.

I don't know that the wall is blockwork for certain, but it sounds too solid to be l&p. I am also fairly certain that it is not supporting any roofing joists since it does not appear to be 'tied in' to the ceiling or roof in any way (which is in itself worrying).

It's almost impossible to tell where the original walls/doors were...since so much appears to have been changed over the years.

But thanks for your help

 

[Penners]

I don't know that the wall is blockwork for certain, but it sounds too solid to be l&p.

I think it would help your decision process if you were to be certain about the construction of the wall. Can you see the top of it, if you go up into the attic/loft? If not, then perhaps you could drill a small hole in it somewhere inconspicious.

A 40 ft drawing room?! That sounds like quite a palace you've got there, Your Grace.

 

[Pford75]

Have now undertaken some investigation.....

It is blockwork, but not 'breeze block', more like a cinder block (which appears to be hollow (but heavy nonetheless).

I'm tending towards the advice here to replace it with a stud wall.....thing is, there is cornicing on both sides of the wall - is there a way to remove the wall and keep the cornice intact, or do I have to accept that some will be lost and then have it re-run from the undamaged profiles in the room? (obviously given the age of the wall, the cornice can't be that old).

As for the size of the drawing room, you're welcome to doff your cap :lol: but like most here, it sucks every last penny from us....but very worthwhile....fairly large (and neglected) house (just over 9000 sq ft)...hopefully by the time we're finished, I'll have picked up some new skills

 

[Gervase]

If it's cinder block, I'd lay good money that your cornice was never run but was merely a stuck-on (stuck up?) piece of prefab plasterwork - the sort of thing you can buy by the linear metre at your local B&Q.
In which case, it's also a fair bet that that particular profile is still available off the shelf.

 

[NT]

I get the feeling youre causing your own problems. If you dont answer the key q asked how can we offer appropriate input.


NT

 

[Pford75]

There is no sag in the ceiling......just a long crack (35-40ft) but the plaster either side seems sound

The floor in the room above is apx. 1-2" lower in the centre of the wall than in the corners.

Gervase - the cornice has been run in situ....it is a reeded cornice which does not look perect enough to be pre-fab

 

[middi]

There is a possibility that the partition may be of wood stud construction wire meshed and hard rendered, giving the impression that it is of solid construction.

If this is the case it would not be as alarming as the weight of a solid brick/block wall.

( still not a good idea if not directly supported or stenghtened below ).

 

[NT]

1" sag over 40 feet is not anything to worry about, the load on the wood is far short of its capabilities.

Sounds like you can move onto the next project.

NT

 

[Penners]

1" sag over 40 feet is not anything to worry about, the load on the wood is far short of its capabilities.

I tend to agree with NT. a 1 - 2" sag over a run of 40 ft doesn't sound like much of a problem.

You've talked about the cornice moulding - is there a gap between it and the ceiling? If not, then the sag would appear to be stable, and nothing to worry about.

 

[Pford75]

As mentioned above, the sag is in the floor (of the 1st floor bedroom) and is a symptom of the unsupported wall in this bedroom.

Of more concern, is the crack in the ceiling of the room below - which is substantial. I'm not worried about the sagging floor (agree this is minimal), but the crack in the ceiling is worrying and really does spoil what is otherwise the 'smartest' room in the house.

My original thinking was that the only way to prevent recurrence of the ceiling crack, was to deal with the cause (ie. the unsupported wall above). The wall is definitely cinder block and since the first floor ceilings are 13'6" (across a 40ft span) I would imagine this is a fairly heavy weight of unsupported wall.

I'm reaching the conclusion that I will have to seek advice from a structural engineer. Given that there is cornice on both sides of the wall (albeit not the original Regency cornice) it will obviously add to the cost/mess etc......but from the posts here and my own deliberations, I can't see an alternative which will guarantee I don't repair the ceiling below and then have a reoccurence.....

Thanks everso, for all your advice.....it's really useful to both get the views...but also to be prompted by the questions that others think of asking

 

[Lime]

In all probability you have nothing immediate to worry about.
If you leave it you obviously need to monitor for any movement.

However I wouldn't be able to get it out of my head until I did something.

 

[NT]

>I'm reaching the conclusion that I will have to seek advice from a structural engineer

I'm just puzzled. 1" over 40ft means the wood is supporting less than a tenth of what its able to, there is no load issue there.

Plaster cracks are caused by movement, and are normal in most types of PP.

Nothing you've told us indicates the cause of the ceiling crack is the wall above, and nothing you've said gives any reason to think the upstairs wall unsupported.

Is there something going on you're not telling us?


NT

 

[Pford75]

Ok....so the ceiling crack runs directly beneath the upstairs wall and in a perfect straight line beneath the wall.....it continues the full length of the wall, until it stops (directly beneath a doorway in the upstairs wall.

I don't think i'm jumping to unrealistic conclusions....it seems that the wall is a possible cause.....but there may be other reasons.

What I don't want to do, is spend time and money repairing the ceiling crack and decorating the upstairs rooms, only to have to 'undo' the work when the crack reappears.

I'll seek some professional advice and let you all know how it goes....

 

[Nemesis]

In my experience, ceiling cracks invariably re-appear regardless.

It may have been there a considerable time. The wall upstairs may also be well supported on the joists, which in period buildings are usually over engineered for the job!

 

[NT]

Ok....so the ceiling crack runs directly beneath the upstairs wall and in a perfect straight line beneath the wall.....it continues the full length of the wall, until it stops (directly beneath a doorway in the upstairs wall.

I don't think i'm jumping to unrealistic conclusions....it seems that the wall is a possible cause.....but there may be other reasons.

So if you have a crack at the edge of the ceiling, do you blame the wall?

I think your imagination is running away with you.


NT