saggy floor problem

[JonnyG]

I incorectly posted this in the projects section before.

I have just bought an ex-local authority flat that is in need of substantial modernisation it is in a West London brick-built 16 floor block. Having a limited budget, I am going to undertake the renovations. I have very limited experience of DIY, but I can follow directions. We have about 6 to 7 weeks before we have to move in.

Just to set the scene, here is a plan of the somewhat unusual layout. It is approx 720 sq ft.

My first, and biggest problem is the floor and walls. Internally, all the floors (except kitchen see later) are 18mm chipboard sitting on a lattice of (4.5cm x 3.5cm) batons at 2 ft centres. Beneath this is a sound insulation material that looks likes polystyrene ceiling tiles that sit on the rough concrete floor as this picture shows.

The electrics of the flat are just slung under this floor.

FLOORS
Planning to install a real wood laminate floor in the hallway and lounge with machined slate in the kitchen area, toilet and bathroom. The bedroom floors seem OK and will be carpeted.
Over the 25 years of life that the existing floor has been down has caused the sound insulation to compact and made the surface uneven, creaky and spongy. The floor to ceiling height is only 232cm so over-boarding the existing is not an option.

I am planning to rip-up the chipboard and renew the sound insulation, then try and re-level the batons before over boarding with either chipboard or plywood, which I intend to screw-fix.

My questions are
Is this the right thing to do?

What material should I use for sound insulation and should I apply it in the same way as before (i.e at the point where the battons meet)?

Would plywood be better than chipboard? The kitchen area is plywood and seems to be OK?


WALLS
Things are made a bit more complex because all the internal walls are plasterboard that is built off this floating floor. It seems that the floor was put down throughout the flat then the walls were built on top. Unfortunately the walls seem to have dropped as the floor has sunk as this pic of the wall / cceiling illustrates.

It also seems that the feet of the walls don?t line up with the batons in the sub-floor.
Obviously, my re-flooring plan starts to get complicated in the hall because I can?t easily cut out the chipboard without the walls collapsing. As this picture shows.

I have thought about running a circular saw along the wall edge either side at 18mm depth removing the chipboard and sliding some timber blocks under the walls, before cutting the exisitng battons and replacing them (i.e. the hall will have it's own sub-floor as would the bathroom toilet etc.

Does this sound reasonable?
Anyone got any better ideas or is there anything I should watchout for.

One last thing, Is there anything I could use under the bath in the bathroom instead of chipboard, this room is more saggy than the others, which I guess is from water spillage.

Thank you in advance,

Jonny G[/b]

 

[salem2000]

Looking at your first picture, it seems that you have your work cut out for you.

At a glance, it looks like a VERY sad attempt to level and sound proof the floor at MINIMAL time and cost, and sadly this will not be easy to fix.

The main problem is the internal walls. If they are floating, ie: not on a firm bed, then this must be the first to be fixed. Cutting the Chipboard either side without supporting the partition will cause it to drop, and that would leave you with no option except replacement. The only way I can see of doing this without removing the walls, is to take the floating floor out from under each wall in sections making sure it is supported along it's lenth and replace this with solid timber on the original (not exsisting) floor. Be aware of cables, pipes, etc.

Never cut what you can't see.

However the chances of raising the partition to it's original position without damage is low, but not impossible.

If it was my choice I would remove each partition, and re-build it from scratch. The reason for this is, if the floor supporting the walls are that bad, what are the partitions built like.

It may be wise to get in a pro, to check what is required, and what is supported by what. I'm amazed that all this work wasn't picked up by your survey.

 

[JonnyG]

Thanks for your reply Salem.
I will certainly be taking your advice about doing the wall under-pin in stages.
Have you got any advice on how to deal with the floor in general?
I have lifted a few more boards and discovered that the concrete floor underneath varies in height by approx (1.5 – 2) cm !! from one end to the other.

 

[salem2000]

If you wanted you could use self-leveling compound. Do you know why the floor was covered in the first place? is it that bad?

 

[jeds]

You've got quite a job on there jonnyg. You say limited budget - how limited? Forget floor finish for the moment. Concentrate on getting the floor sound insulated - you can worry about finishes later.

Looks like you have a concrete floor with an old made-up sound system on top. If the concrete base is ok I would personally favour a tongued and grooved chipboard decking on a sound insulation quilt - Acousticel or something similar. There are loads of options. check the prices?

Don't worry about chipboard flooring. It's much better quality these days and will provide a good durable floor and on a solid concrete deck will provide a sound base for tiles, laminate, carpets etc.

Your problem is going to be continuity of the new system across the whole of the floor. The only way to achieve this is to get under your dropped walls! You could try cutting off, say, 500mm at the base and then piecing a new wall base in after - but it will be very difficlut to get it right.

The alternative is to remove walls and start again. If your budget won't stretch to new walls all round then I would consider a phased approach. i.e. remove a couple of the walls - say between bed 1 and 2, and possibly the lounge - floor that large section from wall to wall leaving a daywork joint butted as close as you can up against the hall and bath walls - understand? (by 'floor', I mean to the chipboard finish)

Then rebuild nice new walls on top of the new system - metal stud wall is not that expensive if you fit it yourself. I'm relying on your ability here mind?

When the budget then allows you go into phase two - hall, bath, kitchen wall etc.

Problems are going to be re-routing the electrics, other services on the walls and time.

 

[JonnyG]

Thanks for the advice lads