Creaking chpboard and dropped floor in newly built extension

[mogwai72]

We had a total renovation of our house last year and built an extension at the same time. The project began in August and ended in December - the build itself was structurally finished (roof on) by October.

Part of the extension was a new garage with bedroom and two bathrooms on top. The upper floor was constructed of chipboard. The bathrooms are separated by a stud wall with no supporting wall underneath (they are over the garage).

We moved into the house in December. About three weeks later we noticed the floor in our bedroom was really creaky all of a sudden. The creaking occurs near the entrance to the ensuite bathroom.

The bathrooms are both fully tiled; the tiles go right to the floor and are grouted along the joint between wall and floor. Pretty soon, the grout began to crack around the bathroom floor edges and on the stud wall between the two bathrooms a large gap opened up (it's probably about half a centimetre at present).

There is a crack in the ceiling in the ensuite, about four inches away from the stud wall that separates them. It's not a huge crack but definitely split plasterboard. The shower tray in the family bathroom was evidently never properly sealed and though it was fine three or four weeks ago, it now leaks because there is a gap opened up between the shower screen and the tray.

The bathroom door started jamming and has got progressively worse. We need to have it taken off and planed. My husband says this is not the builder's responsibility as we used an independent joiner to fit the doors.

It's obvious to me that the floor has dropped and I suspect the joists.

The builder's tiler is coming back this week to put the grout right. He says we need to use flexible sealant around the bottom of the room to allow for settlement. No idea why he didn't think of this in the first place if it's common.

To be honest I'm a bit concerned about it all. We used a structural engineer for the project and spent a fortune on steelwork. We are completely skint at the moment, having just spent all this money on the house but I suspect we need somebody to look at the problem and advise us independently of the builder. I have no idea what a structural engineer's opinion will cost.

The builder keeps asking us for the snag retention fee. In fact the snagging is nowhere near complete and we won't pay until it is. We have raised the issue of the dropped floor but he hasn't had a look at it. He simply says it's 'settlement'. I really get on well with this builder and he has a good reputation but I'm concerned all the same.

Any advice?

 

[^woody^]

You should not get "settlement" in a new or refurbishment scheme

You might get "shrinkage" of second fix timber and finishes (eg cracks to architrave and skirting joints) but nothing substantial

You should not get floors dropping or walls moving, and basic terms you should not have structural movement - especially so as to cause doors binding

Whether a cracked ceiling is due to shrinkage or movement will need to be determined

Tiled floor perimeters should be sealed with a flexible seal in the first place and not grout

You need to determine if the problems are related to specification, design or workmanship. I would probably get the engineer back to comment on his design at no cost ... see what he says and take it from there.

Otherwise get an independent snagging report done (surveyor or specialist snagging company). It is difficult to say if the builder is due his retention money as the defects may not be his fault if not down to workmanship - it will depend on the contractual arrangements between you all

Probably looking at about £300 for a report. It may be you can come to a shared cost arrangement with the builder/engineer if they are at fault

 

[mogwai72]

okay, I'll ask the structural engineer to begin with.

And get the builder to at least look upstairs at the problem.

Thanks for your advice.

 

[big-all]

where the joists stored dry or did they have a lot off exposures [days on end ]off getting wet??

 

[^woody^]

I don't think that there should be that much of an issue with damp timber installation, as there would not be a great deal of shrinkage in the depth.

What would be more common is if the floor was not properly nogged or braced (or shinkage across the width loosed noggins) which would then allow individual joists to distort or twist, and the floor as a whole become less solid

 

[big-all]

I don't think that there should be that much of an issue with damp timber installation, as there would not be a great deal of shrinkage in the depth.

What would be more common is if the floor was not properly nogged or braced (or shinkage across the width loosed noggins) which would then allow individual joists to distort or twist, and the floor as a whole become less solid

whilst you are the expert here woody and i fully agree with your ideas i just thought a say 175m joist at say 18 to 20% moisture [soaked ]would easilly account for 10mm shrinkage

 

[joe-90]

"To be honest I'm a bit concerned about it all. We used a structural engineer for the project and spent a fortune on steelwork."

Well you won't get shrinkage in metalwork. My guess is the problem is the timber hasn't been connected to the steels properly. You may find it easier to make holes in the plasterboard below and have a look.