Sloping floors

[romulus]

We recently moved into a new top floor flat.  It is a kit construction.

Most of the floors are sloping.  Some worse than others.  In the hall the slope is 26mm over the width.  I believe this to be significantly greater than NHBC guidelines.   They appear to slope upwards towards the walls, so although not strikingly obvious, there is a concave effect in the larger rooms.  Some door frames have moved.

We are really worried because the builder called in their structural engineers who says that the foundations are good.  The builder has said it is not a structural problem and more of a cosmetic one, but has not offered a solution.

We are really concerned because we think that rectification would probably mean that the whole interior partitioning etc would have to be stripped out and the flooring re done throughout.  Even then, with the kit construction there may be no guarantee that this problem would not recur.

What are our rights?  What could we expect from the NHBC?  Any advice is appreciated.

[New Home Expert]

By "kit" I am assuming you mean Timber Frame Construction.
This being the case the upper floor will probably have been delivered in sections known as "cassettes" in the trade.
These are located on top of the external timber frame walls and depending of the design, some interior load bearing walls.

You say your hall is 26mm out of level which I can confirm is well outside even the generous tolerances grated by the NHBC for accepted poor quality workmanship. Which states:
1.2 S8 (page 4) (a) level of floor - Maximum 4mm out of level per metre for floors up to 6m across, and maximum 25mm overall in any other case.

The floor cassettes normally are delivered with a thinner than normal plywood decking which is purely for safety during construction. This is then added to with the sound deadening insulation and isolated floating floor construction.
I suspect that the flooring has got wet and cupped between the joists.  The added floor construction has over time followed this contour.

Another explanation would be that the whole floor cassette is out of level or the joist have deformed under loading after drying out because the joist spacing is insufficient.  This would be the most serious situation and most difficult to remedy.

You should write to the house builder and officially inform them of the problem and what you want done about it.
Copy your letter to the NHBC and if the house builder does not sort it out, make a claim.
The partitions should not be on top of the floating floor anyway so these should not need stripping out.
Finally, even if a defect is deemed cosmetic, doesn't mean the house builder can avoid rectification.

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[romulus]

Thank you for your reply.  I believe this site is needed more these days.  I have made a donation.

Yes it is timber frame with a flat roof.  The walls are clad with stone up to the top of the 2nd floor, apart from the wall separating us from an attached block.  It may just be part of the kit.  Our flat on the 3rd floor is fully timber frame with walls of a composite material.

As a layman but having discussed it with a surveyor I believe that the problem could be that the timber frame is tied into the cement block lift shaft which comes up through the centre of the flat to above roof level.  The kit has settled but for some reason has been unable to adjust around the lift shaft.  I don't know why.  All the floors around the lift shaft slope upwards towards it.  The floors also slope towards the peripheral walls of the building so there is an upward slope here also.  The result is a small concave in the larger rooms.  Perhaps there is a lesser slope towards the outer walls. 

The floor appears to be highly specified and is composed of a substantial number of different materials and is probably about 300mm thick.  There are 2 layers of chipboard 3 of plasterboard, acoustic battens, rockwool, joists, resilient bar and more.

Given the structure, do you think it is still possible to level the flooring throughout without removing the dividing walls?  My concern is that once leveled settlement could continue and another slope would result.  Do you think this is possible?

The builder's structural engineer basically talked a lot and said nothing about the severity of the problem or whether it could be rectified.  He did want to emphasise that there was not a problem with the foundations and that was it.

The builder believes it to be just cosmetic, but a marble rolls quite rapidly across the floor in most areas. Do you think we should push for total rectification of the floor throughout the property and not settle for any minimalist approach?

If this went ahead do you think that we should also claim for all expenses like furniture removal and storage, and similar spec temporary accommodation?

Given your experience what is the likelihood of the NHBC supporting total rectification?  Would we better going for an independent structural survey and going down the civil action route?

Any other input that you think may be relevant and helpful is very welcome, as we are still trying to formulate a way ahead.

[New Home Expert]

First of all thank you for your kind donation. All too often people have the expectation of being able to get top class expert specific advice for free just because it is being given online.

The lift shaft will be built in blockwork as it supports the lift, which is also noisy and a fire shaft.
The timber frame floor should be isolated from this, not bearing on the lift block walls or supported on hangers.
As the timber frame dries out it shrinks. It works at at around 12mm per floor. This means that on the effects on the upper floors are higher as are the allowances for this movement. On the third floor shrinkage potential would be at least 30mm.

Once the remedial work is carried out further settlement would be unlikely as the timber only shrinks once and this is usually within the first six months following the heating going on.
The internal partitions should not need to be removed at all but given what you have said, I have no confidence that the correct construction has been followed.

I think you should get this sorted out whilst you are still in the 2 year NHBC warranty and the builder is required to attend to it.  After three years the NHBC warranty is only covers structural defects which this is not.  You would also have trouble selling when the time comes if it is this bad.

The house builder should cover all necessary expenses required whilst doing the work and should include a payment for your inconvenience too.  You may also be able to consider making a claim using the Consumer Code for Home Builders Adjudication Scheme.

It is early days, as I said write to the builder (who is this by the way) and tell them you want it fixed.
The NHBC will help, but the process could be  long and protracted.

[romulus]

Thanks again NHE.  

Considering the good technical advice you provide on this site and the cost of getting an expert in.  I feel that participants should contribute.  I will do so again.

My problem at the moment is that I don't understand the process whereby this can be fixed.  The developer has hinted at screed, but that seems a quick fix solution to me.  The screed would have to go right through the whole flat!

I would appreciate it if you could explain how it could be satisfactorily fixed.

The developer is also getting more tetchy with me and has diminished my problems by saying he doesn't think he can appease me and that we will probably have to resort to NHBC involvement.  All I want are level floors to minimum NHBC standard, and door frames that are not periodically distorting.  There were and are other quite significant issues.  We had a 40 + list of problems.

I now rue the day I bought a new property.  It was my dream home but it has turned into a bit of a nightmare.  We have bought new builds in the past, the last one was 15 years ago, but we never experienced the problems we are having.

I still hope that matters can be fixed, because there are so many things I love about the place.  
However, I am losing confidence.  We are both very stressed and having the odd tiff ourselves because of it.  My wife was really happy where we were before and I turned the screw for this move.

[New Home Expert]

First of all the house builder (WHO ARE THEY?  name and shame) cannot remedy this by screeding.
The fact is, your floor is made of timber.  They cannot realistically be serious about adding up to 30mm of  a non flexible cement based screed on a timber floor that will flex and move!
They can use a special flexible latex which is designed to flatten out small imperfections to floor surfaces such as at abutting panels but only up to 5mm thick.  In your case this would not be suitable.

The problem is something under your floor is solid and has not moved as the timber frame has shrunk back.  My guess is the builder knows what it is.  In all probability the lift shaft is supporting one end of some of the floor joists.  The design should have isolated the floor from the lift shaft completely using trimmer joists etc. In some designs the timber frame cannot take the load at the spans required so steel beams and columns are used for support.  These too do not shrink with the frame and allowances have to be made for shrinkage to prevent what you now have.

The only solution is to take up the floor at the lift shaft and look and see what has been done and what is causing the problem. Then the solution can be considered.  I really do think you should ask the NHBC to investigate in your behalf now and have a meeting at your flat to look at the problem.  They can look under the floor using an endoscope camera without taking the floor up.

[romulus]

Hello NHE

I have involved the NHBC and am now waiting for their response.

From trawling this and other sites I note that sometimes the NHBC are not that effective even in the face of quite significant problems.  If this was to be the case I assume the next step is legal action.  I am then left wondering how effective that would be if the NHBC has not shown much interest.  I am also correct that it may also come down to a wrangle of expert versus expert?  I also understand that once you go 'legal' the NHBC drops the case.  What are the usual chances of success going down the legal route?  Is it any better than using the NHBC?

Something else that has just cropped up is quite significant cooking smells from the flat immediately below.  It was empty until rented just a few days ago.  We were overwhelmed by pan fried cooking smells, and they are still her 24 hours later!  Am I correct in assuming that if cooking smells can get through then smoke can get through so this is a potential hazard, and must be rectified?

At the moment there does not seem to be a light at the end of the tunnel!  I am in need of a positive response!

[New Home Expert]

Report the smell to the house builder in writing and copy your letter to the NHBC.
Yes if you can smell cooking smoke and fire can also get through what is a gap in the floor between your flat and the one below.  I am surprised you are not also affected by noise.
In my professional opinion, Timber "Flame" construction should be banned in multiple occupation dwellings.

You have an NHBC  warranty and should continue to wait for their response and go through the processes. 
When this is known you can then decide on the next course of action.

I am surprised, considering how badly the house builder has built your block of flats and treated you regarding the defects you still continue to choose not name and shame them!

[romulus]

NHE, thanks again for your reply.

The reasons I have not as yet named and shamed them are:

1. They have fixed the majority of our general snagging, although I have had to really keep pushing.
2. They are now making some positive noises over the sloping floors.  At my request they have said that they will respond in writing regarding a possible solution once they have met with their engineer etc.  I will give them only some time for that.
3. I want to keep them on side so don't want to completely alienate them.  The gloves would be completely off if they became more negative.
4. I don't want them to pick up on what is being said here, although I know it could possibly be deduced.
5. They are a relatively small company that build in a very limited geographical area.

The floor is multi-layered.  Thus far the only noise we have heard is the occasional thump of the fire doors as they close, but it is not that loud.  It is early days with someone just having moved in.  It could be the honeymoon period before the surround sound system or computer games console is set up!

From your knowledge what are the usual chances of success going down the legal route?  Is it any better than using the NHBC?  Is it more difficult legally if the NHBC are not that helpful?

[New Home Expert]

You say you refuse to name the builder yet are considering legal action against them?
The legal route could cost you a lot of  money and be a long drawn out process with no guarantee of success unless those involved produce technical witnesses.
I know of one buyer who took Barratt to court after he had successfully won a smaller victory using the consumer Code Adjudication service. After jumping through numerous hoops the case was eventually thrown out after a few minutes of the hearing on a technicality (and he had a winnable case) a year after he started.  He is currently liable for Barratt's £50,000 legal fees but may have got this reduced to £22,000 after yet another battle.

In this instance he could not use the NHBC as it was not a snagging or building defect.
You can use the NHBC and, as I have said about three times now, should do so!
The NHBC claim to find in favour of the home owner about 80% of the time!

[romulus]

This problem with the sloping floors is about to be rectified.

The floors have been inspected by two different structural engineers and surveyors. This was to provide a second opinion.  The general concensus is that there is not a structural problem but for some inexplicable reason, the timber frame cassette has not released around the central concrete stair core that goes right up through the building.  This has led to differential settlement and thus sloping floors around the core.

There are 2 proposals for rectification.  The kit cassette cannot be released around the core, so to adjust for this slope the approximately 60mm acoustic battens which carry the 22mm chipboard floor and lying on top of the kit cassette can be firred (tapered) to provide a level floor.  I understand it would not be structurally sound to break through the ply of the kit to reach the joists.  It seems to be appropriate to basically level the floating floor comprising the acoustic battens and 22mm chipboard above the kit cassette.  This is one proposed solution.

The second proposed solution is to overlay the complete chipboard floor throughout the flat with butt jointed  plywood.  Different thicknesses of plywood would be used across the floor from wall to wall in order to level it.   Due to a difference in height where the plywood sheets butt up, it is along these joins that a  flexible latex type screed would be used.  All the skirtings are to be removed and subsequently replaced.

I seek advice on which would be the best solution of the two.  Is any one of the solutions vastly superior to the other, or would either be satisfactory?

[New Home Expert]

As I said before, the timber frame moves as it dries out and the solid structure, be it structural steelwork or a solid concrete stairwell or lift shaft will not move.
It is essential that the timber frame and the solid components are isolated with an allowance for differential settlement to prevent what has happened here.

Levelling the acoustic battens and floating floor components is the best and only option.
 
The second option bits of ply and latex to level it up is a complete bodge job in my opinion.

[romulus]

Thanks again for your comments.  I appreciate the sharing of your expertise.