Mansard Loft Conversion without raising floor height.

[Mmark]

What I've learnt from going through this, and what advice I was given over this weekend:
1) Always insist on full structural survey for structural diagrams (lifting up lots of floorboards etc), don't do it from architect diagrams alone. (I didn't even know this was available, until I hit this problem).
2) If you hit a problem where diagrams do not match, do not let the builder mitigate this - even if they think they know better - as otherwise you end up limbo situation on who owns the mistakes (where I am now). Stop the work, insist the structural engineer does a site visit and signs off on the updated approach. This way it's clear the structural engineers owns this 100%, if they do something wrong, you must give them the opportunity to rectify it, or they cannot own it.

 

[tony1851]

Did the SE visit the house, or did he work off the architect's plans?

 

[Leofric]

Because the existing floor joists runs the wrong way,

The existing floor joists run front to back as shown on the architect's section drawing. The question is how did the architect expect the new steel beams be installed within the existing floor in that situation , as pointed out it isn't practical.

The builders say the diagram is wrong, the existing joists go the wrong way,

No, the existing joists are shown spanning the correct way, front to back. See above comments .

The engineers design is based on finding a structure within the existing floor and checking it against what the engineer has shown. I assume that the builder did not find any steels there that could be used.”

Why would an engineer
' assume a structure' within the existing floor , and does that mean the new steel beams ( sizes given ) are what the engineer 'showed 'for the architect to put on the drawing
Having said all that it really seems to comes down to whether the existing floor joists were adequate or not. If they weren't the new steel beams would be required anyway so the rest is a bit academic.

If they were adequate you have been presented with extra cost for building work that wasn't necessary.
Amen ,
ps was that proposed plan drawn at a different time to the section, the section shows steel within existing joists ,sizes not specified, and the section specifies what are presumably new joists ​

 

[Mmark]

Did the SE visit the house, or did he work off the architect's plans?

The architects offered to do the structural diagrams for me. There was no SE visit. I wasn’t advised to do so, or even aware that sort of thing was available. And obviously now I really wish I had been given that advice for an SE visit before construction started. Also surprised the builders didn’t advise me this either.

I’d have saved thousands from not having to install a new floor, saved myself 250mm in head height and of course avoided all this stress

 

[Leofric]

I’d have saved thousands from not having to install a new floor

So you are saying the existing floor was adequate without any additional steelwork. If the architect, SE and builder accept this you have grounds for claiming some sort of compensation for the cost of unnecessary building work involved in raising the floor and roof I would have thought (but I am not a contractual expert) As a matter of interest ,how much extra do you think all this extra building work is costing you

 

[Mmark]

So you are saying the existing floor was adequate without any additional steelwork. If the architect, SE and builder accept this you have grounds for claiming some sort of compensation for the cost of unnecessary building work involved in raising the floor and roof I would have thought (but I am not a contractual expert) As a matter of interest ,how much extra do you think all this extra building work is costing you

Because I allowed the builder to mitigate things, rather than insist the structural engineer be given time to assess and own the decision (i.e. give them a chance to correct their mistake), I'll have little grounds to stand on.

I"m guessing the costs of a new floor are somewhere between 5-10K. But tbh, life is too short to go to court over this. I plan to live in the house for the rest of my life, so it was more about the missed opportunity to maximise the head height of the bathroom. Prior to this I could stand upright when using sink and toilet, now you need to stoop. However the main room is OK with 2.2m, as we pushed up the roof.

The one positive thing I've been told, via my architect friend (not the original architect that did the work), is that the floor will now be extremely solid and I can do boxing training on it. So I lost head height in the bathroom, but I've gained a training floor I wasn't expecting to get. So trying to stay positive

 

[Leofric]

via my architect friend (not the original architect that did the work)

Didn't realise the architect friend wasn't the original architect, not that it makes much difference. All I would say is you are a lot more forgiving than a lot of people would be.

 

[Mmark]

Didn't realise the architect friend wasn't the original architect, not that it makes much difference. All I would say is you are a lot more forgiving than a lot of people would be.

In all honesty my wife and I are devastated, but there isn't much we can do now, it's not going to help getting angry at people. The bathroom is just going in now and the space, compared to what we had before, is tiny. The door cannot open inwards, has to be open out, I have to stoop to use sink or toilet. I feel like I've vandalised our house. when I consider how easily this could have been corrected, if we were advised right, it's heart breaking.

We are going to live in it for a year or two, see if we can move on. If I can afford it, I may pay to have the floor redone. The telebeam product seems like it's a nice solution. Builders I ask to quote for this, will think i'm insane....

 

[Leofric]

Don't want to prolong the agony but, as far as the limited headroom in the bathroom is concerned I suppose a dormer window might be the only way to solve that to give more headroom ( at a discounted price perhaps )
What is the telebeam solution
Regards

 

[Mmark]

Don't want to prolong the agony but, as far as the limited headroom in the bathroom is concerned I suppose a dormer window might be the only way to solve that to give more headroom ( at a discounted price perhaps )
What is the telebeam solution
Regards

It’s a good idea, but our bathroom is on the front of the house, this area has strict planning permission rules about that

This is telebeam, looks an easy way to strengthen existing 2.5x7.
https://www.telebeam.co.uk/

For now I’ll live with it, if it irks me in a few years, I’ll get a quote for redoing it. I just hope this thread helps someone else in the same position in the future. The most annoying thing so far, is an open outward door for the bathroom.

For anyone reading this thread
1) always insist on structure engineering visit, that inspects under the flooring before construction begins.
2) If things go wrong, don’t let builder mitigate it, no matter how much of a hurry they are to keep going. Insist on a structural engineer site visit, structural engineer must own the final decision, not the builder.