2nd Storey extension over garaged and extended lounge without underpinning.

[pep411]

Dear all,

I, over the years, inspired by ideas on this forum have taken the plunge and decided to extend my house. Both my children will be going to nearby secondary school, so what was holding us back is pretty much resolved and we do not want to move.

The only bug bear is the the section behind garage is in fantastic nick with solid wood flooring, decorated to high standards and good insulation ( red section in 1st Figure). But I the wall was made of concrete block with no cavity wall. The single leaf brick garage too does not have enough depth. This assumption is based on neighbors who have extended and had to resort to underpinning.

The red section in my figure is already extended portion. I will be resorting to advise from SE when PP is passed. But are there any alternative to underpinning in red and orange section. Will RSJ Box above current ceiling to support extension upstairs be feasible. If yes how will the RSJ be supported.Is it via 1m deep pits filled with concrete?

Also please feel free to suggest any improvisation to proposed layout.

 

[Deluks]

Not entirely clear what the question is here.
We don't know what size your RSJ is for starters.
It sounds like you are trying to use an existing inadequate wall/inadequate foundation to build a second story extension.
Whatever workaround you try to do to avoid undoing your nice wooden floor and decorating, will probably cost many times more than just accepting the disruption and making it look nice again afterwards.

 

[pep411]

My questions is not about RSJ sizes...That as mentioned I will get SE to advise. I am wondering whether RSJ can go above current ceiling. Rather than under the current ceiling, which means disruption to current wall.

 

[freddiemercurystwin]

Got an existing plan so we can see whats what?

 

[pep411]

thank you all. The living room is extended bit with single concrete blocks. Garage is singe leaf brick.

What I was hoping was for rsj wtih pad foundations going above the current flat roof to support upper floor as I am fairly sure the current foundation will not be adequate.

 

[Ivor Windybottom]

You'll need to get someone on-site to physically look at it all, and probably dig a few holes.

I doubt that that anyone's going to be able to give any meaningful guidance from the other end of the internet.

One possible idea off the top of my head could be to replace the garage side wall with a new cavity wall on new foundations, and to continue this wall or just its outer skin along the outside of the LIving Room. Or perhaps also completely replace the Living Room side wall too, giving you the foundations you need and much better insulation inside this room. Obviously you'd lose the garage back door, but you could add a new internal door.

There are dozens of possible approaches to this, but definitely don't let decor dictate - otherwise you might end up spending £10,000 extra to avoid £1000 worth of tidying up after.

 

[freddiemercurystwin]

You can dig some trial holes yourself if you're handy, see if the garage has a decent foundation or not, same applies to the bit behind the garage, only way to get clued up. Was/is the neighbours house built at the same time by the same developer? A good designer should be able to get a good handle on what's required structurally. Do you have any shared drains to build over/near?

Why have you got that beam running parallel with your kitchen island, it won't be supporting anything? Beams can usually be hidden above ceilings so as to achieve a flush ceiling but it's extra cost and disruption to the floors upstairs. You will need to make sure all the first floor bedroom windows will meet the regs for escape windows as you're removing the enclosed escape route. Don't know about deep foundations yet but you'll certainly need deep pockets!

 

[Ivor Windybottom]

Probably £100k++ these days if you want to sit in a chair and watch it all happen.

 

[Ivor Windybottom]

Perhaps much more with that new roof over half the house, which is the only way of avoiding a flat roof.

 

[pep411]

Thank you all guys. This was my 1st home and likely this will be my last home. I am early 40s and 2 children under 10. I envisage living at this property another 25 years atleast.

I am a NHS staff and it was loads of night and weekend shifts. I have saved around £140k including contingency.

I must admit apart stuffing a open wound i am hopeless at anything else I.e.digging a hole or doing any work myself. So I would rather locum and pay a professional to do it for me. So it would be work and watch not sit and watch.

I like the idea of demolishing side walls only as that might be cheaper and less disruptive than underpinning.

Any other suggestions I.e. timber frame or ICF.

Does the layout flow...I have instructed architect based on my needs, but open to different configuration.

 

[Ivor Windybottom]

If your plans change and you do end up selling it, you'll be asked whether it has ever been underpinned. If you say yes then the solicitors and buyer usually go into headless chicken mode. You and your future buyers will pay extra for home insurance forever.

Be wary of open plan. Many followed the trend and regret it, putting back internal walls has become a bit of a thing in recent years.

We plan to combine our current kitchen and dining rooms. But the living room will remain separate, keeping all the cooking smells in the one room. In fact we'll make the living room a food-free zone once we get a nice comfy relaxed dining setup.

Plus with your kids it can be useful to have kid-free (and parent-free) zones. Especially when their friends, girlfriends and boyfriends start turning up.

 

[freddiemercurystwin]

If your plans change and you do end up selling it, you'll be asked whether it has ever been underpinned. If you say yes then the solicitors and buyer usually go into headless chicken mode. You and your future buyers will pay extra for home insurance forever.

Eh? There's a massive difference between structural work necessary for new construction and subsidence. You won't pay extra for this.

 

[pep411]

Eh? There's a massive difference between structural work necessary for new construction and subsidence. You won't pay extra for this.

Yes I would have thought so...mentioning that it has been adequately underpinned to make to structurally sound for extension would be more reassuring as buyer i would think.

 

[stevie888]

What you need is an architect who will listen to what you want and think outside the box where necessary. Regrettably a lot can't/won't do either. Better yet would be a designer who does his own structural work.

There's been a lot of good comments made but if I might add a couple more;

The notion of effectively sitting the new bit on legs to avoid overloading the existing is certainly an option but existing foundations will often be acceptable even though they are perhaps not as deep as if we were starting from scratch.

Have you applied for planning permission yet? Going forwards is often refused.

I doubt personally whether your current budget will be enough: there's some substantial structural work shown.

 

[pep411]

thanks all.. PP is being processed. Going forwards is only bit where porch will be build otherwise rest is all current footprint. 3 neighbors did relatively similar extension. They all came around 100k mark.