Design Ideas for the extension/remodel [Plan B]

[Zak S]

Hi. I am wondering if there are any design ideas you guys can suggest which can work with the existing building without the need to demolish and rebuild (which I am sure would be the best and cleanest but costly option). I have attached the existing measured building survey and topographical survey which I commissioned in Dec last year. You might have seen from some of my other posts including the Ground Investigation Report that:

 

1. Ground is very soft and clayey hence the piles would be required for any extension work and some clever structural planning.
2. Water table is at 1m.
3. Existing foundation are 400m to 1m and hence determined to be unsuitable for second story unless some clever design ideas are required if I am to use the existing building structure.
4. Demolish and build would not be done right away as needs to move in and complete couple of other project as well as sort the planning issue first.
5. I would need to move in from April hence would need to do refresh of the property either including plastering/redecorating/kitchen/bathrooms. 

_2021-20-1 Topographical Survey and Street Scene Layout.pdf _2021-20-2 Existing Plans, Elevations & Sections Layout.pdf

[SimonD]

Clay ground and 400mm to 1m existing foundations does not necessarily preclude second floor extention, but does require the right designer and structural engineer. Solutions can include making the 2nd floor loads less than existing, especially if existing has concrete roof tiles, pad foundations to support point loads, ring beam around existing ground floor walls. I know this because my project uses all of these things and we've got 300mm foundations in places, and that's 300mm below dpc which is 150mm above ground level.

 

How many trial pits/trenches have been dug to obtain information? In ours too few so poor assumptions were made until I insisted on digging and investigating more.

 

When was the original house built?

[Zak S]

8 minutes ago, SimonD said:

How many trial pits/trenches have been dug to obtain information? In ours too few so poor assumptions were made until I insisted on digging and investigating more.

 

When was the original house built?

Thanks. There were three holes dug; one on the front and two at the rear. The banglow was built in 1955-1960

[Zak S]

Update: on the visit today I found that couple of walls on the far right hand side (extension) are sinking and clearly indicates subsidence on the one side. This was not picked up by the big standard valuation by the bank. Completion expected end of March.

 

Please could somebody help with best course of action. Option are:

 

Proceed with Purchase without mentioning it vendor or bank. Risk is that property would be nonsellable as is without redevelopment. Redevelopment is not guranateed

 

Ask vendor to claim on their policy and correct the issue with the risk that any underpinning would reduce the value significantly of the building and would hinder any future sale (if redevelopment cannot be done for any reason). 

 

Ask the vendor to reduce the price off the record (not sure by how much) and accept the risk. 

 

Please could somebody help. I am at a point where this project seems a bit doubtful. 

[Big Jimbo]

If the price you are paying is not within the re-developement value (knock and build) then walk away.

[Mr Punter]

36 minutes ago, Zak S said:

I am at a point where this project seems a bit doubtful. 

 

I would walk away.  Redevelopment and remodelling is a pain at the best of times but the uncertainty of the existing structure tips the balance against it.

 

You may do better getting somewhere smaller if you want to knock down and rebuild.

[Zak S]

50 minutes ago, Big Jimbo said:

If the price you are paying is not within the re-developement value (knock and build) then walk away.

Thanks. How do you calculate this. Where is the profit in the equation. Purchase price + redevelopment cost is around 1.7m. Assuming half half for plot and construction costs. The redeveloped value might be between 1.8-2m on prudent basis. So not great deal of profit. Remodelling the existing banglow sort of goes out of window unless the sinking of the wall of extension is isolated issue which, it seems, it might be.

[Zak S]

17 minutes ago, Mr Punter said:

 

I would walk away.  Redevelopment and remodelling is a pain at the best of times but the uncertainty of the existing structure tips the balance against it.

 

You may do better getting somewhere smaller if you want to knock down and rebuild.

We, especially me, is hugely emotionally invested in the project. It would really hurt badly hence trying to figure out any other options which might work.

[Big Jimbo]

Being hugely emotionally invested is your problem. If you want to buy it and spend a load of money on it, including underpining, then you may well end up with a house that is worth considerable less than you have spent on it. An underpinned house can be worth up to 25% less than a house that has not been. If you are not in a position to knock the house and rebuild something on the site that will atleast allow you to break even then if the plot is your ideal place to live then go ahead. If you end up either way with a house that is worth say 20% less than it cost you, but you love it then it is your choice.

[SimonD]

3 hours ago, Zak S said:

We, especially me, is hugely emotionally invested in the project. It would really hurt badly hence trying to figure out any other options which might work.

 

Honestly, if there are signs of subsidence then you're potentially walking into a money pit. When I was looking, I found the most amazing property with just stunning views. The only problem was that it was being sold following an insurance assessment re subsidence. The so called engineers report from the insurance stated it was settlement, but our surveyor said the report was useless. The risk was too great that we would sink so much money into the ground without anyone seeing it that I took that risk off my offer. The seller didn't accept so we walked.

 

Sometimes it's just better to walk away from something despite the emotional investment. If you're feeling like this now, just wait until you're committed with your money and a problematic development and then the stress will really hit you.

[Zak S]

1 hour ago, SimonD said:

I took that risk off my offer. The seller didn't accept so we walked

How did you determine it. What is the right amount for which it would be something worth taking. Should I show to foundation specialist. One option I was thinking that how much would it cost remove the walls and put in the piles and then rebuild the walls instead if underpinning.  The issue seems to be on one side only in the extension used as utility room (pic attached).

 

There are crack along the lentils,  along the DPC (quite wide that its causing dampness in that area) and in the boundry wall to the side of utility room.

 

The rest of the property seem perfectly fine.

 

 

 

Edited February 25, 2022 by Zak S

[SimonD]

32 minutes ago, Zak S said:

How did you determine it. What is the right amount for which it would be something worth taking.

 

I spoke to a local surveyor and asked him to look at the property and review the insurer's report. He came back to me with a view regarding required remedial work plus a ballpark figure - it was complex due to banking on the side where there was subsidence meaning deep piles. I then assessed the rest of the site, for example poor access and neighbour close by whose garden we'd have to use for some of the work. Added my contingency and offered 200k below asking price.

 

It's definitely worth getting it looked at by someone with relevant knowledge and experience.

Edited February 25, 2022 by SimonD

[Zak S]

1 hour ago, SimonD said:

It's definitely worth getting it looked at by someone with relevant knowledge and experience.

Yes definitely worth doing it. Thanks. I will speak with piling specialist if this is something that he can fix rather than underpinning. I will then ask the vendor to pay the cost.