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[Jilly]

I'm still trying to find a cost effective solution to my foundation problems:

 

Background:

 

Job: Conversion of a block built, featherboard clad, stable (58.56 m2) plus wooden lean to extension (39.04 m2) to create a 2 bedroom dwelling.

 

The stable is constructed from trussed rafters on 140mm thick blockwork walls buttressed by return walls on a slab foundation

Current Foundations: 600mm concrete foundations with no reinforcement

plus 150mm slab on hardcore bed plus light mesh at the bottom. There is no cracking on the concrete floor.

 

Soil analysis: Report available: clay and tree roots on the East side  and South East corner.

Adjacent trees have been removed.

 

Mild cracking on South and East walls 

(It must first be stated that the extent of cracking, if assessed in accordance with BRE Digest No.251 "Assessment of damage in low- rise buildings", is termed as slight, very slight, or negligible. These terms refer to the probable significance of the cracks in respect of structural stability or serviceability, rather than to their effect on the general appearance or saleability of the property. The BRE Digest No.251 also suggests that it is difficult to draw conclusions regarding the causes of movements where the overall crack width is less than 5 mm.)

 

I understand there could be movement between the existing building and the extension.

 

Micropiling and a new raft is about £20K, not sure what will happen to the old slab but expect a few £K more

Underpinning is likely to be substantially more. 

 

Are there any other options? The building is 40 years old and pretty solid (even the Building Control Officer remarked on this). I've looked at injected resin, but this seems to be for remedial subsidence .

 

I buy into the ethos of make do and mend (so maybe I should be on a different forum!) and I'm failing to see why this needs to be done (having lived in a Victorian house with shallow foundations and floorboards over soil near trees)

 

The depth of the raft thickening is not sufficient to meet NHBC requirements for building near trees chapter 4.2.

 

Do I need another structural engineer opinion? Is there no way round it for a conversion? The hippy in me is perfectly happy to live in a structure which has housed 1.5tonnes of moving equine for many years. 

 

 

[Cpd]

13 minutes ago, Jilly said:

I buy into the ethos of make do and mend (so maybe I should be on a different forum!) and I'm failing to see why this needs to be done (having lived in a Victorian house with shallow foundations and floorboards over soil near trees)

 

13 minutes ago, Jilly said:

The hippy in me is perfectly happy to live in a structure which has housed 1.5tonnes of moving equine for many years. 

 

Feeling for you @Jilly  I live in a 100+ year old house with no footings and soil under the floorboards ! The building will be here long after I have departed this mortal plain. I do hope you can find a solution to your problem and hopefully someone will be along with some good advise. It seems like they are trying to fit a square peg in a round hole......

[Ferdinand]

I wonder if you would be better looking into a replacement built in the same spirit. The advantages of self-build will be likely to outweigh the costs of pfaffing with a refurb.

 

(Perhaps This has been covered previously.)

 

You need to look at lifecycle costs in terms of ££ and CO2 eg electricity bills in those 2 dimensions over 25 years.

 

eg look at the place built by @Crofter.

 

 

Edited September 25, 2019 by Ferdinand

[mafaldina]

For what is worth I am converting an old milking parlour c.135m2 into a three bed holiday let. It is of varying ages varying from 100 to 20 years old. 200mm+ solid walls (some block on flat, she stone) built off an eight inch or so slab (no idea whether any reenforcement but no cracks in it). I am in the process of underpinning all round (~65m), 500mm deep, engineer spec. attached. I don't actually think it needs it as there is no sign of movement and no extra loads will be imposed (it has a slate roof, put on 20 years ago) but building control requirement. Not too onerous or prohibitively expensive to do. Might be worth another engineer opinion though. The trouble is, like me, you cannot pull down and rebuild as your right to conversion will be based on converting an existing agricultural building, I suspect.

timber_structure_1.pdf

[Jilly]

Hi thanks, I've just read the following on the Homebuilding and Renovating site, which implies we could demolish without Planning because the building is small. I'll need to explore this fully.  

Conservation Area Consent:

The substantial demolition of an unlisted building within a Conservation Area will require planning permission from the local authority, with the exception of buildings of less than 115m³, or walls or fences 1m high next to a highway, or 2m high elsewhere.

 

Underpinning specified, was between 1.9m (closest to the trees) and 1.6m on the opposite side, so much more difficult to do. 

 

Demolition is likely to cost £8-10k I think. 

[Cpd]

12 minutes ago, Jilly said:

Underpinning specified, was between 1.9m (closest to the trees) and 1.6m on the opposite side, so much more difficult to do. 

Is that depth !!!! Have you got somewhere to burry the old building ? The usual way up here is to just demolish it with a big digger and dump the whole lot in a big depression and re landscape over the top with soil......  not saying it’s the correct way but Round these parts..... about two days work max. (Obviously not if it has dangerous materials) then it’s done at nighttime and that costs more......  any pics ? 

[Jilly]

Yes, that's depth...hence my despair.

 

Just calculated the cubic volume for the demolition in conservation-area-without-planning permission and we are over the specified minimum.

 

People watch you in Conservation Areas. 

 

I guess I could start on a Building Notice and then just live here forever and never finish it... 

 

[Jilly]

[Cpd]

What a bloody shame, yes living in an area where you are “watched” limits what fun you can have. It looks like a great project but only great if it’s possible. 

31 minutes ago, Jilly said:

I guess I could start on a Building Notice and then just live here forever and never finish it... 

 

 

Well that’s option two, option one is to exhaust all other options...... I hope someone on here has some good advise for you.