Extension : floor level 1 foot below ground level

[^woody^]

Surely this is an extension not a conservatory?

 

[Footsoldier888]

Sounds awesome .

With regards to digging down I was just thinking it could undermine a nearby building or retaining wall that may not have much in the way of foundations but it sounds like you have got it all covered.

You say this will be under permitted development. You are certain about this? I take it isn't in a conservation area or that your PD rights were used up with the conservatory? You can establish if it is a lawful development before doing it. PD rights can be removed with extension approval for example, they can be complicated.

Thinking about the party garden wall, however well you get on with your neighbour you might want to get it agreed in writing, it is not unknown for neighbours to change their mind and accuse you of removing their wall, which can be very expensive to resolve.

 

[Ady J]

Sounds awesome .

With regards to digging down I was just thinking it could undermine a nearby building or retaining wall that may not have much in the way of foundations but it sounds like you have got it all covered.

You say this will be under permitted development. You are certain about this? I take it isn't in a conservation area or that your PD rights were used up with the conservatory? You can establish if it is a lawful development before doing it. PD rights can be removed with extension approval for example, they can be complicated.

Thinking about the party garden wall, however well you get on with your neighbour you might want to get it agreed in writing, it is not unknown for neighbours to change their mind and accuse you of removing their wall, which can be very expensive to resolve.

Big thankyou foot & good points

There’s no conservatory or anything else in back garden & this new room ( outhouse ) will be 1.3 meters away from back of house ,

Neighbours -I get on well with landlord & his tenants , the wall between us is over 100 years old & kind of about to fall down so they are all happy something will replace it
They did get a letter from council when plans were submitted (when it was going to be attached as standard extension) & they were fine ( both sides ) they are lovely houses but most of the gardens are a bit tatty as there are nice little parks nearby that people prefer to go I think

Yes all within criteria of permitted development rights,
Council cane round to look when I was considering joining to house meet planning etc , the only point they made that if 2.5 meters high
( permitted development rights route) then the lowest part of garden which happened to be down under base of garden gate at bottom of garden , causing me a lot of extra work as I’m in the process of shifting about 5 tons of earth before I can even start on foundation for the room

The plans I 1st submitted were turned down flat this is why I’m going permitted DR route ,
I’ve shown the council ( another dept) new plans & they’ve agreed I’m within my rights & it’s within criteria to proceed , planning dept doesn’t seem to like the dept that helps with dev right matters

I’m pretty much going right up to the 50% of garden area as house stood in 1948 etc , this is allowing me a nice big room I like high ceilings thus the extra trouble I’m going to by digging down & floor levelliwer etc

The mention of conservatory this is a removable but attractive weather shield so I can go from house to new building without getting rained on etc
( I’ve explained this to council & as long as it’s not connected I’m legal it can be classified as a double glazed greenhouse )
1” gap with compressible rubber weather strip in to fill that gap is the trick
-only 1.3meter wide lean to simple structure

 

[Ady J]

Sounds like it'll be a complete pile of old crap to me.

pilsbury that's not you again is it?

thanks for your feedback Fred ,
What is the crap part ?
All criticism/advice appreciated


Ps my final plan of construction I will be seeking some proffesional advice ( & no doubt pay for it ) prior to me starting to spend the cash out & getting to point of no return etc
I’m enjoying the process of learning and thinking about very best solution for this , I hope to enjoy the new large room trouble free for a long time

 

[Ady J]

Been out in the back garden more in the last month then I have in the 12 years I’ve owned the place for , enjoying it
Getting all the soil out is bit tricky but with a few hours a day come Feb/March things will be really starting as hope to have foundations all dig out & prepped by then

Anyone needs top soil I have lots & lots to give free of charge
( filling big builders sacks in front garden!)

Great there’s forums like this to inspire & help each other

When council planning visited & said an extension plan as submitted would be turned down I stayed up until 4am reading all of the government permitted development rights document (easily found this years pdf on net) & realised although new plan I could still do pretty much what I wanted -a large room filling half of the garden going right down to back wall

 

[Footsoldier888]

Ady just a few more points.

Do you have the PD approval in writing from the council? Someone on the desk giving their opinion is very different from having it in writing, a verbal opinion won't be legally binding.

Regarding your neighbour, however well you get on your legal position will be very weak if they later deny all this. Also if you put founds past the wall line ie on their land then that can be problematical if you have not given legal notice under the Party Wall Act.

About the foundations - how deep will you know to go??? As I understand it the preferred way is to dig out and fill the same day, or over a couple of days max. Is this the idea???

It would be great to see it posted up in the projects section if you have time.

 

[Ady J]

Ady just a few more points.

Do you have the PD approval in writing from the council? Someone on the desk giving their opinion is very different from having it in writing, a verbal opinion won't be legally binding.

No, I don't want one, in fact I find the council a tad of a pain to deal with and zero help,
thankfully building under permitted development rights needs no intervention from the council or planning office

Regarding your neighbour, however well you get on your legal position will be very weak if they later deny all this. Also if you put founds past the wall line ie on their land then that can be problematical if you have not given legal notice under the Party Wall Act.

neighbour is sound, never really there either and happy I'm finally sorting out my wall that looks as though its about to fall down

About the foundations - how deep will you know to go??? As I understand it the preferred way is to dig out and fill the same day, or over a couple of days max. Is this the idea???

based on all info ( original structural engineer report when I underpinnned a se toon of my house when I purchased it 14 years ago , caused by old drain leak )
raft foundation, 700 deep , 600 wide around sides,
150mm deep through centre ,
all steel reinforced

hoping to dig this out and board sides / cover when not working on it so will take a few weeks prior to concrete pour in ...looking into potential pro - cons of this



It would be great to see it posted up in the projects section if you have time.

 

[Ady J]

For a steel reinforced raft foundation I’m wondering why some people also put a DPC under the foundation ( trenches lined with plastic sheet prior to concrete pour in)
Some do , some don’t
Does anyone know why?


I’m planning to compact a layer of hardcore then pour straight onto that ( of course once steel has been constructed within etc )
A plastic sheet under it I fear could actually trap mosture ?

Obviously I’m using DPC’s in correct places above

 

[John D v2.0]

yes indeed it's designed to keep the moisture in the slab so it can cure properly, otherwise it might dry out into the surrounding ground and not reach the proper strength

 

[Ady J]

yes indeed it's designed to keep the moisture in the slab so it can cure properly, otherwise it might dry out into the surrounding ground and not reach the proper strength

Thanks
But obviously a plastic seal underneath the slab ( between bottom of foundation slab & the earth) it may trap mosture in thereafter

Some do this , some don’t
& not quite sure why

Never seems to be done for trench or strip style foundations from my research

 

[John D v2.0]

Thanks
But obviously a plastic seal underneath the slab ( between bottom of foundation slab & the earth) it may trap mosture in thereafter

Some do this , some don’t
& not quite sure why

Never seems to be done for trench or strip style foundations from my research

Maybe based on what you're laying it on (wet clay won't take water out) and the surface area to volume ratio to a lesser degree.
Concrete isn't damaged by being wet, so don't worry about trapping water in it. The only reason you need to dry out out fully is if you're laying a floor on top of it with no DPM. If you don't put a DPM under it, there's a good chance water will stay in there anyway depending on the ground.

 

[Ady J]

Maybe based on what you're laying it on (wet clay won't take water out) and the surface area to volume ratio to a lesser degree.
Concrete isn't damaged by being wet, so don't worry about trapping water in it. The only reason you need to dry out out fully is if you're laying a floor on top of it with no DPM. If you don't put a DPM under it, there's a good chance water will stay in there anyway depending on the ground.

cheers,
I will have a full DPM just below the inner floor final screen, DPM's other places too, there's no clay present here just mud