Front garden excavation for drive

[RandAbuild]

I don't think anyone can advise you without more information regarding the depth of the foundations to your house. It might be 3 feet but could easily be 10 feet, leaving you insufficient space for parking.

 

I would echo what others have said - you need to get a structural engineer to design it for you.

[Margaret dailey]

if that really is the case, then ill have to abandon the whole thing.

 

i was trying to understand the procedure of using the imaginary line to work out how far we can go back but im still having trouble understanding how to do that

[Ferdinand]

I would start off by a conversation with your Council - drop Building Control an email to ask what the requirements are for your proposal. They should be happy to engage, and may even visit depending on whether we are all still under house arrest.

 

They need to know the level change, and the other dimensions.

 

Personally I think that a vertical retaining wall is perhaps not the best, as the house will exert a significant horizontal force - a sloping wall may be less expensive and I think there should be space to fit it in.

 

Ferdinand

 

Edited April 26, 2020 by Ferdinand

[Margaret dailey]

i think the reason i am having difficulty in understanding the 45 degrees rule is i think because the drawings illustrate the level of the land needed to be dug out is straight not slopped but if you look at the pcis of the front of house, you can see the current level is sloped. so dont know if that clears anything up

[ProDave]

Can we have some basic measurements, the length measured horizontally from your front wall to  the boundary (hold the tape measure up at the boundary end to get it level)

 

And the height from the pavement level  to the existing ground level at the house. Again while you have your tape measure held horizontal for that first measurement, use a second tape measure to measure what height you have to hold it above the pavement to get it horizontal.

 

Then @Onoff can re work his drawing to the actual scale.

 

It would then give an idea of what height retaining wall you are likely to be looking at and whether it is viable or not.

 

All the pictures give the impression of a very steep slope to your garden at present.

[Margaret dailey]

ok  ill go measure up. thanks all and speak to you soon. just need to wait for neighbour to help me out as im not as agile as i once was.  lol

[Declan52]

The 45 degree explanation is the safe option. So dig down at the front of your house frontage and keep going till you hit concrete. Will take an HR or 2 but then you will know the depth the concrete is at. Once you know that then you can make a judgement call on the rest. If the concrete is deep enough and you won't be within the 45 degree line then great. Otherwise your risking the front of the house sliding and that's not where you want to be. Thats where a SE will earn their money. Keeping your house where it's meant to be.

Have you considered a slight slope as in maybe up to 25/30 degrees to park on. Will mean not as much soil needs removed and should get you closer to the front before you cross that 45 degree line.

But the important bit to find out is the depth of your house concrete. So don't remove anymore soil until this is found and then it's a decision on of you can proceed safely or not without involving a SE.

[ProDave]

I did some work a couple of years on a bungalow on a slope like that. The whole front garden had started to slide down and come away from the house. It turned out the foundations were not that deep so there was a lot of work involved, underpinning the foundations, and then building a new retaining wall a few feet in front of the house to stop the same happening again.

 

It is this situation we are trying to avoid you accidentally creating.

[Margaret dailey]

Declan52,

 

thanks for your advise,

 

im not stable on my feet so i cant have any slope at all. so it needs to be flat ground which i park on.

 

in regards to digging at the front of the house, once we reach the concrete, how will we know if the concrete is deep enough?

[Margaret dailey]

ProDave, yes exactly that, lol

 

can you recall how much distance between the front of the house and the retaining wall you put in.

 

[ProDave]

4 minutes ago, Margaret dailey said:

ProDave, yes exactly that, lol

 

can you recall how much distance between the front of the house and the retaining wall you put in.

 

It wasn't me that put the wall in, I am an electrician, I merely observed what else was happening while I did my bit.

 

The wall was about 6 feet tall, and probably 4 or 5 feet in front of the house.  It was built of concrete blocks laid flat and 2 blocks deep so quite substantial with buttress sections as well on part of it that got re buried in the front garden and at the two ends it turned in towards the house.  If I had predicted it would have been of interest to anyone I would have photographed it.

 

In this case I think the retaining wall was built so they had something solid so they could re fill the gap between the house wall and the retaining wall with solid infill laid in layers compacting as they went.

[scottishjohn]

2 hours ago, Margaret dailey said:

thankyou all for your advise and help...

 

if i can answer some questions,

 

a disabled parking spot is not an option outside so im not considering that at all.

 

in respect of a surveyor i do not have the funds to be able to afford that. 

 

i have a neighbour who has very kindly offered his help to dig out the soil for me for a small amount. so the digging cost is not an issue. 

 

and as for a u shaped wall, my brother is going to build that for me with blocks as he done this before in his own house.   so hopefully costs wont be too much.

 

it was a little bit soil but now its mostly clay and a little bit sand.

 

in respect of my neighbours, they have just moved in but have now said they want to do the same, they have a little space in front which u cant see in the picture where they park their small clio sideways and then a retaining wall painted green and covered in bushes which you can just about see in picture but not a lot of space for the car to park so they want to dig back also now,

 

im just loking for advise  in regards how much soil/land needs to be left.  i can get all of it dug out, thats not an issue, its just we dont know how far back we can go without it being a risk 

 

so if someone can roughly just say how much in feet we should retain, and then put in the concrete wall right across, that would be helpful.

 

i am of the opinion that we should leave at least 3 ft from bay wall, then put in block wall and then that should leave about 20 ft to the boundary

you may find big concrete lego blocks is the cheapest way to make a solid retaining wall of the height required

have you worked out how high it will be if you go back to where you suggest.-doubt a single block wall will be heavy enough to do the job

the big blocks at 1.3ton each will hold that back fine I would think 

[Declan52]

18 minutes ago, Margaret dailey said:

Declan52,

 

thanks for your advise,

 

im not stable on my feet so i cant have any slope at all. so it needs to be flat ground which i park on.

 

in regards to digging at the front of the house, once we reach the concrete, how will we know if the concrete is deep enough?

You will have a measurement of X cm to your concrete. Then it's a bit of maths  to work out a Y cm of the 45 degree angle and where it will come into contact with your flat driveway. You will already know the difference in height from your path at the front of the house and the path on the road. So you will subtract X from this measurement to give you Z. 

But the most crucial thing to find out is this concrete depth. Everything rests on this.

See how much a difference this makes on this pic. You want it as deep as possible.

[Margaret dailey]

You say buttress sections, can you explain please what that means.

 

And what did you mean the two ends turned in?

 

Our plan was to turn out away from house to make a u shape.

[scottishjohn]

If you get the neighbour on board at this time  you will save the need for a dividing wall between you 

and one simple straight retaing wall with onlyone ned for you to build 

 foundation for the lego blocks -tilt them back 5 degrees -one row -job done if you use 600mm x 1800 x 600mm ones

https://www.eliteprecast.co.uk/interlocking-precast-concrete-blocks/legato-interlocking-concrete-blocks/

this site evn has all the cls you need --but maybe buy cheaper ones from other suppliers

[Margaret dailey]

The pallet i have already bought are 440mm, 240mm, 100mm

 

Which are just standard concrete blocks 

 

Ive also got 10 wider ones.

 

Will these not do the job?

[scottishjohn]

out of interest what is your budget

[epsilonGreedy]

1 hour ago, Margaret dailey said:

if that really is the case, then ill have to abandon the whole thing.

 

 

One of your later photos shows an already sharp incline from pavement upto the base of your house, so you need to move ahead cautiously. You say you cannot afford a SE so I assume you cannot afford the £50k plus costs of structural fixes to your house and also the neighbours if both houses start to slip & crack a little towards the new carport hole.

[ProDave]

1 hour ago, Margaret dailey said:

The pallet i have already bought are 440mm, 240mm, 100mm

 

Which are just standard concrete blocks 

 

Ive also got 10 wider ones.

 

Will these not do the job?

You are going to need a LOT more than one pallet of blocks to build your wall.

[HerbJ]

2 hours ago, RandAbuild said:

I don't think anyone can advise you without more information regarding the depth of the foundations to your house. It might be 3 feet but could easily be 10 feet, leaving you insufficient space for parking.

 

I would echo what others have said - you need to get a structural engineer to design it for you.

 

1 hour ago, Ferdinand said:

I would start off by a conversation with your Council - drop Building Control an email to ask what the requirements are for your proposal. They should be happy to engage, and may even visit depending on whether we are all still under house arrest.

 

They need to know the level change, and the other dimensions.

 

1 hour ago, Declan52 said:

So don't remove anymore soil until this is found and then it's a decision on of you can proceed safely or not without involving a SE.

 

Forgive me if this seems rather blunt and harsh but it needs to be said.

 

You must stop and listen to the advice you are being given above and seek professional assistance starting with an experienced structural engineer.   The consequence of continuing without a complete understanding of your house foundations and the slope are likely to be catastrophic. As as described by @ProDave below- it may lead to failure of the current house foundations and the collapse of the front of both your and your neighbour's houses, leading to a far larger cost than the original retaining wall.  Your building insurance company may not respond to such damage if it caused by your own negligence in NOT take seeking professional advice. 

 

Lots of nice people on BH are trying to give you some guidance on how to proceed to plan the work and get some idea of cost and what is possible but none of this advice can be relied on to undertake the work - none of them have seen the job site, nobody has carried out any site Investigation works and they are certainly not structural engineers, qualified to undertake a full design of the works to ensure structural integrity of the retaining wall and ensure structural integrity of the existing house

 

1 hour ago, ProDave said:

I did some work a couple of years on a bungalow on a slope like that. The whole front garden had started to slide down and come away from the house. It turned out the foundations were not that deep so there was a lot of work involved, underpinning the foundations, and then building a new retaining wall a few feet in front of the house to stop the same happening again.

 

You CANNOT AFFORD THE CONSEQUENCES OF NOT taking professional advice!!!  

 

 

 

[Jeremy Harris]

I'll add emphasis to the above.  Retaining walls are very serious structures, we had to build a big one when we built our house.  Any retaining wall that is more than 1.2 metres high MUST be designed by a structural engineer, or use an approved retaining wall product that has been assessed as being suitable for use in those circumstances.  I'd also add that a critical factor will be the surcharge load imposed by the mass of the house - you cannot assume that the "45° rule" will be acceptable without knowing the exact nature of your soil, the surcharge load from the mass of the house and the nature of the house foundations.  The latter could be pretty much anything, from almost no foundations (building on corbelled bricks was fairly common in older houses) to a deep trench foundation. 

 

The consequences of continuing to dig that bank away without understanding all the above could easily be very serious indeed, especially if we get a period of heavy rain.

 

As an idea of what a proper block retaining wall, that has zero surcharge load (only supports a garden above, not the very much greater mass of a house) looks like, these are photos of ours.  It's built from 215mm wide hollow blocks, double thickness at the base, with steel reinforcement bars running through the hollows, which are embedded in RC35 concrete.  This wall is 430mm thick at the base, and sits on a foundation that is 500mm thick reinforced concrete, between 1.5 metres and 2 metres wide:

 

 

 

 

 

 

 

[Margaret dailey]

Hi thanks all for advice.

 

Budget wise is only a few hundreds for parts.

 

All labour is free as my neighbours and brother in law is helping me.

 

I respect your advice on here and if its the case i need a se then ill have to give up and stop everything. And leave the front as it now.

 

Prodave, i have taken the measurements you have asked for.

 

So from the top at the bay window, to the bottom at the boundary line, ensuring it stays high and level and straight,  the distance was 29ft

 

As for how high, i used a rope, tied to bottom of wall at bay window and ran down straight and tied it to the lamppost adjacent to front of house and then used a spirit level to check rope was straight and then messaged from rope down to footpath at boundary.   On one side it was 9ft high and the other was 7.4ft high.  And thats because of slope of fooftpath.

 

So 29th length from bay wall to boundary 

 

And max height is 9ft.

 

 

[Margaret dailey]

[Margaret dailey]

If you look at last 2 pics you can see the blue rope going from bay window wall across to lampost. Kept tight to give a straight line and then measurement taken down which was 9ft.

[Jeremy Harris]

6 minutes ago, Margaret dailey said:

And max height is 9ft.

 

 

That is going to be a very substantial retaining wall that's needed, it's very close in height to our 2.5 metre maximum height wall, so you can expect the design of a vertical block wall to be very similar to the one shown in the photos I posted earlier, I think.

 

Very definitely not a DIY job at all, unless you have the skill and experience to design and build reinforced concrete structures to Eurocode standards