Jump to content

Front garden excavation for drive


Recommended Posts

I've heard of instances where councils have fined people for being parked on the parking space they have created in front of their house because they have driven across the pavement where there is no approved dropped kerb.

  • Like 1
Link to comment
Share on other sites

Also a neighbour just told me i would need a 12ft wall with 3ft buried as foundation. 

 

He said he didnt think the ground infront is supporting the houses and in fact the houses have deep foundation and therefore we can go back as far as we want but then the retaining wall has to be thick and strong.

 

He advised a 12ft wall with 3ft buried, so 9ft wall.

 

As for the actual wall, double blocks, laid flat as opposed to stacked, and then concrete filled between the wall and ground behind. 

 

At least 8 pipes for drainage. 

 

Link to comment
Share on other sites

So 9ft high at the house, even if you only dig 20ft into the bank, that's a 6ft retaining wall you need.  You really are not just going to build that with a pallet of ordinary blocks with no professional input, at least not if you want it (and your house) to stay standing.

 

I think the best you can hope for on your budget is like your neigbour, a short parking bay to park parallel to the road. You might need to buy a shorter car and practice your parallel parking to get it in there.

Link to comment
Share on other sites

12 hours ago, Margaret dailey said:

Also a neighbour just told me i would need a 12ft wall with 3ft buried as foundation. 

 

He said he didnt think the ground infront is supporting the houses and in fact the houses have deep foundation and therefore we can go back as far as we want but then the retaining wall has to be thick and strong.

 

He advised a 12ft wall with 3ft buried, so 9ft wall.

 

As for the actual wall, double blocks, laid flat as opposed to stacked, and then concrete filled between the wall and ground behind. 

 

At least 8 pipes for drainage. 

 

 

 

Absolutely not, there is no way a wall like that would comply with the requirements, and it could easily (almost certainly, I think) invalidate your house insurance.  You cannot build a retaining wall that is higher than 1.2 metres (just under 4ft) without it being designed and certified by a structural engineer.  The foundation structure alone for a vertical retaining wall that is that high will require sufficient horizontal foundations to withstand the overturning moment from the imposed loads, together with an anti-slip key projecting below the foundation slab.

 

Our structural engineered charged us £350 to design our retaining wall, including drawings and a full specification.  Our wall (as in the photo's posted earlier) varies from around 1.4 metres at the lower end to 2.6 metres at the highest end, so at it's highest it is very similar in height to the one you need.  This is the SEs design for our wall, it might give you an idea of what is needed:

 

20130228093748130.pdf

 

20717.pdf

 

I'd just add that I've had a fair bit of flack from some professionals here, and elsewhere, for suggesting that people do more stuff themselves, and avoid using professionals if they are able to.  In the case of a retaining wall, despite being able to design one, there is absolutely no way I would, the risk is just far too great if it fails.

  • Like 3
  • Thanks 1
Link to comment
Share on other sites

15 minutes ago, Margaret dailey said:

Also a neighbour just told me i would need a 12ft wall with 3ft buried as foundation. 

 

He said he didnt think the ground infront is supporting the houses and in fact the houses have deep foundation and therefore we can go back as far as we want but then the retaining wall has to be thick and strong.

 

He advised a 12ft wall with 3ft buried, so 9ft wall.

 

As for the actual wall, double blocks, laid flat as opposed to stacked, and then concrete filled between the wall and ground behind. 

 

At least 8 pipes for drainage. 

 

The most important words in that post"he didn't think". No body knows or well ever know unless find out how deep the concrete founds of the house are. That is the big unknown on this. 

Look at it this way.

Best case scenario is you dig out the soil and end up with a 9ft wall which will need to be maybe over 1m wide at the bottom and then reducing in thickness as it gets higher ending up 225mm at the top. Cost wise considering it will need plastered will be fairly expensive. You will have the cost to dispose of all that soil,concrete for the base, at least 1200mm wide, a lot of blocks, concrete copings for the top, sand and cement for mortar, cost to lay them then plaster to finish them . This won't be a cheap job. Your going to be into many thousands.

Worst case. The concrete founds of your house are to shallow and  you dig out to much and the front of your house ends up on the street.

 

Link to comment
Share on other sites

29 minutes ago, Declan52 said:

and the front of your house ends up on the street.


along with part of next door with no house insurance?. Like @Jeremy Harris and others on here I like DIYing whatever I can BUT  this is something only professionals can advise you on.

Link to comment
Share on other sites

I dont thing that story related to me.

 

I do have a builder who will come a build the wall. I suspect everyone is assuming i was going to try myself.

 

He has already said it will be around 9ft high with 3 ft buried for foundation and has said he has been building extentions for a long time. 

 

I suspect the way im going to go is carry on digging but instead leaving 4 ft between retaining wall and bay wall, ill leave 5ft. Double block the wall, with columns each side. And then a wall of concrete between wall and soil

Link to comment
Share on other sites

2 minutes ago, Margaret dailey said:

I dont thing that story related to me.

 

 

It COULD if you dig to within 4ft of the bay window and 9ft down, without knowing how deep the foundations are.   If the ground starts to give way under the house, that is EXACTLY what will happen.

 

Link to comment
Share on other sites

7 minutes ago, Margaret dailey said:

I suspect the way im going to go is carry on digging but instead leaving 4 ft between retaining wall and bay wall, ill leave 5ft. Double block the wall, with columns each side. And then a wall of concrete between wall and soil

if you intned to do this then it will definately be cheaper to use these concrete lego blocks ---dig it out make foundation for them then just drop them in --done in a day with a telhandler

Iam not saying you should not get an SE -- ytou should but look at the website I copied you and see how quick and easy and sue the calculation section

but no way you will do this job for a few hundred quid --

get your builder to quote for number of blocks +cement +then concrete required 

It will be alot more than the blocks for sure

cheapest Iahve seen 600mm x600mm x1500mm blocks is £70 each

Edited by scottishjohn
Link to comment
Share on other sites

8 minutes ago, Margaret dailey said:

I dont thing that story related to me.

 

I do have a builder who will come a build the wall. I suspect everyone is assuming i was going to try myself.

 

He has already said it will be around 9ft high with 3 ft buried for foundation and has said he has been building extentions for a long time. 

 

I suspect the way im going to go is carry on digging but instead leaving 4 ft between retaining wall and bay wall, ill leave 5ft. Double block the wall, with columns each side. And then a wall of concrete between wall and soil

 

 

If you're using a builder, please check very carefully that he has a structural engineer available to underwrite the design, as you may need to prove to your insurance company that the retaining wall has been designed and certified in accordance with Eurocode 7/BS 8002.  Our retaining wall is a similar size, and our insurers (both of them) needed confirmation of this (although neither asked us for it, the requirement was buried in their terms and conditions).   Bear in mind that it's mandatory to have the design and construction done professionally if the wall is over 1.2 metres (just under 4 ft), I believe, or if the retaining wall has any surcharge (which yours does, the mass of the house on the retained ground).

 

It's not difficult to design a wall like this, and an SE won't charge a great deal.  Our Se charged us just £350, which considering that the retaining wall cost over £30,000 to build in total, wasn't a lot to pay for peace of mind and ease of getting house insurance.

Link to comment
Share on other sites

Just now, Margaret dailey said:

These concrete lego blocks, where can i get these and how many will i need. 

 

The wall will be approx 16ft across.

just google concrete lego blocks 

Isent you link to the market leader -which also has a calcultion function to work out how big blocks you need

Link to comment
Share on other sites

6 minutes ago, Margaret dailey said:

These concrete lego blocks, where can i get these and how many will i need. 

 

The wall will be approx 16ft across.

 

 

There are several systems of interlocking blocks.  I looked at using Stepoc, but there are others: https://www.andertonconcrete.co.uk/range/structural/

 

All MUST have a suitable foundation base, plus drainage, and for a retaining wall with a high surcharge you MUST ensure that there is temporary shoring in place to support the house foundations, as you will need to dig a fair bit further back into the bank in order to allow for the width of the base of the wall, plus the batter angle.  Most of the interlocking block companies will include the cost of the structural design and certification in the price for the blocks, or at least the two or three I spoke to would.  The only reason we didn't use  one of these systems was because of the thickness of the wall at the base, they do take up a lot more room than a vertical retaining wall.

Link to comment
Share on other sites

1 minute ago, Margaret dailey said:

And rough how much for those 25 blocks.  From what i have read, most of the options i cant follow due to budget,  but I feel this option is best for me and wont blow my budget.

 

Im just building wall at the moment and will worry about rendering and etc later

 

 

You can't easily render a "lego" block type wall, as it will be stepped back at the batter angle.  The blocks interlock and lean back to provide the required retaining capacity, and when ordering them you MUST inform the company of the high surcharge load imposed by the house, as that will have a great deal of bearing on the design they provide.

Link to comment
Share on other sites

sorry but this has disaster written all over it  for all the reasons others have given 

make sure your builder has insurance and you get fixed price 

 But iwouls still do it with blocks so simple and it is used world wide for tyhis very job

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...