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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Building Questions >> retaining wall https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1097860810 Message started by yozman on Oct 15^th, 2004, 6:20pm

Title: retaining wall
Post by yozman on Oct 15^th, 2004, 6:20pm

building garage extension onto house i have a raised garden to the side where i intend to extend. the height is about 1 metre i will be going all the way to the boundary
which meets the pavement. i would like to go all the way
to the boundary line to get 3 metres width for my extension what is the best way to do this ie do i need to build retaining wall and then my garage wall seperately
or is there a way i can use my new garage wall to retain the pavement.

Title: Re: retaining wall
Post by Robbo on Oct 15^th, 2004, 7:08pm

Dont see a problem with building up to your boundary limits, though would you have any problems with others being in such close proximity, am thinking of vandals and graffiti artists.

Title: Re: retaining wall
Post by yozman on Oct 15^th, 2004, 8:48pm

no problem i live in a cul de sac very quiet

Title: Re: retaining wall
Post by splinter on Oct 15^th, 2004, 10:56pm

Just wondering if you might be getting involved with building regs here .1)doe's your'e property including the garage have to be a certain distance from the public highway(if it's a new build) 2)as the garage is 1 metre below the pavement level you might have to construct a concrete retaining wall ,which for you're own benifit at least wants to be water proof.Like I said just wondering :)

Title: Re: retaining wall
Post by yozman on Oct 16^th, 2004, 12:59pm

had plans passed no problems regarding retaining wall
that is my question can i use my new garage wall to retain
or will i have to build a seperate one ???

Title: Re: retaining wall
Post by Robbo on Oct 16^th, 2004, 4:34pm

as long as it is constructed in the manner of a retaining wall as opposed to a regular4" two skinned cavity wall
I build with clinker blocks... one laid �on flat with one laid on the four inch next to it..... then a further block laid flat on the one allready laid, so now two flats and one regular are at the same height.
Then alternate this by laying your blocks flat on the other side and regular alongside this. Or in other words upright block to the inside on first course then to the outside on second course and so on and so forth.
This gives you a 12" solid wall retainer, above ground you can revert back to brick/block cavity. Tanking the wall below ground will prevent any ingress of moisture. A call to planning will clear up any issues , we can only advise we dont implement the legislation.

Regards

Robbo.

Title: Re: retaining wall
Post by yozman on Oct 16^th, 2004, 4:52pm

thanks robbo good advice could you explain tanking i have a rough idea about it but not clear on matter my understanding is that it is like dpc but laid down the wall
and tied into brickwork but how deep below bottom course
and how far above ground level and what about drainage holes do i need them or not

Title: Re: retaining wall
Post by Robbo on Oct 16^th, 2004, 5:04pm

Its really just to stop any water ingress and being as it is only a garage and not a habbitable room then you will not need to go to the lengths you would as in the basement of a house.
A simple bitumen painted on type of membrane would surfice try the range of products available from "sika" they semm to have a product for any circumstances... would get good advice on sika products from your local merchants if you find nothing on the web . I assume they have a web site as they are a big company.

Title: Re: retaining wall
Post by Kesh on Oct 17^th, 2004, 12:03am

I had a customer a while back, whose garage was acting as a retaining wall for the road.

He had a surveyor check the situation out, & the result was that the local authority had responsibility for retaining the highway, & they came & built a secondary wall inside his garage for this purpose.

Just thinking you may be able to get the structural work done for you!

In this case the road surface was about 8 feet above the garage floor, & it took a bit of negotiating, but the authority accepted responsibility in the end.

Title: Re: retaining wall
Post by JerryD on Oct 17^th, 2004, 12:25pm

My garage is built as a retaining wall, it retains 7 feet at the rear and from 7 feet down to 4 feet down one side, (We live on the side of a hill)

We built these two walls from 9" hollow concrete blocks, threaded over 25mm h/t bars cast into the foundation concrete. The hollows in the blocks were filled as work progressed with strong, wet concrete (5:1) which totally encased the reinforcing bars.

This was the approved method, designed by a structural engineer, no guesswork involved!

HOWEVER................ due to wet weather during construction, the earth bank started to collapse slightly and started filling the 'gap' between the rear of this wall and the bank (about 600mm gap), so we couldn't tank the rear of this wall as we had intended. (no access for excavator now) so we gave up on the idea. We finally fully backfilled hard against the blockwork and thought no more about it.

About 10 years later we started getting water through the rear wall due to hydrostatic pressure of surface water behind the wall. Only in a couple of spots but it was annoying to get puddles in the (otherwise dry) garage.

In the end I had to tank the interior in the same way you'd tank a basement, the materials cost nearly �1,000 (yes, one thousand pounds!) but it did stop the leaks. (the garage is 12 metres wide and 7 metres deep)

So what would have been a hundred quids worth of 'blackjack' turned out to be an expensive job.

So, in answer to your question, yes you can use the garage wall as the retaining wall, but the retaining wall has to be able to take the loading put on it. I would definately 'blackjack' the back of the wall before backfilling but by the sound of it, you may not have room to do this if you are building right up to the boundary??