concrete block wall

[blocky71]

Hi all, at the bottom of my garden i have a 7ft drop onto about another 20 ft square of land. The wall holding back the garden is just a single skin brick wall thats well past its heyday. Its bowing and has some cracks also. Its not got any worse in the 3 years i`ve had property but i intend to build a shed on the plot so want to sort out wall first. My intention is to build a new wall in front of the old one from concrete 9x17 inch blocks laid on there side. It will be about 20 feet long and 6 to 7 feet tall. Will this be ok? as i`m not sure how stable the earth is behind original wall so am wary of removing old brickwork. The foundations are soft too so no chance of building a new wall on the old foundation. Also would like to know suggested footing depth and width for this new wall and should it have reinforcing piers constructed in wall? if so at what points? If you havent fallen asleep yet reading this i appreciate your time. Please also see pics. Any constructive advice would be great, any "smart alec" comments also welcome. I need something to make me laugh about this project! //www.diynot.com/network/blocky71/albums/

 

[noseall]

That is some serious slab of wall.

I would be considering a 900mm wide foundation down to good earth and minimum 450mm thick.

I would then build a 440mm thick wall using 100mm dense concrete blocks laid end on (to achieve the thickness). The thickness may be halved higher up.

I would then skin the blocks in a decorative brick.

I have not a clue if the above advice is adequate or overkill, so i would seek advice from an S.E.

You may be able to build this in front of the existing but that will leave the existing wall extremely vulnerable once you dig the new foundation trench. It may require shoring.

 

[Shytalkz]

A couple of possibles:

Build some buttress walls at intervals, let the old wall span between them. Strengthen the old wall by cutting in Helibar every third joint.

Install some steel posts at intervals cast into bases and bolted to the wall, with channels horizontally spanning between the posts. Not a particularly pretty option.

 

[blocky71]

Hi and thanks for replies, i like the idea of laying the blocks end on at least for bottom of wall, i hadn`t thought about that and i feel it maybe overkill but i dont wanna be repeating this in 10 years when i`m into my pipe and slippers!. The wall/reinforcing when built will be hidden by a shed hopefully so aesthetically i`m not to concerned. I had the same concerns about digging out the footings and weakening whats already there. I think maybe i`ll incorporate both ideas, shawing up whats already in place then building new wall?. I have about half the blocks needed already reclaimed from another part of the garden so ideally i`d like to use them as its free and saves trying to store or get rid of. Back to ebay now on the hunt for a 2nd hand mixer. If your near kent and have one for sale get in touch. Thanks again, look forward to any more comments

 

[r896neo]

There is no chance that the single brick wall you see is in fact that.

Its probably constructed more like what noseall suggested and the top 1 oot or so is the facing single brick skin. Have you dug down a bit from the higher area to see what's there?

 

[blocky71]

On further investigation it is as you rightly said r896neo a double skin ( i knocked out a loose brick and found another skin behind) the skin behind is in worse condition from what i could see!. I`m not sure if this changes anything except if i was to demolish i`d end up with double the rubble!. I think unless any one points out reasons not to i`m going to go ahead with shawing up old wall, digging new foundations and building the block wall in front. If i do this would it be better to leave the gap between new and old wall (approx 6-8 inches) unfilled or would back filling it with concrete be a good idea?. I`m unsure whether it would make the wall stronger or would it just put more stress on new wall? thanks again for advice

 

[noseall]

You are better off back-filling the space betwixt walls, but use something preamble like loose rubble or pea gravel, particularly low down.

 

[r896neo]

It's probably fair to guess there is some sort of land drain behind there, are there weep holes in the existing wall or do you know of any drainage?

.........forget all that dumbass here only just noticed the link to your album.

I'd go for nosealls option but if doing so you obviously need to take the drainage into consideration.