Construction in Cornwall

Stand pipe, Snack wagon and disciplinary stocks are now in place...

 

 

Okay, I have to ask. What makes that a "retaining wall?

 

I would have expected at least block on flat, if not two layers filled with rebar and concrete.

 

you appear to just have a single skin wall.

 

I am sure there is more to it, it just doesn't make sense -  yet.
 

17 minutes ago, ProDave said:

Okay, I have to ask. What makes that a "retaining wall?

 

I would have expected at least block on flat, if not two layers filled with rebar and concrete.

 

you appear to just have a single skin wall.

 

I am sure there is more to it, it just doesn't make sense -  yet.
 

 

1st skin, steels already set in to the concrete, second skin will be built in front in approx 6 course batches then concrete between the skins, along with additional reinforcing mesh in the "cavity". The external side of this wall will be tanked, as will the internal wall of of the second skin. 

 

Once all all that is complete a standard cavity wall will be built inside this lot to form the structure of the house. So this whole wall will end up with 4 "skins"

 

By all accounts apparently this wall is majorly over specified and could probably retain a mountain when it's complete. 

Yes that makes sense now. Look forward to seeing it take shape.
 

Quote

 

 

Looking great - some real progress being made - looking forward to seeing this one go up.

These photos probably best show the full structure of the retaining wall, 5 courses complete on the inner skin now, ready to be filled with concrete tomorrow. Then another 5 courses next week and repeat...

I'm sorry to say this but please be careful! We did a similar construction and it went wrong. The photos have disappeared off eBuild.

 

Posted 03 January 2015 - 10:42 PM

wmacleod, on 03 January 2015 - 10:10 PM, said:

In light of http://www.ebuild.co...-object-lesson/

!!!!!!!!!!!!!!

Ah well, never mind, I was only warning you because I know that horrible feeling when you get a bang followed by the sounds of a couple of tons of concrete raining down, I think most folk who have worked with concrete above 4ft have heard it at one time or another! It is very disheartening to lift it all into the mixer, place it, and then clear it out of the way again before it sets. Pokers are necessary to do the job right and get the concrete properly compacted around the rebar but they do have to be treated with respect. Makita do a 4ft battery operated one which is ideal if you can do lower lifts, just the right power and controllability. These things happen, don't let it get you down, a few days off does the world of good. Did you end up getting readymix in the end, surely you didn't manage to get it mixed and placed that quick?!

I aimed to fill up a 30 m retaining wall (225mm cavity) about 1.2 m up all in one go - That was going to take 8 m3... a full wagon load. Smart thinking... I'll get the 8 m3 as ready mix and save money on a full load.

Then after getting about 2 m3 in... POP - I did tell the wagon driver to slow down and move to a different shoot but my Dad said no we will get more in here and let it level its way out.

BIG MISTAKE

In reality, no matter how we filled it up on the day it would have popped open probably. Fortunately I managed to get another 2 m3 - 3 m3 in the rest of the wall and get it nicely evenly leveled out to just about level with the DPC skirt (DANGER POINT). This was partly due to the gutsy approach of the wagon driver and him aiming it from his wagon without a wooden shoot into some areas of the wall with military accuracy - WHAT A GUY!

Enough was enough and I lost my bottle and told the driver to dump the rest at the top of the site.

After firstly finishing what was in the wall and carefully compacting it with the poker to a good standard I turned to salvaging blocks from the slurry of concrete which laced the blow out area. I was really tired at this point it was about 7 PM and pitch black. I just threw them into a pile and focused on scooping away the concrete and dumping it a few feet away in a low spot that needed building up with hardcore anyway.

Now we got to about 8:30 PM, I'm tired, cold and dripping wet with sweat - It froze really hard that night and was getting very cold!

A quick drive to the local chippy and co-op and I get back with extra large chips, steak pie, sticky toffee pudding, and a bottle of wine which I stash in the microwave for later.

Back onto clearing up the blocks and cleaning them off.

As soon as that's done back to the top of the site... and the dumped concrete greats me - see the photo.

I raked this out to the best of my ability but now I'm really, really tired and it's time to call it a night before I injure myself!

Grab my food and hit the sheets... no logs in my log burner in the caravan tonight... our chainsaw had broken.

FORTUNATELY it froze very hard that night and when I tackled the 'not planned' hard standing at 6 AM it's still workable and I can level it out. I clean off the blocks more, stack them nice and tidy and travel back home for a week break...

Now we get to this stage and I post on here for advice - http://www.ebuild.co...632#entry103632

When I say "Annoyingly I need to mix about 4m3 of C35 grade concrete on site... Ready mix is not an option, trust me if I could do that I would!"

It's due to the previous events. I managed to rebuild the wall and get the 4 m3 shortfall placed by mixing it all in my 90ltr mixer. Mixing it all on my own and shooting it down the slope using a large un-perforated twin wall drain pipe - It worked very well and the concrete I mixed seems very, very strong and to a good standard. All solid as a rock now and I've enjoyed my Christmas break but eager to get back up there and carry on.

Attached Files

I think I know where your pictures have disappeared to... in the dictionary next to "having a mare!" Hopefully the only similarities we have are the steak pie and chips tomorrow evening! I'm well aware of the risks though, but it's the builders call on this one. 

I hope it all went to plan! Which waterproofing membranes are you using?

Edited October 2, 2016 by iSelfBuild

1 hour ago, iSelfBuild said:

I hope it all went to plan! Which waterproofing membranes are you using?

 

Concrete in to about 3 courses, everyone has accepted this will be a slower process to avoid issues such as you experienced, I think a couple more concrete loads over next week then hopefully finishing the pour early next week. 

 

Tabking is RIW double drain on the outside face and RIW flexiseal on the inside. That's what the structural engineer spec'd however speaking to my builder last week he said that the tanking supplier is looking at designing and specifying a different system, we shall see what they come up with and make a decision. 

On 9/27/2016 at 20:33, Grosey said:

 

1st skin, steels already set in to the concrete, second skin will be built in front in approx 6 course batches then concrete between the skins, along with additional reinforcing mesh in the "cavity". The external side of this wall will be tanked, as will the internal wall of of the second skin. 

 

Once all all that is complete a standard cavity wall will be built inside this lot to form the structure of the house. So this whole wall will end up with 4 "skins"

 

By all accounts apparently this wall is majorly over specified and could probably retain a mountain when it's complete. 

How did you come to the decision to use this wall structure, it looks like it will take a lot of room? 

 

No Doubt it would do the job but would ProDave's solution not provide just as strong but thinner alternative, perhaps with wall ties added for lateral support.

5 hours ago, Gimp said:

How did you come to the decision to use this wall structure, it looks like it will take a lot of room? 

 

No Doubt it would do the job but would ProDave's solution not provide just as strong but thinner alternative, perhaps with wall ties added for lateral support.

 

 

Structural engineers design, I purchased the plot with detailed planning permission so wasn't involved at that stage. However from what I've been told this is a fairly standard level of construction to obtain building regs nowadays. Even if it does appear to be OTT. 

 

Updated pic pic as of today BTW -

 

Also concrete being shovelled in by hand - the lads earned their brew after this lot!

 

 

48 minutes ago, Grosey said:

 

 

Structural engineers design, I purchased the plot with detailed planning permission so wasn't involved at that stage. However from what I've been told this is a fairly standard level of construction to obtain building regs nowadays. Even if it does appear to be OTT. 

 

Updated pic pic as of today BTW -

 

Also concrete being shovelled in by hand - the lads earned their brew after this lot!

 

 

Ah, I see still surprises me that they would do it like that as it looks like you will end up with massively thick walls and of course the real wide foundations which must be a bit with the concrete. The shovelling in surprises me also, I would have thought it more usual to build to the top first then concrete mixer pour into it all in one continuous form without split. Not that it is likely to be a problem necessarily with a wall that thick and I guess it looks like you have the space there for thick walls but I still wonder if the method is best practice. Would be interesting to see what Pro Dave thinks of this or another engineer perhaps. 

You couldn't pour concrete into that wall if it was built both skins to the top as it would burst out. The wall would need to be 225mm wide min with extra thick piers built in every 4-5m. 

What are the guys using to ensure the concrete is fully filling the gap, a vibrating poker or a long stick???

20 minutes ago, Declan52 said:

You couldn't pour concrete into that wall if it was built both skins to the top as it would burst out. The wall would need to be 225mm wide min with extra thick piers built in every 4-5m. 

What are the guys using to ensure the concrete is fully filling the gap, a vibrating poker or a long stick???

 

Vibrating poker, first experience of one of those today - Crikey that's a powerful vibrator!!!

If you think the wall is thick now there's still the standard cavity wall to go inside this one which forms the structure of the house!

15 hours ago, Declan52 said:

You couldn't pour concrete into that wall if it was built both skins to the top as it would burst out. The wall would need to be 225mm wide min with extra thick piers built in every 4-5m. 

What are the guys using to ensure the concrete is fully filling the gap, a vibrating poker or a long stick???

Would be surprised if it would burst out with the walls having a few days to set. I know this is often the pitfall of ICF blocks which is part of what puts me off them, but a can't see why a wall with set joints would act like that.

The pressure of the wet concrete would cause the bottom row to move out. It's only held in place my the weight of the wall and friction. Have seen many a retaining wall burst out that where thicker than that. 

Guess the vibrator is only so long also 

Wall fully up, 2 more pours next week on Monday and Tuesday to fill it. The logistics of this caused a bit of headscratching as to how to get the concrete up and in that wall - the plan seems now to be a bucket on a telehandler, 2 blocks sat straddling the wall with shovels scraping out of the bucket and in to the wall - or if the drivers good pour it straight in. We shall see. 

 

Then to tank and backfill behind, then I'll finally stop the civil engineering and get on with building a house

 

 

2 hours ago, Grosey said:

Wall fully up, 2 more pours next week on Monday and Tuesday to fill it. The logistics of this caused a bit of headscratching as to how to get the concrete up and in that wall - the plan seems now to be a bucket on a telehandler, 2 blocks sat straddling the wall with shovels scraping out of the bucket and in to the wall - or if the drivers good pour it straight in. We shall see. 

 

Then to tank and backfill behind, then I'll finally stop the civil engineering and get on with building a house

 

 

 

Just out of interest, how tall is the wall going to be per storey? 

 

 

21 minutes ago, Gimp said:

Just out of interest, how tall is the wall going to be per storey? 

 

Not sure if I fully understand the question, but this is the completed height for the retaining wall. This ground floor is all garage/workshop and finished garage floor to finished 1st floor is 3m

11 hours ago, Grosey said:

 

 

 

Not sure if I fully understand the question, but this is the completed height for the retaining wall. This ground floor is all garage/workshop and finished garage floor to finished 1st floor is 3m

Just wondered as I am looking to go quite high on the garage to first floor of my own build I am planning, but looking up the Part A Building regs it looks like they only allow a max permitted 2.7 Meters finished floor to bottom on ceiling height per storey on multi-storey dwellings. This is a pain for me as I would like to go slightly higher to take maximum advantage of the view and siting.

10 hours ago, Gimp said:

Just wondered as I am looking to go quite high on the garage to first floor off my own build I am planning but looking up the Part A Building regs it looks like they only allow a max permitted 2.7 Meters finished floor to bottom on ceiling height per storey on multi-storey dwellings. This is a pain for me as I would like to go slightly higher to take maximum advantage of the view and siting.

 

Ah wasn't aware of the building regs but I expect that is where my 3m floor to floor came from. By the time block and beam first floor is in I expect my garage floor slab to garage ceiling will be no more than 2.7m.