Forum: Site Works
Topic: Query re laying concrete blocks?
started by: Forestboy1978

Posted by Forestboy1978 on 09 Mar. 2017,19:32
Hi guys,

Basically a wall fell down and I quoted to put a 6ft panel fence in its place.

They wanted 2  course concrete block base and panels on top. Concrete is to hold in soil.

So anyway I've started the job and put in most of the posts without the panels so I can lay the courses tomorrow and let them go off before slotting in the panels.

Issue is this.. the concrete foundation was terrible. Great for me cos I anticpated 3 hours a hole and it's only been 1 hour per hole but crap for the new blocks. The foundation is stepped on the hills as you'd expect but it's not level.

I was thinking of either of these things

1- Make a bedding of 3:1 mortar and make it as thick as needed to keep the bottom course level

or 2 - Cut blocks and the right angles to accomodate the unlevel foundation.

I think I prefer option 2 as I don't want to be having to make 2 difference mortar mixes simultaneously. I.e 3:1 for bedding the bottom course and 4:1 for every where else. Might get tricky.

Also in area where the foundation doesn't step down in line with my panels I have the odd 8 inch step down to the next part of wall foundation that I need to make levels up. Same question really. Cut a block or fill with mortar? It's only 2 courses so it's not a house or anything but it still needs to be strong.

Ta guys

Posted by rxbren on 09 Mar. 2017,19:49
Would have been better off using concrete posts and concrete gravel boards instead of the 2 courses of block
Thick layer of mortar not ideal
If the concrete foundation is terrible what's to stop it being the cause of your block wall failing

Posted by Forestboy1978 on 09 Mar. 2017,21:00
Concrete gravel boards aren't strong enough for this. It's clay. It'll pop them no trouble whatsoever.

Well, that's my issue re the concrete foundation. I do think it has settled to it's final destination now though but yeah. I mean the wall was there for 30 years before it fell apart also. I'm just wondering what's best to get the area level for the bottom course.

I'll put some photos up tomorrow but by then I'll have started laying the blocks.

Posted by jwill on 09 Mar. 2017,21:27
Blocks on flat or 2 course high 4" thick?
Posted by Forestboy1978 on 09 Mar. 2017,21:52
Quote (jwill @ 09 Mar. 2017,20:27)
Blocks on flat or 2 course high 4" thick?

They're not going flat.

8.5 inch height 4 inch depth 16 inch length.

Posted by seanandruby on 09 Mar. 2017,22:28
You can't be serious about a thick bed?  Maybe you could scabble and level the base with grano, or drill rebar in lacers and place a shutter then concrete a mini wall. Or as you say: cut blocks to suit, or break out and start again.
Posted by Forestboy1978 on 09 Mar. 2017,22:46
Quote (seanandruby @ 09 Mar. 2017,21:28)
You can't be serious about a thick bed?  Maybe you could scabble and level the base with grano, or drill rebar in lacers and place a shutter then concrete a mini wall. Or as you say: cut blocks to suit.

I was serious. We are talking about creating a bed that increases from about 1 cm to about 3 inches over the span of 2 meters to hold  2 courses concrete blocks. I mean 3:1 would be almost or as strong as the concrete blocks themselves surely so what would be the harm.

Or maybe just laying a dry concrete bed underneath the areas where the foundation has sunk. Laying the first course with a bit of SBR to aid stick. Let it go off for a bit and come back and lay the second course as normal?

Posted by lemoncurd1702 on 10 Mar. 2017,07:55
If the foundation has sunk then the foundation is F****d. Stop twatting about and lay a new one, by the time you fart around trying to level the existing one which sounds unsuitable, you'd have had it done anyway.
Posted by Forestboy1978 on 10 Mar. 2017,08:53
Sure cos I factored in excavating and re laying a concrete foundation into my fence quote.....
Posted by seanandruby on 10 Mar. 2017,09:04
Don't think you'll get amyone advising you on a thick mortar bed, it's not the done thing, 10 ml, 15 ml tops, bedding joint etc: yours will be a major bodge and this site is called paving expert after all  :;):   :)
Posted by Forestboy1978 on 10 Mar. 2017,19:08
OK, no thick mortar bed. Got it!

Haven't got round to doing the blocks yet but have all posts in. Bear in mind the courses will be broken with the posts and then the ends of each course will be mortared into the groove in the post for slotting the panels in.

So what I've decided to do is lay a flat concrete bed to lay the blocks onto. It is only 3 panels that need this as the rest of the foundations are level. I'll have to cut and break out some conrete at the high pount to allow me to get a suitable depth of concrete to shutter in.

Any issues with this I'm all ears?

Posted by Forestboy1978 on 10 Mar. 2017,19:09
Quote (lemoncurd1702 @ 10 Mar. 2017,06:55)
If the foundation has sunk then the foundation is F****d. Stop twatting about and lay a new one, by the time you fart around trying to level the existing one which sounds unsuitable, you'd have had it done anyway.

Sorry mate. Was in a massive piss this morning when I replied.

Ta for input.

Posted by jwill on 10 Mar. 2017,22:00
So is a 4" block wall with mortared perps stronger than a conc gravel board with regards to retaining?
Posted by seanandruby on 10 Mar. 2017,22:40
... Maybe the client wants it.
Posted by lemoncurd1702 on 10 Mar. 2017,22:46
Quote (Forestboy1978 @ 10 Mar. 2017,18:09)
Quote (lemoncurd1702 @ 10 Mar. 2017,06:55)
If the foundation has sunk then the foundation is F****d. Stop twatting about and lay a new one, by the time you fart around trying to level the existing one which sounds unsuitable, you'd have had it done anyway.

Sorry mate. Was in a massive piss this morning when I replied.

Ta for input.

No worries, I know what it's like, we've all been there.
Posted by lutonlagerlout on 10 Mar. 2017,23:55
I would rather use a 300mm concrete gravel board and back it up with haunched concrete
sounds like a pig of a job, proper job would be a  a new foundation but as said not priced for
am I missing something  but isnt it the golden rule of fencing never to erect all the posts without the panels in? if slotted posts are used?
cheers LLL :)

Posted by rxbren on 11 Mar. 2017,09:36
I always do all fences by setting first post or wall plate, dig next hole, fit panel/gravel board/arris rails to previous set post and new post then level and set new post and carry on so
Posted by Forestboy1978 on 11 Mar. 2017,09:44
Quote (lutonlagerlout @ 10 Mar. 2017,22:55)
I would rather use a 300mm concrete gravel board and back it up with haunched concrete
sounds like a pig of a job, proper job would be a  a new foundation but as said not priced for
am I missing something  but isnt it the golden rule of fencing never to erect all the posts without the panels in? if slotted posts are used?
cheers LLL :)

Not really. If you want to work in the wind for example, or delivery on panels has been screwed up  you can put the posts in they just have to be spot on.
Posted by Forestboy1978 on 11 Mar. 2017,10:01
Here's an example of a fence that was done that way as the panels were the wrong size on delivery so we had to get on with it.

< https://www.dropbox.com/sh....ia?dl=0 >

Posted by seanandruby on 11 Mar. 2017,10:38
I use 2 lengths of batten with noggins at the right distance for spacing, sometimes had to be done as Forest says.
Posted by dig dug dan on 11 Mar. 2017,17:14
Quote (lutonlagerlout @ 10 Mar. 2017,22:55)
I would rather use a 300mm concrete gravel board and back it up with haunched concrete
sounds like a pig of a job, proper job would be a  a new foundation but as said not priced for
am I missing something  but isnt it the golden rule of fencing never to erect all the posts without the panels in? if slotted posts are used?
cheers LLL :)

Correct. Its a pain slotting them in afterwards, especially more so kn your own, however inhave designed a tool for doing it with ease :)
Posted by Forestboy1978 on 11 Mar. 2017,21:41
Quote (seanandruby @ 10 Mar. 2017,21:40)
... Maybe the client wants it.

Precisely, it's what the client specifically requested. But yeah it would be a damn sight stronger than concrete gravel boards which are weak as piss and not really designed for terracing land at all.

I would have gone for what Tony recommended myself but they wanted what they wanted.

Posted by digerjones on 11 Mar. 2017,22:13
Quote (dig dug dan @ 11 Mar. 2017,16:14)
Quote (lutonlagerlout @ 10 Mar. 2017,22:55)
I would rather use a 300mm concrete gravel board and back it up with haunched concrete
sounds like a pig of a job, proper job would be a  a new foundation but as said not priced for
am I missing something  but isnt it the golden rule of fencing never to erect all the posts without the panels in? if slotted posts are used?
cheers LLL :)

Correct. Its a pain slotting them in afterwards, especially more so kn your own, however inhave designed a tool for doing it with ease :)

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