Shuttering for concrete

[lord_seagrave]

Hi chaps,

I feel slightly out of my depth here, so I’m hoping you can help.

These fence posts are attached to the single skin brick wall with three big coach bolts. The corner posts have an extra bolt at 90 degrees. The wall’s about 3’ high, the posts are 10’.

I think I would like to cast concrete around the bottom of the posts. The wall is sturdy, but once the trellis is attached to the tops of the posts, the whole thing is going to be quite top-heavy.

 

So, a couple of questions - how deep do I surround them with concrete OR should I make a foundation out of concrete and then brick round the posts?

What should I make the shuttering/form out of, and how sturdy does it need to be?

Do I need to line the shuttering with anything?

How long do I leave it on?

In terms of making the concrete - 1part cement to 4 parts ballast, yes? Do I need to worry about anything?

Sorry for all the noddy questions, but this is far beyond my usual playing-in-the-garden.

LS

[Lord v]

How high are you back filling? Or is the level going to be left like that?

[Rim Fire]

Use ply for shuttering as for depth is it going to an eye sore or don't it matter and your mix when you say ballast will it be sand and chips mixed if so 4to1 is ok more than enough 

[lord_seagrave]

About two bricks’ worth. You can see the salty line where the ground was. 

I could definitely make it higher, though. The ground is MK clay, and so it needs a load of something digging in.

 

LS

1 minute ago, Rim Fire said:

Use ply for shuttering as for depth is it going to an eye sore or don't it matter and your mix when you say ballast will it be sand and chips mixed if so 4to1 is ok more than enough 

What thickness of ply, do you reckon? Can I get away with 3mm? I don’t want to spend more than I have to, but I also don’t want to waste my time if it’s not going to be strong enough.

LS

[Lord v]

150 - 200mm of concrete really isn't going to do much - the rotational load will still be transferred to the bolts before the concrete ever does anything. Plus only 75mm of your post will be in the concrete.

Are the bolts resinned in?

 

 

[CharlieT]

Support for the panels will be provided by the stakes, not the wall. Wind is your main consideration. As a rule of thumb, a third of the stake should be in the ground, I would use a minimum of a foot of concrete. 

[Mice!]

if you use ply for your shuttering have a look for a wood reclamation yard, we have one in Preston. You can buy sheets of used ply for a lot cheaper than normal.

[Munzy]

Personally I would take the posts off and sink them into the ground surrounded by concrete/postfix.

Once you have the trellis on and covered in climbers a strong gust of wind will take that wall down in an instant with a nice clean break along the mortar line just below your lowest bolt. Don’t forget, mortar doesn’t glue bricks together, it’s job is to keep them apart.

[Lord v]

15 minutes ago, Munzy said:

Personally I would take the posts off and sink them into the ground surrounded by concrete/postfix.

 

Wot that man said.

 

[Yellow Bear]

Other option is to buttress the wall with brick or concrete  piers, say 500 out at bottom to nothing at top of wall at about 300 wide.

[haynes]

How about concrete repair posts dug in and concreted at the base of each post then coach screwed to the wooden post. Nice easy fix no shuttering needed and they won't go rotten.  Or they could also be used as buttress' to the wall. Again dug in half there depth and concreted and resin anchored to the wall. There steel reinforced to boot. 

[scotslad]

Another for wot munzy said, complete waste of time putting any concrete round  those posts.

 

U would be better starting again from scratch or stick a 2nd post in beside the ones already there.

 

How windy is the area?

Usually for a 6ft solid timber fence we'd be putting in 4x4 posts 8'6" or 9ft long, u'd probably get away with 3" posts, u could still put an extra bolt in the wall to

[Winston72]

1 hour ago, Munzy said:

Personally I would take the posts off and sink them into the ground surrounded by concrete/postfix.

Once you have the trellis on and covered in climbers a strong gust of wind will take that wall down in an instant with a nice clean break along the mortar line just below your lowest bolt. Don’t forget, mortar doesn’t glue bricks together, it’s job is to keep them apart.

+1 or your gonna be rebuilding hat single skin wall the next time a hedgehog farts on it

[lord_seagrave]

Thanks guys - glad I checked in before going any further.

The wall’s own foundations precluded digging the posts in, but I think I can get a post in the ground in front of them.

If not, is there any merit in building brick pillars around the posts to the height of the wall (I can ‘tie’ the new brickwork to the existing wall, yes?)

Thanks again for all the input. It’s a sheltered spot, but I don’t want to take any risks.

 

LS

[Munzy]

9 minutes ago, lord_seagrave said:

Thanks guys - glad I checked in before going any further.

The wall’s own foundations precluded digging the posts in, but I think I can get a post in the ground in front of them.

If not, is there any merit in building brick pillars around the posts to the height of the wall (I can ‘tie’ the new brickwork to the existing wall, yes?)

Thanks again for all the input. It’s a sheltered spot, but I don’t want to take any risks.

 

LS

I wondered if the footing for the wall is the reason you didn’t sink the posts in the first place.

Sinking posts in front of the existing ones (thus avoiding the footing) and bolting through the new and old posts sounds like the cheapest and strongest solution to me.

[Yellow Bear]

1 hour ago, Munzy said:

Sinking posts in front of the existing ones (thus avoiding the footing) and bolting through the new and old posts sounds like the cheapest and strongest solution to me.

AS Haynes said earlier "concrete repair posts dug in and concreted at the base of each post then coach screwed to the wooden post.  no risk of rot that way

[Munzy]

1 hour ago, Yellow Bear said:

AS Haynes said earlier "concrete repair posts dug in and concreted at the base of each post then coach screwed to the wooden post.  no risk of rot that way

[scotslad]

Wot do u call a concrete repair post??

Never heard of anything called that before, possibly call it something different thou.

Have to admit very rarely use conrete posts (apart from for security fencing) for timber fencing, never like the look of them.

[Yellow Bear]

8 hours ago, scotslad said:

Wot do u call a concrete repair post??

Sometimes referred to as a concrete spur - about a meter long (most of which is buried)  with holes to bolt to post.

[amateur]

16 hours ago, haynes said:

How about concrete repair posts dug in and concreted at the base of each post then coach screwed to the wooden post. Nice easy fix no shuttering needed and they won't go rotten.  Or they could also be used as buttress' to the wall. Again dug in half there depth and concreted and resin anchored to the wall. There steel reinforced to boot. 

That's what I did when one of our perimeter fence-posts snapped in a gale (well, it was all but rotted through).

This would take far less time and materials

[lord_seagrave]

Concrete spurs duly purchased, ready to be concreted in and joined to the posts.

LS

[scotslad]

13 hours ago, Yellow Bear said:

Sometimes referred to as a concrete spur - about a meter long (most of which is buried)  with holes to bolt to post.

Don't think i've ever seen or even heard of them. Seen the metal spiky things u fix a post too but there rubbish.

Every day's a school day, away to search for them now!

 

Ps LS u will prob have the same problem again with the founds, i'd just break it away, hard work pinching it, but a SDS drill/breaker wouldn't take that long to get throu it