Fix Timber to Concrete Fence Post

[superdon]

After a bit of advice. I need to fix some 4x2 to the flat edge of a concrete fence post. It'll be about 6 foot or so long. This is on two posts to create something I can attach a gate to. I'll brace across the top.

I've read all about the issues with drilling concrete posts, and looked at alternatives (like the postfix brackets) but can't seem to find a way that will be reliable so think drilling is the only way forward?

Now, what fixings should I use. Was looking at through bolts. How about wall bolts? Or coach bolts all the way through?

I was thinking of three fixings per post. I don't mind spending money on the fixings if they will be reliable.

Any help would be great.

 

[johnny2007]

Stainless steel coach bolts.

 

[superdon]

Stainless steel coach bolts.

Thanks. The downside with these is having to drill all the way through I guess, which is why I had looked at the other options.

Do you think 2 of these per post (top, middle, bottom) will be ok or better with 3?

What size would you suggest and any idea where I can get then. I would think I am looking at 180mm long?

 

[johnny2007]

3 is best.
Length depends on the post and timber thickness.
Go for M10 bolts.

 

[superdon]

Thanks again. Posts are 4 inch and timber is 2 inch.

Can you point me to a supplier of these, struggling to find them

 

[superdon]

Can find some exterior grade ones, rather than stainless. https://www.screwfix.com/p/timco-in...cXIPjd4l78gEznjLDXzlmBLgyZqeaD3YaAqIAEALw_wcB

These be good enough?

 

[johnny2007]

Can find some exterior grade ones, rather than stainless. https://www.screwfix.com/p/timco-in...cXIPjd4l78gEznjLDXzlmBLgyZqeaD3YaAqIAEALw_wcB

These be good enough?

Can't see the link, but the green ones are equally good for exterior.
You need 7 inch + to go through post and timber, unless you want to recess the timber with a 19mm cutter and have the nut inside the wood.
In that case you would need 6 inch.

 

[superdon]

Thanks - yes they are the green exterior. I'll have a look for the right size as the ones I linked to were 200mm and would need to be cut.

Next query. I have my own mains combi drill and can borrow a SDS drill. Which shall I use and what drill bit will get me through the post with least grief!

 

[johnny2007]

Sds, definitely.
However, it's a gamble to use hammer action in those posts as they can crack.
Have you got a core bit?
You can buy a cheap one from screwfix/Toolstation.
A bosch employee 20 years ago gave me a set of 3 drill bits designed to go through anything without hammer action.
They work perfectly, but i never seen them in any shop.

 

[johnny2007]

I think this is the newer version.
Search screwfix website

BOSCH STRAIGHT SHANK MULTIPURPOSE DRILL BIT 10 X 250MM

 

[superdon]

I've found that multipurpose bit.

I don't have a core bit.

Happy to buy whichever is best....

 

[superdon]

And just before I do buy the stuff...can I confirm I am not missing an easier solution.

Heres a pic of the fence posts. There is an old gates that has just been leaning in the gap for 10+ years. Time to sort it!

The gate shown is 900mm wide (seems to be standard. Gap between the posts is approx 915 or 920mm. I think the posts have been put too close together? There are no holes manufactured into the posts.

Any thoughts?

 

[superdon]

 

[johnny2007]

Did a similar job before the lockdown.
I built the gate myself, but the opening was 900mm.
Make sure you take into consideration the rebate in the posts where the support timber will go.
Those posts crack if you try to use hammer action.
Get that bosch drill bit, slide it out often so to get rid of debris whilst drilling and arm yourself with a small sprayer so to use some water to avoid overheating.
My drill bits went through in no time.
Good thing is that the concrete in these posts have little aggregates, so are much softer than the council 1950's.

 

[superdon]

Thanks mate. So I will stick with my first idea, with your suggestion of coach bolts, SDS drill (not hammer), and that Bosch bit.

When you say take into account the rebate, what did you mean?

And that's lead me to remember I somehow need to fit some timber to act as a rebate. Any ideas?

Just to confirm.everything, here's a bad sketch of the plan...