Dave's Balcony

[ProDave]

The ones I was looking at are described as "A2 304 Stainless Steel"  I am sure I have been told Stainless is more brittle?

 

Thanks for your link @Onoff, but at £16 per screw, no thanks.

[PeterW]

39 minutes ago, ProDave said:

The ones I was looking at are described as "A2 304 Stainless Steel"  I am sure I have been told Stainless is more brittle?

 

Thanks for your link @Onoff, but at £16 per screw, no thanks.

4 is £5 per screw - they do this to stop people buying one or two and they are a good supplier. If you email them what you want (in total) they will give you a price for the lot as you’ll also need coach bolts etc for uprights to frame etc 

 

edited to add its £46.18 for 8 inc VAT and £3.50 delivery to the darkest Highlands …

[joe90]

3 hours ago, joe90 said:

my thoughts are that that’s a lot of leverage over the distance.

Yes I get it’s not cantilevered but perhaps “bending” is a better word fir what I mean!. Two people stood on the deck next to the wall 🤔. M12 sounds much better, can you get the coach bolts long enough for what you want? Or Get M12 threaded stainless rod welded to the coachbolt 🤷‍♂️.

 

edit, I am OCD and tend to over engineer stuff 😎

Edited September 5, 2022 by joe90

[Onoff]

46 minutes ago, ProDave said:

The ones I was looking at are described as "A2 304 Stainless Steel"  I am sure I have been told Stainless is more brittle?

 

It is more brittle, less ductile maybe a better term but fine for what you're doing. (I have seen A2/304 used by the seaside and peppered with holes like a Swiss cheese).

 

A2 = 304 as A4 = 316 just denotes the corrosion resistance. Amount of chromium or something.

 

Even if strength grade 70 as opposed to 80 you're good to go with it.

 

Fyi. 3 bolts, 2 on the left are galvanised. First one is grade 4.6, low tensile strength. Second is grade 8.8  generally considered the start of high tensile fixings (you then get 10.9, 12.9 etc). Can be tricky to galvanise or zinc plate 10.9 and above as you risk hydrogen embrittlement. Other finishes are available like cad plating, sheradising etc. Its why car bolts are generally "black".

 

If a fixing has no strength grade treat as the lowest. We discard them tbh.

 

On the right then is an A2 70 bolt, so the lowest corrosion grade and lowest strength. You could just as easily get an A4 80.

 

 

[ProDave]

So where I am at, I can get galvanised M12 250mm coach screws at a sensible price but they only have 5 in stock, awaiting an idea of when they may get more They are described as to DIN 517 specification.  Or Stainless steel M12 250mm coach bolts at a LOT more than the galvanised ones.  Stainless and Aluminium spacers is not a good match, though a good dose of Duralac solves that issue on boats.

[PeterW]

Why not just use 20mm galvanised thick wall conduit and spray the ends with galv spray ..?

[ProDave]

That's the screws ordered.  By widening the search, I found someone with M12 by 240mm mild steel plated in stock at a sensible price and acceptable delivery cost, so they got my order.

[ProDave]

I have most of what I need to start building this.  All the screws, spacers, joist hangers and the timber.

 

I settled on 150mm square Larch posts from the local saw mill.

 

The one remaining bit of hardware I need to source is the post feet to support the bottom of the two 150mm square posts.

 

I have in mind a simple U made of 150mm wide stainless or galvanised steel.  The bottom of the U will bolt to the ground supports in place and the posts will sit inside the U not all the way to the bottom so it does not touch the ground and be bolted through with 2 long bolts, probably M12 threaded rod and nuts on both ends.

 

Simple question, can you buy such post feet as an off the shelf item, or is it time to approach one of the local fabricators?

[markc]

Def local fabricator then get them galvanised, or you could use stainless of course

[ProDave]

5 minutes ago, markc said:

Def local fabricator then get them galvanised, or you could use stainless of course

That's what I am thinking.  I have found a few that look inadequate to me, some examples:

 

 

 

 

[markc]

We used to use a similar design to this for steel and timber connection. Look really good and not difficult to fabricate.

[joe90]

Cost. Fabrication vs bought 🤷‍♂️

[SteamyTea]

1 hour ago, ProDave said:

I have found a few that look inadequate to me, some examples

I think our @Ed Davies,  your neighbour (ish), had some made up locally.

Edited September 18, 2022 by SteamyTea

[Iceverge]

 

I used these for my garage. 

 

Quite robust. would recommend. 

Edited September 18, 2022 by Iceverge

[Onoff]

Concealed ones maybe?

 

https://www.fencepostspikes.net/PUW90?

[ProDave]

I did consider the concealed ones but that just gives me the engineering challenge of cutting a nice neat straight slot in the bottom of each post.

[Triassic]

As a balcony is a building Control thing, has anyone used second hand timber to build one and what did BC say?

 

 

[Onoff]

1 hour ago, Triassic said:

As a balcony is a building Control thing, has anyone used second hand timber to build one and what did BC say?

 

 

 

Time for some C24 stencils methinks... 😉

[Onoff]

On 18/09/2022 at 12:35, ProDave said:

I did consider the concealed ones but that just gives me the engineering challenge of cutting a nice neat straight slot in the bottom of each post.

 

Run a router up the centre each side as deep as the bit will go, then use as a guide to handsaw the middle. 

[markc]

1 hour ago, Triassic said:

As a balcony is a building Control thing, has anyone used second hand timber to build one and what did BC say?

 

 

If you upped the section sizes by 50% then you would be pretty safe with BC for reclaimed or non marked timber but then you have to look at the aesthetics, cost of bigger timbers and additional loads so often costs much more to use reclaimed. I used to build some pretty big roof trusses and the mention of reclaimed pretty much doubled the price.

[JohnMo]

A bit of a brain dump

 

The structural design of our decking, (part of my structural design certificate) with a big fall in some areas (7m drop), has 4x M16 bolts/stubs at 8.8 strength rating at each metal to wood interface.  All wood is C24 with external preservative treatment.  External framing is 220x45 all doubled up.  All joists are on hangers.  Long joists are 220x45 C24 and the shorter ones 170x45 C24.

 

Balastrade design ratings depend on how far you can fall. But is all rated at 0.75 (forget the units) on ours.

 

 

[ProDave]

16 minutes ago, Onoff said:

 

Run a router up the centre each side as deep as the bit will go, then use as a guide to handsaw the middle. 

But the hand sawn bit is wider than a single cut but too narrow for two close by single cuts.  Tried stuff like that before without much luck.

[markc]

2 minutes ago, ProDave said:

But the hand sawn bit is wider than a single cut but too narrow for two close by single cuts.  Tried stuff like that before without much luck.

Put 2 hand saws together, bolt through hanging hole at the tip and a clamp near the handles to pull blades together, odd to use but does the job

[Iceverge]

I used a circular saw and cut from both sides to max depth. It required 2 x parallel cuts from both sides.  

 

Then I carefully used a chainsaw to finish the cuts. Not joinery quality but good enough for a shed. Macrocarpa does cut nicely however.  

 

 

[Simplysimon]

On 18/09/2022 at 12:35, ProDave said:

challenge of cutting a nice neat straight slot in the bottom of each post.

i would use a chop saw but would never advise someone else to do so 😉