Attaching a wood bearer to a metal post at an angle

[WA_decker]

Hi there,

I have had a patio built recently out of steel. It has 90 x 90 metal posts. I am using these to attach the bearers of the deck I am going to be building underneath. I am not sure what would be the best way to attach the wood bearer to the metal posts when they are at an angle.

When they are at 90 degrees I will be using joist hangers for each end of the bearers. But for a specialised angle I am thinking of either Option A or B in terms of attaching these to the posts(see attached pic). Not sure what type of screws would be best if I did go with Option A.

Option B seems like a lot more work but allows me to use a joist hanger for the bearer which could be more supportive in terms of load rather than two screws like in Option A.

Any thoughts on this one?

Thanks for any opinions...

[SilentButDeadly]

Pryda's Split Joist Hangers will be your friend http://www.pryda.com.au/catalog.php?sectionid=20&type=Hangers%20and%20Truss%20Boots&conn=JHS (http://www.pryda.com.au/catalog.php?sectionid=20&type=Hangers%20and%20Truss%20Boots&conn=JHS) if you can find them!!

Failing that...I'd be welding some plates on the post and bolting the bearers up to them.

Because neither option a nor (especially) option be are going to be very good solutions. Although option a could be improved using an L bracket under the bearer.

[pawnhead]

Another type here if you don't need to go in the corner:
http://www.pryda.com.au/catalog.php?sectionid=20&type=Hangers%20and%20Truss%20Boots&conn=LFSL (http://www.pryda.com.au/catalog.php?sectionid=20&type=Hangers%20and%20Truss%20Boots&conn=LFSL)

Why don't you just cut a vee out of the bottom of a standard hangar? You could easily bend the flanges.

[Dirty Doogie]

Put a blob of concrete around the steel post and sit bearer end on it.

In most cases the strength of the 90 x 90 steel columns they use for pergola roofs are not sufficient to carry floor loads as well. Just a guess but it is probably only 2 mm wall.

ring the pergola people to check.

[silentC]

In most cases the strength of the 90 x 90 steel columns they use for pergola roofs are not sufficient to carry floor loads as well. Just a guess but it is probably only 2 mm wall.
I hope that's not true because part of my house, and all of my neighbour's house, are resting on 90x90x2mm Duragal piers!

[Dirty Doogie]

HI silent,

But do the piers extend up to hold a roof ?? I'd be a bit concerned about 2 mm steel trying to hold a load fixed to the side - but maybe I worry too much LOL

I still think a blob of concrete under the end of the bearer is easiest!

[brynk]

gday WA_decker

here is an option if you can obtain some angle & aren't inclined to weld even though you'll need to do a bit of cutting...

90x90x6 EA cut as shown with the backspan the full width of the column & then bolted x 3 to the post - be sure to go through the entire column & onto the other side and use good-sized washers. this will spread the load from the angle onto both walls of the column.

the screw into the underside of the bearer would need to be at least 50 from the end of the bearer to avoid splitting, and the hole in the angle should be slightly larger that the screw's shaft, to allow for a bit of movement.

scuse my dodgy paint markup - now, how do i attach a file...

[silentC]

But do the piers extend up to hold a roof ??
Well, as a matter of fact they do. I have Duragal posts which hold up the verandah floors and roofs all the way around the house.

[pawnhead]

HI silent,

But do the piers extend up to hold a roof ?? I'd be a bit concerned about 2 mm steel trying to hold a load fixed to the side - but maybe I worry too much LOL

I still think a blob of concrete under the end of the bearer is easiest!Unipiers (http://www.bluescopesteel.com.au/index.cfm?objectid=AFF127E6-09E5-11D4-89F100C04FCF6B8F) are only 65x65x2 or 75x75x2.5 and they can be designed to carry floor and roof loads. The separate adjustable capping piece is fixed into the sides just using tek screws, the number being dependent on the load.
There's a pdf with specs there that you can download.

[Dirty Doogie]

Hi john - looks like I do worry too much LOL!

[Dirty Doogie]

Well I was still worried about fixing a side load on 2 mm wall shs - this is why -

a little while ago I was working on a building site and sat on a 3.5 metre length of 90mm x 2mm shs lying between 2 sawhorses to eat my lunch. (I didnt know it was thin wall shs at the time)

One of the guys yells out "dont sit on that!!! You F@#$head!"

My weight (about 100kgs) had deflected the shs about 15 mm over 3.5 metre length. I was amazed. The steel guy ran around swearing and denigrating me and the shs .

This morning I was doing some work prac on a site ( I'm doing the work prac as part getting a Builders liscence) so I asked the architect about side load fixing on thin wall shs.

He pulled out an engineering manual ( by Lysart ) showing the connection required.

Assuming the existing shs is the correct size and grade for the new load --
The side load has to be transfered to 2 parallel walls of the SHS using a bracket and a back plate on the other side of the shs. The combined bolthole diameters have to be a max 30% of the width of the face being fixed to, but 6 mm max dia tek screws recommended (????). Although in this case you would have to use bolts to transfer the load.

So the design suggested by BynK seems to be the right direction with the addition of a small piece of plate on the back face of the column.

You learn stuff everyday

I still think it is easier for WA to simply put another little concrete pad under the end of the bearer/joist though.

Doog

[silentC]

The Duragal flooring system includes a verandah sleeve, which slides over the 90x90. It's about 4mm thick and has two welded lugs top and bottom to take a 150mm bearer. There's also a version with four lugs for 90 degree junctions. These are what you use to fix side loads for verandah or split-level floors. Otherwise, the bearer sits directly on top and there is an assortment of brackets to attach them, including the screw-up adjustable one.

At the top of the post, you notch out the post to take the 150mm beam and either weld or bolt - but the weight in that case is directly on top of the post, rather than hanging off the side.

Interestingly, the bearers are also 2mm - 150x50. They are very strong on edge but bow easily on the flat as you would expect.

If this was a Duragal job, there is a 45 degree plate that is designed for fixing hip joists that could be used for this. For timber, I don't know. I reckon I'd be inclined to do the whole thing with steel - birdmouth the bearer and weld it to the post.

[Dirty Doogie]

I'm just checking out all the uni pier and steel flooring design charts - I was considering using a steel floor for my next project - a Warwick cottage renovation due to start when I sell this place.

The number of design warnings is a bit perturbing - dont use steel subfloor with treated pine decking - dont let copper touch it, set tek screws in one action etc etc.

Silent - I can't find any of those specialist brackets on the Bluescope site yet - but it seems they are designed to do the transfer of load to parrallel sides of the post. Such highly engineered stuff! Did you mention that your subfloor is made from it? if so - are there any problems??

Doog

[silentC]

Here's what you need: http://www.onesteel.com/productspecs.asp?specID=3087

I've got one section of sub floor held up with it because it was too high for brick piers. Bearers and joists are all Hyspan LVL. The verandahs and decks are all framed with Duragal. The guy up the hill from me has the whole subfloor made from Duragal, including bearers and joists. No problems thus far. We welded ours but the guy up the hill has tek screwed everything according to the Onesteel guidelines.

One thing that you need to be aware of, they don't recommend Duragal within a couple of kms of the coast, so if you're on the beach, it's no good for you.

[Dirty Doogie]

Thanx silent - I was looking at the wrong steelmaker lol!

[brynk]

Here's what you need: http://www.onesteel.com/productspecs.asp?specID=3087

I've got one section of sub floor held up with it because it was too high for brick piers. Bearers and joists are all Hyspan LVL. The verandahs and decks are all framed with Duragal. The guy up the hill from me has the whole subfloor made from Duragal, including bearers and joists. No problems thus far. We welded ours but the guy up the hill has tek screwed everything according to the Onesteel guidelines.

One thing that you need to be aware of, they don't recommend Duragal within a couple of kms of the coast, so if you're on the beach, it's no good for you.


a gem - added to my collection, thanks! the only prob is if the the deck was existing, which might pose a difficulty getting the sleeve over the post in one piece. spose you could just cut it in half anyway.

yes the backplate Doog mentions is definately better than individual washers. if you used the same 90x90 ea you could use a piece of the angle cut in half.

[silentC]

the only prob is if the the deck was existing
I've got that exact situation right now. I've decided to add a deck and one of the posts is already in place holding up the verandah roof, so I'm planning to slit a sleeve up the middle and weld it back together around the post.

[Dirty Doogie]

Hi silent,

wouldn't you be a bit worried about the heat from welding damaging the zincalume/gal coating on the column?

Doog

[silentC]

There's a Duragal welding guide on the OneSteel site too. It's just a matter of setting things up right, using the right electrode and watching the heat. We also paint on some cold gal over the weld and surrounding area. We used a stick welder last time but my BIL is bringing his MIG this time.

Edit: But I see what you're getting at in this case. We'll run a bead around the top and bottom of the sleeve as well, so the outside face of the column will be sealed up. Any heat damage to the zinc will be inside. Even if you're just tek screwing, they still recommend a sealant at all joins to exclude moisture.

[WA_decker]

Silent C, congrats on the 10K posts. I went through the whole metal subsurface thoughts and came to the conclusion that is was extremely expensive. You can send a plan through to bluescope for the same type that One Steel do and they give you a ballpark estimate. For a 72sqm deck it was around $7000 just for the substructure!!!! But I have guestimated structural H3 MGP10 pine at around $2000 for the same deal.
I found termites about 6 months ago about 1 metre from the house where my deck is going. Hence I am extremely worried about termites. (As doogie has commented about in earlier posts). The whole concept of attaching piers, bearers and joists looks very appealing to me from the onesteel brochure that you may have been referring to above
http://www.onesteel.com/images/db_images/productspecs/DFS%20Brochure.pdf
when looking at the Verandah Sleeves. Do you happen to know if prices are as outlandish in the One Steel area?
Some posts are good and bad...after deciding that I couldn't have a steel deck and started down the path of wood, you have just re-fired the dream...so Silent C is steel outa this world compared to the price of wood and using stirrups onto bearers or have I hugely miscalculated costs here and steel could be an option...?

[silentC]

It's definitely more expensive than say treated pine or F7 hardwood, as you already know. It's a bit more expensive than LVL, but you wouldn't be using that for a deck anyway.

I bought the steel for a 2x2 deck last week and it cost $470 for the joists and bearers. It only comes in 8 metre lengths. I already had the posts and the sleeves left over from the last job.

I haven't got current prices for anything else because it's a couple of years now since I bought it all. I bought all the stuff for a 16sq.m deck late last year and it cost about $1,500.

When I built the house, I saved quite a bit, more than 50%, by buying seconds. Seconds are usually where the coating is a bit rough or it has some damage. Because a lot of mine is not seen or will be painted, I got away with it. You can also get the non-internally painted stuff quite a bit cheaper, but I wouldn't recommend that unless you are going to weld on end caps.

I think there are basically two indications for using steel: termites and bush fire danger. I think if you start looking at fire-treated timber it can get quite expensive (although I didn't quote it). It's also quite easy to work with. If you're not going to weld it, you don't really need any special tools - just a screw gun, caulking gun and an angle grinder or cut-off saw. I bought a GMC cut-off saw for about $90.

I find it easier to work with than hardwood, which was probably my only other alternative. It doesn't bow or twist. The wind up pillar connections make it dead easy to level but they are pricey and once you've levelled it, they're useless.

Best thing I can recommend is that you use the flooring guide I linked to earlier to work out what you need and then ring OneSteel and see what price they can give you. Ask about the seconds, it makes a huge difference on a big job.