fix sliding door header directly to steels?

[Tom]

Hi all, latest one waking me at 4.30AM: do we fix our sliding door headers directly to the cantilever steels - or do we fix eg some ply to the steels then fix to this? Or possibly some thermal break material (armatherm or similar) to the steel instead of wood? Slider's are these: https://www.cortizo.com/en/sistemas/ver/93/cor-vision-plus-sliding.html

Below is the detail from the architects, so looks like wood or similar between the header and steel, would be good to hear what the consensus is.

door header detail.pdf

[Conor]

Directly. 

 

(That's how ours were done, the company specified 5mm tolerance)

[Dave Jones]

may not be needed depending on the side fixings, adhesive foam is surprisingly strong.

[Jonny]

Depends how much tolerance/flex there is in the steel. You don’t necessarily want the doors tight up to it

[Gus Potter]

49 minutes ago, Tom said:

Hi all, latest one waking me at 4.30AM: do we fix our sliding door headers directly to the cantilever steels - or do we fix eg some ply to the steels then fix to this? Or possibly some thermal break material (armatherm or similar) to the steel instead of wood? Slider's are these: https://www.cortizo.com/en/sistemas/ver/93/cor-vision-plus-sliding.html

Below is the detail from the architects, so looks like wood or similar between the header and steel, would be good to hear what the consensus is.

door header detail.pdf 906.93 kB · 2 downloads

Hello Tom.

 

It would not be my first choice of option. You also mention the word cantilever! .. and that indicates that close examination is required.

 

The starting point is to look at what the steel is holding up. How much dead weight is there that does not change and how much variable load could be applied to the steel (call this live load) as it is the live load that will cause the steel to move up and down... deflect. Sometimes a steel also has to resist wind uplift.. it can bend upwards too.. not often, but it can happen occasionaly depending on building geometry.

 

The most probematic case is where the steel bends downwards and jambs the doors. Personally I would like to see some gap.. say 10 - 15mm to allow for a bit of play and to give the steel somewhere to go. Looking ahead if you do get a problem with the doors sticking you want to be sure that you could tweek the frame at a later date... if it's fixed hard to the steel this closes off some of your options when maintaining the doors.

 

Just as an aside and for all. If you have a goal post frame..a column at each side and a header beam then if the connection is between the header beam and the column inner flange you can sometimes get bolt slip and this causes the header beam to drop a fraction. Clearly if the header beam is connected so that the beam rests on top of the columns this is not an issue for downwards loading.

 

For a lot of steelwork we don't use what are called tension controlled bolts or High Strength Friction Grip bolts (HSFG) as it adds to the cost. These bolts are designed / intended to prevent slip amongst other things. We normally use Ordinary bolts in a hole with a +2.0mm hole in the steel. Thus if you are using a 16mm diameter bolt it goes in an 18mm hole. Now it may seem tight when you put it in but occasionally you may get a phone call saying "we have just heard a bang" is our building falling down? Sometimes it just means the steel has dropped a little and come to rest. But these high end doors are a bit sensitive and that may be enough to cause a problem. leave a gap and if the steels drop up to 1.0 mm after a hot summers day then the gap should head off sticky door issues at the pass.

 

The other thing is that when it snows or you maybe get wind pressure on the roof forcing it downwards the steel moves up and down... it's just doing it's thing. Fix the doors to the steel and they too will have to follow this movement. Introduce a bit of "give" and it's one less stress that the doors frames need to cope with. Apparently less stress leads to a longer life!

 

I would go for a gap between the steel and the top of the door frame even if you have bifolds which often need to be fitted tight top to bottom as it allows you to maintain in the long term. Say you have bifolds and one leaf fails, burst frame joint say. It may be that to get it all to work properly you need to adjust the door head a little.. fixed hard to the steel then what do you do next?

 

Hope this helps you slumber.

 

 

 

 

 

 

[Tom]

2 hours ago, Gus Potter said:

Hope this helps you slumber.

 

It does, Gus, many thanks. And thanks Conor, Dave and Jonny.

So, approx 6 hours to go until the next issue bubbles to the surface in my subconscious...