New Build project. 100mm inner leaf to 100mm cavity to 100mm outer leaf. Bi-fold 3160mm wide.

 

I have a steel in the midfloor (holding up the ridge of the roof) that needs to sit on the wall above the bi-fold (see image below). Structural engineer solution is to use a 152 x 89 UB16 to the inner leaf (spot welded) to an 8mm bottom plate across the cavity as the lintel. The steel in the midfloor can then sit on a padstone within the masonry above.

 

Option 1: Have a steel company supply the 152 x 89 UB16 spot welded to the 8mm steel plate. Then once on site, cut and position my own PIR insulation on the lintel with cavity tray above. Is this allowed for a new build considering all the SAP calcs, and building regs, and cold bridge issues?

 

Option 2: Buy a ready made Keystone X/K-90 Extreme Load (other image below). I believe this may be quite expensive.

 

Your experienced opinions would be greatly appreciated thanks.

 

 

My thoughts are stick to what the structural engineer said, then design in your insulation. 

How is the steel holding up a ridge as it’s flush with the floor ..? 

Keystone 3600 will be close to £650 I expect which is much more than a steel of the same spec although .... I am not sure the calcs are correct !! Without seeing all the loads, I can’t see how a single 152x89 is taking the floor load, upper wall and the point load of a ridge ..?
 

I know I’ve not had a lot of coffee today but I’m getting about a 52mm deflection at the point load ..!! @Gus Potter does that sound like a very skinny beam to you for an opening that size ..?

I would never use a lintel over bifolds 

Always a steel 

Slightest sag and your doors won’t open 

1 hour ago, PeterW said:

How is the steel holding up a ridge as it’s flush with the floor ..? 

Keystone 3600 will be close to £650 I expect which is much more than a steel of the same spec although .... I am not sure the calcs are correct !! Without seeing all the loads, I can’t see how a single 152x89 is taking the floor load, upper wall and the point load of a ridge ..?
 

I know I’ve not had a lot of coffee today but I’m getting about a 52mm deflection at the point load ..!! @Gus Potter does that sound like a very skinny beam to you for an opening that size ..?

 

Thanks for this (yes that's my feeling, the Keystone would be much more expensive).

The steel over the bi fold would be a 152x89 UB16 (Beam B). That would support the padstone above which would hold a 152x152 UC (Beam D) which is perpendicular to Beam B going inwards across the house. Beam D would support 4no 100x50 C24 (ridge posts) from Beam D up to underside of ridge. Hope that helps.

Edited June 6, 20215 yr by Johnny Jekyll

Thanks everyone, any more opinions and comments are much appreciated.

Ok something odd about those values - are you sure the beams are the right way round ..??!

 

I’d need to see the plans proper as that block plan doesn’t make entire sense to me. If there is a gable (or a hip..?) on that end wall then the loading on that steel can’t be right. 

On 06/06/2021 at 15:23, PeterW said:

Ok something odd about those values - are you sure the beams are the right way round ..??!

 

I’d need to see the plans proper as that block plan doesn’t make entire sense to me. If there is a gable (or a hip..?) on that end wall then the loading on that steel can’t be right. 

PM'd you Peter thanks.

Does anyone know how the RSJ's are arranged for over a bi-fold, is it two separate RSJ's?

 

How would you render onto the outer RSJ? 

Depends on the requirement but you can get them fitted with brackets to take a render board. Also depends on the outer leaf load 

 

How big is the opening ..?

1 hour ago, PeterW said:

Depends on the requirement but you can get them fitted with brackets to take a render board. Also depends on the outer leaf load 

 

How big is the opening ..?

 

Two of them, 3m and 3.6m.

I wonder if you use a 89mm wide UB, recessed slightly then the render board could go flush with the block work

So why not just go for an XHD Steel lintel (or a steel with an 8mm bottom welded plate) and then put a standard Naylor concrete on the front face ..? Will stop it bending and also dead easy to render straight on to.