Steel supports between two Bi fold doors

[jamie91279]

Im in the process of building a garden room, two walls will be block and the other two will be Bi-fold doors. I was originally going to build a brick pillar where the two doors meet but my friendly builder suggested installing a steel 4 inch post between the doors. This will support the two lintels over the bi folds.

Ive had a look on line and i came across https://www.thegardenroomguide.co.u...to-enhance-your-garden-connection/2024/09/04/ which provides some images of the type of thing im after.





My first question is where would the best location to install the post, on the external wall in the corner level with the brick course, this is what one of the builders suggeted. However friendy architect sugested inside of the external brick course. If externally the brickwork would need to finish at the column which would need to be clad. If inner of the block i would need to clad internally.

Secondly, i was going to install a 100 SHS in the corner which will support a 150 x 100 RSJ above and fix the steel to the padstone on top of the dense outer blockwork wall. I have spoken to a friendly structural engineer who has suggested that due to the lateral load of the bifolds then i will need to install a steel goalpost arrangement, the SHS can be installed within the 100mm cavity and the RSJ span between the three 100 SHS vertical posts.

Has anyone done anything similar before and if so what solution did you use?

Any help would be appreciated.

Thanks Jamie

 

[freddiemercurystwin]

Inside, then the steel will be able to be insulated, you do end up with a more chunky corner but these fancy pants photos never show the condensation that must occur on the the inside faces of the column.

Position your columns at the jambs in the inner skin, then they wont be a massive cold bridge either. SE's friendly or not often pick the easiest solution without giving a hoot about cold bridging etc.

 

[jamie91279]

Thanks freddiemercurys twin. Just to clarify you would install the steel as shown on the layout below? If so how would you finish round the post?

 

[freddiemercurystwin]

With plaster/plasterboard, whatever you're using to finish the inside of the blockwork. The bifolds should be set back say 75mm back from the outer face of the outer skin.

 

[jamie91279]

Thanks you. Just wondering the RSJ will not sit directly over the Bifold. Will i need a plate welded to the bottom of the rsj to fix the bifold to and the same with the vertical shs to meet the bi fold doors?

 

[freddiemercurystwin]

Do you have masonry over the top too? Assuming your bifolds are floor supported they can be fixed back to the columns and beam above with window fixing clips.

If you have masonry over the top then you will need something to support the outer skin so a flat plate welded to the bottom of your RSJ will suffice, ideally you would fit an angle lintel just for the outer skin (to avoid a cold bridge altogether) but here it may not be possible given your corner column set up.

 

[jamie91279]

No masonary over the top as the building is within permitted development so need to keep the height to 2.5mts from external floor level. Was going to use joist hangers from the top of the steel to support the wooden joists.

Ive just spoken to a builder and he is suggesting the RSJ should sit over the outside wall along with the external post so the bifold has something to fix to. He is suggesting the bifold is 75mm deep and will line up with the inner side of the outer blockwork cavity leaving around 25mm from the front face. The steel should be insulated and clad to stop sweating.

Also he queried the use of a goalpost arrangement and suggested fitting a padstone across the inner and outer block walls and fixing the steel to the padstone as i will have at least a 675mm wall to fix to. Something like the below. This should reduce any lateral movement through the upper RSJ steel and wall?

Whats your thoughts on this? It makes sense to me, as long as the steel structure is tied into everything will be a neater installation?

Anyone done this?

 

[freddiemercurystwin]

That's all incorrect for all the reasons already mentioned.

 

[jamie91279]

Thanks freddie mercurys twin, just having another think on this as the vertical steel is 100mm and the bifolds fixing to the inner face there wont actually be any steelwork on the inside of the warm building? The two Bi folds will butt up against each other at the corner, if that makes sense so the post wil sit behind them? I could foam-fix PIR to the steel eternally then clad?

Also is it possible for a structural engineer to calculate the lateral load of the blockwork wall to illiminate a secondary goalpost shs, im assuming that this is possible but maybe more difficult to calculate that steel?

 

[freddiemercurystwin]

Any SE will be able to do all that.

 

[robinbanks]

SE's friendly or not often pick the easiest solution without giving a hoot about cold bridging etc.

Builders too

 

[stevie888]

Builders too

And let's not forget architects from the list.

 

[noseall]

Builders too

And let's not forget architects from the list.

It's fair to say that cold bridging is often approached as an afterthought, by all until after it's too late. Its rare to to see a designer mention potential cold spots and the means to alleviate.

We now work with the suppliers and ask for knock-ons in vulnerable places, i.e. window/door heads and jambs, so that we have room to add a modest layer of insulation, prior to plaster-boarding and say allow for an additional layer across the upright studs (as well as between) regards lantern light-well insulation etc.

In the images below you will see a plate welded beam with insulated plasterboard being foam fixed to it. Plus we make the lantern uprights slimmer so that they can have insulation across them. In the last two images there is insulation dabbed onto internal/external masonry.....

insofit2.JPG

• noseall
• 12 Oct 2025

insofit1.JPG

• noseall
• 12 Oct 2025

insofit4.JPG

• noseall
• 12 Oct 2025

insofit3.JPG

• noseall
• 12 Oct 2025

insofit6.JPG

• noseall
• 12 Oct 2025

insofit5.JPG

• noseall
• 12 Oct 2025

 

[noseall]

Builders too

Not all.

 

[freddiemercurystwin]

Shameless plug

Really, little of that has anything to do with the OPs queries.