Advice of Box/Goalpost Steel beam to open up back of house

[noob17]

Hi all,

I am new to the forum but I would appreciate some advice on my situation. I have consulted with a SE who has advised me that if I wanted to open up the back of the original house (onto the extension) I would have to put a steel beam box to support the back wall of the house.

The house is fairly wide (9m). Currently there is a central pillar which supports a 3m beam from the left had side of the house and another 5.5m beam from the right side of the house.

So in order to remove that central pillar, the SE has said I need to put a box made of steel beams along top and bottom and both sides to withstand the weight. The house has a second floor and I do plan on converting the loft into rooms in the future.

Having spoken to another SE and two other builders, they are of the opinion that a goal post type setup would be sufficient for my needs.

Does anyone have any experience in this and can provide advice?

PS - I have attached a planning doc for you to get an idea of what I am talking about. The green and red dotted lines are the two current beams. The purple circle is the wall we want to remove which will open up the back of the house.

Thanks

 

[tomfe]

I am not sure what the purpose of the bottom steel would be. It's not going to be for racking or to spread the weight.
If you are happy with a goal post arrangement, then go with that.

 

[theprinceofdarkness]

Goal posts will work if the internal pads and external pads exceed the area of the foundations holding up the centre "pillar" in the house. This is because I rather presume that you cannot put your pillars in the centre of the internal pad .
Frank