Suggested RSJ size?

[spagettilegs]

I'm building a new porch and removing an existing entrance. At the moment there are three exiting lintels over a door and two side lights. I'd like to remove the existing doors, sidelights and exiting lintels to install double french doors with sidelights which will extend from wall to wall (2.6m)

 

It's a timber frame house with a block leaf so the blockwork above the entrance isn't supporting anything other than the blockwork itself. The entrance wall I want to remove is 2.6m and the question I have is what size RSJ should be installed to support the blockwork above which is approximately 1,500kg. 

 

Thanks in advance for any assistance.

Edited August 9, 2022 by spagettilegs

[markc]

Good morning, at 2.6m I would be going for a lintel, no need for a beam.

Birtley do a good range of lintels for timber frame plus blockwork but a quick search will pull up suitable products.

[George]

This is the sort of thing to hire an engineer for. Free advice is worth what you pay for it...

 

Few issues to be aware of...

 

A single leaf lintel would normally work but from your description I think you are removing all of the wall entirely between the two perpendicular side walls? If you are doing that you will be bearing into the 100mm thick side walls, and you won't be able to get the 150mm bearing length required for lintels. So a steel beam is a better option as 100mm bearing is fine for them.

 

Secondly, has the timber frame been designed to span 2.7m at that location? You can't just take out the inner timber frame and hope it doesn't deflect (especially if you would use a timber frame lintel).

 

This is Part A Building Regulations work so a BCO will need to sign it off, they may want structural engineer calculations.

[Mr Punter]

It would be a good plan to remove the plasterboard from the inside so you can see what you have there.  I imagine there are several load bearing studs between the small openings plus either end.  You will also need to see how the top has been designed.  Once you have opened this up you can get an engineer to do the design and calcs.  Bear in mind the timber frame may be taking the roof and first floor loadings.

[spagettilegs]

Many thanks for the replies. 

Edited August 9, 2022 by spagettilegs

[spagettilegs]

13 hours ago, George said:

This is the sort of thing to hire an engineer for. Free advice is worth what you pay for it...

 

Few issues to be aware of...

 

A single leaf lintel would normally work but from your description I think you are removing all of the wall entirely between the two perpendicular side walls? If you are doing that you will be bearing into the 100mm thick side walls, and you won't be able to get the 150mm bearing length required for lintels. So a steel beam is a better option as 100mm bearing is fine for them.

 

Secondly, has the timber frame been designed to span 2.7m at that location? You can't just take out the inner timber frame and hope it doesn't deflect (especially if you would use a timber frame lintel).

 

This is Part A Building Regulations work so a BCO will need to sign it off, they may want structural engineer calculations.

Many thanks for the replies. I figured a steel rsj would be the best option as it would go the 2.6m width. 
would a 100x100 or 200x200 be the best thickness?

[George]

Sorry but you really should get a structural engineer to help. 

 

There's a few other things to consider which can't be covered on an internet forum.

[PeterW]

You also need to consider the cavity trays required here. You’re making an external wall internal, so above the roofline you should be installing a cavity tray between the timber frame and the blockwork. 
 

Also who designed and built the steel frame for the entrance as it’s normal for the post to go below the upper beams, not be welded to it. There also doesn’t look to be any lateral restraint on the steels to the walls. What is going to be enclosing the front ..? Glass ..?