Removing wall bricks ready for RSJ

[Bladders]

Hi everyone,

This is my first post. I've had a scan around to see if my question has been answered already, but it doesnt look like it has - apologies if thats not the case.

 

I'm opening my kitchen into an extension that the previous owners built on the side of the house. They left the old door opening which now enters into the new room rather than the garden that used to be present. I'm removing a 3 meter section of this wall to run the kitchen through. I have had a Structural Engineer produce calculations for the RSJs to go in and they've been delivered. The wall that I'm opening up used to be the outside wall and runs right up to the gable end. It's conventional house brick outer course with celcon on inside course. The kitchen ceiling joists are supported by this inside wall resting actually on the celcon rather than joist hangers) and I have acrow props to take the load off until the inside steel goes in. 

My question is about removing bricks from the former outside wall. Do I have to use strong boy attachments to acrow props to take the load of the wall above where the outer RSJ will go or is there a certain amount I can remove before it looses it strength? I need to remove 3 courses, but over 3 meters.

 

Regarding the pad stones. These weren't mentioned in the calcs but are you able to use one large pad stone per end to bridge the cavity or will I have to buy 4 smaller ones (150mm min bearing and a width of 4 inches to match the brick / celcon course) which is 2 per RSJ. Other than pad stones, would engineering bricks also do?

 

If I've missed any vital info, or you need anything else in order to help then please let me know. I can upload the drawings if they would help.

[markc]

Hello and welcome, hopefully they are not ordinary celcon blocks and actually high strength ones or concrete or similar.

you definitely need to support the brickwork with strong boys or a cascade failure is likely. Leave the supports in until the beam is in, grouted and the gap under the bricks packed solid.

you can use one pad across both leaves but that’s a big cold bridge, I’m assuming you are having an inner and outer beam? Or just one?

Edited April 19 by markc

[Annker]

Yes you certainly will need temporary support of the external leaf.

That is a significant opening and if I understand correctly has two storey of brickwork above it.

 

Similarly I'd question supporting the inner leaf by solely propping the existing joisting.

Sounds to me like a job for needles penetrating both leafs.

  

[Bladders]

Hi Mark,

 

I'm hoping the same thing. I could be wrong about the inside blocks but they do look very similar to celcon. The house was built in lat 1990s so I dont know what the regs were at the time.

Didn't consider the cold bridge. Both sides of the Pad Stone will still be inside the house rather than one face being outside and bridging through.

 

There are 2 RSJ, one to support each course and thanks for confirming the position with the brickwork - strong boys it is!

 

Cheers,

[nod]

1 minute ago, Annker said:

Yes you certainly will need temporary support of the external leaf.

That is a significant opening and if I understand correctly has two storey of brickwork above it.

 

Similarly I'd question supporting the inner leaf by solely propping the existing joisting.

Sounds to me like a job for needles penetrating both leafs.

  

Plus 1 

Needles are by far the easiest and safest 

If you have a Stihl saw You can cut a lintel into four to save buying padstones 

[Bladders]

1 minute ago, nod said:

Plus 1 

Needles are by far the easiest and safest 

If you have a Stihl saw You can cut a lintel into four to save buying padstones 

I have searched about to see if you can substitute padstones for steel reinforced lintels and I couldn't find anything definite. This would be useful as I will be removing 2 such lintels from the single doorway that is already present. Regarding needling through. Yeah I've considered this but the RSJs need to go hard up to as close the the existing ceiling as possible so the needles would be in the way of where the RSJ will need to be.

 

Thanks all for your useful insights.

[Annker]

15 minutes ago, Bladders said:

I have searched about to see if you can substitute padstones for steel reinforced lintels and I couldn't find anything definite. This would be useful as I will be removing 2 such lintels from the single doorway that is already present. Regarding needling through. Yeah I've considered this but the RSJs need to go hard up to as close the the existing ceiling as possible so the needles would be in the way of where the RSJ will need to be.

 

Thanks all for your useful insights.

Typically needles penetrate the building in the room above the room where the steel is being installed.

Yes they are disruptive and result in more remedial works but they are a significantly more robust and safer method of providing temporary support vs strongboys particularly in wide openings such as yours.

 

No doubt strongboys and back propping joisting is used also by some, ultimately it's your call.   

Edited April 19 by Annker

[Russell griffiths]

Remember to position the steels in the room on the floor before you put the acros and needles in, once you have it all propped you sometimes cannot get the steels in. 
 

I have seen this a few times. 
 

if the celcons are not strong enough you might need to chop them back and build up in 7n lightweight concrete blocks. 
you can also change the cavity into one solid pier. 

[Bladders]

Morning all, 

Just wanted to say thanks for all the input so far just in case it wasnt clear. I worked as a building labourer / apprentice for a good few years (about 30 years ago) so I have some capability but by no means an experienced builder (or what the up to date techniques are etc) so this site, and your help, has been invaluable.

 

Can I ask about acrow jack spacing with strong boys? Whats the rule of thumb? Every meter for my application?

[Bladders]

Just making sure, in addition to having an engineer draw up the calculations after assessing the wall, do I also need to involve local Building Control? 

[Redbeard]

Yes, I think you need BC. You already have the calcs so do a Building Notice, which is just a pro forma telling them briefly what the works are and when you will start (no less than 2 days from the date of the notice) ... and a fee. I have not read all the thread but it is structural work. Any that I have ever done has needed BC approval.

[markc]

Strong boys are good for 300kgs ish each, and spacing is usually much less than 1m. From past experience about 500mm apart with a brick story above, but SEcwill have used a load to calc the beam so that’s the load you should use to determine number of supports

[Bladders]

Hi everyone. I thought I'd give an update and take the opportunity for to thank everyone for their input. It gave me the confidence to get this job done and gave me some extra pointers to think about that I hadnt considered.

So, both the RSJs are up, I used a bunch of strong boys to support the former outer leaf and props with planks to support the joists in the kitchen. Everything went smoothly after a bit of thought about the order of propping one side, getting RSJs into the room, strongboys on the other side etc.

 

I have taken the walls under the new RSJs down to the DPc at floor level but would like to ask about what the best plan is for closing the cavities on both sides. I've seen these cavity closers but wanted your input first.

 

Let me know if pics would help.

 

Cheers,

[Super_Paulie]

My builder used closers but in most places where I could I took them away and closed them off with PIR foamed into the cavity. Seems way more rigid rather than a rattley bit of plastic.