RSJ bearing loads and padstones

29 Jun 2006
Reaction score
United Kingdom
Hello all

I wonder if anyone can give me some advice with regard to calculating and specifying bearings for an RSJ installation in a domestic dwelling.

I own a 1918 brick built house and am about to remove a chimney breast in a ground floor room on the party wall in the rear tenement. The left side of the chimney has a nice original dresser built in so I am aiming to retain the left wall of the stack and use it as a bearing for the RSJ. Being a mechanical engineer by training I have done the calc's to determine the imposed loads on the RSJ (which only need to support the floor above as there is no first floor stack) and have spec'ed the RSJ accordingly. However I have no idea how to assess the structural capability of the brick and mortar and spec the padstone to support the RSJ.

If it negates the need to calc I could just remove the wall and replace it with OTT concrete block masonry.

My council seem a bit too relaxed and are happy to give me the go ahead but 'we don't check your calc's'. But I want the job done properly and I don't want to be in the mire when I come to sell the house and surveyors get involved.

If anyone has an idea's how I can do the job right without the need for a structural engineer I'd appreciate it.


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Hello Alan, can`t help with calcs. but I`ve a `little ` experience! Is the mortar, lime or cement based? Either way, use solid engineers as padstones. On the breast wall can you get 2 courses deep by 9" by 13.5" wide? On the other end 3 courses deep by 4" by 27" on the bottom course will be ample. Regards JohnCo.
Thanks JohnCo

One end of the beam will sit in the rear wall of the property (two layer interleaved brick) while the other, as I've mentioned, could sit on the left wall of the breast. I'm unsure of the construction of he left wall until I start to dismantle.

I'm considering just paying the £300 structural engineer fee at the moment as I dont want to be in any trouble when I come to sell the property. Whilst I wouldn't do less than a thorough job this wouldn't help me if calc's for the works got raised as a problem in survey.

I do have one other question however. I am removing another stack elsewhere in the house. How do I support the upstairs stack when removing the ground floor stack? I can't get needles through to support above the RSJ level so how do I adequately support the chimney before I install the RSJ?

Thanks again for your help.


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What size is the wall your bearing onto(both ends)? Also what quality is the brick/mortar? Also what size beam are you intending to use and what span?

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