Load bearing advice

[cjard]

I have a structure, 20 metres wide, that I've sketched below:



Walls are a foot(ish) thick, no cavity, a slate roof is supported by 4 large metal trusses, of a triangle pattern. In the centre line of the building under the valley of the roof, are vertical posts supporting one end of these trusses. The other ends of the trusses sit on concrete pad stones, embedded in the wall

There are practically no holes in the rear wall at present

I would like to form new openings in the rear wall, for doors and windows. I had presumed that keeping a continuous column of brick, say a metre wide, directly under each pad stone/truss landing, would provide sufficient support to the trusses. My brother was talking about it differently. I didn't really get what he was saying, about 45 degree angles spreading own from the point where the truss beds on the wall, but not all the way to the wall base, as openings could be cut in the lower part of the wall, so long as it was adequately supported with a lintel, it doesn't have to be assumed that the load will act vertically, but in the upper part, this triangle of wall shouldn't have any cuts.... I understood part of his words, but he was a bit tired and incoherent so...

..Where can I put windows/patio doors etc, in a wall that looks like this, without it being structurally compromising? or, should I be looking to install 4 vertical RSJ rising up from the floor, to support the trusses and then do whatever with the wall? I was rather hoping for a "outside of the continuous column that is directly under, and X millimetres either side of the truss landing, do what you like" because between each truss is 4metres so if I had a column of brick 1m wide under each truss landing, that's 3m of opening per "bay"

The wall is, I believe, a double skin of engineering brick with lime mortar, with one header course per 2 or 3 (I forget) stretcher courses

Thanks guys

 

[tony1851]

The critical point here is not necessarily the width of your remaining brickwork under each truss, but the height of the wall. Brickwork can take considerable load in compression, but if a wall or pier is too slender, it can be subject to tensile loads due to wind.

 

[cjard]

The wall is 5 metres high, and the location is quite windy, though this wall is not on the prevailing side. The front wall (prevailing) has buttress supports that are approx. 300x400 under 2 of the trusses and a significant stonework façade near the other 2 trusses. It's also a solid wall (but it too will have holes cut for windows)

 

[tony1851]

For a verticaly-unsupported wall 1-brick thick, 5m is quite high. The fact that it is on the leeward side is of no consequence because you will still get wind suction on that side.
Tbh, if you are putting reasonably-sized openings in, you really need to get some input from a local SE. As what you are proposing constitutes structural alterations, you would in any case need to go through Building Control and they would ask to see justifying structural calcs.

 

[cjard]

For a verticaly-unsupported wall 1-brick thick, 5m is quite high. The fact that it is on the leeward side is of no consequence because you will still get wind suction on that side.
Tbh, if you are putting reasonably-sized openings in, you really need to get some input from a local SE. As what you are proposing constitutes structural alterations, you would in any case need to go through Building Control and they would ask to see justifying structural calcs.

I think it's 2 bricks thick, and the bricks are quite a bit larger than the ones I built my bungalow out of.. But even at 2 bricks thick I take the point that it would be quite a column. I guess I'd be looking at SE involvement anyway; at the moment this was purely for the purposes of drawing plans to present to the planning dept. BC and SE probably not a feature yet if LPA turn round and say "no chance"..

So I guess I should draw up what I want , possibly with oversize openings because theyre more likely to permit making them smaller than larger if I go for amendment.. Bro probably quite wisely said "mo' holes, mo' money"
Thanks tony!

 

[noseall]

1/2 brick thick = 102mm.

1 brick thick = 215mm.

2 bricks thick = 450mm.

Approximately metric. Imp's are a bit thicker.