Rough idea of loading?

[MonkeyHunter]

Hi,

Can someone give me a rough idea of how much weight bears on the back wall of my house? I am trying to work out if it is feasible to open up the whole of the back of the house when i plan to extend next summer.

Details:

Mid terrace house, 2 floors @ 8 foot floor to ceiling hight , the wall is Cavity and both leaves are brick, wall approx 17' long, the joists (7x2) run parallel to the wall, the roof is supported by this wall, and the loft rafters pick up on it, so it is supporting the ceiling of the 1st floor.

At the moment there are 2 large openings, one in the kitchen where it has been knocked through by previous owner, and one for patio doors in the dining room. There is a central bit of wall aprox 4 foot, and this is what i would like to remove when i extend.

I understand that this span is rather large, however at the moment i am about to construct a new internal wall, this wall is not currently going to be load bearing, however it has occurred to me that i could make it such, so that when i extended i could span from the top of the new extension wall to the new internal wall with an RSJ, in order to pick up some of the load from any RSJ used to span the existing wall like an 'H' This having the advantage that i can make the foundations for the new walls any size necessary.

If anyone can follow this and tell me if they think its feasible, and also roughly what sort of load the current wall is imposing, i would appreciate it.

Cheers!

 

[masona]

Can someone give me a rough idea of how much weight bears on the back wall of my house?

A lot depends on type of footing you have, mine doesn't have a solid footing just slab! You may need to have underpinning, you will need a expert advice

 

[jeds]

Roof load will be in the region of 1.75kN/m².
Ceiling load about 0.25kN/m².

If the roof is 5.2m x 5m that gives you about 46kN. Don't forget you have to add half the span of the new lean-to roof - say, 12.5kN plus the ceiling load at about 7.5kN. So your total roof load will be about 65kN or 12.5/m at 5.2 span.

The outer brick walling will be in the region of 6kN/m. The inner wall is usually lighter but you might as well take it as the same to account for plaster finish. This gives you 63kN or 12kN/m at 5.2 span.

So your total load will be about 130kN or 25kN/m if the span is 5.2m. A pair of beams around about 254x102 bolted together should be sufficient.

This is obviously only a rough guide and you definitely need to have it properly checked on site and also the beam/s properly designed. In any case you will need worked calcs for building control.

 

[MonkeyHunter]

Thanks guys,

Very helpful and Jeds i appreciate you taking the time for a more in depth reply.

I do have footings, and the slab bears on compacted ash on top of soil.

One of the reasons for asking now, is that i want to cut the slab so I can make the footing for my new internal wall, and wanted to get an idea of how wide i should make it.

Cheers!

 

[ModernMaterials]

Can someone give me a rough idea of how much weight bears on the back wall of my house?

Yeah a proper engineer would if you paid him or her.

Or you could just trust it to some stranger who types on diy forums

*giggle*

 

[MonkeyHunter]

Can someone give me a rough idea of how much weight bears on the back wall of my house?

Yeah a proper engineer would if you paid him or her.

Or you could just trust it to some stranger who types on diy forums

*giggle*

Don't worry I will get it all specked out by a SE when i come to do it, but that will be next summer at the earliest.

 

[Robert too]

I would be more concerned as to what the remaining piers are , and what they will be sitting on .

You will most likely need to enter into party wall agreements with both neighbours