Advice: Extension Steel Work

Wolf82

So work on our mid terraced town house rear extension is due to start next week. Unfortunately we had to find a new structural engineer (we were getting nowhere fast with the old one). All along we had planned for 400mm masonry nibs for the steel to sit on as specified by the architect and original engineer. However the new engineer is saying we need 800mm nibs to spread the load which is a massive problem for our kitchen design and overall space.

The only workaround I’ve been offered is to have a picture frame steel installed reducing the projection back to around 400mm. The quote for this was £10k.

Does anyone have any advice on other ways to get around this problem? If not is £10k a reasonable cost to expect.

Many thanks.

Doozergirl

The structural engineer will know what they're talking about.

There are different forces at play on houses and so you can't always remove as much as you want the 'easy' way of simply spanning across with one steel.

If your house is detached, then a rough rule of thumb is that you can remove 2/3s of a wall, leaving 1/3 behind. The original corners are precious and more vulnerable to lateral loads, so you need to retain more wall there than you can inside.

The more you want to remove, the more engineering is going to have to take place.

Really ridiculously vague points I'm making, but given that we have virtually no detail, nor are we able to offer professional advice, it might help make some sense of what you've been told.

It's not great a great indiciation from the original engineer that you had to part ways, presuming you were unhappy in some way, and then the new one has told you this.

Wolf82

Thanks Doozergirl.

Yep, unfortunately the old engineer wasn’t returning calls etc and we were quickly running out of time before the build starts. Just frustrating that the piers have doubled in size.

I appreciate I haven’t been very descriptive (not sure I could if I wanted to with all the jargon).

The only piece of information I have the engineer is that the load bearing on the ground is calculated to be 110kN/m2. Any smaller nibs and we are relying on the foundations of our neighbours.

jk0

Maybe you could 'lose' an extra 300mm inside a dummy upper cupboard. If you need more than that, just have a tiled pilaster in the run of cupboards, and have a dummy lower cupboard.

snowcat75

Fabrication is my day job, However without either a set of tangible drawings or an eye over the job its impossible to comment.


With structural calcs its very often possible to do the same job in different ways different engineers have different ideas.... someone like myself can often have another and plenty of times I have asked if something can be changed to simplify or what's drawn isn't practical and they will approve he alterations.


I would guess the new design might require columns (UC) on pad stones in the ground for the new Beam to sit on?