Starting a large upstairs renovation but need floor deflection sorted first - I don't have confidence in tradesman in my area
I am undergoing a complete upstairs renovation in September, including a new kitchen, bathroom, flooring, and associated works.
There is a substantial amount of floor deflection in the kitchen area caused by two issues. Firstly, the existing floor joists are only 140mm deep and span approximately 3.9m. Secondly, there is a short strutting beam sitting on the kitchen wall which I intend to remove as part of the renovation.
I am a licensed KBL builder, so the fit-out side of the project is well within my wheelhouse, however structural work is certainly not. I engaged an engineer, right off the bat I was a little worried as he was quite a bit younger than me (i am in my 30's). The engineering plans have been returned, however I am still chasing him for bearer connection details.
One of the biggest challenges has been finding someone willing to quote the work. I have contacted 11 builders/carpenters and only one has provided a quote after being supplied with engineering plans, detailed descriptions and photographs. He can't do it till December and can't commit to a firm date - useless.
I have a few carpenter mates in the industry, but my original intention was to outsource the structural work entirely. If something goes pear-shaped, I'd prefer the responsibility to sit with a contractor rather than a friend. Given the difficulty I've had finding anyone interested in the job, I am now considering using a mate instead.
I've already paid for the kitchen, selected the stone, and taken two weeks off in September to complete the renovation, so I'm starting to get desperate.
This is where my apprehension lies. Increasing the joist size and connecting them to the central steel I-beam bearer doesn't seem particularly problematic. Welding connection plates to the steel bearer appears relatively straightforward.
Connecting the new joists to the external bearers is where my concerns begin. My mate wants to use 175mm F17 hardwood joists but has suggested notching them slightly to sit over the bearer. I don't like this idea at all, it seems completely counterintuitive to remove material from the very member I'm increasing in size to address the deflection issue.
The existing kitchen floor joists are 170mm deep and are notched in exactly the same manner so how is this any different?
How would you typically connect larger joists to the external bearer in this situation while ensuring the floor performs properly long-term? I intend to tile the upstairs kitchen floor and install stone benchtops, so there will be additional dead load compared to the existing setup. I want to make sure this is done correctly the first time and would appreciate any advice.
Please see the pictures attached.
First are the photos I sent the engineer before the site visit
Second are the engineering plans
Third is a picture of the external bearer noting that half way through the house the bricks step out infront of the bearer. For the other half they are flush with it.