upcoming extension advice

mattu27 · 7 Oct 2019

Notch7 said:
Yes I was only joking, it is best for steels to be painted in red oxide, it is certainly best practice........ the structural engineer and building control will put that on their drawing by defaut.

Internally there is a chance of condensation and damp causing a bit surface rust.

I know you were, the main reason it's annoyed us is because the builders said that they would be primed and have certain plates and holes predrilled but they've came as stock steels but we've paid the same price.

They take lots of photos of their work for advertising so we thought that seeing as we're paying for it, painted steels would look more professional. But hey ho.

^woody^ · 7 Oct 2019

mattu27 said:
Thanks Woody,

I've included a photo to show what I saw.

Hopefully it clears it up. I believe that the builders are planning to install the joists and floor immediately after the steels are in place so that they can start the first floor brickwork.

I noticed that the masonry hangers say to either top fix by using a hilti nail gun or to have a minimum of 670mm of fully cured masonry above them before they will accept any loading. That was the main reason for the worrying about securing them down. Is this the case?

Thanks

Those hangers can go right on the top of the beam (no real need to hilti nail) or if there needs to be a bit of wall first then that should have gone off for a day, unless they dry pack the hanger and then build over it. As long as its all done with care to properly build in each hanger.

The thing to ensure, is that the hangers are deeper than the beam, as you cont want to be seeing an ugly boxed beam below the ceiling. If those masonry hangers wont acheive this, then you really need to consider lowering the ceiling level, or fixing timber hangers to a timber within the beam web. Or if the beam will project above the floor level, as it's 133 wide, then the wall could be lined to thicken it up to cover the beam width. This will all need to be considered in context of what is possible or important in terms of the levels or wall thickness.

mattu27 · 7 Oct 2019

So here's what I was thinking, I've drawn a bit of something to run it past you guys and see if it makes sense. Plan is (hopefully) to use a 225mm deep hanger which are 10mm short apparently making it 215mm.

The beam is 203 so that will leave a 12.5mm gap between the steel and the plasterboard at the bottom. As we're going off the piers I'm thinking that the steel will sit flush to the inner house wall and rest approx 30mm into the original double brick pier (hope that makes sense from the photo.

So a 195mm joist with 22mm chipboard will make 217 and leave the finished floor height level with the top of the steel beam, this should mean that the steel will be fully encased within the void and we achieve max ceiling height in the garage.

Thanks

Leofric · 7 Oct 2019

mattu27 said:
As we're going off the piers I'm thinking that the steel will sit flush to the inner house wall and rest approx 30mm into the original double brick pier

Do you mean the steel beam will only have 30mm bearing on to the brick pier

mattu27 · 7 Oct 2019

Leofric said:
Do you mean the steel beam will only have 30mm bearing on to the brick pier

I hope not! No it will be fully bearing on the 210mm brickwork beneath it, hard to see on the photo but the piers are now in effect 300 deep.

Leofric · 7 Oct 2019

mattu27 said:
I hope not! No it will be fully bearing on the 210mm brickwork beneath it, hard to see on the photo but the piers are now in effect 300 deep.

You've lost me, I don't see any piers 210mm wide or 300mm deep

mattu27 · 7 Oct 2019

Leofric said:
You've lost me, I don't see any piers 210mm wide or 300mm deep

I should rewrite it really. The new steel is basically going to sit on a 220mm ledge (when finished). Should have just wrote that earlier

There are 4 piers to support the steel across an 8m length, each pier being 440mm wide X 220 deep

mattu27 · 18 Oct 2019

Morning all, can someone confirm that this is the best method of fitting the joists within the new insulated void. Does what I'm proposing make sense? Or is there a better way?

Can we additionally prop the joists with say 4 X 2 before the 3 courses of block are laid above to support them and stop and movement?

Thanks, Matt

^woody^ · 18 Oct 2019

Yes thats OK.

If you fix all the joists together with a lath or suchlike on the top or bottom near the hangers, this stops them moving

mattu27 · 18 Oct 2019

Thanks again,

Good plan with the lath, got plenty lying about.

The thinking behind the 4x2 was to support vertically so that the hanger rear doesn't lift up from the steelwork once the joists are hung and the blocks are initially being laid.

I can't take them moving much as there won't be a substantial weight on them intially.

Thinking about the cabershield+ 22mm floor as it's moisture resistant enough to withstand being exposed to this awful weather.

Thanks

^woody^ · 18 Oct 2019

Props will help if you are battening it out and working off the joists, but if not it will be Ok. But it wont do any harm if you are a worrier.

mattu27 · 18 Oct 2019

Yes builders are planning on installing the floor straight away and working off that so there will be load on it but will try to keep it to a minimum until the three courses of fibolites are laid and cured.

Steels in on Monday, they're planning on installing the steel via genie lift then building the piers up beneath it and removing the loft once all cured.

If the weather holds out..

mattu27 · 22 Oct 2019

Just an update and a few more questions.

Steels have gone in across the piers and the builders have packed them with slate but maybe only a 100mm square under each pier. Assuming they're going to mortar up the rest of the area but with there being a 440mm wide platform shouldn't more of this be used? Or is it ok to pack a small area then mortar the rest?

Also noticed that the new joists are 10mm low in comparison to the originala house joists, we're using 21mm chipboard and I'm guessing that the house will be a similar thickness. Should I pull them up on this and get them to correct before it's too late?

Thanks

John D v2.0 · 23 Oct 2019

We had the same issue because the old josts are 7x2s and the new ones are whatever the millimetres are, and they lined up the downstairs ceiling rather than the upstairs floor.
It's not ideal but it probably makes sense that way round, I'd have preferred them to rip down some bigger timber if possible.

247 Developers · 26 Oct 2019

Great idea

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