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2015-Oct-31 - Wooroloo - Loft Floor Joists #12
I have a few projects running in parallel here at the moment.

There is the ongoing need to reduce the fuel load around our residential house.

I'm also finalising the structural design for the ensuite bathroom & communal toilet areas.

Plus the beam across the corridor to take much of the loading from the front portion of the roof.

Finally, I am testing out fabricating my own right angle brackets for fixing the floor joists over the top plates of the stud walls.

Today was also complicated by my utility not working.

It has had an intermittent fault where it cuts out (usually on our street) and then spontaneously fixes itself after waiting for an hour.

But now we have a full on, permanent fault - which in a way is a good thing. Alex, our very friendly and helpful mobile mechanic is in the process of working through a number of potential causes. He took the distributor away and I believe that he is checking it for oil ingress.

Anyway - this made the day a little more difficult - I would have liked to visit site just to take some more measurements for the loft floor and to record the dimensions of my remaining PFC 150 stock.

Still - there was plenty I could still do from home.

My top priority for the day was to test out fabricating my own joist brackets.

I have a 2.4 metre length of heavy duty angle iron - 130 mm x 75 mm x 8 mm.

It was probably originally a lintel.

I wanted to take two 80 mm sections of it, drill some mounting holes and test these brackets on site.

I also wanted to make a start on the beam over the corridor.

Both projects involved cleaning up with a rotary steel brush, rust converting and the use of a cut off saw.

I spent the first two hours of the morning reducing the fire risk on the East side of the house before contemplating producing any sparks. Fortunately this was just a continuation of the cleanup work I have been doing.

I raked up a large area and ran several barrow loads of leaves through a mulcher.

The beam across the corridor is going to need some side arms of PFC 150, around about 400 mm long. I sorted through my various offcuts and managed to source enough without cutting in to longer stock.

The main beam will be two x 2 metre PFCs welded back to back.

These came from the 4 m length that I decided I could not use about 6 weeks ago due to a bow in it.

However, once cut in half, clamped and welded back to back - this will be a perfect piece of steel.

In the end I had quite a few pieces of steel, arranged across two sets of carpentry horses, awaiting cleanup.

It took me an hour to clean all the surfaces with a rotary wire brush and after this I gave them all a coating of rust converter.

Because I wanted to make a start on the brackets, I only gave the angle iron two hours of reaction time. The other pieces I allowed four hours. The reaction looks complete with all rust areas now converted to black Ferric Phosphate.

I used a cut off saw to cut off two 80 mm sections, made up a drilling template and used a drill press to create one base hole and two purlin fixing holes on each bracket.

Have a look at the photograph - they look pretty good to me. 80 x 75 base and 80 x 125 upright, 8 mm thick.

I estimate that I can create 30 brackets from the piece of steel I already have. However, I need another 60 after that. For this I would need to buy a 6 metre length at $180. ie $3 per bracket ignoring the cost of cut off disks, painting and my time.

I know I saw some brackets at Midland Timber that might also do the job.

They are a little smaller, probably 6mm thick, but already galvanised and holes punched.

I will have to find out the price they can offer me if I purchase 100 of them.

Again, I need to get out on site and do a survey to accurately work out how many I really need.

Possibly, if I hunt around I could pick up some appropriate lintels for next to nothing.

I just have to think of the trade off between money and my time.

So that particular project is on hold until I make a few inquiries.

There is still a lot of work on the corridor beam I can be getting on with. I intend to notch and weld in 4 x 400 mm arms - so a fair bit of cutting, shaping and welding to do.

I was marking up the ensuite area on top of the stud frames last weekend.

My original intention was to terminate to the north and sourth of this area over a C150 purlin and then switch to C100 purlins back to back in the set down area.

This is what was indicated on the plans from my original structural engineer.

However all this changed after a conversation with Dave, my current adviser.

He told me that the floor would be safe enough, but that it would have some bounce over 4 metres.

This is not a good thing for a wet area that needs to remain water proof, tiled and grouted.

We changed the plan to three PFC 150's running East / West with PFC 100's welded back to back as a right angle beam.

I believe I have enough PFC 150 out on site for this job but I need to shop around for the PFC 100.

The last PFC 100 I bought was 4 mm rolled.

This was fine for its purpose but I want something "gruntier" for this job.

I can use 6.7mm / 4.2 mm C purlins welded back to back, or 100 UC or SHS 100 with up to 9mm wall thickness.

I have emailed Dave to ask for his advice.

So that project is on hold at the moment as well.

Lintel to use to make brackets

First two test brackets

Cleaning up and rust converting PFC 150

Ensuite area in the loft

Structural design