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Wazza187
17th Jan 2012, 04:52 PM
Hi Guys,

I have a double brick house, circa 1928. It is currently uninhabited while we are doing fairly major work to it.
I'll be installing an attic ladder (red rectangle on picture) and since I currently have a ceiling down in one of the rooms, I have easy access to install big flooring sheets into the roofspace. (Don't want ladder in hall, as this is prime load bearing territory for storage.)

My intention is to use the area for storage only (uninhabitable space), and the area in Yellow would be where the main load would go, as it is well supported by strong brick internal walls, however, since the costs aren't massive, I am considering flooring the entire space, and marking the area where heavy loads can go. (if I only floor a small section, I'd have to put up walls / rails and eventually I will use closed cell insulation to make the area, or a portion of, dustproof. Would be easier if I can just eventually staple the insulation/dustproofing to the rafters when I'm finished, rather than build another structure.

I would not be modifying the roof trusses/support at all, as there is enough open space already.

The ceiling joists are hardwood, at 450mm centres, and (from memory) are about 100mmx~60-75mm?, they hang across the rooms (left to right) and rest on wood ontop of the internal and external brick walls.

There is no current insulation, so I was planning on installing R2.5 90mm insulation (insulco acousti therm), and some type of flooring sheet directly on top of the ceiling joists, it's pretty simple and honest up there, removed old water tank, and no more water pipes in roof, only electrical, I will leave cutouts around jboxes and light positions (all pendant lights, no halogens), will run the cables ontop of flooring for easy access. (it's all new wiring, no conduit)

Old ceilings where horsehair/plaster with timber lapping(?), new Ceilings are Unispan 10mm Gyprock (25% lighter than normal plasterboard), so some weight reduction already.

My question is.... what flooring to use?

Obvious, cheapest answer is 19mm Yellowtounge, as i already have 450mm centres, but I am worried it may be too heavy?
At about twice the price, would 12mm Plywood be better? (is weight difference significant?)

Just from grabbing prices off bunnings website, Yellowtongue would be ~$999 (3600x900x19 @ ~$37), 12mm Plywood = $1800 (2400x120x12 @ ~$45)
Anyone know the weight difference? or any other suggestions as to what should be done?

Thanks!

87860

Wazza187
18th Jan 2012, 01:37 PM
OK, so I had another look today, and I'll just put flooring over the main walls (shown in blue). Green is access ladder.

I've gone off the idea of putting plywood directly on ceiling joists, and have 2 alternate methods which I'm, deciding upon.

1). Put in new 6x2 bearers next to 4x2 Ceiling joists (in same direction) at 450 centres, 12mm plywood / 19mm yellowtongue ontop of that.
This will be stronger, and more expensive I think. also, considering the other Ceiling joist will be in the way, it's going to be really annoying putting in insulation since the spacing will be messed up.
(ceiling joists not show)
87865


2). Put new 4x2 Batons perpendicular to and on top of existing ceiling joists (only in blue area), as shown in yellow.
(assuming beams left to right are the ceiling joists) and 12mm plywood or 19mm yellowtongue on that.
This will be easier and cheaper, also I can lay one layer of ~90mm insulation between original joists, then baton and another layer of 90mm insulation between the batons.

So, option 1 or 2?
and 12mm ply or yellowtounge?

Anyone have any comments?

87866

Wazza187
31st Jan 2012, 03:35 PM
Wow... overwhelming response...

Anyway, I went with batons going across Ceiling joists, and added new 2 laminated beams to hold the attic ladder.
I then put Yellowtongue ontop, about 80% completed at the moment, seems good. Batons seem to have added a lot more strength than just putting Yellowtounge up, and since I'm only doing above the brick walls, I'm not too concerned about the weight, there was a 250L hot water tank up there across 3 ceiling joists, over the walls for 80 odd years anyway.
I used MGP10 2x4 for the batons, but think this was overkill, could have used smaller wood, but this made my double runs of insulation easier, which is also overkill, but why not.

Hope this helps someone.
Cheers.

Waz.

johnc
31st Jan 2012, 04:19 PM
Yellow tounge is the way to go, cheap and cheerfull, and sufficient for any load you have up there. Roof spaces are places you put things until they have been there long enough to not feel guilty about throwing them out. Bit like tupperware for leftovers same sort of thing. As for what you should use I have no idea but battens are probably overkill and I would have put insulation between floor and roof..

Wazza187
31st Jan 2012, 04:43 PM
:-)

Thanks for the reply!

Yeah, it's overkill, but at least I can be confident in it.
I did put a double layer of 90mm insulation. One between the joists, and one ontop and perpendicular to them, between the batons. So R value is ~5 not including yellowtongue... so should be a well insulated hallway:-) but insulation doesn't exactly cost much for an area this size.
I will also eventually setup the storage area as 'dust proof' using closed cell insulation. for the rest of the roof, I'll prob insulate above the height of the joists, to about R3.5, should be a big difference, we previously had no insulation at all and froze our arses off in Winter.

Cheers!

Ashore
31st Jan 2012, 08:45 PM
When your running your new cables , Make sure you run a baton alongside them and clip them to the side of the baton, so nothing can be dropped on them or get caught on anwthing you are moving around.