[a dense loner]

i think you need to do some work on your house andy rather than give advice on someone else's. that was aimed at you guru, but could equally apply to banks

[Andy B]

Very true

[uptown]

Very true

Very true too 

[andysnook]

Small update having had a good look at the attic this morning.

The roof angle will actually provide a 56 degree wall if I fix ply directly to the rafters (steeptastic)

The rafters are 2"x4" at 16" spacing.  The roof is 6'3" high

The only interruption to the open space is two LARGE horizontal beams running along the length of the roof and touching the rafters about 2 ft off the floor.  It will also be possible to use both sides of the roof.

I'll try to get photos when I eventually find my camera.

Thanks again for everyone's input - much appreciated.

[Dr T]

The only interruption to the open space is two LARGE horizontal beams running along the length of the roof and touching the rafters about 2 ft off the floor.  It will also be possible to use both sides of the roof.

sand them smooth in places and affix dirty little screw ons??

[Probes]

Youd be fine fixing straight to it. The roof will have be designed to take some serious extra load. If you imagine a foot of wet snow on your roof and each cubic foot could weigh up to 9kg then a scrawnny climber and a few ply sheets wont even bother it.

Youd probably want to check the ceiling though you'll be falling onto, you could have issues here especially in the middle of the span between walls.

[rodma]

The rafters are 2"x4" at 16" spacing.  The roof is 6'3" high

I've never seen 4x2s as rafters before, maybe that's an english detail. At least the spacing is good and tight, 16" centres is perfect, as 48" is standard sheet width.

[SA Chris]

aiming a big fan at the woody

A few big fans at Jacko's funeral.

[andysnook]

Quick update - plans are going well, loads of holds, bolts, ply.

Question - what screws to use for attaching ply to the 2x4 rafters ?

I'm guessing standard wood screws are fine ? (Like SPAX)

Anyone got any thoughts on what length (70mm?) and diameter (5mm?) screws to use ?

Thanks again everybody.

[Jim]

I used 10x2" screws to attatch the ply to the supports

[rodma]

Quick update - plans are going well, loads of holds, bolts, ply.

Question - what screws to use for attaching ply to the 2x4 rafters ?

I'm guessing standard wood screws are fine ? (Like SPAX)

Anyone got any thoughts on what length (70mm?) and diameter (5mm?) screws to use ?

Thanks again everybody.

Spax are great and 5 x 50, 60 or 70 would be fine

[andysnook]

Spax are great and 5 x 50, 60 or 70 would be fine

Pre-drill the holes in the ply ?

[Jim]

depends on how powerfull your screwdriver is

[rodma]

Spax are great and 5 x 50, 60 or 70 would be fine

Pre-drill the holes in the ply ?

Countersink just enough to swallow the head of the screw (should finish flush with the face of the ply), spax self drill.

Proper job

[fraser33]

I've just finished builing my own woodie and I used Sterling board, which is a lot lighter and easier to handle
than ply. (not quite as strong, true, but it's still enough). 18mm think with a t&g edge all round (so you won't
need intermediate dwangs, which are the timbers you'd have to install running between the rafters to help
support the panel joints) plus its easier to screw into. Your rafter sizes and centres are ideal. I would pre-drill
the fixing holes where you connect to the rafters, but not bother with countersinking - the screws will bite right
into the timber sufficiently to leave them flush. I'd use either no. 8 or preferably no. 10, 50mm long screws

Also, double up the boards when drilling for the t-nut grid to save on wasted energy and use a big chunky auger bit
for speed.

Good luck!

F

[andysnook]

Super stuff guys - fingers crossed it all seems to be coming together now.  I'll probably post some pics as I start to assemble it.

[Jim]

If you've not built a woody before, the hardest bit is holding the boards against the rafters until you get the first couple of screws in. Get a couple of mates round and don't try it on your own unless you like pain.
If your screwdriver is powerfull enough then don't bother pre drilling the holes and certainly don't bother counter sinking them, its a woody ffs, not a sideboard your building

[dave]

always countersink your screws!! that way you can A. put holds over the top of them, and B. not rip our fingernail off when you accidentally drag your fingers over one.

[Jim]

every electric screwdriver I have ever used has been powerfull enough to counter sink the screws into the softwood or ply.
n.b  don't build a woody without an electric screwdriver of some sort unless you've got a lot of time on your hands

[rodma]

If you've not built a woody before, the hardest bit is holding the boards against the rafters until you get the first couple of screws in. Get a couple of mates round and don't try it on your own unless you like pain.
If your screwdriver is powerfull enough then don't bother pre drilling the holes and certainly don't bother counter sinking them, its a woody ffs, not a sideboard your building

I always put acouple of screws in to hold the sheet in place and then countersink all the rest of the holes before putting the screws in.

I may be a bit of a perfectionist, but I don't think anyone likes an ugly or jaggy woody 

[Dr T]

I may be a bit of a perfectionist, but I don't think anyone likes an ugly or jaggy woody 

you obviously haven't seen the one the reddicks use.... they seem to like it,
wouldn't be caught dead on it me....
in fact it's a good "how not to do it" example....

[d88ve]

Srewing direct to rafters should be fine as long as it isn't on a cheap new build. I did it in a large roof space in a pre-war house, no problems or any movement.

Reminds me of a certain talented climber from manchester whose loft contained a small board which was not only ridiculously steep but required him to traverse across the loft entrance therefore giving the training sessions the added spice of avoiding the prospect of a horrendous fall out of the loft past the landing and onto the stairs!!!  Terrifying

[rodma]

certainly don't bother counter sinking them, its a woody ffs, not a sideboard your building

Here's my sideboard (well, storage facility anyway)