[andysnook]

Hi all,

I'm hoping to build a woody in the loft, the roof provides a nice 45 degrees which is great.  So, its tempting to screw my ply sheets directly to the rafters - but of course I'm concerned about whether the rathers can take this kind of loading.

I've seen loads and loads of plans and examples of home walls on the net, but struggling to find many examples of anything screwed directly to the rafters.

Anyone ever tried this ?  Or is there a good reason people dont do it this way ?

Thanks in advance for all your thoughts

A.

[dave]

I was going to do this at my old crib but opted for a much smaller cellar board instead because I couldn't convince myself that it wasn't going to pull the roof down.

[andysnook]

I was going to do this at my old crib but opted for a much smaller cellar board instead because I couldn't convince myself that it wasn't going to pull the roof down.

Yeah that's basically my worry.  I do actually have room for a free standing wall, but its a lot more to build and wont be as wide/tall etc.

[Serpico]

I've got an attic room but opted for a free standing board, partly because of concerns about fixing anything to the roof but mainly because I didn't want it steeper than 35deg. The board itself is a 10'x8' A frame design, the 2 legs are 4"x2" tied back with another 2 lengths of 4"x2" to the base of the wall.

[Andy B]

How fat are your rafters?

[slackline]

How fat are your rafters?

[account_inactive]

Think about the way the framework has been built and how it will support your structure. A cellar joist will take more weight than your roof beams  

If you can build an a-frame without loosing too much space then that would be the way to go.  My cellar is a bit damp and not the best arena for athletic endeavors

[andysnook]

How fat are your rafters?

I'll check tonight, from memory I'd say they look like 2x6 but I could be wrong - less than 2 feet apart though

[andysnook]

How fat are your rafters?

Very good

11st

Looks like the free-standing approach is definitely winning at the moment.

[dave]

I think the nail in the coffin for my idea of an attic woody was watching scouse footless across my 2x6" roof beam on some screwed-on wood holds and seeing the entire beam flex like the tacoma narrows bridge (cast your minds back to a-level physics classes).

[Andy B]

How fat are your rafters?

I'll check tonight, from memory I'd say they look like 2x6 but I could be wrong - less than 2 feet apart though

Assuming that's in inches, and there's not already any movement in them [and possibly depending on whether I owned the property], I'd be getting tempted to attach the board directly to them.

gr, who comes on here regularly, used [a long time ago] to have a board which was attached directly to the rafters in the communal attic of a big old [rented] house. If he doesn't see this you could pm him for some advice.

[Andy B]

I think the nail in the coffin for my idea of an attic woody was watching scouse footless across my 2x6" roof beam on some screwed-on wood holds and seeing the entire beam flex like the tacoma narrows bridge (cast your minds back to a-level physics classes).

Scouse's campusing exactly matched the resonance of your joist? that's incredible. Rafters at less than two foot intervals, attached to each other by 18mm boards will move a lot less than swinging on a single one. And Scouse is a big boy.

[rodma]

Hi all,

I'm hoping to build a woody in the loft, the roof provides a nice 45 degrees which is great.  So, its tempting to screw my ply sheets directly to the rafters - but of course I'm concerned about whether the rathers can take this kind of loading.

I've seen loads and loads of plans and examples of home walls on the net, but struggling to find many examples of anything screwed directly to the rafters.

Anyone ever tried this ?  Or is there a good reason people dont do it this way ?

Thanks in advance for all your thoughts

A.

Could you post a picture up of the structure (including horizontal timbers between the two pitches) so I can have a peek.

A well constructed roof should be designed to handle serious wind loadings and some snow loads.

Hanging a couple of sheets of ply and the weight of 1 climber should get nowhere near the design loads.

I think the nail in the coffin for my idea of an attic woody was watching scouse footless across my 2x6" roof beam on some screwed-on wood holds and seeing the entire beam flex like the tacoma narrows bridge (cast your minds back to a-level physics classes).

If this was on the horizontal bracing, then you should expect that it would flex a fair bit. If it was on the actual pitched rafters, then that's quite scary.

[r-man]

Here's a pic of a friend's attic woody. Seems to work pretty well. The plywood isn't nailed to the roof beams, but sits on a rung (nailed to the beam) at either end.

[andysnook]

Hi Rodma, I'll certainly do that.  I'm moving in over the next couple of days so I'll get one posted as soon as I can.

Thanks again everyone for your input on this

[dave]

that looks awesome - he should try and get rid of a few holds though, looks a bit crowded on there.

[r-man]

It hasn't been up long, holds are still being added.

[T_B]

Dunno about anyone else, but at the mo, my attic must be about c40 degrees celcius! I can barely hang the washing up, nevermind pull down.

[dave]

is there a gap behind that for t-nuts or is it a screw-on only setup? looks like a smart solution to the attic woody problem.

[r-man]

There is a slight gap, but it's just screw ons. Wooden holds only on this board. I'm sure you could use t-nuts if you wanted.

T_B, we've found aiming a big fan at the woody cools it down significantly.

[Jaspersharpe]

Dunno about anyone else, but at the mo, my attic must be about c40 degrees celcius! I can barely hang the washing up, nevermind pull down.

  

It used to get warm enough in our cellar even with a big fan. Looks like a good setup though. The least obtrusive board ever?

[andysnook]

Dunno about anyone else, but at the mo, my attic must be about c40 degrees celcius! I can barely hang the washing up, nevermind pull down.

I had thought of this too - and have dealt with it by applying a good helping of denial...

[fashionguru]

Hi,  I built one a fair few years back in an ex's loft.

This was attached to a frame work that its was attached direct to the beams.

It was a fairly large affair with a 40deg 8ftwall at one side and the a 30deg 8ft with a 4 ft step roof at the other.

No problems with the roof as I know but the floor did give problems.

it was not a floating floor so was direct on to ceiling bellow and repeated falling over the time cracked this and made a mess.

Dont know if its still up but bet the roof gave in if it was.

Tony S

[rodma]

it was not a floating floor so was direct on to ceiling bellow and repeated falling over the time cracked this and made a mess.

We're in a top floor flat, but I think the downstairs neighbours don't have a cornice or anything like that in the room below our campus board. At least, I hope they don't ???

[uptown]

My very first board was fixed directly onto the rafters - I used marine grade ply and fixed regularly with some structurally fat screws - I  had no probs at all and was told that if anything it would strengthen the roof structure - in a way its just an expensive over engineered cross bracing!
My one tip would be to pilot the screw holes well and use good quality stainless fixings as I had real trouble removing those fat boys and sheared most of the heads off - attics are reknowned for humidity and condensation which backed up with old fashioned roofing felt make them corrode and seize. The board is still there now afaik - 21 years and counting!
More crucial to the size of the rafters is the size and spacing of your purlins - if they aren't sturdy or aren't there at all you may struggle with rafter flexing leading to broken slates. The Victorians were notorious for under speccing roof timbers. What age is the property?

[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)