Gable truss ladder for shed - couple of questions

[Hallsy]

Hi guys, I'm part way through building a shed/summerhouse, 3.6 x 3.0m, gable across the long wall, 3x2 framework with 4x2 A frame trusses (with 3x2 bottom cord), 17.5' pitch. The framework is finished so I'm now moving onto the roof - weather permitting!!

I'd like to extend the front gable using 4x2 gable ladders.

Like this:

Could someone advise what the max advisable overhang should be? 400mm? The roof will be over boarded with 18mm ply, then most likely underlay & felt shingles.

Is there anything I should do to prevent sagging? Bolt rather than screw to gable truss? Any need for strapping across the top, or even gallow brackets?

Other question I have, the framework is unclad at the mo, but covered with breathable membrane. Should I clad the gable truss before fitting the gable ladders, or does it make no difference whether cladding is sandwiched or not?

I was planning on fitting the cladding after the gable ladders in case I want to remove it in the future without disturbing the roof (shrinkage/damage).

Any advice much appreciated

 

[noseall]

A 4" x 2" will span aboot 1.8m according to span tables and you are allowed about 450mm - 600mm overhang, depending on how it is fixed/supported.

My guess is that you would be wise to fix a pair of stubby gallows mid-span to deal with the span and sag issues.

 

[Hallsy]

Hi Noseall, thanks for your advice.

I had looked at various methods of extending the gable, considered drop gable, but having seen other builds with 'flying' ladders, so to speak, I went with that method in mind & cracked on building the A frames.

I did wonder about gallows brackets, but hadn't considered span so was thinking of supporting the ends - your mid point suggestion makes sense!

The total rafter length is around 1970mm iirc, so span is around 1800, a touch longer I'd say without measuring.

I had planned to nog the gable to first truss at 16" centres, same as the ladders, thinking that that will also help support the cantilever.

If I went with gallows brackets midpoint, should I birdsmouth the rafters to suit, or place them under a noggin that is set plumb (so bearing face square to gallow bracket) rather than square to rafter?

As ever, pictures speak a thousand words, and this is the build as it stands...

2016-05-11_11-07-00 by Hallsy01, on Flickr

2016-05-11_11-06-09 by Hallsy01, on Flickr

Well, it's actually covered in membrane at the moment due to our typical British weather!!

 

[^woody^]

400mm overhang should be OK for 4x2.

Screws will be OK to fix the ladder, just increase the frequency and number - 2 every 400mm should do it. I dont think that gallows brackets will be needed.

You can clad any time

 

[noseall]

I dont think that gallows brackets will be needed.

You can clad any time

Lol, seeing the image - no they won't.

 

[Hallsy]

Thanks guys. I suppose I could put the ladders up, and if they seem to sag, could add some brackets later.

I also wondered about passing some lengths of 4x2 or 3x2 under the ladder, gable truss & first truss, then attach to undersides. Not the prettiest, but would only be seen on inside of roof structure.

Noseall - you say you've changed your mind since seeing the photo.....is that good or bad?

 

[Hallsy]

Also been suggested I could use a 4x2 sub fascia to support the ends a little, I did consider that, but I've nogged along the ply join line, so if I have an extra 2 inches on end of rafter, I'll have to move the noggins to suit!! Not a big deal I know, but it's the principal

 

[noseall]

Noseall - you say you've changed your mind since seeing the photo.....is that good or bad?

Only good.