Removing redundant planks from roof trusses

[Chris Styles]

Im really sorry if this is the *third* time you've seen this, I have just be told that I should post links, and not attachments (fair doos really)... Since I've not seen the original post, I assume lots of people havent.

The piccy I wanted to send it at :

original posting read :

I want to open up my loft a bit more so I can start storing stuff up > there. > One of the things that really gets in the way, and will really get in the > way when I come to board the loft is all the 4" x 1" x very long > (~16")planks that have been nail across the trusses. the fact that they go > at an angle across lots of trusses make me think that they were put there > to > hold the trusses in place while the rest of the roof way put on. > > I have attached a piccy of my trusses - there are 3 different types of > these > nailed planks. > > 1) The ones highlighted in green are a major pain, because I am planning > to > put new joists (8"x3"x 16') in parallel with the trusses and put the new > floor on that, because the trusses are made form 3"x2", and look as flimsy > as hell. Obviously I'll not be able to put the new joists in with the > green > planks in place. > > 2) The ones highlighted in red. these too are a major pain because it will > stop me moving around in newly floored loft. The trusses are about 10' at > the apex, so I could put them high up running the length of the loft under > the apex, if that helped. > > 3) The ones in yellow are not really too much of a pain, but I suppose If > I > wanted to insulate between the rafters, and the plasterboard the inside, > they might get in the way... > > Any comments?

Steve said they are for bracing, which I'd figured, but I'd figured it was just for during construction.

As per the original posting, the green highlighted planks i'd expect to offer the least bracing. Thinking of the trusses like dominoes, I'd see how the the others would help, but not the gree ones.

So, If I were to remove the green ones, but add a few extra ones to the inside of the roof ( the yellow ones ) does that sound sensible.

On that basis, if I were to significantly beef up the ones ones on the inside of the roof, would it then seem safe to remove the red ones?

I'm trying to work out what i need to do, or can do to remove at least the green ones, and maybe the red ones. The green ones are the show stoppers, the red ones can be worked around..

Cheers

Chris

[EricP]

I have peculiar and apparently functionless bits nailed haphazardly around the roof. They are so flimsy, I always thought they were just steadies used to stop the roof bits falling over before they were nailed into place.

I also have some mysterious alloy brackets nailed to the apex of the wall. They look like coat hanger supports, and seem to do absolutely nothing.

[Guy King]

The message from "Chris Styles" contains these words:

- without them there's nothing (apart from the gable ends) to stop the roof slumping sideways. The roof strength was all calculated with the assumption that they'd be there. The green ones on the floor are probably not /quite/ so important - they just stop the frames moving around while they're being installed - however I'd not be keen on removing them without fitting bracing between each bay to stop the potential for them all to kink sideways under snowload or the like.

[Phil L]

The green ones aren't important, but I'd be a bit wary of plonking 8X3's on top of the existing ceiling joists...fine if they are going to be affixed to masonry at each end for support, but just crossing the 3X2's with them is defeating the object, the 8X3's will add to the stress not relieve it.

You can re-position these, *provided* they are tight up to the masonry at each side....as they are now, they prevent the roof from twisting and bulging, this can safely be achieved horizontally by making sure they are fixed (at every available truss) with 3 inch screws or 4 inch nails and touching the blockwork prior to fixing, using a joist hanger (utilise every nail hole) on each wall is also a good idea.

They'll have to stay in the way :-p You can get around them easily enough..

Not so...it is for during construction, but they need to be there afterwards too.

The green ones were probably put there by the builders for no other reason than access for electricians, plumbers, insulation fitters etc.

The green and red ones only provided (during construction maybe) a bit of stability prior to the roof being done, now that there are dozens of roof battens above the felt, and all affixed to each truss, none of the trusses can move side to side anymore and the green ones can be safely got rid of altogether because the trusses are now also braced from underneath with plasterboard :-p

The red ones can go horizontally, as described above

[Weatherlawyer]

You can whip them all out with impunity. Pay no attention to the studs on here that might post alarmist trash about them.

Take a large crow bar up with you and if you have any difficulty removing them use a chainsaw on them.

They make excellent firewood and can be used with impunity on your organic garden. They are especially good of soft fruit such as strawberries, as they discourage slugs and form a very good bedding mulch for them.

[ironer]

//snip//

Both you & the OP would be WELL ADVISED to leave these struts (technically braces) WELL ALONE.

In normal weather they are hardly needed but once the wind blows and the snow lies deep over the roof they come into their own.

When you build a trussed roof it is quite noticeable how bending and floppy it starts off. However once the specified bracing is nailed on (WITH the specified STOUT nails) it is remarkable how stiff the whole thing becomes.

Laths used to support slates are flimsy in comparison and are not a substitute for the specified bracing.

If you want to visualize what's happening try making a model basic roof out of small short strips of wood. Observe how floppy it is, then attach diagonal cross pieces & watch how it stiffens up. Notice how even an apparently flimsy brace stiffens up a framework out of all proportion to its size.

IOW Don't touch without prior reference to the original truss designer or failing that someone equally learned in truss design. The Trussed Rafter Association

has plenty of info on bracing & trusses, inparticular:

deals with braces.

These are galvanized steel straps.

Compare your roof with an aeroplane's wings. See any similarity? Some of these restraint straps help keep your roof anchored to your house walls. Too heavy to fly, I hear? Not a bit of it There's been some well documented disasters where a roof has literally taken off in a wind storm.

Other similar struts help brace the house walls to the floors to make a rigid structure - just like truss braces..

There's quite a bit of info (or at least once was - I haven't looked recently) about the use of restraint straps in the Building Regs.

IOW leave well alone unless well understood.

HTH

[Guy King]

The message from "Chris Styles" contains these words:

This is from the Timber Research Wossname - covers how to get round bracing that's in the way...

[Staffbull]

Those plans look easier to follow than the ones I got from the truss plant!!!

[Guy King]

The message from "Staffbull" contains these words:

When you look at where the forces are going to run, it all makes sense.

[Chris Styles]

Nah, the 8x3's are to run parallel with wht existing trusses, sitting on the wallplates,, with an extra 1" padding so that if the 8x3's deflect, they won't hit the plasterboard...

The green ones are the major problem. Some say they are essential, some say they are not even needed. Think more research is needed, or at least add a bunch more bracking BEFORE moving them...

Cheers

Chris

[John Rumm]

Based on what I can see and a bit of guesswork, I would say the green ones are easiest to replace since they don't have much of a structural part to play. You can use noggins between the new joists to replace the function of these members. All they are doing now is adding a little lateral rigidity to the lower bits of the truss. The ceiling alone ought to do this so long as it is well fixed to the trusses and the plasterboards are staggered. This is actually much the same as removing the tie beams used in conventional loft joinery.

You can see how I dealt with those on my loft here:

red and yellow sections are more important - although less than they were now the roof is built. It is not uncommon for the roof to be poorly (if at all) fixed to the gable ends, so you need some triangulated bracing to retain torsional rigidity of the roof. You could probably use a herringbone section under the ridge. If you retain (and perhaps enhance) the yellow bracing, then the red could go without much reduction in rigidity.