Trussed roofs - adding extra timbers.

[SolarCity]

Okay, I'm beginning to fret more and more about my lack of work and the crazy prices that I'm seeing.

Can I ask other installers if they reinforce trussed roof timbers? I know they will take the extra weight structurally but it is my understanding that the fixing required are too large for the timber (generally).

This is relatively time consuming and an extra expense so I wonder if I'm going over the top?

Any input would be appreciated.

 

[SRE]

Depends on the size of the timber, we rarely get anything less than 50mm so don't unless it's needed structurally. We're quiet too -got other work to keep us busy at the minute but that won't last long. I never thought I'd say it but I'm even contemplating not renewing MCS later this year if it stays like this.

 

[Gavin A]

we've been fixing an extra 75x30mm rafter to each rafter we fix to on trussed roofs with the smallest 75x38mm rafters just to be on the safe side, and because it really doesn't cost much or take much time if you then only mount to every other rafter anyway.

I don't know if it's really necessary or not, but it gives me peace of mind, so it's worth it from that aspect alone, as I know that the roof bolts don't comply with the 4xd rule on those rafters, although I've also seen no sign of them splitting the rafters.

 

[solarsavings]

The euro codes are design guides not robust documents so you do not have to comply with them!!!!. I have built a lot of cut roofs and put up more than enough trussed roofs to worry about euro code 5. You thinks its quicker/better to add scabs (battens) to the sides of the top cord to improve the fixing or to add extra roof hooks to resist tear out of the screws. Me, I don't bother with scabs unless it's in an exposed location but we always double up on roof hooks at either side of the array.

 

[Gavin A]

The euro codes are design guides not robust documents so you do not have to comply with them!!!!. I have built a lot of cut roofs and put up more than enough trussed roofs to worry about euro code 5. You thinks its quicker/better to add scabs (battens) to the sides of the top cord to improve the fixing or to add extra roof hooks to resist tear out of the screws. Me, I don't bother with scabs unless it's in an exposed location but we always double up on roof hooks at either side of the array.

Good to know you also view it as a guide rather than THE LAW, but it costs very little, doesn't take long, and we had been doing this instead of paying structural engineers fees and spending sodding hours trying to fill in the forms for the online guys, so I figured if we just added an extra rafter instead that'd guarantee there weren't going to be any problems, and I trust an extra piece of wood more than an SE I've never met tbh.

It's really a stop gap solution until I can get an SE to sign off on standard truss constructions.

 

[solarsavings]

For about £140 you can become a member of TRADA and get access to all their design guides, calculators, forum etc. When you have some spare time ;-) take a look at how trussed roofs work and why adding scabs can (not will) cause more problems than they cure.

 

[solarsavings]

Have a look here https://www.trada.co.uk/membership/prof_wizard

http://www.trada.co.uk/downloads/membership/GettingthemostfromyourTRADAMembership.pdf

 

[SolarCity]

Thanks for the input fellas.

Gavin, how do you fix your extra timbers? We bolt them together and it takes a good couple of hours to do at least. This often pushes us into a second day.

SS, why does adding scabs to trusses cause problems? It weakens the structure?

 

[Gavin A]

using the same 6.3mm self tapping roof bolts we use for screwing the brackets in.

Our SE approved this method for previous strengthening work we've done for purlins, so it should be fine for this purpose as long as you're screwing them in at regular intervals.