Weakened roof trusses

[richchad]

Thanks for that big-all,

It may be difficult to fit ply past the bottom screws as they are close to horizontal ceiling joist.

Just wondering if it would be stronger to fit two extra braces as in this rough drawing... would need to fit them in between existing and fix with plates I guess?

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[big-all]

if you get to the end just make sure on one side at least top and bottom [both if possible] that the ply overlaps the other timbers with at least 4 screw in each timber possibly needing to drill a pilot hole through the plates but just the plate lol

use pvu foaming glue and dont force the ply to tight to the wood if the bracket holds it off as this stuff fills 5mm gaps easily
http://www.toolstation.com/documents/search/index.html?searchstr= 93568

 

[richchad]

I think I may have a problem getting plywood the length of the whole truss, 3m+, wondered if I should just put ply each side of where screws are fitted in say 500mm lengths rather than one long piece?

As any un-drilled timber should still be as strong as it was originally?

 

[big-all]

yes sorry should have thought off that although you can get 10ft sheets

i tend to go ott so just join the ply mid way between 2 fixings

it probably wont collapse in the next 50 years but i like to be cautious

 

[richchad]

yes sorry should have thought off that although you can get 10ft sheets

i tend to go ott so just join the ply mid way between 2 fixings

it probably wont collapse in the next 50 years but i like to be cautious

Right, will get some sheet ply already cut into 70mm wide strips and go with that.

Just a quick question, what size and type of screws, something like No5 x 40mm countersunk goldscrews and any cheap PVA wood glue I guess?

 

[big-all]

these with the glue i mentioned above 3.5mm pilot no need to countersink just screw till the head is on the surface or if you do countersink go for between 0 and 1mm depth only
http://www.toolstation.com/shop/Scr...Countersunk+Pozi+Screw+8x134/d90/sd850/p72945

3 or 4 beads 1mm wide at 14-28-42-56mm or 17-34-52mm along the length

 

[richchad]

these with the glue i mentioned above 3.5mm pilot no need to countersink just screw till the head is on the surface or if you do countersink go for between 0 and 1mm depth only
http://www.toolstation.com/shop/Scr...Countersunk+Pozi+Screw+8x134/d90/sd850/p72945

3 or 4 beads 1mm wide at 14-28-42-56mm or 17-34-52mm along the length

Okay, thanks for that, might get 1"1/2 screws as truss width is only 35mm.

Thanks for your help......

 

[big-all]

yep they will be fine although you have 12mm 35mm 12mm

 

[WestmidsChippy]

What makes you so sure that they are structurally weaker now than before the panels were fitted?

I would think the risk is low but what the risk is I am not sure, are the timbers going to suddenly give way with the weight of the roof or will they just bend over time?

Just wanted to find an easy way to be sure it is safe I guess.

I wouldnt worry at all about the roof giving way or even sagging in anytime soon. I would be worried if i were you though if you still living in the same place 20 years from now.

will remind you of being at a beach when you look down your street