What difference does it make if your 2x4's are flat or on edge. Posted 13:19 (#1103083 - in reply to #1102865) Subject: Re: Building question-roof perlings flat or on edge The flush mounted purlins with joist hangers also help with bird problems. Posted 13:13 (#1103074 - in reply to #1102665) Subject: Re: Building question-roof perlings flat or on edge Joist hangers are made for 2x4 and hold the ends a lot better than toe nailed. A 2x4 on edge has relative bending strength 64.3. the proportional to the width and to the height cubed.Ī 2x4 flat has relative bending strength 11.8. Posted 12:39 (#1103030 - in reply to #1102665) Subject: RE: bending strengthīending strength is proportional to bhhh e.g. Flat perlins make roof into good sail too in high winds.īest materials in the world are worth very little if the build quality is poor. If 'everybody' is laying those purlins flat, it's no wonder snowloads are bringing down the barns. Posted 10:12 (#1102865 - in reply to #1102710) Subject: RE: Building question-roof perlings flat or on edge Use long ringshank nail into truss and also nail 2x4's together on joint.

Use 18' or even 20' 2x4's on edge so they overlap 1' to2' every 4th truss. Posted 09:04 (#1102758 - in reply to #1102665) Subject: RE: Building question-roof perlings flat or on edge Better yet would be to used the galvanized steel brackets so they could be screwed between the trusses, that would make the roof alot stronger than just nailing 16' long 2x4s on top of the trusses like most barns use. On edge and I'd cut them to 46 3/8' long and toe nail them in between the trusses instead of just nailing them to the top. Posted 08:38 (#1102710 - in reply to #1102665) Subject: RE: Building question-roof perlings flat or on edge Never saw them laid flat around here always upright, always looked like flat would be easy way but afraid they would bow over time but 4 ft. Posted 08:28 (#1102694 - in reply to #1102665) Subject: Re: Building question-roof perlings flat or on edge Around here I see a bigger space between rafter/truss, and they are always on edge. How far apart are the purlins? You get a fair bit of snow in SD at times I'd think, but on 4 foot centers it probably does work either way. Posted 08:20 (#1102679 - in reply to #1102665) Subject: Re: Building question-roof perlings flat or on edge

He just said each person wants them different. What way would give more strength in the roof? I could see it would be a little easier to screw down with the 2x4's flat but I would think there would be more strength on edge. Posted 08:14 (#1102665) Subject: Building question-roof perlings flat or on edgeīuilder said I could do it either way. ( logon | register )īuilding question-roof perlings flat or on edge Jump to page : 1 Now viewing page 1

Purlin and rafter spacing 12 metal roof