I just got a job that requires an 8X7ft (1-4x8 & 1-3x8) PCV board mounted between two 4X4in pieces of treated lumber.
I was going to use 12ft 4x4's buried 4 foot into the ground and use 3-2x4's to back the PCV to help with flexing.
My concern is this enough to support the weight of this sign...
any thoughts or ideas??
Attached is a back view of the idea...
Thanks in advance Posted by Chuck Churchill (Member # 68) on :
How thick is the PVC? It seems to me that all but the thickest PVC might bend or crack over that top cross support in high winds.
I would be more inclined to use a composite of aluminum/PVC/aluminum. A long time go when we started our sign business I made a sign similar to this (but smaller) out of 3mm PVC. It lasted about two weeks before the cold cracked it and the wind busted it up.
Posted by Dave Sherby (Member # 698) on :
I'm not a fan of PVC but I live in cold climate. Only the thickest PVC might work here. If you are using thick PVC which I assume you are if you are concerned about weight, it might withstand the cold in your area and not break.. My concern with your layout is the 4x4's. Eight foot tall 4x4's are going to look like skinny little stilts on a sign that high. Plus 4x4's have very little rot protection and will have a tendency to warp badly. I'd go with 6x6's, and they will take the weight. I'd also use white wood 2 x 6's instead of 2x4's for the cross members, and prime and paint them. No need for treated wood above ground if you seal them up. Again, less warpage.
Posted by David Macomber (Member # 10854) on :
Thanks guys. These are great suggestions. This is the first large sign I've ever done so I am really going at it blind right now. So, every little bit helps...
Keep em coming. Posted by Doug Allan (Member # 2247) on :
drawing to scale helps visualize your end result. I agree with dave that the posts will look skinny, but if it's just a billboard type thing, the asthetics of the posts are not as critical. if this will be someone's business identity, there is a lot you could do to improve it.
As far as durability, I wouldn't use PVC, but i believe 4x4's and 2x4's would be sufficient. I would use 1/2" MDO plywood, and to get my seam in the center, i would cut 2 sheets to 4x7. I would also use 4 cross pieces, & set my posts 6 feet apart.
Burying 4' is not easy around here.. but we don't have frost, so I've settled for 3' in good solid (not sandy) soil. I'll add diagonal bracing at times.
Here is the drawing done to scale:
Posted by Dale Feicke (Member # 767) on :
I think I'd prefer to do MDO plywood over PVC too.
But if you have to use PVC, use your pole set-up, but use 6X6's for the uprights, and use Doug's crossbar setup, with 2X4's near the top and bottom of the PVC, for better support.
Posted by Gerald Lauze' (Member # 6443) on :
One more hand up for MDO. You can get the sheets preprimed and even pre-painted..white only.
G
Posted by Chuck Churchill (Member # 68) on :
If you switch to MDO be sure to paint it real good. That white coat they put on it is meant to be a primer coat. A couple of years facing South or West and it will turn to chalk and fall off. If you go with a aluminium/PVC composite (aka Dibond, Alucabond, and a lot of other "bonds") you can get it in primary colours ready to stick on vinyl or paint images. Saves a big substrate preparation step (your time and money).
Posted by Sam Staffan (Member # 4552) on :
Hello David,
All above have good suggestions on the faces. There are great products to use MDO, alumalite, Dibond etc, that will probably work better than the PVC.
But back to the question of what size posts to use.
I like your sketch they look balanced to the size sign your showing.
Try drawing your sketch to scale and I think you will get better perspectives on what sizes will work best.
Like I said I like yours, but I put in into scale (and I think Doug did too) just to show you what 4x4's and 2x4's would look like.
I think it will help you in the long run for great layouts and for what products you can use efficiently cosy wise to do the projects.
Your posts when brought up to a close scale lay out at 127" x 7". an odd size unless you plan of boxing the posts to get that size. See what I mean on costs?.
Any assistants needed give a ring I am just not a good nor fast typer.
Posted by David Macomber (Member # 10854) on :
These posts are such a great help. You've all saved me alot of time, money and embarrassment.
![[Smile]](smile.gif)
