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bt_1999_66

04:03AM | 03/18/03
Member Since: 03/17/03
5 lifetime posts
Bvtools
Hello Everyone...!

I am new to this BB and had a question. I just finished building an approx. 470 sq. ft. covered Deck. This was built with No. 2 Pressure treated southern pine. I used screws from top to bottom. The felt and the shilgles on the roof where the only nails used. The roof is supported by a total of 8 4"x4"s and on the center I used a 4"x6" for heavy support and stability. These have a 24" deep concrete base with a bell shape, 18" at the top of the base and 20-24" bottom concrete base. I copnsider this to be pretty solid. Now that I am finished I estimate to weight of the roof to be close to 2300 lbs. With this said I now notice that when I check the roof to see if it moves/sway when I try to pull on a post it does move ever so slightly, very slowly and for approx 3-4 seconds it continues to move.

The questions are...

Is this normal...?

Is the slight moving/swaying, and the fact that it has 2300 lbs of weight something that I should be concerned with...?

Please advise and thank you...!

rpxlpx

04:25AM | 03/18/03
Member Since: 03/13/00
1675 lifetime posts
When you say it continues to move, do you mean in one direction, or back and forth?

bt_1999_66

04:32AM | 03/18/03
Member Since: 03/17/03
5 lifetime posts
It continues to move back and forth for a few seconds and eventally stops.

Also, this should help you visualize it better.

It's a flat roof, not gable. The tall side of the deck is approx. 10.5' top to bottom, the short side is approx 8' top to bottom. It has no knee braces yet, but I have been told by a friend that this should aliviate this somewhat...

Benny

[This message has been edited by bt_1999_66 (edited March 18, 2003).]

Altereagle

06:47AM | 03/18/03
Member Since: 12/27/02
543 lifetime posts
This sounds like a problem for wind shear, imagine if you can simple push it and it moves what wind will do.

Couple of questions...
1. Is it free standing or attached
2. Is the roof a gable, what is the pitch
3. How many 4x4 braces do you now have running from post to post, and in which directions.
4. What is the on center & span of the rafters & size of joists or collar ties if you didn't use joists.

I would keep everyone off of the deck just for now. If you have a friend that is a carpenter or contractor you may want to have him/her come over inspect the project.

For a interim fix until you can get the structure repaired properly take 2-2x4 and nail them cross ways onto the end and two sides from the bottom of the 4x4 post to the tops. Use 3 16d in each end & a min. of two at the apex. The shear of the nails in the apex is what will give the structure the strength until you get it fixed.

If I had to take a wild guess I would say you'll need collar ties a 1/2 ply shear panel gable and braces at the posts through bolted.

A professional on site would be the best if you can get that though.


Altereagle

06:59AM | 03/18/03
Member Since: 12/27/02
543 lifetime posts
By the way... you mention using screws. That is a common mistake for beginners to assume that a screw is better than a nail.

That isn't so, nails have engineer shear strength required for stuctures. Screws have good holding power for the most part but in tension, that's good once you have a slolid structure.. for instance a deck.

You want the approx. 2500# shear of a galv 16d nail at specified connections #10 shanks at the steel hangers etc. where once the framing is completed screwing down the deck for tension.

A building with studs screwed to the plates would not pass inspection for another example. So there is a proper application of fasteners, and it's actually part of the code.

bt_1999_66

07:08AM | 03/18/03
Member Since: 03/17/03
5 lifetime posts
Try the link below for some pics....

As a beginner, I did not understand most of the terms you have just mentioned. As far as "simply pushing it" no, I have to try and rock it somewhat for it to do this. As a matter of fact, I just returned from lunch and there are thunderstorms here in Houston. I just saw it take approx. 30-40 mile an hour gusts and it did not move....

Take a look at these pics and you may see for yourself as to the actual construction method that I used. These where taken prior to the plywood, felt and shingle installation which now has been completed.
http://photos.yahoo.com/bc/bt_1999_66/lst?.dir=/Deck+March+11

Any comments are welcome....

Altereagle

05:55AM | 03/19/03
Member Since: 12/27/02
543 lifetime posts
Diagonally brace from the 4x4 post will help, but I don't recognize that building technique so I wouldn't know where to place them. It wasn't inspected was it.
It looks in the picture like you've used 1x on edge to a hanger in the center of the 4x4 in some places? Hopefully they are 2x..
I think it will take someone on site to help you out, but it shouldn't move at all in any way in any direction so go for that. The good news is the house will block a lot of the wind.
Thanks for the pics, really tells the full story.

bt_1999_66

07:37AM | 03/19/03
Member Since: 03/17/03
5 lifetime posts
Thanks for your response....

I have used 2"x6" throughout, other than the 2"x8"'s supporting the rafters....

Again, Thanks...!

Piffin

05:52PM | 03/19/03
Member Since: 11/06/02
1281 lifetime posts
Here are the problems as I see from the pictures,

The outside 2x8 that supports all the rafters is nopt bearing directly on the 4x4, meaning that the few nails holding the 2x8 up are the only thing holding all the weigt of the roof.
Ooops - the screws holding...
You don't mention what kind of screws you used. A common mistake is to use drywall screws which are terribly brittle. They are not structural in any way and will snap off at the merest whisper. In the paper face of drywall, they don't meet resistance but when torsioned up tighjt against a wood surface and then loadedd with weight, they are a failure in the making. deck screws are somewhat better but still not designed for shear strength in an aplication like this. You need additional hardware or lag screws.

All joist hangers come with specific instructions what kind of nails to use. If you used screws instead, you have bought trouble. Most hangers require a special case hardened nail. Some are designed to work with 8d nails or 10d nails such as Simpson LUS hangers.

It apears that you have no knee braces or kickers to prevent sway. If the unit were attached directly to the house, the plywood sheathing, when nailed on, will give diagonal bracing to the top surface plane but wioll not stop the bending of the 4x4 posts.

If, as appears, your plywood is not on yet, you will gain some solidity when you install it, but you still need to either atach to the house, or put in diagonal knee braces to the posts.

Your work looks very neat and well done with the exception of the above mentioned items.
Good luck


bt_1999_66

01:37AM | 03/20/03
Member Since: 03/17/03
5 lifetime posts
Regarding the screws that I used, yes these are Galvanized Deck Screws.

And yes the Plywood is on together with the felt and shingles, which added some stability.

My next was to put the "knee braces" which I think will comletly solve the "sway" issue. I will install knee braces on all the posts, including the middle.

Thank you for your suggestions, and thanks for the comments about the work looking neat and well done, thus I had never, ever done anything like this.

Regards,

Ben

[This message has been edited by bt_1999_66 (edited March 20, 2003).]

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