New Deck question

[beckhamk]

Hi guys - I have a few questions about adding a deck to our cabin.

1) I recently got a black and decker 12 steps to building a deck and it says we can use lag screws or lag bolts.  Which do you prefer any why?  Any reason go with a non-attached ledger and add additional footers/posts to replace attaching to cabin?

2)  We only have house wrap on at this time so no trim or siding yet. Should we place anything at all behind the ledger that would be attached to the rim header joists?  In addition, if we attached the ledger to the cabin should we leave room for the outside corner trim to come down passed the ledger. Or should that trim stop at the ledger and then start down below the botom of the ledger?

3) Which method do you recommend for the post/footers?  put the post in the hole with the concrete around it or poor contrete with a j bolt method?

4) As for pooring the concrete - is there a bad temperature not to poor these?

[Squirl]

4) As for pooring the concrete - is there a bad temperature not to poor these?

Special arrangements usually need to be taken below 40 degrees. Depending on how much colder, sometimes just protecting it from the wind is enough.  Insulation and/or auxiliary heating is recommended when the average temp is below freezing. Add warm, not hot water to the mix.  When I do it with day time temps above freezing and night time below, I prefer to use quick setting concrete, so that most of the strength is set before possible freezing.  Quick setting concrete is made from Type III cement and is not the same as adding calcium hydroxide (aka thermo lube, quick setter, etc.).  It is against code to use calcium hydroxide with rebar. 

It is a pain in the behind to do cement work in the freezing weather.  I wouldn't do it if not necessary.

[MountainDon]

There is a lot of good, up to date (code wise) deck information in the following article. I have no idea how good the B&D book is.

http://www.structural101.com/Support-For-Exterior-Deck.html

and the pertinent IRC sections are... R502.2.2 thru % 502.2.4


Basically, lag bolts with washers and nuts are preferred as they are more secure. But lag screws work if they penetrate into the main member far enough. If you are fastening to a rim joist it is probably not thick enough unless it was designed/built to attach a deck to. Also if that ledger is to attach to a rim joist how is the rim connected to the joist ends? That can also be a failure point. Can the ledger support hold the additional weight of half the deck? Adding a row of piers along the house wall with another farther out does have some advantages.

I can't find another link I had with drawings of proper pier to beam connections. But IIRC it is no longer advised or permitted(/) to place beam on top of pier, or to use 4x4's. I believe 6x6 are used with a saddle (/) notch cut in one side to accept up to a doubled 2x to make a beam (or use a 4x). Then it is through bolted. The bolt keeps the beam in place laterally and the notch supports the weight. The bolt carries no weight at all.

[Redoverfarm]

Hi guys - I have a few questions about adding a deck to our cabin.

1) I recently got a black and decker 12 steps to building a deck and it says we can use lag screws or lag bolts.  Which do you prefer any why?  Any reason go with a non-attached ledger and add additional footers/posts to replace attaching to cabin?

Non attached ledger enables any water or moisture to escape and not rot the ledger and subsequent rim joist(ledger attached to)

2)  We only have house wrap on at this time so no trim or siding yet. Should we place anything at all behind the ledger that would be attached to the rim header joists?  In addition, if we attached the ledger to the cabin should we leave room for the outside corner trim to come down passed the ledger. Or should that trim stop at the ledger and then start down below the botom of the ledger?

I would use a flashing behind the ledger followed by an ice guard or storm guard material.  Metal against PT lumber will corrode and eventually fail unless it is copper ( $$ )  The ice guard/storm guard membrane will break that contact.  You can use plastic wood product as block outs off the rim joist at the location of your anchors which will allow any moisture/water to run between the rim joist and ledger. I would run the siding down to the finished floor allowing at least 1/2 gap between the siding and the deck floor.  You should slip the flashing up under the house wrap at least 6" if possible.

3) Which method do you recommend for the post/footers?  put the post in the hole with the concrete around it or poor contrete with a j bolt method? 

You will need below grade PT lumber if you set the post in the ground.  Others may tend to disagree but I usually just concrete the post in and slope the concrete from the post out to allow drainage away from the post.

4) As for pooring the concrete - is there a bad temperature not to poor these?

Normally concrete will cure/dry within 48 hours.  So unless you are seeing below freezing temps within that 48 hours I would not worry 

[UK4X4]

http://www.awc.org/Publications/DCA/DCA6/DCA6-09.pdf

DEck building guide based on 2009 IRC

Fig 8 is what Don mentions above

[MountainDon]

Thanks UK, that is precisely the article I was thinking of. 

....and for those building without the legal need to follow code; this is one of those things that does make sense to me anyways.

[Don_P]

There are some good visuals on this page, basically a different set of drawings to illustrate DCA6;
http://www.nachi.org/deck-inspections.htm

[beckhamk]

Got a few questions here....

1) When determining the max overhang allowed - i assume this is the Lj/4 calc.  So if a 2x10 max span is 15'  we would use 15/4 = 3.75' max overhang?  If so is that for each side of the overhang or split between the two beams on a free standing deck?

2) If we went with a freestanding deck - how exactly do you attach the rim joist to the joists that are closest to the house?  Would we have to layout the joist and nail the rim joist first and then push back towards the house?

3) Building the beam to sit on the 6x6 notched ledger - Am I correct that I do not want overlapping seams and never have these in between the girder span?  Meaning that I will just double up my 2x material and have the beams simlpe sitting in the middle of the 6x6 ledger bolted and the same with the next build up beam going to the next post?     So for a single 6x6 post i would have the butt ends sitting together on the post with a total of 4 bolts (2 in each of the build up beam ends)?

thanks,

[beckhamk]

I also wanted to get input on the post piers/footings.  I was assuming i would need to use 12" concrete tubes going down below the frostline.  The pdf that was presenter here is saying 20" for  an 8' Lb  and <= 14' Lj span.    Is that really saying i need 20" round concrete tube for this?

[Don_P]

I normally pour a 2' square footing under deck posts. Sonotubes make columns, they are talking about the size of the footings. I do not typically install sonotubes but run the ground contact rated 6x6's down to the footing.

Question #1, you can cantilever l/4 paste either or both of the girders... fig 3 in DCA6
#2, joist hangers
#3, You would prefer to overlap end joints on the girders, this is the reason for the 8' max girder span. For example, the inner girder could start as a 16'er resting on 3 posts while the next ply would start with a 8'er and would splice across the solid 16'er. I have no problem with 2 bolts/post one high left, the other low right even if there is an exposed joint, just connect the plies together well. This is up to interpretation, I like to leave more post.

[MountainDon]

I do not typically install sonotubes but run the ground contact rated 6x6's down to the footing.

Transitioning from a sonotube tp a wood post provides another possible failure point; sometimes called a hinge point.