Author Topic: Deck ledger / sheathing installation order  (Read 7408 times)

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MarkAndDebbie

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Deck ledger / sheathing installation order
« on: November 07, 2007, 02:46:32 PM »
My shed is almost done and I'm looking toward the cabin - doing the sketchup.

I would like to build in this order
1. block crawlspace (done) (4' high)
2. cabin floor (advantec on GP I-beams)
3. GP Fiberstrong rimboard (flush vertically with block)
3. Deck Ledger (through bolted ~6" down from Cabin floor)
4. Vinal flashing attached to top of cabin floor continuing to bottom of ledger.
5. deck joist hangers
6. rest of deck
7. walls
8. 15# felt on walls down to top of decking boards.

I would like to build the deck before the walls to give me more room to move, but I am not sure about the flashing/sheathing. It would be too late to sheath all the way down to the bottom of the rimboard - which is what I would do if I were not doing the deck first.

If it's ok to do this way, how far should the sheathing come down? felt? Should I try to "tuck the felt under"?

Thanks guys!

Offline Redoverfarm

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Re: Deck ledger / sheathing installation order
« Reply #1 on: November 07, 2007, 03:28:30 PM »
Mark just remember that water loves gravity so design and build to prevent it from ruining everything.  I would not install the sheeting all the way to the bottom of the rim joist as there would be the potential of rot. I also would not take it all the way down to the deck top but hold it 1/2" above the deck so that it would not wick the water. If using OSB it can really act like a sponge.  

I see that you are using vinyle flashing. Good Move as the pressure treated lumber will eat up aluminum. Some still use but place a layer of felt or ice guard between the two.

You mentioned tucking the felt. I hope you meant under the deck and not under the wall partition. What moisture would follow this down to the inside. There is nothing to say you can't run it to the bottom of your rim joist maybe a little further to insure it doesn't stop at the block top and run back in between the block and the rim joist.

Most deck builders I have talked to usually suggest a free standing deck seperated from the house or use vinyle blocks to allow water to run between the house and the ledger board to avoid rotten sills.

Offline MountainDon

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Re: Deck ledger / sheathing installation order
« Reply #2 on: November 07, 2007, 04:22:00 PM »
Well, as John said above and as PEG has been heard to say more than once "think like water".

I was not familiar with FiberStrong rim boards so I looked it up. I see it's an OSB-like product. I'm not sure I'd want to use it for my rims any more than I'm likely to use OSB for my floor sheathing. OMMV.

In one place   http://products.construction.com/portal/server.pt?open=512&objID=204&PageID=24436&cached=true&mode=2&src=P&companyId=NST24234&celId=NST783
there is a statement "FiberStrong® Rim Board has been tested and approved as a rim board and starter joist by APA-EWS. FiberStrong® Rim Board has not been evaluated as a structural joist, rafter, header or ledger. " And yet they illustrate a method how to properly attach a ledger to it. Confuses me.

Seems to me IF it ever got wet and began its expanding and delaminating trick like OSB it would be a recipe for trouble.

Tucking the felt under would be a bad idea, if you mean to tuck it under the backside of the sheathing. IMO, that could lead to capillary wicking of moisture up behind the sheathing, possibly soaking into that FiberStrong stuff as well.

I'm not sure why you want to put the flashing over the ledger. With the flashing behind the ledger as shown below, any water will be kept away from the inside part of the house/floor. IMO, the ledger belongs "outside" and the flashing should have as few perforations as possible.

IF you were to do it your way you'd want the sheathing to extend down past the wall sill plate to floor joint to help keep water out of that area. A drip edge at the lower edge of the sheathing, then your building felt/wrap. Finally your finish wall material.


« Last Edit: November 07, 2007, 04:52:10 PM by MountainDon »
Just because something has been done and has not failed, doesn’t mean it is good design.

Offline Redoverfarm

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Re: Deck ledger / sheathing installation order
« Reply #3 on: November 07, 2007, 07:19:52 PM »
Don I think the illustration to the right although for a two story would be the correct way. It shows SS washers as spacers to allow water to drop between the PT ledger and flashing to a drip edge.  I am a little surprised that they show metal flashing on the left side against the PT lumber.  Although they didn't indicate what type of metal. Copper is OK with PT but aluminum is not. But who can afford copper flashing now days.  I wonder why he indicated that he could not extend sheeting at this point to cover the rim joist unless he has installed a termite shield?

Offline MountainDon

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Re: Deck ledger / sheathing installation order
« Reply #4 on: November 07, 2007, 08:02:28 PM »
I wonder why PT is specified for the ledger? Unless it's right close t0 ground level it's not really necessary in many places. Is the entire deck going to be PT? Of course the necessity may vary depending on weather conditions.  :-/  I'm not really sure of the necessity of using washers/spacers as shown. The rest of the deck is exposed?  :-/

Here's a diagram I didn't take time to find earlier. It's basically that 2 story reduced to a single floor.



Mark didn't come right out and state the reasons why he wanted to do this in the order he presented, although I can imagine that if there is sloping ground around this side of the building it would be nice to have a level deck to work up from. That would be the situation where I'm going to be building.

However, many of my past great ideas for doing things in an unconventional manner/order have more often than not revealed shortcomings in my thought processes. In the end it may simply not be good building practice to alter the "conventional"order of assembly. Let's what other thoughts there are while we wait for Paul [PEG] to stop by.
« Last Edit: November 07, 2007, 08:03:16 PM by MountainDon »
Just because something has been done and has not failed, doesn’t mean it is good design.

Offline Redoverfarm

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Re: Deck ledger / sheathing installation order
« Reply #5 on: November 08, 2007, 02:38:02 AM »
Don I think the washers are to allow a channel for water to pass and not lay trapped between the PT and rim joist.  

Offline MarkAndDebbie

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Re: Deck ledger / sheathing installation order
« Reply #6 on: November 08, 2007, 03:07:47 AM »


Good picture. I remember reading that.

Rim Board- I would use wood, but the I-beams are 11 7/8ths not 11.5. I could rip 3/4 inch plywood, but that sounds like a pain and I don't know that it would be stronger. I plan on blocking on the inside with wood although they say I don't need to.

PT - yes the entire deck will be PT. It is a deck - not a porch (at least on the side we're talking about).

Termite shield - I am putting one (actually the same vinyl stuff) over the block - under the pt sill plate. Green in the diagram.

Scale of diagram - I didn't change the scale, but the rim is ~12" - ledger half way down. It's a 10" ledger - so it would come down lower on the block by ~3".

Spacing the ledger out - I don't mind doing the washers to leave a gap. That sounds easier than forming the vinyl around ledger tight to the house.

Timing problem - You are right Don. I wanted to finish the deck before putting up the walls to give myself more flat room to work. Remember my block wall is 4' + 1' joist - so just climbing up and down would be work. Also gives me a good place to keep materials out of the muck. So this is why I indicated I couldn't bring the sheathing all the way down to the block - the bolts holding the ledger on would be in the way. This was sort of the crux of the questions. I can do the wall first and sheath all the way down, but if the alternative is OK - then I'd do that.

tucking - I am going to try the thick sleepers (I think Don posted a link that suggested 3/8's - I'll have to go back an search)  over the OSB - then my T1-11. With that gap I was not sure I would need the z-strip in the diagram. I though I might should run the felt down the OSB -> under the bottom edge of the OSB -> over the vertical flashing between the ledger and vinyl (obviously I could only go to the bolt). But if that would wick - that would be BAD.

So is there a better way to put the deck on early and flash (red part)?

I am OK with "Mark, just do the walls first." Just a thought experiment at this point.

Thanks!

Offline Redoverfarm

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Re: Deck ledger / sheathing installation order
« Reply #7 on: November 08, 2007, 04:23:12 AM »
I think the reason for the Z strip is that it is a little more permanent than felt. Felt has a tendency to tear off and if exposed to the elements(wind, air and etc.) it usually becomes brittle.

As for blocking you could use solid vinyle cut 2-4" wide to bolt through when putting the ledger.

As for the bolts and being in the way. What type are you using?  Lag, carriage or other?  A spade bit would recess the head into the ledger before drilling the primary hole would make it concealed or flush. Either way washers should be used in addition to the bolts to give it more holding strength.

I hope you don't think I am nitpicking your plans but I would hate to see in 10 years that you would have to replace structural members because of rot.  The time spent now is only 1/3 of the time would would have to spend repairing or replacing.  That time could be better spent adding on that addition that you haven't thought about yet.

Offline MarkAndDebbie

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Re: Deck ledger / sheathing installation order
« Reply #8 on: November 08, 2007, 11:30:33 AM »
Z-Strip it is.

My plan was hex head between the joists (16" oc). So the head is not the part in the way. I meant I couldn't put the flashing (red in diagram) after the deck was up. The middle of the bolt / washers / solid vinyl would be in the way.

No! you're not nitpicking. I asked the questions because I want the answers. Free advice is much cheaper than mistakes :) Watch for my "lessons learned" post coming soon to the Projects section and you'll see I should have asked more questions ;)

Offline MountainDon

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Re: Deck ledger / sheathing installation order
« Reply #9 on: November 08, 2007, 02:04:24 PM »
your modified illustration... red line for flashing...  That would seem to be a viable alternative method, with the wall sheathing, felt, z strip etc installed later and extended down past where the flashing takes a right angle bend.

sleepers / furring strips.... the 3/8" thickness/spacing  comes from physics. The physics of water states that a gap of 3/8" between surfaces is sufficient to totally prevent capillary action and it is far enough to break the surface tension of any water running down so it will not bridge the gap. Larger is fine.

ledger bolts... if you used carriage bolts with the nuts on the inside, under the floor the bolts would then only leave a small rounded head to be "in the way"   :-/  But doing it "the red line way" the bolt choice won't matter.

z-strip.... much more permanent like John pointed out.

blocking on the inside for bolts...  or large diameter washers, like fender washers would help with extra pull through resistance. 4" x 4" steel plates if you have access to scraps would be good too.

You did a nice job of modifying/editting my drawing   :)  Be sure to bring the flashing edge below the point of the lowest wood.

« Last Edit: November 08, 2007, 02:08:27 PM by MountainDon »
Just because something has been done and has not failed, doesn’t mean it is good design.

Offline Redoverfarm

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Re: Deck ledger / sheathing installation order
« Reply #10 on: November 08, 2007, 03:58:50 PM »
Mark just as a after tought. Are you planning on sheeting the floor before installing the deck?  If so what would prevent you from putting the vinyle flashing on as you indicated in Dons (pretty) picture before attaching the ledger. That way the bolts would not interfere with the flashing installation.  This would also not prohibit you from sitting your wall partitions on top as you indicate in the red highlighted area.

I have never used vinyle flashing before. How easy is it to break(bend) 90's and the like?

Offline MarkAndDebbie

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Re: Deck ledger / sheathing installation order
« Reply #11 on: November 08, 2007, 04:41:15 PM »
Yes Redoverfarm - after our discussion here, that is my plan.

The vinyl cuts easily with a packing knife. My previous attempt at bending did not yield good results, but that was due to my method I think. I put it over a 2x4 and ran my hammer (when the hammer is in your hand...) down both edges. It bent enough to install, but I'll work at it with more conviction for the house. I imagine that a little heat would really help and a sharper corner than a 2x.
« Last Edit: November 08, 2007, 04:42:23 PM by MarkAndDebbie »

Offline desdawg

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Re: Deck ledger / sheathing installation order
« Reply #12 on: November 09, 2007, 03:27:41 AM »
Maybe an old blow dryer for drying hair would help if it wouldn't be too slow.
I have done so much with so little for so long that today I can do almost anything with absolutely nothing.

Offline glenn kangiser

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Re: Deck ledger / sheathing installation order
« Reply #13 on: November 09, 2007, 07:16:41 AM »
The small electric heat guns work great for bending plastic - careful - they can burn it.
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Offline MarkAndDebbie

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Re: Deck ledger / sheathing installation order
« Reply #14 on: November 09, 2007, 04:37:39 PM »
I have a heat gun (something Debbie uses for calligraphy maybe?). However, I think that an old iron with some buffer in between might be best. It would double as the pressure.  

Offline Redoverfarm

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Re: Deck ledger / sheathing installation order
« Reply #15 on: November 09, 2007, 04:43:36 PM »
Mark if you can't get it worked out breaking the vinyle you might consider a two piece flashing.  You coule use metal for the top portion that could be easily formed and allow it to drop down 1-2" then insert your vinyle up behind it. As long as the metal is not behind the PT lumber you will be OK.  I believe in an earlier post you stated that the deck was going to be dropped down.

Offline MarkAndDebbie

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Re: Deck ledger / sheathing installation order
« Reply #16 on: November 10, 2007, 01:17:18 AM »
Quote
Mark if you can't get it worked out breaking the vinyle you might consider a two piece flashing.  You coule use metal for the top portion that could be easily formed and allow it to drop down 1-2" then insert your vinyle up behind it. As long as the metal is not behind the PT lumber you will be OK.  I believe in an earlier post you stated that the deck was going to be dropped down.

Thanks. That might be easier. There will be at least 4" for the transition.

I may not have been clear earlier - the vinyl is EASY to work with. I was unhappy with my slipshod work not the vinyl. I can bend it with my hands - it will not break. It was just not as clean a line (sort of bumpy and bowed until I nailed something on top of it).

Sorry if I beat the dead horse. I didn't want the vinyl getting a bad name. I think it may have some other advantages as well (less expansion than aluminum).

Offline MountainDon

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Re: Deck ledger / sheathing installation order
« Reply #17 on: November 10, 2007, 07:00:15 AM »
HD has a tool for bending a lip in sheet metal flashing. Should be available other places too. Maybe you could check that out... see if it'll work with the vinyl. You could also try using sections of steel... clamp one on each side of the vinyl and bend a little, move it along, repeat, repeat. It's not going to be easy to achieve a machine bent appear doing it by hand. Been there, done that.

You might look into metal roofing drip edge. Available in many colors from metal roofing specialists. HD carries maybe 5 or six colors. My local Metal Mart carries a dozen or more. If you ran the vinyl top to bottom of the rimboard/ledger board distance and capped it with the drip edge that would achieve your desired result.

Just because something has been done and has not failed, doesn’t mean it is good design.

 

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