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colaminecanary 07-30-2007 10:59 AM

Deck ledger/carriage bolt question
Hey there,
I'm looking for some advice on attaching a ledger board to our house.

First of all, the house is double-brick construction and currently has a small deck on the second level (rear). The existing deck's ledger appears to be properly bolted through the bricks and the joist. We are currently remodeling the main floor bathroom which is at the back of the house. Consequently, we have access to the rear joist through the yet-to-be-finished bathroom ceiling.

Eventually (within a year or two) we plan to rebuild and widen the existing deck. So we have decided that now would be a good time to attach the ledger board since we have access to the appropriate space inside the house. If we wait, we'll have to tear into the ceiling again later.

Sorry for the long intro... anyways, we bought the longest carriage bolts we could (12"), however they are about an inch short. So we have to go somewhere to find 14" bolts. The double brick is very thick and the joist is 3" instead of 2", plus a gap between the bricks and joist. But here is what I'm struggling with... We were thinking that the bolts should be fed from the inside out, with the nuts on the outside. When we feed the bolts we plan to use masonry-to-metal concrete filler in the bolt holes so that they will be permanently attached to the house. But the joist spacing inside is 10".

How are we supposed to feed the bolts from the inside out when the space between the joists is 4" less than the length of the bolts? All references I have seen to using carriage bolts has them fed from the inside out. Should we forget that and feed them from the outside in? The problem with that then is if the ledger needs to be changed, all of the bolts will need to come out whereas if we put them inside-out, presumably we could reuse those bolts if we ever needed to change the ledger doe to rot or anything like that.

Or should we forget the bolts and use lag screws? the inner joist is certainly hefty enough to take them. I am quite certain that bolts are the proper code just about everywhere these days though.

Thanks in advance for any advice!

concretemasonry 07-30-2007 11:10 AM

Have you considered a free-standing deck? It eliminates the structural and leakage problems associated with ledgers. Many deck designers will rarely do a deck with a ledger for those reasons.

In many areas, lag screws are not permitted. All screws and bolts must be able to resist the corrosive effects of the treated wood.

I did not see any mention of flashing. You cannot install a ledger with carriage bolts or lag screws without it.

colaminecanary 07-30-2007 11:33 AM

I definitely would prefer to use the bolts and not screws, and I am quite sure that the code requires it.

I spoke with the "experts" at the building centre regarding flashing and they told me that their design guidelines only require flashing for installation against siding and not against brick. I was surprised to hear that myself. But on the other hand, I can't see an advantage to flashing when the wood abuts the brick. With siding, it makes sense to me that the flashing goes under the flap of siding above and gives the water a path to follow. Against brick, you either have to caulk along the top of the flashing and pray, or caulk along the top of the ledger itself and pray.

Actually, my opinion is that the best thing we can do is throw a few washers between the ledger and the brick so that the wood is a few mm off the brick surface and there will be nowhere for water to sit and rot the ledger from the backside-out.

I am reluctant to design for a freestanding deck. The house is a serious structure that I think we should take advantage of. This thing was built in the heydey of real construction. The bricks are structural, not decorative and are fully doubled (8 inches thick maybe?) and the interior joist is 3 inches thick.

To me, the only cause for worry from attaching to the house is the possibility of water getting into the walls through the bolt holes. To avoid this, we plan to completely fill the holes with (I can't remember the name of the product, but it is meant to bond metal to brick - it is essentially concrete) before putting the bolts through.

I have read lots of opinions that ledger boards are a bad idea, but its seems mostly to stem from the troubles associated with rotting wood, and mostly when a deck is bolted to a framed house with siding, or with veneer bricks. Am I wrong in thinking that bolting a ledger to an actual brick structure is more feasible than when you are dealing with newer homes and flimsy siding etc?

edit to add:
This is a second level deck, we are talking 15 feet up. Building freestanding at that height opens a whole new can of structural worms, no?

Clutchcargo 07-30-2007 12:24 PM

63 Attachment(s)

Originally Posted by concretemasonry (Post 55239)
In many areas, lag screws are not permitted. All screws and bolts must be able to resist the corrosive effects of the treated wood.

Galvanized lag screws wouldn't work for this application?

warnerww 07-30-2007 01:45 PM

If you can't find bolts long enough try using all thread then you can put a washer and a nut on the inside and outside.

Dansbell 07-30-2007 01:48 PM

It sound to me like you have a solid wall to attach to. I have epoxied rods into block walls for attaching a ledger beam for a roof. I don't see why you couldn't do something like that here. you would drill your bolt hole 8 or 10 inches deep and epoxy your stud into the wall. You could also use a wedge anchor to attach the ledger. That is unless your building department has specified through bolts. You may ask how they feel about wedge anchors for your application.

coalminecanary 07-30-2007 02:07 PM

Thanks for the ideas guys. All-thread is a great idea and solves both of my problems -- bolt length and entry-angle from the inside. Dansbell, I am pretty sure local codes require bolt-through even though the wall is solid... probably a "just in case" measure...

coalminecanary 07-30-2007 02:45 PM

Great, I sourced some galvanized rods in 10 foot length so I can cut to desired length and galv-dip the cut ends.

What about the idea of spacing the ledger a few mm off the bricks with extra washers? Good/bad/ugly?

Thanks again!

warnerww 07-30-2007 03:20 PM

The only problem I see with the spacer Idea is that washers will not be big enough to stop the ledger board from rolling or moving a little. I like the idea as long as the all thread coming out of your house is sealed properly. Just not sure a regular round washer would be enough. I would rather see a piece of aluminum or other non corrosive metal cut in a rectangular shape that is as long as the width of you ledger board .

coalminecanary 07-31-2007 07:16 AM

Yes, I am thinking that it might be better to protect the wood from the top and just make sure to pay attention to it. I still don't understand exactly how flashing would work with the ledger against brick. Would it be useful in this application? It fully makes sense to me when combined with siding but how would you seal the top of the flashing piece against the bricks?

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