Hello,
I want to add a deck to my new home (built in 2008). Unfortunately where we need the deck to go there is a 8″x8″x8″ HVAC intake pipe that extends out from the rim board. I am at a lost on how one would go about setting up the framing around said pipe. Any advice would be greatly appreciated.
Nancy
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Replies
nancy
If free standing (posted), keep the beam away from the house, box around the outlet/intake-head off the shorter joist.
If a ledger to house, stop the ledger, pick it up again on the other side of the outlet/intake and do the same-head off the short joist if layout puts it there, otherwise just cross block between 2 joists to carry weight of the decking but allow the outlet/intake to have enough room for it's trouble free operation.
Depends on how you frame it and where exactly the outlet/intake is in relationship to the framing and decking. Also, it matters the configuration of the piping-some exit straight out-others turn down and still others have a dome-exit-in the center-air enters around the perimeter...
You got a picture of the proposed location and the piping?
Here is a picture of the situation. The joists will run perpendicular to the house, so with a bit of planning I could lay it out so the HVAC intake would be in between two joists.
My husband (the engineer) would like the deck to be completly freestanding of the house. I, (the architect) am alright with the house attaching to the rim board because I am more leary of pouring peirs on the disturbed soild near the existing foundation and the added cost of pouring twice the number of piers. He is worried about rotting out the rim board. Thoughts?? Any suggestions to ease this age old battle between the architect and the engineer?
Is that an air intake or an exhaust? In the first case you need to take precautions to prevent it from being blocked, in the second case you need to do that and also take into account that moisture will drip from there.
(Or is it a radon fan, in which case you really don't have to be as careful.)
Where will the deck fall, height wise, relative to the thing?
deck height
currently the deck's ledger will hit right at that intake/exhaust. It is not a radon fan- that vent's though the roof. It goes to our furnace.
I can space the joists so that it will fall between them. When it is all framed in, it will vent/intake under the deck, which will have at least 3' of space between it and the ground.
deck vs hvac intake
Here is a picture of the situation. The joists will run perpendicular to the house, so with a bit of planning I could lay it out so the HVAC intake would be in between two joists.
My husband (the engineer) would like the deck to be completly freestanding of the house. I, (the architect) am alright with the house attaching to the rim board because I am more leary of pouring peirs on the disturbed soild near the existing foundation and the added cost of pouring twice the number of piers. He is worried about rotting out the rim board. Thoughts?? Any suggestions to ease this age old battle between the architect and the engineer?
form after function....
I'm with the engineer on this unless the disturbed soil thing is a major issue
the 8"x8"x8" projection
Retired Mechanical HVAC engineer ... The picture looks like an exhaust/intake for a high efficency warm air furnace or a A.O. Smith Vertex Hot water Heater... If you have either, down load the installation instructions where it can be moved to The directions are simple .. It can go to the side (look for the clearance's) snow height if applicable or it can go thru the roof The contractor used the KISS rule ( shortest distance) Have intalled two of Hi-Eff. units in my daughter's home and have the same termination point as you photo shows ... Look in the basement and see if two PVC pipes are connected to the larger diameter.See attached diagram
8"x8"x8" projection
it is an exhaust/intake for an air furnace. It could be moved to a little further down the wall, but now my engineering husband is now even more unhappy, keeps muttering "More holes" . It would be a two day project to move it- the basement has drywalled ceilings, so it's not a project we would like to do if we don't absolutely have to.
So what kind of clear space do I need to provide around this vent? If I space the joists at 16 oc and had it in between them, the deck would be right above the vent, but it would have at least 3' of clear space underneath the deck. Is this adaquate?
Thank you for your help
Nancy
There's a goofball here that will chide me for suggesting this, but................
contact the hvac installer or the supplier of the equipment (if the info isn't in the instruction manual) and ask them for starters.
Sometimes the simplest answer works.
Best of luck.
By all means ...
By all means, feel free not to answer the question. After all, every furnace manual I ever read came with complete insturctions on how to frame a deck. So I am sure a manual would be very helpful. LOL. And of course consulting and engineer would be great advice, why did I not think of that? LOL
listen........
DoRight wrote:
By all means, feel free not to answer the question. After all, every furnace manual I ever read came with complete insturctions on how to frame a deck. So I am sure a manual would be very helpful. LOL. And of course consulting and engineer would be great advice, why did I not think of that? LOL
There's a few that are getting pretty sick of your BS comments that do absolutely nothing but take up space.
By all means ...
By all means, feel free not to answer the question. After all, every furnace manual I ever read came with complete insturctions on how to frame a deck. So I am sure a manual would be very helpful. LOL. And of course consulting and engineer would be great advice, why did I not think of that? LOL
Ya know, maybe some time with a therapist would help with your mental issues.
What your furnace manual does not tell you how to buiid a deck?
What your furance manual does not tell you how to build a decK?
Of course your could consult an engineer.
I suggest you take your medications on time if you are so sensitive or have no sense of humor. Good Grief.
Get a life.
I don't have a deck, or an engineer or a furnace manual, but I do have a life and a sense of humor, and you're playing along with it. Now take your meds and go to bed.
Calvin's point is that every high-efficiency furnace manual that I've seen (which is admittedly not that many) contains several pages of info and diagrams for how pipes should be routed in various cases, along with clearances that must be maintained. This is a very good source of info on how to correctly deal with the OP's problem, vs just having a bunch of BSing old farts guess at a proper approach.
Instruction manual
I did find the instruction manual and all it says that the "direct vent concentric wall termination needs to be 12" in above grade" Nothing is noted about any other required clear space. I suppose a call into Lennox will be on my Monday to-dos.
Yeah, you really need to find the instructions for the furnace and follow them. In most cases they're quite specific in terms of how you can route the pipes and how far they must be from various house features.
Vent @ Deck
If you simply frame aroung it, snow build up on the deck could now cover / block the vent / intake?
vent @ deck
good point, I will have to take that into consideration being that I am now living in the snow belt.
Combustion air?
Is this a combustion air intake?
combustion air
According to figure 21 in the Lennox manual it is a "direct vent concentric wall termination" it looks like it is venting the exhaust at the end of the vent (the big pipe) while intaking air closer to the wall at the large part of the cone.
The manual doesn't say anyting about required clear space around the vent other then a min 12" above grade.
Clearances
See attached. Judging by dimension M you need to be 12" below the deck.
Thank you!
Thanks Mike
I have that diagram in the manual but it does not have the deck number.
Ok, so I guess I know what I will be redesigning while watching the Football game tomorrow.
Also note that there needs to be 3 feet clearance to an "inside corner". If the vent is behind, eg, a built-in bench, arguably the bench would have to be at least 6 feet wide and 3 feet deep.
Nancy, the image that Mike posted is typical -- there's a lot more info than simply distance above grade.
A mechanical inspection would include wanting to know what the manufacturer lists as appropriate free space around it, as others have suggested. It's simply how these questions are answered and if you were my client it's a no-brainer to get the specs before construction begins.
A two day project to the move the vent is the price to pay for retrofitting a deck after the fact.
As for free standing verses attached, freestanding is better for both the deck and house, the only downside being time and cost. Unless the soil around the house has set for at least a year, the footings for the deck closest to the house will need to be deep enough to reach undisturbed soil, or adjustable post bases should be used to level the deck as the footings sink as the soil settles.
current deck theory
I plan on giving Lennox a call on monday and see what they recomend as free space. Currently I'm thinking of incorporating a built in bench seat that would not have a floor deck below it so I could get the 12" clear space above the vent and would not have to worry about snow pileing up and blocking the vent.
I soil around the house has sat for almost 4 years. It looks like It's coming down to a "six in one hand half dozen in the other" kind of thing in regards to free standing vs attached. In cases like that I usally just call up the inspector and see what he has to say and what he likes. If he's going to give me more problems over one way more then the other then we will go the easier way.
Vent @ Deck
Nancy: Just an aside. Even as an GC / Arch-designer, I have had a hard time talking to the folks at Lennox. If you are not a autherized dealer, they for some reason seem reluctant to give out spec. info. Hope you have better luck.
Good call on contacting your building department regarding the freestanding deck. In some locations they have a printed set of guidelines that, if followed, preclude the need for engineering. In other locations they specifically require an engineer's stamp on a freestanding deck.
If you google free standing deck pdf I believe at least one city's prescribed building guidelines come up to give you an idea of what's typical. There is a good deal of extra wood that goes into it, but 20 years from now you'll benefit from the better water shedding of the free standing deck. Quite honestly if it were my house I'd be comfortable with either since the ledger option is mostly dependant on the method used by the installer and the better it's flashed behind and on top of the ledger the fewer problems you'll have. In fact if it's done correctly there isn't a reason a ledger-type system can't last indefinitely.
If a relative were to hire the job out I'd suggest they go with the free standing if they can afford it since it's more idiot proof.
My personal prefference for flashing a ledger with the type of siding you have is to make a cutout through the siding that's an inch overcut in all directions and slide flat galvanized flashing behind the siding to both sides and up as far as possible, but at least a few inches. If you don't mind the extra cost get a pressure treated ledger suitable for burial, which simply has a higher concentration of the bug-killing stuff in it - it will definitely be a special order.
Use spacers behind the ledger allowing at least 1/4" of airspace - some specs use a number of large washers, while others use 1-1/2" wide steel strap predrilled for the through bolts. Simpson has hot dipped galvanized large square washers that are available off the shelf so that's what I'd normally go with. Two 1/2" hot dipped through bolts every 16" to match the floor joist spacing is what I'd use. On every other floor joist I'd add a simple angle plate through-bolted to both the floor joist and rim joist/ledger combined with another heavy angle on the deck joists) - again simpson heavy angle brackets are available at the big box stores. This locks the floor joists to the ledger as well as almost anything (short of sceismic anchors, which are only slightly moreexpensive). You can buy pre-cut strips or use the thicker ice and water sheild and cut the strips yourself, which is the better option.
I just replaced the top on a deck that wasn't flashed or through-bolted and it pulled away from the rim joist and water rotted the ledger from behind.